Synthesis and characterization of pyrrole-based group 4 PNP pincer complexes

Synthesis and characterization of pyrrole-based group 4 PNP pincer complexes | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Synthesis and characterization of pyrrole-based group 4 PNP pincer complexes Gerald Tomsu, Berthold Stöger, Karl Anton Kirchner This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-3517952/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 09 Feb, 2024 Read the published version in Monatshefte für Chemie - Chemical Monthly → Version 1 posted 3 You are reading this latest preprint version Abstract The synthesis, characterization and reactivity of several group 4 metal complexes featuring a central anionic pyrrole moiety connected via CH 2 linkers to two phosphine donors is described. Treatment of [P(NH)P- i Pr] with [MCl 4 (THF) 2 ] (M = Zr, Hf) in the presence of base yields the dimeric complexes [M(PNP i Pr )(µ-Cl)(Cl) 2 ] 2 featuring two bridging chloride ligands. These complexes react with sodium cyclopentadienyl and SiMe 3 I to give the mononuclear complexes [M(PNP i Pr )(η 5 -Cp)(Cl) 2 ] and [M(PNP iPr )(I) 3 ], respectively. The latter react with MeMgBr to form the trialkyl complexes [M(PNP iPr )(Me) 3 ]. Upon treatment of [Ti(NMe 2 ) 4 ] with [P(NH)P- i Pr] a complex with the general formula [Ti(PNP i Pr )(NMe 2 ) 3 ] is obtained. DFT calculations revealed that the most stable species is [Ti(κ 1 N - PNP i Pr )(NMe 2 ) 3 ] featuring a κ 1 N -bound PNP ligand. When [P(NH)P- i Pr] is reacted with [Ti(NMe 2 ) 4 ] in CH 2 Cl 2 complex [Ti(PNP iPr )(Cl) 2 (NMe 2 )] is formed. Treatment of a solution of [P(NH)P- i Pr] ( 1 ) and [Zr(NMe 2 ) 4 ] with SiMe 3 Br affords the anionic seven-coordinate tetrabromo complex [Zr(PNP i Pr )(Br) 4 ][H 2 NMe 2 ]. The corresponding hafnium complex [Hf(PNP i Pr )(Br) 4 ][H 2 NEt 2 ] is obtained in similar fashion by utilizing [Hf(NEt 2 ) 4 ] as metal precursor. All complexes are characterized by means of NMR spectroscopy. Representative complexes were also characterized by X-ray crystallography. Pincer Complexes Pyrrole Titanium Zirconium Hafnium Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Introduction Among the many types of transition metal complexes found in the chemical literature, pincer complexes play a particular role which have received tremendous attention for many decades [ 1 – 17 ]. The possibility of their rational and modular design enables, for instance, the generation of highly active catalysts for a range of chemical transformations with high selectivity. PCP pincer complexes, where the ligands bear phosphine donors tethered via CH 2 , O, or NR linkers to an aromatic anionic benzene backbone, are still one of the most common types. In the last couple of years pincer ligands which feature a monoanionic N-heterocyclic backbone, e.g., carbazole-, pyrrole- and acridane-scaffolds, connected to phosphine (amido diphosphine PNP pincer ligands) have become an increasingly important class of compounds [ 18 ]. Within the large class of amido diphosphines, we are interested in PNP pincer ligands which feature a central anionic pyrrole moiety connected via CH 2 linkers to two phosphine donors. These ligands are designed to form five-membered chelates upon coordination to a metal ion. The first transition metal complexes containing pyrrole-based PNP ligands were reported in 2012 independently by the groups of Gade [ 19 ], Mani [ 20 ] and Tonzetich [ 21 ]. Accordingly, a large number of transition metal complexes has been prepared to date using this class of ligand. With respect to group 4 metals pyrrole-based PNP pincer complexes are rare [ 22 , 23 ]. We have recently described several Ti(IV) and Ti(III) PNP complexes [ 24 ] which were shown to undergo ketone insertion reactions into a Ti(IV)-P bond thereby forming new complexes with tridendate PNO-ligands. Herein we report on the synthesis, characterization and reactivity of pyrrole-based M(IV) (M = Ti, Zr, Hf) PNP pincer complexes. Representative X-Ray structures and DFT calculations are presented. Results and Discussion We have recently shown [ 24 ] that [P(NH)P- i Pr] ( 1 ) reacts with [TiCl 4 (THF) 2 ] in the presence of base to yield the Ti(IV) complex [Ti(PNP i Pr )(Cl) 3 ] ( 2 ). If the same reaction is performed with [MCl 4 (THF) 2 ] (M = Zr, Hf), instead of monomeric analogs, the dimeric complexes [Zr(PNP i Pr )(µ-Cl)(Cl) 2 ] 2 ( 2 ) and [Hf(PNP i Pr )(µ-Cl)(Cl) 2 ] 2 ( 3 ) featuring two bridging chloride ligands are obtained in 76 and 80% isolated yields (Scheme 1 ). Noteworthy, the analogous zirconium complex featuring the bulkier PNP tBu ligand was reported by Nishibayashi and coworkers [ 22 ]. Complexes 2 and 3 were characterized 1 H, 13 C{ 1 H}, and 31 P{ 1 H} NMR spectroscopy and elemental analysis. These complexes are highly symmetric as they display singlets at 40.2 and 42.8 ppm, respectively, in the 31 P{ 1 H} NMR spectrum. Likewise, in the 1 H NMR spectrum the pyrrole hydrogen atoms give rise to singlets at 5.85 (2H) and 5.86 (2H) ppm. In the 13 C{ 1 H} NMR spectrum, the pyrrole carbons exhibit singlets at 138.3 and 137.9 ppm and 107.2 and 107.7 ppm assignable to the quaternary and tertiary carbon atoms, respectively. Reactions of [Zr(PNP i Pr )(µ-Cl)(Cl) 2 ] 2 ( 2 ) and [Hf(PNP i Pr )(µ-Cl)(Cl) 2 ] 2 ( 3 ) with 1 equiv of sodium cyclopentadienyl (CpNa) in THF at room temperature gives the corresponding mononuclear complexes [M(PNP i Pr )(η 5 -Cp)(Cl) 2 ] (M = Zr ( 4 ), Hf ( 5 )) in 90% and 93% yields, respectively(Scheme 2 ). These complexes were characterized by 1 H, 13 C{ 1 H}, and 31 P{ 1 H} NMR spectroscopy. In the 1 H NMR spectrum the Cp ligands of 4 and 5 exhibits triplet resonances at 6.70 ( J HP = 1.2 Hz) and 6.40 ppm ( J HP = 1.1 Hz), respectively. In the 13 C{ 1 H} NMR spectrum the Cp rings give rise to signals at 115.6 and 114.0 ppm. The molecular structure of 5 was confirmed by X-ray analysis. In addition, a structural view is shown in Fig. 1 with selected bond distances and angles reported in the caption. This complex adopts a five-legged piano-stool geometry around the hafnium center with the P, N, P atoms of the pyrrole moiety and the two chloride ligands as the legs. The analogous Zr complex with a PNP tBu ligand was reported recently [ 22 ]. Figure 1. Structural view of [Hf(PNP i Pr )(η 5 -Cp)(Cl) 2 ] ( 5 ) showing 50% thermal ellipsoids (H atoms are omitted for clarity). Selected bond lengths (Å) and bond angles (deg): Hf1-N1 2.237(7), Hf1-Cl2 2.484(2), Hf1-Cl1 2.485(3), Hf1-C22 2.51(1), Hf1-C23 2.54(1), Hf1-C21 2.54(1), Hf1-C19 2.54(1), Hf1-C20 2.55(1), Hf1-P1 2.751(2), Hf1-P2 2.771(3), Cl1-Hf1 Cl2 160.03(8), P1-Hf1-P2 139.39(7). Treatment of a solution of [Zr(PNP i Pr )(µ-Cl)(Cl) 2 ] 2 ( 2 ) and [Hf(PNP i Pr )(µ-Cl)(Cl) 2 ] 2 ( 3 ) in toluene at room temperature with an excess of SiMe 3 I afforded, after workup, the triiodide complexes [Zr(PNP i Pr )(I) 3 ] ( 6 ) and [Hf(PNP i Pr )(I) 3 ] ( 7 ) in 87 and 87%, respectively, isolated yields (Scheme 3 ). Crystals suitable for X-Ray diffraction were obtained by layering a saturated CH 2 Cl 2 solution of 7 with n -pentane. The solid-state structure of 7 was established by single-crystal X-ray diffraction. A molecular view is depicted in Fig. 1 with selected bond distances given in the captions. This complex has a distorted octahedral geometry with bond angles of 175.57(2)° (I1-Hf1-I2), 180.0° (N1-Hf1-I1) and 145.21(6)° (P1-Hf1-P1). Figure 2. Structural view of [Hf(PNP iPr )(I) 3 ] ( 7 ) showing 50% thermal ellipsoids (H atoms are omitted for clarity). Selected bond lengths (Å) and bond angles (deg): Hf1-N1 2.143(6), Hf1-P1 2.737(1), Hf1-I1 2.8051(8), Hf1-I2 2.7922(4), P1-Hf1-P1 145.21(6), I2-Hf1-I2 175.57(2), I2-Hf1-I1 87.78(1), N1-Hf1-I1 180.0°. Complexes [Zr(PNP i Pr )(I) 3 ] ( 6 ) and [Hf(PNP i Pr )(I) 3 ] ( 7 ) are readily alkylated with MeMgBr affording [Zr(PNP i Pr )(Me) 3 ] ( 8 ) and [Hf(PNP i Pr )(Me) 3 ] ( 9 ) in 80 and 82% isolated yields (Scheme 4 ). These complexes again were characterized by 1 H, 13 C{ 1 H}, and 31 P{ 1 H} NMR spectroscopy and elemental analysis. The Zr and Hf-bound methyl groups of 8 and 9 give rise to one triplet resonance at 1.04 ( J HP = 3.8 Hz) and 0.74 ppm ( J HP = 3.9 Hz), respectively, in the 1 H NMR spectrum. In the 13 C{ 1 H} spectrum, corresponding resonances at 60.6 and 59.4 ppm were observed. The equivalence of the three methyl groups is analogous to the observations for [M(PNP)(Me) 3 ] (PNP = N(C 6 H 3 -o-Me-2-P i Pr 2 ) 2 and N(o-C 6 H 4 -2-P i Pr 2 ) 2 , M = Zr, Hf) [ 25 – 27 ] and [Hf(PNP)(Me) 3 ] (PNP = N(SiMe 2 CH 2 PR 2 ) 2 , R = Me, i Pr, t Bu) [ 28 ] which is indicative of exchange among the methyl group sites that is rapid on the NMR timescale at ambient temperature. No static geometry can result in equivalent methyl groups in 8 and 9 . This can be seen from the DFT calculated structure of [Zr(PNP i Pr )(Me) 3 ] ( 8 ) depicted in Scheme 4 . The coordination environment about Zr in 8 can be described as a bicapped tetrahedron, with the two neutral P donors capping the faces of the N-Zr-Me 3 tetrahedron. The 1 H and 13 C chemical shifts exhibited by the Me groups of 8 and 9 are comparable to those previously reported in similar compounds. For example, Ozerov’s and Liang’s [M(PNP)(Me) 3 ] (M = Zr, Hf) and Fryzuk’s [Hf(PNP)(Me) 3 ] compounds resonate in their 1 H NMR spectra in the 0.5–0.9 ppm range [ 25 – 28 ]. Another strategy to afford Ti(IV) PNP complexes is the utilization of the amido-precursor [Ti(NMe 2 ) 4 ]. The targeted amido complex [Ti(PNP i Pr )(NMe 2 ) 3 ] ( 10 ) was considered to allow more functionalization possibilities in contrast to the above halide congeners. After stirring a solution of [P(NH)P- i Pr] ( 1 ) and 1 equiv of [Ti(NMe 2 ) 4 ] in toluene at 80°C for 48 h, after workup, an amido complex tentatively assigned as [Ti(PNP i Pr )(NMe 2 ) 3 ] ( 10 ) was isolated as red oil in quantitative yield (Scheme 5 ). The 1 H, 13 C{ 1 H}, and 31 P{ 1 H} NMR spectra of 10 revealed that this complex is highly symmetric in solution which is not in agreement with [Ti(PNP i Pr )(NMe 2 ) 3 ] ( 10 ) with the PNP ligand coordinated in κ 3 PNP -fashion. Singlet resonances were observed for the dimethylamido groups in the 1 H and 13 C{ 1 H} NMR spectra at 3.14 and 44.6 ppm, respectively. Likewise, in the 31 P{ 1 H} NMR spectrum a singlet resonance is found at 6.2 ppm. The chemical equivalence of the NMe 2 substituents and the phosphine moieties can be rationalized by isomerization reactions involving P-metal bond dissociation reactions. For titanium, DFT calculations revealed that the most stable species is [Ti(κ 1 N - PNP i Pr )(NMe 2 ) 3 ] ( κ 1 N -10 ) featuring a κ 1 N -bound PNP ligand (Fig. 3). This compound is more stable by 36.6 and 87.5 kJ/mol, respectively, than the corresponding complexes with the PNP ligand being coordinated in κ 2 PN - and κ 3 PNP -fashion. This finding may suggest a fast equilibrium M M(κ 1 N -PNP i Pr )(NMe 2 ) 3 ] M(κ 2 PN -PNP i Pr )(NMe 2 ) 3 ] M(κ 3 PNP -PNP i Pr )(NMe 2 ) 3 ] Ti 0.0 35.6 87.5 Zr 0.0 -2.5 4.3 Hf 0.0 -6.0 8.6 Figure 3. DFT calculated structures of (a) [Ti(κ 1 N -PNP i Pr )(NMe 2 ) 3 ] ( κ 1 N -10 ), (b) [Ti(κ 2 PN -PNP i Pr )(NMe 2 ) 3 ] (( κ 2 PN -10 ), and (c) [Ti(κ 3 PNP -PNP i Pr )(NMe 2 ) 3 ] ( κ 3 PNP -10 ). Free energies in kJ/mol for [M(PNP i Pr )(NMe 2 ) 3 ] (M = Ti, Zr, Hf) featuring κ 1 -, κ 2 -, and κ 3 -bound PNP ligands. between κ 1 N -10 and κ 2 PN -10 in solution, whereas the formation of κ 3 PNP- 10 seems to be unlikely. For comparison, in the case of Zr and Hf the energies of all three species are similar and may thus be in equilibrium with one another (Fig. 3). In fact, such a behavior was observed recently by Ballman and co-workers for [M(PNP)(NMe 2 ) 3 ] (PNP = N(CH 2 -o-C 6 H 4 PPh 2 ) 2 and N(C 6 H 4 - o -CH 2 PPh 2 ) 2 ), M = Zr, Hf). In addition, they were able to structurally characterize a κ 2 PN -bound hafnium complex [ 29 ]. Interestingly, when [P(NH)P- i Pr] ( 1 ) was reacted with 2 equivs of [Ti(NMe 2 ) 4 ] in CH 2 Cl 2 at 40°C complex [Ti(PNP i Pr )(Cl) 2 (NMe 2 )] ( 11 ) was obtained in 92% isolated yield (Scheme 7 ). This complex was fully characterized by 1 H, 13 C{ 1 H}, and 31 P{ 1 H} NMR spectroscopy and elemental analysis. Additionally, the molecular structure of 11 was confirmed by X-ray analysis. A structural view is shown in Fig. 4 with selected bond distances and angles reported in the caption. The coordination geometry around the titanium center corresponds to a slightly distorted octahedron where the PNP ligand and the amide ligand define the equatorial plane and the two chloride ligands the axial positions. The two Ti-N bonds exhibit different bond distances being 2.114(1) Å for Ti1-N1 and 1.9390(1) Å Ti1-N2 which may be attributed to the fact that the dimethylamido ligand is both a stronger σ and π-donor than the nitrogen atom of the pyrrole moiety. Figure 4. Structural view of [Ti(PNP i Pr )(Cl) 2 (NMe 2 )] ( 11 ) showing 50% thermal ellipsoids (H atoms are omitted for clarity). Selected bond lengths (Å) and bond angles (deg): Ti1-N1 2.114(1), Ti1-N2 1.9390(1), Ti1-Cl1 2.3419(3), Ti1-P1 2.5877(4), Cl1-Ti1-Cl1 177.34(2), P1-Ti1-P1 150.85(2), N1-Ti1-N2. 180.0. Treatment of a solution of [P(NH)P- i Pr] ( 1 ) and [Zr(NMe 2 ) 4 ] (1 equiv) in toluene at 120°C for 72 h and subsequent addition of SiMe 3 Br (3.5 equiv) at room temperature afforded, after workup, the anionic seven coordinate tetrabromo complex [Zr(PNP i Pr )(Br) 4 ][H 2 NMe 2 ] ( 13 ) in 80% yield (Scheme 7 ). The corresponding hafnium complex [Hf(PNP i Pr )(Br) 4 ][H 2 NEt 2 ] ( 14 ) was obtained in similar fashion by utilizing [Hf(NEt 2 ) 4 ] as metal precursor. These complexes are very air and moister sensitive. It has to be noted that, according to our knowledge, monomeric seven coordinate group 4 metal pincer complexes are unknown. In addition to the NMR spectroscopic characterization, the solid-state structure of 13 was determined by X-ray crystallography. A molecular view is depicted in Fig. 5 with selected bond distances given in the caption. The coordination sphere of the seven-coordinate Zr(IV) center may be described as a distorted pentagonal bipyramidal geometry. Figure 5. Structural view of [Zr(PNP i Pr )(Br) 4 ][NH 2 Me 2 ]⋅CH 2 Cl 2 ( 12 ⋅CH 2 Cl 2 ) showing 50% thermal ellipsoids (H atoms, the [NH 2 Me 2 ] + cation and CH 2 Cl 2 are omitted for clarity). Selected bond lengths (Å) and bond angles (deg): Zr1-N1 2.251(4), Zr1-Br1 2.7763(7), Zr1-Br2 2.7352(7), Zr1-Br3 2.5865(7), Zr1-Br4 2.6323(7), Zr1-P1 2.772(1), Zr1-P2 2.785(1), Br3-Zr1-Br4 177.53(3), N1-Zr1-Br1 139.68(9), N1-Zr1-Br2 142.48(9), N1-Zr1-Br3 94.6(1) N1-Zr1-Br4 87.6(1) P1-Zr1-P2 135.33(4), Br2-Zr1-P1 148.96(3), Br1-Zr1-P2 150.87(3). Conclusion In sum, we described the synthesis and reactivity of several new group 4 metal complexes containing a central anionic pyrrole moiety connected via CH 2 -linkers to two i Pr donors. As starting materials [MCl 4 (THF) 2 ] (M = Zr, Hf) and [M(NMe 2 ) 4 ] (M = Ti, Zr) as well as [Hf(NEt 2 ) 4 ] were utilized. Treatment of [P(NH)P- i Pr] with in the presence of base to yields the dimeric complexes [M(PNP i Pr )(µ-Cl)(Cl) 2 ] 2 (M = Zr, Hf) featuring bridging chloride ligands. These dimeric complexes are precursors for several monomeric group 4 complexes including [M(PNP i Pr )(η 5 -Cp)(Cl) 2 ] and [M(PNP i Pr )(I) 3 ]. The latter react with MeMgBr to give trialkyl complexes of the type [M(PNP iPr )(Me) 3 ]. Interestingly, if [P(NH)P- i Pr] is reacted with [M(NMe 2 ) 4 ] (M = Ti, Zr) and [Hf(NEt 2 ) 4 ] complexes of the type [M(PNP i Pr )(NMe 2 ) 3 ] and [Hf(PNP i Pr )(NEt 2 ) 3 ] were obtained. DFT calculations revealed that the most stable species is [Ti(κ 1 N - PNP i Pr )(NMe 2 ) 3 ] featuring a κ 1 N -bound PNP ligand. In solution, there is a fast equilibrium between complexes where the PNP ligand is coordinated in κ 1 N - and κ 2 PN -fashion. The formation of a species where the PNP ligand is coordinated in κ 3 PNP- fashion seems unlikely. On the other hand, in the case of Zr and Hf, the energies of all three species are similar and may thus be in equilibrium with one another. Finally, if a solution of [P(NH)P- i Pr] and [Zr(NMe 2 ) 4 ] was treated with SiMe 3 Br the anionic seven-coordinate tetrabromo complex [Zr(PNP i Pr )(Br) 4 ][H 2 NMe 2 ]. The corresponding hafnium complex [Hf(PNP i Pr )(Br) 4 ][H 2 NEt 2 ] was obtained in similar fashion by utilizing [Hf(NEt 2 ) 4 ] as metal precursor. EXPERIMENTAL All manipulations were performed under an inert atmosphere of argon by using Schlenk techniques or in an MBraun inert-gas glovebox. The solvents were purified according to standard procedures [ 30 ] The deuterated solvents were purchased from Eurisotop SAS and dried over 4 Å molecular sieves. The ligand precursor [P(NH)P- i Pr] ( 1 ) (2,5-Bis[[bis(1-methylethyl)phosphino]methyl]-1 H -pyrrole) was prepared according to the literature [ 31 ]. All other starting materials are known compounds and were used as obtained from commercial sources. 1 H, 13 C{ 1 H}, and 31 P{ 1 H} NMR spectra were recorded on Bruker AVANCE-250, AVANCE-400 and AVANCE-600 spectrometers. 1 H and 13 C{ 1 H} NMR spectra were referenced internally to residual protio-solvent and solvent resonances, respectively, and are reported relative to tetramethylsilane (δ = 0 ppm). 31 P{ 1 H} NMR spectra were referenced externally to H 3 PO 4 (85%) (δ = 0 ppm). Synthesis of Bis-[2,5-bis[[bis(1-methylethyl)phosphino-κ 2 P ]methyl]-1 H -pyrrolato-κ N ](µ-chloro)(dichloro)zirconium(IV)], [Zr(PNP i Pr )(µ-Cl)(Cl) 2 ] 2 (2, C 36 H 68 Cl 6 N 2 P 4 Zr 2 ) A solution of [P(NH)P- i Pr] ( 1 ) (200 mg, 0.61 mmol) in THF (8 cm 3 ) was treated with n BuLi (419 µL, 1.6 M in n -hexane, 0.67 mmol, 1.1 equiv.) at -78°C. After stirring for 30 min at this temperature the reaction mixture was allowed to reach room temperature and stirred for further 30 min and [ZrCl 4 (THF) 2 ] (219 mg, 0.58 mmol, 0.95 equiv.) was added. Upon stirring for 1 h, all volatiles were removed under reduced pressure and the orange oily residue was redissolved in toluene (10 cm 3 ). The orange solution was filtered through a syringe filter (PTFE, 0.2 µm), which was washed with toluene (2 x 8 cm 3 ). After evaporation of the solvent, the residue was washed with n -pentane (3 x 10 cm 3 ) until the washing phase was colorless. The product was obtained as beige powder. Yield: 230 mg ( 76%). 1 H NMR (400 MHz, CD 2 Cl 2 , 25°C) δ = 5.85 (s, 2H, Pyr 3,4 ), 3.29–3.22 (m, 4H, CH 2 ), 2.40–2.24 (m, 4H, C H CH 3 ), 1.42–1.28 (m, 12H, CHC H 3 ), 1.23–1.09 (m, 12H, CHC H 3 ). 13 C{ 1 H} NMR (101 MHz, CD 2 Cl 2 , 25°C) δ = 138.3 (C q , Pyr 2,5 ), 107.2 (Pyr 3,4 ), 25.0 (CH 2 ), 19.2 ( C HCH 3 ), 18.3 (CH C H 3 ). 31 P{ 1 H} NMR (162 MHz, CD 2 Cl 2 , 25°C) δ = 40.2. Anal. Calcd for C 36 H 68 Cl 6 N 2 P 4 Zr 2 : C, 41.26; H, 6.54; N, 2.67. Found: C, 41.40; H, 6.46; N, 2.82. Synthesis of Bis-[2,5-bis[[bis(1-methylethyl)phosphino-κ 2 P ]methyl]-1 H -pyrrolato-κ N ](µ-chloro)(dichloro)hafnium(IV)], [Hf(PNP i Pr )(µ-Cl)(Cl) 2 ] 2 (3, C 36 H 68 Cl 6 N 2 P 4 Hf 2 ) This complex was prepared analogously to 2 with [P(NH)P- i Pr] ( 1 ) (200 mg, 0.61 mmol), n BuLi (419 µL, 1.6 M in hexane, 0.67 mmol, 1.1 equiv.) and [HfCl 4 (THF) 2 ] (283 mg, 0.58 mmol, 0.95 equiv.) as starting materials. Yield: 298 mg (80%). Single crystals for X-Ray diffraction measurement were obtained by layering a saturated CH 2 Cl 2 solution with n -pentane. 1 H NMR (600 MHz, CD 2 Cl 2 , 25°C) δ = 5.86 (s, 2H), 3.28 (s, 4H), 2.34 (bs, 4H), 1.39–1.31 (m, 12H), 1.18 (bs, 12H). 13 C{ 1 H} NMR (151 MHz, CD 2 Cl 2 , 25°C) δ = 137.9 (C q , Pyr 2,5 ), 107.7 (Pyr 3,4 ), 24.9 ( C HCH 3 ), 21.0 (CH 2 ), 19.3 (CH C H 3 ), 18.4 (CH C H 3 ). 31 P{ 1 H} NMR (243 MHz, CD 2 Cl 2 , 25°C) δ = 42.8. Anal. Calcd for C 36 H 68 Cl 6 N 2 P 4 Hf 2 : C, 35.37; H, 5.61; N, 2.29. Found: C, 35.20; H, 5.78; N, 2.35. Synthesis of [2,5-bis[[bis(1-methylethyl)phosphino-κ 2 P ]methyl]-1 H -pyrrolato-κ N ](η 5 -cyclopentadienyl)(dichloro)zirconium(IV)], [Zr(PNP i Pr )(η 5 -Cp)(Cl) 2 ] (4, C 23 H 39 Cl 2 NP 2 Zr) To a solution of 2 (100 mg, 0.095 mmol) in THF (6 cm 3 ) NaCp (79.5 µL, 2.4 M in THF, 0.19 mmol, 2 equiv.) was added at room temperature whereupon the solution became immediately dark red. Upon stirring for 1 h, the solvent was evaporated and the residue was redissolved in toluene (10 cm 3 ). The solution was filtered through a syringe filter (PTFE, 0.2 µm). Upon evaporation of the solvent and washing of the residue with n -pentane (2 x 10 cm 3 ) the product was obtained as brown powder. Yield: 95 mg ( 90%). 1 H NMR (600 MHz, CD 2 Cl 2 , 25°C) δ = 6.70 (t, J = 1.2 Hz, 5H, Cp), 5.78 (s, 2H, Pyr 3,4 ), 3.20–3.14 (m, 4H, CH 2 ), 2.34–2.26 (m, 4H, C H CH 3 ), 1.32–1.28 (m, 12H, CHC H 3 ), 1.28–1.23 (m, 12H, CHC H 3 ). 13 C{ 1 H} NMR (151 MHz, CD 2 Cl 2 25°C) δ = 135.0 (t, J = 4.3 Hz, C q , Pyr 2,5 ), 115.6 (Cp), 105.8 (t, J = 4.5 Hz, Pyr 3,4 ), 25.5 (t, J = 5.9 Hz, C H CH 3 ), 25.3 (dd, J = 9.5, 8.0 Hz, CH 2 ), 19.6 (d, J = 7.9 Hz, CH C H 3 ). 31 P{ 1 H} NMR (243 MHz, CD 2 Cl 2 , 25°C) δ = 36.2. Anal. Calcd for C 23 H 39 Cl 2 NP 2 Zr: C, 49.90: H, 7.10; N, 2.53. Found: C, 50.10; H, 7.26; N, 2.22. Synthesis of [2,5-bis[[bis(1-methylethyl)phosphino-κ 2 P ]methyl]-1 H -pyrrolato-κ N ](η 5 -cyclopentadienyl)(dichloro)hafnium(IV)], [Hf(PNP i Pr )(η 5 -Cp)(Cl) 2 ] (5, C 23 H 39 Cl 2 NP 2 Hf) This complex was prepared analogously to 4 with 3 (250 mg, 0.20 mmol) and NaCp (170 µL, 2.4 M in THF, 0.40 mmol, 2 equiv) as starting materials. Yield: 243 mg (93%). Single crystals for X-Ray diffraction measurements were obtained by layering a saturated CH 2 Cl 2 solution with n -pentane. 1 H NMR (600 MHz, CD 2 Cl 2 , 25°C) δ = 6.40 (t, J = 1.1 Hz, 5H, Cp), 5.64 (s, 2H, Pyr 3,4 ), 3.11–3.00 (m, 4H, CH 2 ), 2.25–2.16 (m, 4H, C H CH 2 ), 1.19–1.15 (m, 12H, CHC H 3 ), 1.15–1.11 (m, 12H, CHC H 3 ). 13 C{ 1 H} NMR (151 MHz, CD 2 Cl 2 , 25°C) δ = 134.9 (t, J = 4.2 Hz, C q , Pyr 2,5 ), 114.0 (Cp), 106.2 (t, J = 4.4 Hz, Pyr 3,4 ), 25.5 (t, J = 6.8 Hz, C HCH 3 ), 25.1 (d, J = 8.9 Hz, CH 2 ), 25.0 (d, J = 9.0 Hz, CH 2 ), 24.2 (d, 13.5 Hz, CH C H 3 ), 19.6 (CH C H 3 ). 31 P{ 1 H} NMR (243 MHz, CD 2 Cl 2 , 25°C) δ = 37.8. Anal. Calcd for C 23 H 39 Cl 2 NP 2 Hf: C, 41.10: H, 6.13; N, 2.19. Found: C, 41.20; H, 6.26; N, 2.02. Synthesis of [2,5-bis[[bis(1-methylethyl)phosphino-κ 2 P ]methyl]-1 H -pyrrolato-κ N ](triiodo)zirconium(IV)], [Zr(PNP i Pr )(I) 3 ] (6, C 18 H 34 I 3 NP 2 Zr) To a solution of 2 (100 mg, 0.095 mmol) in toluene (10 cm 3 ) SiMe 3 I (407 µL, 2.86 mmol, 30 equiv.) was added at room temperature and stirred for 1 h. During addition of SiMe 3 I the solution became orange and a precipitate was formed. The solution was decanted and the remaining residue was extracted three times with toluene (10 cm 3 ). The organic layers were combined and all volatiles were removed under reduced pressure. The orange residue was washed with n -pentane (3 x 10 cm 3 ) affording 6 as orange powder. Yield: 120 mg (78%). 1 H NMR (400 MHz, CD 2 Cl 2 , 25°C) δ = 5.88 (s, 2H, Pyr 3,4 ), 3.48–3.32 (m, 4H, CH 2 ), 2.63–2.48 (m, 4H, C H CH 3 ), 1.45–1.18 (m, 24H, CHC H 3 ). 13 C{ 1 H} NMR (101 MHz, CD 2 Cl 2 , 25°C) δ = 139.1 (t, J = 5.3 Hz, Pyr 2,5 ), 108.6 (t, J = 4.3 Hz, Pyr 3,4 ), 27.2 (t, J = 7.0 Hz, C HCH 3 ), 26.7 (t, J = 9.9 Hz, CH 2 ), 20.1 (CH C H 3 ), 19.7 (CH C H 3 ). 31 P{ 1 H} NMR (162 MHz, CD 2 Cl 2 , 25°C) δ = 56.5. Anal. Calcd for C 18 H 34 I 3 NP 2 Zr: C, 27.08; H, 4.29; N, 1.75. Found: C, 27.30; H, 4.18; N, 1.32. Synthesis of [2,5-bis[[bis(1-methylethyl)phosphino-κ 2 P ]methyl]-1 H -pyrrolato-κ N ](triiodo)hafnium(IV)], [Hf(PNP i Pr )(I) 3 ] (7, C 18 H 34 I 3 NP 2 Hf) This complex was prepared analogously to 6 with 3 (100 mg, 0.082 mmol) and SiMe 3 I (249 µL, 2.5 mmol, 30 equiv.) as starting materials. Yield: 57 mg (87%). Single crystals for X-Ray measurements were obtained by layering a saturated CH 2 Cl 2 solution with n- pentane. 1 H NMR (400 MHz, CH 2 Cl 2 , 25°C) δ = 5.84 (s, 2H, Pyr 3,4 ), 3.56–3.40 (m, 4H, CH 2 ), 2.73–2.49 (m, 4H, CHC H 3 ), 1.38 (ddt, J = 10.2, 7.1, 3.6 Hz, 24H, CHC H 3 ). 13 C{ 1 H} NMR (101 MHz, CD 2 Cl 2 , 25°C) δ = 139.0 (t, J = 4.8 Hz, Pyr 2,5 , C q , Pyr 2,5 ), 109.4 (t, J = 4.3 Hz, Pyr 3,4 ), 27.5 (t, J = 9.9 Hz, CH 2 ), 27.2 (t, J = 8.2 Hz, C HCH 3 ), 20.1 (d, J = 6.4 Hz, CH C H 3 ). 31 P{ 1 H} NMR (162 MHz, CD 2 Cl 2 , 25°C) δ = 62.3. Anal. Calcd for C 18 H 34 I 3 NP 2 Hf: C, 24.41; H, 3.87; N, 1.58. Found: C, 24.52; H, 3.93; N, 3.77. Synthesis of [2,5-bis[[bis(1-methylethyl)phosphino-κ 2 P ]methyl]-1 H -pyrrolato-κ N ](trimethyl)zirconium(IV)], [Zr(PNP i Pr )(Me) 3 ] (8, C 21 H 43 NP 2 Zr) A suspension of 6 (60 mg, 0.075 mmol) in toluene (5 cm 3 ) was treated with MeMgBr (0.23 mmol, 161 µL, 1.4 M, 3 equiv) in THF/toluene (1:4) at room temperature. During the addition of MeMgBr a clear solution was formed. Dioxane (116 µL, 1.35 mmol, 6 equiv) was added for precipitation of magnesia salts. Upon stirring for 1 h, all volatiles were evaporated under reduced pressure and the white residue was redissolved in n -pentane (5 cm 3 ). The reaction mixture was filtered through a syringe filter (PTFE, 0.2 µL) to afford a pale orange solution. After evaporation of the solvent the product was obtained as orange oil. Yield: 28 mg (80%). 1 H NMR (400 MHz, C 6 D 6 , 25°C) δ = 6.26 (d, J = 0.9 Hz, 2H, Pyr 3,4 ), 2.90 (d, J = 6.1 Hz, 4H, CH 2 ), 1.94 (dq, J = 14.4, 7.2 Hz, 2H, C H CH 3 ), 1.04 (t, J = 3.8 Hz, 9H, Zr-CH 3 ), 0.99 (dd, J = 13.6, 7.1 Hz, 12H, CHC H 3 ), 0.92 (dd, J = 12.8, 7.1 Hz, 12H, CHC H 3 ). 13 C{ 1 H} NMR (101 MHz, C 6 D 6 ) δ 136.6 (t, J = 6.3 Hz, C q , Pyr 4,5 ), 107.0 (t, J = 4.3 Hz, Pyr 3,4 ), 51.7 (Zr-CH 3 ), 23.9–23.4 (m, CH 2 ), 23.3–23.0 (m, C HCH 3 ), 18.3 (d, J = 7.4 Hz, CH C H 3 ). 31 P{ 1 H} NMR (162 MHz, C 6 D 6 , 25°C) δ = 27.9. Anal. Calcd for C 21 H 43 NP 2 Zr: C, 54.51; H, 9.37; N, 3.03. Found: C, 54.40; H, 9.13 6; N, 3.18. Synthesis of [2,5-bis[[bis(1-methylethyl)phosphino-κ 2 P ]methyl]-1 H -pyrrolato-κ N ](trimethyl)hafnium(IV)], [Hf(PNP i Pr )(Me) 3 ] (9, C 21 H 43 NP 2 Hf) This complex was prepared analogously to 8 with 7 (60 mg, 0.067 mmol) and MeMgBr (0.20 mmol, 145 µL, 1.4 M, 3.5 equiv) as starting materials. Yield: 31 mg (82%). 1 H NMR (400 MHz, C 6 D 6 , 25°C) δ = 6.24 (s, 2H, Pyr 3,4 ), 2.93 (d, J = 5.6 Hz, 4H, CH 2 ), 2.05–1.88 (m, J = 7.2 Hz, 4H, C H CH 3 ), 1.02–0.86 (m, 24H, CHC H 3 ), 0.74 (t, J = 3.9 Hz, 9H, Hf-CH 3 ). 13 C{ 1 H} NMR (101 MHz, C 6 D 6 , 25°C) δ = 136.5–136.1 (m, Pyr 2,5 ), 106.8–106.6 (m, Pyr 3,4 ), 59.4 (t, J = 6.4 Hz, Hf-CH 3 ), 22.6 (d, J = 7.1 Hz, CH 2 ), 22.3 (d, J = 10.1 Hz, C H CH 3 ), 17.6 (dt, J = 18.1, 1.2 Hz, CH C H 3 ). 31 P{ 1 H} NMR (162 MHz, C 6 D 6 , 25°C) δ = 30.8. Anal. Calcd for C 21 H 43 NP 2 Hf: C, 45.86; H, 7.88; N, 2.55. Found: C, 45.98; H, 8.06; N, 2.69. Reaction of Tetrakis(dimethylamido)titanium(IV), ([Ti(NMe 2 ) 4 ]), with (2,5-Bis[[bis(1-methylethyl)phosphino]methyl]-1 H -pyrrole), [P(NH)P- i Pr] (1). Formation of [2,5-bis[[bis(1-methylethyl)phosphino]methyl]-1 H -pyrrolato]tris-(dimethylamido)titanium(IV)], [Ti(PNP iPr )(NMe 2 ) 3 ] (10) A solution of [P(NH)P- i Pr] ( 1 ) (100 mg, 0.31 mmol) and [Ti(NMe 2 ) 4 ] (71 µL, 0.31 mmol) in toluene (4 cm 3 ) was stirred for 2 days at 80°C. After removing of all volatiles under reduced pressure, 10 was obtained as red oil. 1 H NMR (400 MHz, C 6 D 6 , 25°C) δ = 6.42 (s, 2H, Pyr 3,4 ), 3.14 (s, 18H, NCH 3 ), 2.82–2.77 (m, 4H, CH 2 ) 1.90–1.64 (m, 4H, C H CH 3 ), 1.08 (dd, J = 7.1, 3.6 Hz, 12H, CHC H 3 ), 1.05 (dd, J = 7.1, 2.3 Hz, 12H, CHC H 3 ). 13 C{ 1 H} NMR (101 MHz, C 6 D 6 , 25°C) δ = 136.7 (d, J = 12.4 Hz, C q , Pyr 2,5 ), 107.7 (d, J = 4.9 Hz, Pyr 3,4 ), 44.6 (CH 3 ), 24.8 (d, J = 11.7 Hz, CH 2 ), 24.3 (d, J = 14.8 Hz, C HCH 3 ), 20.4 (d, J = 14.8 Hz, CH C H 3 ), 19.5 (d, J = 10.6 Hz, CH C H 3 ). 31 P{ 1 H} NMR (162 MHz, C 6 D 6 , 25°C) δ = 6.2. Synthesis of [2,5-bis[[bis(1-methylethyl)phosphino-κ 2 P ]methyl]-1 H -pyrrolato-κ N ](dichloro)(dimethylamido)titanium(IV)], [Ti(PNP i Pr )(Cl) 2 (NMe 2 )] (11, C 20 H 40 Cl 2 N 2 P 2 Ti) A solution of [P(NH)P- i Pr] ( 1 ) (100 mg, 0.31 mmol) and [Ti(NMe 2 ) 4 ] (142 µL, 0.62 mmol, 2 equiv.) in CH 2 Cl 2 (5 cm 3 ) was stirred for 12 h at room temperature. After removing of all volatiles under reduced pressure, the product was obtained as brown solid. Yield: 140 mg (92%). Single crystals for X-ray diffraction measurements could be obtained from a saturated n -pentane solution at -20°C. 1 H NMR (400 MHz, CD 2 Cl 2 , 25°C) δ = 6.40 (Pyr 3,4 ) 3.13–3.04 (m, 4H, CH 2 ), 2.50 (s, 6H, NC H 3 ), 1.88–1.60 (m, 4H, C H CH 3 ), 1.45–1.15 (m, 24H, CHC H 3 ). 13 C{ 1 H} NMR (101 MHz, CD 2 Cl 2 , 25°C) δ = 135.2 (Pyr 2,5 ), 105.9 (Pyr 3,4 ), 44.5 (CH 3 ), 24.8 (CH 2 ), 20.2 (CH C H 3 ), 18.4 (CH C H 3 ). 31 P{ 1 H} NMR (162 MHz, C 6 D 6 , 25°C) δ = 54.0. Anal. Calcd for C 20 H 40 Cl 2 N 2 P 2 Ti: C, 49.10; H, 8.24; N, 5.73. Found: C, 48.95; H, 8.39; N, 5.82. Synthesis of Dimethylammonium[2,5-bis[[bis(1-methylethyl)phosphino-κ 2 P ]methyl]-1 H -pyrrolato-κ N ](tetrabromo)zirconium(IV)], [Zr(PNP i Pr )(Br) 4 ] [NH 2 Me 2 ] (12, C 20 H 42 Br 4 N 2 P 2 Zr) A solution of [P(NH)P- i Pr] ( 1 ) (200 mg, 0.61 mmol) and [Zr(NMe 2 ) 4 ] (163 mg, 0.61 mmol) in toluene (5 cm 3 ) was stirred at 120°C for 72 h. The reaction mixture was then allowed to reach room temperature and SiMe 3 Br (282 µL, 2.1 mmol, 3.5 equiv) was added. After 5 min an orange precipitate was formed. All volatiles were removed under reduced pressure and the residue was washed with n -pentane (4 x 10 cm 3 ). The product was obtained as orange powder. Yield: 383 mg (80%). Single crystals for X-Ray diffraction measurement were obtained by layering a saturated CH 2 Cl 2 solution with n -pentane. 1 H NMR (400 MHz, CD 2 Cl 2 , 25°C) δ = 7.64 (bs, 2H, H 2 NMe 2 ), 5.90 (s, 2H, Pyr 3,4 ), 3.27 (d, J = 6.4 Hz, 4H, CH 2 ), 2.94 (s, 6H, Zr-N-CH 3 ), 2.58–2.40 (m, 4H, C H CH 3 ), 1.34 (dd, J = 13.5, 7.2 Hz, 12H, CHC H 3 ), 1.24 (dd, J = 12.0, 7.1 Hz, 12H, CHC H 3 ). 13 C{ 1 H} NMR (101 MHz, CD 2 Cl 2 , 25°C) δ = 137.6 (t, J = 5.6 Hz, C q , Pyr 2,5 ), 106.3 (Pyr 3,4 ), 36.2 (Zr-N-CH 3 ), 24.9 (t, J = 5.2 Hz), 21.4 ( C HCH 3 ), 18.9 (CH C H 3 ), 18.0 (CH C H 3 ). 31 P{ 1 H} NMR (162 MHz, CD 2 Cl 2 , 25°C) δ = 39.7. Anal. Calcd for C 20 H 42 Br 4 N 2 P 2 Zr: C, 30.67; H, 5.40; N, 3.58. Found: C, 30.88; H, 5.24; N, 3.72. Synthesis of Diethylammonium[2,5-bis[[bis(1-methylethyl)phosphino-κ 2 P ]methyl]-1 H -pyrrolato-κ N ](tetrabromo)hafnium(IV)], [Hf(PNP i Pr )(Br) 4 ][NH 2 Et 2 ] (13, C 22 H 46 Br 4 N 2 P 2 Hf) A solution of [P(NH)P- i Pr] ( 1 ) (200 mg, 0.61 mmol) and [Hf(NEt 2 ) 4 ] (228 µL, 0.61 mmol) in toluene (5 cm 3 ) was stirred at 120°C for 48 h. The reaction mixture was allowed to reach room temperature and SiMe 3 Br (282 µL, 2.12 mmol, 3.5 equiv.) was added. After stirring for 1 h the precipitate was filtered through a syringe filter (PTFE, 0.2 µl) and washed with toluene (3 x 10 cm 3 ). All volatiles were removed under reduced pressure. After washing of the residue with n -pentane (10 cm 3 ) the product was obtained as orange powder. Yield: 390 mg (81%). 1 H NMR (400 MHz, CD 2 Cl 2 , 25°C) δ = 7.66 (bs, 2H, H 2 NEt 2 ) 5.86 (s, 2H, Pyr 3,4 ), 3.38–3.34 (m, 2H, CH 2 P), 3.30 (q, J = 7.4 Hz, 4H, NC H 2 CH 3 ), 2.59–2.44 (m, 4H, C H CH 3 ), 1.46 (t, J = 7.3 Hz, 6H, NCH 2 C H 3 ), 1.39–1.22 (m, 24H, CHC H 3 ). 13 C{ 1 H} NMR (101 MHz, CD 2 Cl 2 , 25°C) δ = 138.4 (C q , Pyr 2,5 ), 108.2 (Pyr 3,3 ), 42.5 (N C H 2 CH 3 ), 25.8 (t, J = 7.6 Hz, C HCH 3 ), 24.7 ( C H 2 P), 19.7 (CH C H 3 ), 19.3 (CH C H 3 ), 11.5 (NCH 2 C H 3 ). 31 P{ 1 H} NMR (162 MHz, CD 2 Cl 2 , 25°C) δ = 49.9. Anal. Calcd for C 22 H 46 Br 4 N 2 P 2 Hf: C, 29.40; H, 5.16; N, 3.12. Found: C, 29.81; H, 5.32; N, 3.02. X-ray Structure Determination X-ray diffraction data of 5 , 7 , 11 and 12 ⋅CH 2 Cl 2 (CCDC 2301968, 2301969, 2301970, and 2301972) were collected at T = 100 K in a dry stream of nitrogen on a Bruker Kappa APEX II diffractometer system using graphite-monochromatized Mo- K α radiation (λ = 0.71073 Å) and fine sliced φ - and ω -scans. Data were reduced to intensity values with SAINT and a correction for absorption effects was applied with the multi-scan approach followed by a spherical absorption correction using SADABS or TWINABS [ 32 ]. The structures were solved by the dual-space approach implemented in SHELXT [ 33 ] and refined against F 2 with SHELXL [ 34 ]. Non-hydrogen atoms were refined with anisotropic displacement parameters. H atoms attached to C were placed in calculated positions and thereafter refined as riding on the parent atoms. The positions of the ammonium hydrogen atoms in 12 were refined freely. Crystals of 5 were systematically twinned by reflection at (1–10) owing to local pseudo-symmetry. Molecular graphics were generated with the program MERCURY [ 35 ]. Computational Details The computational results presented have been achieved in part using the Vienna Scientific Cluster (VSC). Calculations were performed using the Gaussian 09 software package [ 36 ] with the PBE0 functionals without symmetry constraints, the Stuttgart/Dresden ECP (SDD) basis set to describe the electrons of titanium, zirconium and hafnium and a standard 6-31G** basis for all other atoms as already described previously [ 24 ]. Declarations Funding Open access funding provided by Austrian Science Fund (FWF). Acknowledgements Financial support by the Austrian Science Fund (FWF) is gratefully acknowledged (Project P 32570-N). The X-Ray center of the Vienna University of Technology is acknowledged for financial support and for providing access to the single-crystal diffractometer. Data availability All relevant data are included in the manuscript. References Gossage RA, van de Kuil LA, van Koten G (1998) ) Acc Chem Res 31:423 Albrecht M, van Koten G (2001) Angew Chem Int Ed 40:3750 van der Boom ME, Milstein D (2003) Chem Rev 103:1759 Singleton JT (2003) Tetrahedron 59:1837 Liang LC (2006) Coord Chem Rev 250:1152 Morales-Morales D, Jensen CM (2007) The Chemistry of Pincer Compounds. Elsevier Nishiyama H (2007) Chem Soc Rev 36:1133 Benito-Garagorri D, Kirchner K (2008) Acc Chem Res 41:201 Choi J, MacArthur AHR, Brookhart M, Goldman AS (2011) Chem Rev 111:1761 Selander N, Szabo KJ (2011) Chem Rev 111:2048 Bhattacharya P, Guan H (2011) Comments Inorg Chem 32:88 Schneider S, Meiners J, Askevold B (2012) Eur J Inorg Chem 2012:412 van Koten G, Milstein D (2013) Organometallic Pincer Chemistry. Springer, Berlin Heidelberg Szabo KJ, Wendt OF (2014) Pincer and Pincer-Type Complexes: Applications in Organic Synthesis and Catalysis. Wiley-VCH Asay M, Morales-Morales D (2015) Dalton Trans 44:17432 Murugesan S, Kirchner K (2016) Dalton Trans 45:416 Moulton CJ, Shaw BL (1976) J Chem Soc Dalton Trans 1020 Merz LS, Ballmann J, Gade LH (2020) Eur J Inorg Chem 2023 Gruger N, Wadepohl H, Gade LH (2022) Dalton Trans 41:14028 Kumar S, Mani G, Mondal S, Chattaraj PK (2012) Inorg Chem 51:12527 Venkanna GT, Ramos TVM, Arman HD, Tonzetich ZJ (2012) Inorg Chem 51:12789 Sekiguchi Y, Meng F, Tanaka H, Eizawa A, Arashiba K, Nakajima K, Yoshizawa K, Nishibayashi Y (2018) Dalton Trans 47:11322 Idelson C, Webster L, Krämer T, Chadwick FM (2020) Dalton Trans 49:16653 Tomsu G, Stöger B, Kirchner K (2023) Organometallics 42:2999 Weng W, Yang L, Foxman BM, Ozerov OV (2004) Organometallics 23:4700 Brammell CM, Pelton EJ, Chen C-H, Yakovenko AA, Weng W, Foxman BM, Ozerov OV (2011) J Organomet Chem 696:4132 Liang LC, Chien PS, Hsiao YC, Li CW, Chang CH (2011) J Organomet Chem 696:3961 Fryzuk MD, Carter A, Rettig SJ (1992) Organometallics 11:469 Sietzen M, Batke S, Antoni PW, Wadepohl H, Ballmann J (2017) Dalton Trans 46:5816 Perrin DD, Armarego WLF (1988) Purification of Laboratory Chemicals, 3rd edn. Pergamon, New York Kessler JA, Iluc VM (2014) Inorg Chem 53:12360 Bruker computer programs (2020) APEX3, SAINT, SADABS. Bruker AXS Inc., Madison, WI) Sheldrick GM (2015) Acta Crystallogr A 71:3 Sheldrick GM (2015) Acta Crystallogr C 71:3 Macrae CF, Edgington PR, McCabe P, Pidcock E, Shields GP, Taylor R, Towler M, van de Streek J (2006) J Appl Cryst 39:453 Frisch MJ, Trucks GW, Schlegel HB, Scuseria GE, Robb MA, Cheeseman G Jr, Barone V, Mennucci B, Petersson GA, Nakatsuji H, Caricato M, Li X, Hratchian HP, Izmaylov AF, Bloino J, Zheng G, Sonnenberg JL, Hada M, Ehara M, Toyota K, Fukuda R, Hasegawa J, Ishida M, Nakajima T, Honda Y, Kitao O, Nakai H, Vreven T, Montgomery JA Jr, Peralta JE, Ogliaro F, Bearpark M, Heyd JJ, Brothers E, Kudin KN, Staroverov VN, Kobayashi R, Normand J, Raghavachari K, Rendell A, Burant JC, Iyengar SS, Tomasi J, Cossi M, Rega N, Millam JM, Klene M, Knox JE, Cross JB, Bakken V, Adamo C, Jaramillo J, Gomperts R, Stratmann RE, Yazyev O, Austin AJ, Cammi R, Pomelli C, Ochterski JW, Martin RL, Morokuma K, Zakrzewski VG, Voth GA, Salvador P, Dannenberg JJ, Dapprich S, Daniels AD, Farkas Ö, Foresman JB, Ortiz JV, Cioslowski J, Fox DJ (2009) Gaussian 09, revision A.02. Gaussian Inc., Wallingford. Scheme Schemes 1-7 are available in the Supplementary Files section. Supplementary Files Onlinefloatimage11.png Scheme17.docx Cite Share Download PDF Status: Published Journal Publication published 09 Feb, 2024 Read the published version in Monatshefte für Chemie - Chemical Monthly → Version 1 posted Reviewers invited by journal 02 Nov, 2023 Editor assigned by journal 02 Nov, 2023 First submitted to journal 01 Nov, 2023 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-3517952","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":245743930,"identity":"cd859c34-03f2-421d-8581-52bbe72c1d37","order_by":0,"name":"Gerald Tomsu","email":"","orcid":"","institution":"TU Wien: Technische Universitat Wien","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Gerald","middleName":"","lastName":"Tomsu","suffix":""},{"id":245743931,"identity":"510c386d-4085-480b-943a-f62a05a0d653","order_by":1,"name":"Berthold Stöger","email":"","orcid":"","institution":"TU Wien: Technische Universitat Wien","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Berthold","middleName":"","lastName":"Stöger","suffix":""},{"id":245743932,"identity":"2f016d22-122e-4868-9850-f9adca7f7698","order_by":2,"name":"Karl Anton Kirchner","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABEElEQVRIie2OsUrDQBiA/6NwU+DWPxTjK1wIpLr0WRoC7RJwVSiSLO2krhFFX6FTV08OziXVNYNDQOgcl4Ig4qWKBMzZ1eE+ODju7rvvB7BY/iEIQAQI3O4AjvXq7VagpRS8pdA/le8dmfHWnUFx56tKQHFwxK7O7l9Obt6jxUNPVTAdArtNO5W+M+ECSjzMnx9jf7Xk0ULSCQcVA6ruigdjPVaNnGMSuplWltIJEaie1aSw9Y8yeMuuG4VtED4E7BuUPjaV8qtCsnRboUhmArhBcXNdGRXIsUwCN1VBcCdpiNF57Phq1Kng05hUtTrlLE/813Tq7V1eyDXWm6HnSdGdafj9mz5xzO8tFovFsotPlWZakFvcRZkAAAAASUVORK5CYII=","orcid":"https://orcid.org/0000-0003-0872-6159","institution":"Vienna University of Technology: Technische Universitat Wien","correspondingAuthor":true,"submittingAuthor":false,"prefix":"","firstName":"Karl","middleName":"Anton","lastName":"Kirchner","suffix":""}],"badges":[],"createdAt":"2023-10-31 01:41:57","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-3517952/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-3517952/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s00706-024-03171-x","type":"published","date":"2024-02-09T15:01:37+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":46168421,"identity":"58ecc63a-e16d-4d47-ace2-c1a761497db3","added_by":"auto","created_at":"2023-11-09 16:23:51","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":37935,"visible":true,"origin":"","legend":"\u003cp\u003eStructural view of [Hf(PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003e\u003c/sup\u003e\u003csup\u003ePr\u003c/sup\u003e)(h\u003csup\u003e5\u003c/sup\u003e-Cp)(Cl)\u003csub\u003e2\u003c/sub\u003e] (\u003cstrong\u003e5\u003c/strong\u003e) showing 50\u0026nbsp;% thermal ellipsoids (H atoms are omitted for clarity). Selected bond lengths (Å) and bond angles (deg): Hf1-N1 2.237(7), Hf1-Cl2 2.484(2), Hf1-Cl1 2.485(3), Hf1-C22 2.51(1), Hf1-C23 2.54(1), Hf1-C21 2.54(1), Hf1-C19 2.54(1), Hf1-C20 2.55(1), Hf1-P1 2.751(2), Hf1-P2 2.771(3), Cl1-Hf1 Cl2 160.03(8), P1-Hf1-P2 139.39(7).\u003c/p\u003e","description":"","filename":"F1.png","url":"https://assets-eu.researchsquare.com/files/rs-3517952/v1/be6d650286a4166c636e2972.png"},{"id":46169053,"identity":"b7a86cfe-7d9d-46d6-b181-c4c566fa5b25","added_by":"auto","created_at":"2023-11-09 16:31:51","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":33143,"visible":true,"origin":"","legend":"\u003cp\u003eStructural view of [Hf(PNP\u003csup\u003eiPr\u003c/sup\u003e)(I)\u003csub\u003e3\u003c/sub\u003e] (\u003cstrong\u003e7\u003c/strong\u003e) showing 50\u0026nbsp;% thermal ellipsoids (H atoms are omitted for clarity). Selected bond lengths (Å) and bond angles (deg): Hf1-N1 2.143(6), Hf1-P1 2.737(1), Hf1-I1 2.8051(8), Hf1-I2 2.7922(4), P1-Hf1-P1 145.21(6), I2-Hf1-I2 175.57(2), I2-Hf1-I1 87.78(1), N1-Hf1-I1 180.0°.\u003c/p\u003e","description":"","filename":"F2.png","url":"https://assets-eu.researchsquare.com/files/rs-3517952/v1/33caa618997286b2248f6667.png"},{"id":46168416,"identity":"195c0b19-2e78-4b98-bfc8-0043ee5c1d03","added_by":"auto","created_at":"2023-11-09 16:23:51","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":48104,"visible":true,"origin":"","legend":"\u003cp\u003eDFT calculated structures of (a) [Ti(k\u003csup\u003e1\u003c/sup\u003e\u003cem\u003eN\u003c/em\u003e-PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003e\u003c/sup\u003e\u003csup\u003ePr\u003c/sup\u003e)(NMe\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e3\u003c/sub\u003e] (\u003cstrong\u003ek\u003c/strong\u003e\u003csup\u003e\u003cstrong\u003e1\u003c/strong\u003e\u003c/sup\u003e\u003cem\u003e\u003cstrong\u003eN\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e-10\u003c/strong\u003e), (b) [Ti(k\u003csup\u003e2\u003c/sup\u003e\u003cem\u003ePN\u003c/em\u003e-PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003e\u003c/sup\u003e\u003csup\u003ePr\u003c/sup\u003e)(NMe\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e3\u003c/sub\u003e] ((\u003cstrong\u003ek\u003c/strong\u003e\u003csup\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/sup\u003e\u003cem\u003e\u003cstrong\u003ePN\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e-10\u003c/strong\u003e), and (c) [Ti(k\u003csup\u003e3\u003c/sup\u003e\u003cem\u003ePNP\u003c/em\u003e-PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003e\u003c/sup\u003e\u003csup\u003ePr\u003c/sup\u003e)(NMe\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e3\u003c/sub\u003e] (\u003cstrong\u003ek\u003c/strong\u003e\u003csup\u003e\u003cstrong\u003e3\u003c/strong\u003e\u003c/sup\u003e\u003cem\u003e\u003cstrong\u003ePNP\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e-10\u003c/strong\u003e). Free energies in kJ/mol for [M(PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003e\u003c/sup\u003e\u003csup\u003ePr\u003c/sup\u003e)(NMe\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e3\u003c/sub\u003e] (M = Ti, Zr, Hf) featuring k\u003csup\u003e1\u003c/sup\u003e-, k\u003csup\u003e2\u003c/sup\u003e-, and k\u003csup\u003e3\u003c/sup\u003e-bound PNP ligands.\u003c/p\u003e","description":"","filename":"F3.png","url":"https://assets-eu.researchsquare.com/files/rs-3517952/v1/55f9a6d703f185b233053b87.png"},{"id":46168417,"identity":"b30aff5b-75b8-497d-8e26-0d7269f5c689","added_by":"auto","created_at":"2023-11-09 16:23:51","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":24916,"visible":true,"origin":"","legend":"\u003cp\u003eStructural view of [Ti(PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003e\u003c/sup\u003e\u003csup\u003ePr\u003c/sup\u003e)(Cl)\u003csub\u003e2\u003c/sub\u003e(NMe\u003csub\u003e2\u003c/sub\u003e)] (\u003cstrong\u003e11\u003c/strong\u003e) showing 50\u0026nbsp;% thermal ellipsoids (H atoms are omitted for clarity). Selected bond lengths (Å) and bond angles (deg): Ti1-N1 2.114(1), Ti1-N2 1.9390(1), Ti1-Cl1 2.3419(3), Ti1-P1 2.5877(4), Cl1-Ti1-Cl1 177.34(2), P1-Ti1-P1 150.85(2), N1-Ti1-N2. 180.0.\u003c/p\u003e","description":"","filename":"F4.png","url":"https://assets-eu.researchsquare.com/files/rs-3517952/v1/0b4a6e082578f527dee95515.png"},{"id":46169055,"identity":"f67b4490-f47c-4ac3-88dc-82c0aa3853f3","added_by":"auto","created_at":"2023-11-09 16:31:51","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":26265,"visible":true,"origin":"","legend":"\u003cp\u003eStructural view of [Zr(PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003e\u003c/sup\u003e\u003csup\u003ePr\u003c/sup\u003e)(Br)\u003csub\u003e4\u003c/sub\u003e][NH\u003csub\u003e2\u003c/sub\u003eMe\u003csub\u003e2\u003c/sub\u003e]×CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e (\u003cstrong\u003e12\u003c/strong\u003e×CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e) showing 50\u0026nbsp;% thermal ellipsoids (H atoms, the [NH\u003csub\u003e2\u003c/sub\u003eMe\u003csub\u003e2\u003c/sub\u003e]\u003csup\u003e+\u003c/sup\u003e cation and CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e are omitted for clarity). Selected bond lengths (Å) and bond angles (deg): Zr1-N1 2.251(4), Zr1-Br1 2.7763(7), Zr1-Br2 2.7352(7), Zr1-Br3 2.5865(7), Zr1-Br4 2.6323(7), Zr1-P1 2.772(1), Zr1-P2 2.785(1), Br3-Zr1-Br4 177.53(3), N1-Zr1-Br1 139.68(9), N1-Zr1-Br2 142.48(9), N1-Zr1-Br3 94.6(1) N1-Zr1-Br4 87.6(1) P1-Zr1-P2 135.33(4), Br2-Zr1-P1 148.96(3), Br1-Zr1-P2 150.87(3).\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e","description":"","filename":"F5.png","url":"https://assets-eu.researchsquare.com/files/rs-3517952/v1/4a438be31ccae4263c1c1e44.png"},{"id":51006130,"identity":"94ed679d-ecf8-4b0c-a805-9b424acaa2e9","added_by":"auto","created_at":"2024-02-12 15:14:00","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":831795,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3517952/v1/ea877697-a9ef-4786-82f0-ae04279965cf.pdf"},{"id":46169054,"identity":"f108daa1-c657-4416-a5ad-e6dff0808415","added_by":"auto","created_at":"2023-11-09 16:31:51","extension":"png","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":17039,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage11.png","url":"https://assets-eu.researchsquare.com/files/rs-3517952/v1/d44308998ecf2eb2c8da4dba.png"},{"id":46169056,"identity":"f30bf031-ec88-4875-9820-e22230b7d453","added_by":"auto","created_at":"2023-11-09 16:31:51","extension":"docx","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":249591,"visible":true,"origin":"","legend":"","description":"","filename":"Scheme17.docx","url":"https://assets-eu.researchsquare.com/files/rs-3517952/v1/89f800dedef44c2d20bf396e.docx"}],"financialInterests":"","formattedTitle":"Synthesis and characterization of pyrrole-based group 4 PNP pincer complexes","fulltext":[{"header":"Introduction","content":"\u003cp\u003eAmong the many types of transition metal complexes found in the chemical literature, pincer complexes play a particular role which have received tremendous attention for many decades [\u003cspan additionalcitationids=\"CR2 CR3 CR4 CR5 CR6 CR7 CR8 CR9 CR10 CR11 CR12 CR13 CR14 CR15 CR16\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. The possibility of their rational and modular design enables, for instance, the generation of highly active catalysts for a range of chemical transformations with high selectivity. PCP pincer complexes, where the ligands bear phosphine donors tethered \u003cem\u003evia\u003c/em\u003e CH\u003csub\u003e2\u003c/sub\u003e, O, or NR linkers to an aromatic anionic benzene backbone, are still one of the most common types. In the last couple of years pincer ligands which feature a monoanionic N-heterocyclic backbone, e.g., carbazole-, pyrrole- and acridane-scaffolds, connected to phosphine (amido diphosphine PNP pincer ligands) have become an increasingly important class of compounds [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Within the large class of amido diphosphines, we are interested in PNP pincer ligands which feature a central anionic pyrrole moiety connected \u003cem\u003evia\u003c/em\u003e CH\u003csub\u003e2\u003c/sub\u003e linkers to two phosphine donors. These ligands are designed to form five-membered chelates upon coordination to a metal ion. The first transition metal complexes containing pyrrole-based PNP ligands were reported in 2012 independently by the groups of Gade [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e], Mani [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e] and Tonzetich [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. Accordingly, a large number of transition metal complexes has been prepared to date using this class of ligand. With respect to group 4 metals pyrrole-based PNP pincer complexes are rare [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. We have recently described several Ti(IV) and Ti(III) PNP complexes [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e] which were shown to undergo ketone insertion reactions into a Ti(IV)-P bond thereby forming new complexes with tridendate PNO-ligands.\u003c/p\u003e \u003cp\u003eHerein we report on the synthesis, characterization and reactivity of pyrrole-based M(IV) (M\u0026thinsp;=\u0026thinsp;Ti, Zr, Hf) PNP pincer complexes. Representative X-Ray structures and DFT calculations are presented.\u003c/p\u003e"},{"header":"Results and Discussion","content":"\u003cp\u003eWe have recently shown [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e] that [P(NH)P-\u003cem\u003ei\u003c/em\u003ePr] (\u003cb\u003e1\u003c/b\u003e) reacts with [TiCl\u003csub\u003e4\u003c/sub\u003e(THF)\u003csub\u003e2\u003c/sub\u003e] in the presence of base to yield the Ti(IV) complex [Ti(PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003ePr\u003c/sup\u003e)(Cl)\u003csub\u003e3\u003c/sub\u003e] (\u003cb\u003e2\u003c/b\u003e). If the same reaction is performed with [MCl\u003csub\u003e4\u003c/sub\u003e(THF)\u003csub\u003e2\u003c/sub\u003e] (M\u0026thinsp;=\u0026thinsp;Zr, Hf), instead of monomeric analogs, the dimeric complexes [Zr(PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003ePr\u003c/sup\u003e)(\u0026micro;-Cl)(Cl)\u003csub\u003e2\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003e (\u003cb\u003e2\u003c/b\u003e) and [Hf(PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003ePr\u003c/sup\u003e)(\u0026micro;-Cl)(Cl)\u003csub\u003e2\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003e (\u003cb\u003e3\u003c/b\u003e) featuring two bridging chloride ligands are obtained in 76 and 80% isolated yields (Scheme \u003cspan refid=\"Sch1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Noteworthy, the analogous zirconium complex featuring the bulkier PNP\u003csup\u003etBu\u003c/sup\u003e ligand was reported by Nishibayashi and coworkers [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. Complexes \u003cb\u003e2\u003c/b\u003e and \u003cb\u003e3\u003c/b\u003e were characterized \u003csup\u003e1\u003c/sup\u003eH, \u003csup\u003e13\u003c/sup\u003eC{\u003csup\u003e1\u003c/sup\u003eH}, and \u003csup\u003e31\u003c/sup\u003eP{\u003csup\u003e1\u003c/sup\u003eH} NMR spectroscopy and elemental analysis. These complexes are highly symmetric as they display singlets at 40.2 and 42.8 ppm, respectively, in the \u003csup\u003e31\u003c/sup\u003eP{\u003csup\u003e1\u003c/sup\u003eH} NMR spectrum. Likewise, in the \u003csup\u003e1\u003c/sup\u003eH NMR spectrum the pyrrole hydrogen atoms give rise to singlets at 5.85 (2H) and 5.86 (2H) ppm. In the \u003csup\u003e13\u003c/sup\u003eC{\u003csup\u003e1\u003c/sup\u003eH} NMR spectrum, the pyrrole carbons exhibit singlets at 138.3 and 137.9 ppm and 107.2 and 107.7 ppm assignable to the quaternary and tertiary carbon atoms, respectively.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eReactions of [Zr(PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003ePr\u003c/sup\u003e)(\u0026micro;-Cl)(Cl)\u003csub\u003e2\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003e (\u003cb\u003e2\u003c/b\u003e) and [Hf(PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003ePr\u003c/sup\u003e)(\u0026micro;-Cl)(Cl)\u003csub\u003e2\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003e (\u003cb\u003e3\u003c/b\u003e) with 1 equiv of sodium cyclopentadienyl (CpNa) in THF at room temperature gives the corresponding mononuclear complexes [M(PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003ePr\u003c/sup\u003e)(η\u003csup\u003e5\u003c/sup\u003e-Cp)(Cl)\u003csub\u003e2\u003c/sub\u003e] (M\u0026thinsp;=\u0026thinsp;Zr (\u003cb\u003e4\u003c/b\u003e), Hf (\u003cb\u003e5\u003c/b\u003e)) in 90% and 93% yields, respectively(Scheme \u003cspan refid=\"Sch2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). These complexes were characterized by \u003csup\u003e1\u003c/sup\u003eH, \u003csup\u003e13\u003c/sup\u003eC{\u003csup\u003e1\u003c/sup\u003eH}, and \u003csup\u003e31\u003c/sup\u003eP{\u003csup\u003e1\u003c/sup\u003eH} NMR spectroscopy. In the \u003csup\u003e1\u003c/sup\u003eH NMR spectrum the Cp ligands of \u003cb\u003e4\u003c/b\u003e and \u003cb\u003e5\u003c/b\u003e exhibits triplet resonances at 6.70 (\u003cem\u003eJ\u003c/em\u003e\u003csub\u003e\u003cem\u003eHP\u003c/em\u003e\u003c/sub\u003e = 1.2 Hz) and 6.40 ppm (\u003cem\u003eJ\u003c/em\u003e\u003csub\u003e\u003cem\u003eHP\u003c/em\u003e\u003c/sub\u003e = 1.1 Hz), respectively. In the \u003csup\u003e13\u003c/sup\u003eC{\u003csup\u003e1\u003c/sup\u003eH} NMR spectrum the Cp rings give rise to signals at 115.6 and 114.0 ppm. The molecular structure of \u003cb\u003e5\u003c/b\u003e was confirmed by X-ray analysis. In addition, a structural view is shown in Fig.\u0026nbsp;1 with selected bond distances and angles reported in the caption. This complex adopts a five-legged piano-stool geometry around the hafnium center with the P, N, P atoms of the pyrrole moiety and the two chloride ligands as the legs. The analogous Zr complex with a PNP\u003csup\u003etBu\u003c/sup\u003e ligand was reported recently [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cb\u003eFigure 1.\u003c/b\u003e Structural view of [Hf(PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003ePr\u003c/sup\u003e)(η\u003csup\u003e5\u003c/sup\u003e-Cp)(Cl)\u003csub\u003e2\u003c/sub\u003e] (\u003cb\u003e5\u003c/b\u003e) showing 50% thermal ellipsoids (H atoms are omitted for clarity). Selected bond lengths (\u0026Aring;) and bond angles (deg): Hf1-N1 2.237(7), Hf1-Cl2 2.484(2), Hf1-Cl1 2.485(3), Hf1-C22 2.51(1), Hf1-C23 2.54(1), Hf1-C21 2.54(1), Hf1-C19 2.54(1), Hf1-C20 2.55(1), Hf1-P1 2.751(2), Hf1-P2 2.771(3), Cl1-Hf1 Cl2 160.03(8), P1-Hf1-P2 139.39(7).\u003c/p\u003e \u003cp\u003eTreatment of a solution of [Zr(PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003ePr\u003c/sup\u003e)(\u0026micro;-Cl)(Cl)\u003csub\u003e2\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003e (\u003cb\u003e2\u003c/b\u003e) and [Hf(PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003ePr\u003c/sup\u003e)(\u0026micro;-Cl)(Cl)\u003csub\u003e2\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003e (\u003cb\u003e3\u003c/b\u003e) in toluene at room temperature with an excess of SiMe\u003csub\u003e3\u003c/sub\u003eI afforded, after workup, the triiodide complexes [Zr(PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003ePr\u003c/sup\u003e)(I)\u003csub\u003e3\u003c/sub\u003e] (\u003cb\u003e6\u003c/b\u003e) and [Hf(PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003ePr\u003c/sup\u003e)(I)\u003csub\u003e3\u003c/sub\u003e] (\u003cb\u003e7\u003c/b\u003e) in 87 and 87%, respectively, isolated yields (Scheme \u003cspan refid=\"Sch3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). Crystals suitable for X-Ray diffraction were obtained by layering a saturated CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e solution of \u003cb\u003e7\u003c/b\u003e with \u003cem\u003en\u003c/em\u003e-pentane. The solid-state structure of \u003cb\u003e7\u003c/b\u003e was established by single-crystal X-ray diffraction. A molecular view is depicted in Fig.\u0026nbsp;1 with selected bond distances given in the captions. This complex has a distorted octahedral geometry with bond angles of 175.57(2)\u0026deg; (I1-Hf1-I2), 180.0\u0026deg; (N1-Hf1-I1) and 145.21(6)\u0026deg; (P1-Hf1-P1).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cb\u003eFigure 2.\u003c/b\u003e Structural view of [Hf(PNP\u003csup\u003eiPr\u003c/sup\u003e)(I)\u003csub\u003e3\u003c/sub\u003e] (\u003cb\u003e7\u003c/b\u003e) showing 50% thermal ellipsoids (H atoms are omitted for clarity). Selected bond lengths (\u0026Aring;) and bond angles (deg): Hf1-N1 2.143(6), Hf1-P1 2.737(1), Hf1-I1 2.8051(8), Hf1-I2 2.7922(4), P1-Hf1-P1 145.21(6), I2-Hf1-I2 175.57(2), I2-Hf1-I1 87.78(1), N1-Hf1-I1 180.0\u0026deg;.\u003c/p\u003e \u003cp\u003eComplexes [Zr(PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003ePr\u003c/sup\u003e)(I)\u003csub\u003e3\u003c/sub\u003e] (\u003cb\u003e6\u003c/b\u003e) and [Hf(PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003ePr\u003c/sup\u003e)(I)\u003csub\u003e3\u003c/sub\u003e] (\u003cb\u003e7\u003c/b\u003e) are readily alkylated with MeMgBr affording [Zr(PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003ePr\u003c/sup\u003e)(Me)\u003csub\u003e3\u003c/sub\u003e] (\u003cb\u003e8\u003c/b\u003e) and [Hf(PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003ePr\u003c/sup\u003e)(Me)\u003csub\u003e3\u003c/sub\u003e] (\u003cb\u003e9\u003c/b\u003e) in 80 and 82% isolated yields (Scheme \u003cspan refid=\"Sch4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). These complexes again were characterized by \u003csup\u003e1\u003c/sup\u003eH, \u003csup\u003e13\u003c/sup\u003eC{\u003csup\u003e1\u003c/sup\u003eH}, and \u003csup\u003e31\u003c/sup\u003eP{\u003csup\u003e1\u003c/sup\u003eH} NMR spectroscopy and elemental analysis. The Zr and Hf-bound methyl groups of \u003cb\u003e8\u003c/b\u003e and \u003cb\u003e9\u003c/b\u003e give rise to one triplet resonance at 1.04 (\u003cem\u003eJ\u003c/em\u003e\u003csub\u003e\u003cem\u003eHP\u003c/em\u003e\u003c/sub\u003e = 3.8 Hz) and 0.74 ppm (\u003cem\u003eJ\u003c/em\u003e\u003csub\u003e\u003cem\u003eHP\u003c/em\u003e\u003c/sub\u003e = 3.9 Hz), respectively, in the \u003csup\u003e1\u003c/sup\u003eH NMR spectrum. In the \u003csup\u003e13\u003c/sup\u003eC{\u003csup\u003e1\u003c/sup\u003eH} spectrum, corresponding resonances at 60.6 and 59.4 ppm were observed. The equivalence of the three methyl groups is analogous to the observations for [M(PNP)(Me)\u003csub\u003e3\u003c/sub\u003e] (PNP\u0026thinsp;=\u0026thinsp;N(C\u003csub\u003e6\u003c/sub\u003eH\u003csub\u003e3\u003c/sub\u003e-o-Me-2-P\u003cem\u003ei\u003c/em\u003ePr\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e and N(o-C\u003csub\u003e6\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e-2-P\u003cem\u003ei\u003c/em\u003ePr\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e, M\u0026thinsp;=\u0026thinsp;Zr, Hf) [\u003cspan additionalcitationids=\"CR26\" citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e] and [Hf(PNP)(Me)\u003csub\u003e3\u003c/sub\u003e] (PNP\u0026thinsp;=\u0026thinsp;N(SiMe\u003csub\u003e2\u003c/sub\u003eCH\u003csub\u003e2\u003c/sub\u003ePR\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e, R\u0026thinsp;=\u0026thinsp;Me, \u003cem\u003ei\u003c/em\u003ePr, \u003cem\u003et\u003c/em\u003eBu) [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e] which is indicative of exchange among the methyl group sites that is rapid on the NMR timescale at ambient temperature.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eNo static geometry can result in equivalent methyl groups in \u003cb\u003e8\u003c/b\u003e and \u003cb\u003e9\u003c/b\u003e. This can be seen from the DFT calculated structure of [Zr(PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003ePr\u003c/sup\u003e)(Me)\u003csub\u003e3\u003c/sub\u003e] (\u003cb\u003e8\u003c/b\u003e) depicted in Scheme \u003cspan refid=\"Sch4\" class=\"InternalRef\"\u003e4\u003c/span\u003e. The coordination environment about Zr in \u003cb\u003e8\u003c/b\u003e can be described as a bicapped tetrahedron, with the two neutral P donors capping the faces of the N-Zr-Me\u003csub\u003e3\u003c/sub\u003e tetrahedron. The \u003csup\u003e1\u003c/sup\u003eH and \u003csup\u003e13\u003c/sup\u003eC chemical shifts exhibited by the Me groups of \u003cb\u003e8\u003c/b\u003e and \u003cb\u003e9\u003c/b\u003e are comparable to those previously reported in similar compounds. For example, Ozerov\u0026rsquo;s and Liang\u0026rsquo;s [M(PNP)(Me)\u003csub\u003e3\u003c/sub\u003e] (M\u0026thinsp;=\u0026thinsp;Zr, Hf) and Fryzuk\u0026rsquo;s [Hf(PNP)(Me)\u003csub\u003e3\u003c/sub\u003e] compounds resonate in their \u003csup\u003e1\u003c/sup\u003eH NMR spectra in the 0.5\u0026ndash;0.9 ppm range [\u003cspan additionalcitationids=\"CR26 CR27\" citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAnother strategy to afford Ti(IV) PNP complexes is the utilization of the amido-precursor [Ti(NMe\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e]. The targeted amido complex [Ti(PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003ePr\u003c/sup\u003e)(NMe\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e3\u003c/sub\u003e] (\u003cb\u003e10\u003c/b\u003e) was considered to allow more functionalization possibilities in contrast to the above halide congeners. After stirring a solution of [P(NH)P-\u003cem\u003ei\u003c/em\u003ePr] (\u003cb\u003e1\u003c/b\u003e) and 1 equiv of [Ti(NMe\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e] in toluene at 80\u0026deg;C for 48 h, after workup, an amido complex tentatively assigned as [Ti(PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003ePr\u003c/sup\u003e)(NMe\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e3\u003c/sub\u003e] (\u003cb\u003e10\u003c/b\u003e) was isolated as red oil in quantitative yield (Scheme \u003cspan refid=\"Sch5\" class=\"InternalRef\"\u003e5\u003c/span\u003e). The \u003csup\u003e1\u003c/sup\u003eH, \u003csup\u003e13\u003c/sup\u003eC{\u003csup\u003e1\u003c/sup\u003eH}, and \u003csup\u003e31\u003c/sup\u003eP{\u003csup\u003e1\u003c/sup\u003eH} NMR spectra of \u003cb\u003e10\u003c/b\u003e revealed that this complex is highly symmetric in solution which is not in agreement with [Ti(PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003ePr\u003c/sup\u003e)(NMe\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e3\u003c/sub\u003e] (\u003cb\u003e10\u003c/b\u003e) with the PNP ligand coordinated in κ\u003csup\u003e3\u003c/sup\u003e\u003cem\u003ePNP\u003c/em\u003e-fashion. Singlet resonances were observed for the dimethylamido groups in the \u003csup\u003e1\u003c/sup\u003eH and \u003csup\u003e13\u003c/sup\u003eC{\u003csup\u003e1\u003c/sup\u003eH} NMR spectra at 3.14 and 44.6 ppm, respectively. Likewise, in the \u003csup\u003e31\u003c/sup\u003eP{\u003csup\u003e1\u003c/sup\u003eH} NMR spectrum a singlet resonance is found at 6.2 ppm. The chemical equivalence of the NMe\u003csub\u003e2\u003c/sub\u003e substituents and the phosphine moieties can be rationalized by isomerization reactions involving P-metal bond dissociation reactions. For titanium, DFT calculations revealed that the most stable species is [Ti(κ\u003csup\u003e1\u003c/sup\u003e\u003cem\u003eN\u003c/em\u003e- PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003ePr\u003c/sup\u003e)(NMe\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e3\u003c/sub\u003e] (\u003cb\u003eκ\u003c/b\u003e\u003csup\u003e\u003cb\u003e1\u003c/b\u003e\u003c/sup\u003e\u003cb\u003eN\u003c/b\u003e\u003cb\u003e-10\u003c/b\u003e)\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003efeaturing a κ\u003csup\u003e1\u003c/sup\u003e\u003cem\u003eN\u003c/em\u003e-bound PNP ligand (Fig.\u0026nbsp;3). This compound is more stable by 36.6 and 87.5 kJ/mol, respectively, than the corresponding complexes with the PNP ligand being coordinated in κ\u003csup\u003e2\u003c/sup\u003e\u003cem\u003ePN\u003c/em\u003e- and κ\u003csup\u003e3\u003c/sup\u003e\u003cem\u003ePNP\u003c/em\u003e-fashion. This finding may suggest a fast equilibrium\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"No\" id=\"Taba\" border=\"1\"\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eM\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eM(κ\u003csup\u003e1\u003c/sup\u003e\u003cem\u003eN\u003c/em\u003e-PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003ePr\u003c/sup\u003e)(NMe\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e3\u003c/sub\u003e]\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eM(κ\u003csup\u003e2\u003c/sup\u003e\u003cem\u003ePN\u003c/em\u003e-PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003ePr\u003c/sup\u003e)(NMe\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e3\u003c/sub\u003e]\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eM(κ\u003csup\u003e3\u003c/sup\u003e\u003cem\u003ePNP\u003c/em\u003e-PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003ePr\u003c/sup\u003e)(NMe\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e3\u003c/sub\u003e]\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTi\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e35.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e87.5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eZr\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e-2.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4.3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHf\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e-6.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e8.6\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cb\u003eFigure 3.\u003c/b\u003e DFT calculated structures of (a) [Ti(κ\u003csup\u003e1\u003c/sup\u003e\u003cem\u003eN\u003c/em\u003e-PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003ePr\u003c/sup\u003e)(NMe\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e3\u003c/sub\u003e] (\u003cb\u003eκ\u003c/b\u003e\u003csup\u003e\u003cb\u003e1\u003c/b\u003e\u003c/sup\u003e\u003cb\u003eN\u003c/b\u003e\u003cb\u003e-10\u003c/b\u003e), (b) [Ti(κ\u003csup\u003e2\u003c/sup\u003e\u003cem\u003ePN\u003c/em\u003e-PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003ePr\u003c/sup\u003e)(NMe\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e3\u003c/sub\u003e] ((\u003cb\u003eκ\u003c/b\u003e\u003csup\u003e\u003cb\u003e2\u003c/b\u003e\u003c/sup\u003e\u003cb\u003ePN\u003c/b\u003e\u003cb\u003e-10\u003c/b\u003e), and (c) [Ti(κ\u003csup\u003e3\u003c/sup\u003e\u003cem\u003ePNP\u003c/em\u003e-PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003ePr\u003c/sup\u003e)(NMe\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e3\u003c/sub\u003e] (\u003cb\u003eκ\u003c/b\u003e\u003csup\u003e\u003cb\u003e3\u003c/b\u003e\u003c/sup\u003e\u003cb\u003ePNP\u003c/b\u003e\u003cb\u003e-10\u003c/b\u003e). Free energies in kJ/mol for [M(PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003ePr\u003c/sup\u003e)(NMe\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e3\u003c/sub\u003e] (M\u0026thinsp;=\u0026thinsp;Ti, Zr, Hf) featuring κ\u003csup\u003e1\u003c/sup\u003e-, κ\u003csup\u003e2\u003c/sup\u003e-, and κ\u003csup\u003e3\u003c/sup\u003e-bound PNP ligands.\u003c/p\u003e \u003cp\u003ebetween \u003cb\u003eκ\u003c/b\u003e\u003csup\u003e\u003cb\u003e1\u003c/b\u003e\u003c/sup\u003e\u003cb\u003eN\u003c/b\u003e\u003cb\u003e-10\u003c/b\u003e and \u003cb\u003eκ\u003c/b\u003e\u003csup\u003e\u003cb\u003e2\u003c/b\u003e\u003c/sup\u003e\u003cb\u003ePN\u003c/b\u003e\u003cb\u003e-10\u003c/b\u003e in solution, whereas the formation of \u003cb\u003eκ\u003c/b\u003e\u003csup\u003e\u003cb\u003e3\u003c/b\u003e\u003c/sup\u003e\u003cb\u003ePNP-\u003c/b\u003e\u003cb\u003e10\u003c/b\u003e seems to be unlikely. For comparison, in the case of Zr and Hf the energies of all three species are similar and may thus be in equilibrium with one another (Fig.\u0026nbsp;3). In fact, such a behavior was observed recently by Ballman and co-workers for [M(PNP)(NMe\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e3\u003c/sub\u003e] (PNP\u0026thinsp;=\u0026thinsp;N(CH\u003csub\u003e2\u003c/sub\u003e-o-C\u003csub\u003e6\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003ePPh\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e and N(C\u003csub\u003e6\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e-\u003cem\u003eo\u003c/em\u003e-CH\u003csub\u003e2\u003c/sub\u003ePPh\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e), M\u0026thinsp;=\u0026thinsp;Zr, Hf). In addition, they were able to structurally characterize a κ\u003csup\u003e2\u003c/sup\u003e\u003cem\u003ePN\u003c/em\u003e-bound hafnium complex [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eInterestingly, when [P(NH)P-\u003cem\u003ei\u003c/em\u003ePr] (\u003cb\u003e1\u003c/b\u003e) was reacted with 2 equivs of [Ti(NMe\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e] in CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e at 40\u0026deg;C complex [Ti(PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003ePr\u003c/sup\u003e)(Cl)\u003csub\u003e2\u003c/sub\u003e(NMe\u003csub\u003e2\u003c/sub\u003e)] (\u003cb\u003e11\u003c/b\u003e) was obtained in 92% isolated yield (Scheme \u003cspan refid=\"Sch7\" class=\"InternalRef\"\u003e7\u003c/span\u003e). This complex was fully characterized by \u003csup\u003e1\u003c/sup\u003eH, \u003csup\u003e13\u003c/sup\u003eC{\u003csup\u003e1\u003c/sup\u003eH}, and \u003csup\u003e31\u003c/sup\u003eP{\u003csup\u003e1\u003c/sup\u003eH} NMR spectroscopy and elemental analysis. Additionally, the molecular structure of \u003cb\u003e11\u003c/b\u003e was confirmed by X-ray analysis. A structural view is shown in Fig.\u0026nbsp;4 with selected bond distances and angles reported in the caption. The coordination geometry around the titanium center corresponds to a slightly distorted octahedron where the PNP ligand and the amide ligand define the equatorial plane and the two chloride ligands the axial positions. The two Ti-N bonds exhibit different bond distances being 2.114(1) \u0026Aring; for Ti1-N1 and 1.9390(1) \u0026Aring; Ti1-N2 which may be attributed to the fact that the dimethylamido ligand is both a stronger σ and π-donor than the nitrogen atom of the pyrrole moiety.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cb\u003eFigure 4.\u003c/b\u003e Structural view of [Ti(PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003ePr\u003c/sup\u003e)(Cl)\u003csub\u003e2\u003c/sub\u003e(NMe\u003csub\u003e2\u003c/sub\u003e)] (\u003cb\u003e11\u003c/b\u003e) showing 50% thermal ellipsoids (H atoms are omitted for clarity). Selected bond lengths (\u0026Aring;) and bond angles (deg): Ti1-N1 2.114(1), Ti1-N2 1.9390(1), Ti1-Cl1 2.3419(3), Ti1-P1 2.5877(4), Cl1-Ti1-Cl1 177.34(2), P1-Ti1-P1 150.85(2), N1-Ti1-N2. 180.0.\u003c/p\u003e \u003cp\u003eTreatment of a solution of [P(NH)P-\u003cem\u003ei\u003c/em\u003ePr] (\u003cb\u003e1\u003c/b\u003e) and [Zr(NMe\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e] (1 equiv) in toluene at 120\u0026deg;C for 72 h and subsequent addition of SiMe\u003csub\u003e3\u003c/sub\u003eBr (3.5 equiv) at room temperature afforded, after workup, the anionic seven coordinate tetrabromo complex [Zr(PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003ePr\u003c/sup\u003e)(Br)\u003csub\u003e4\u003c/sub\u003e][H\u003csub\u003e2\u003c/sub\u003eNMe\u003csub\u003e2\u003c/sub\u003e] (\u003cb\u003e13\u003c/b\u003e) in 80% yield (Scheme \u003cspan refid=\"Sch7\" class=\"InternalRef\"\u003e7\u003c/span\u003e). The corresponding hafnium complex [Hf(PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003ePr\u003c/sup\u003e)(Br)\u003csub\u003e4\u003c/sub\u003e][H\u003csub\u003e2\u003c/sub\u003eNEt\u003csub\u003e2\u003c/sub\u003e] (\u003cb\u003e14\u003c/b\u003e) was obtained in similar fashion by utilizing [Hf(NEt\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e] as metal precursor. These complexes are very air and moister sensitive. It has to be noted that, according to our knowledge, monomeric seven coordinate group 4 metal pincer complexes are unknown. In addition to the NMR spectroscopic characterization, the solid-state structure of \u003cb\u003e13\u003c/b\u003e was determined by X-ray crystallography. A molecular view is depicted in Fig.\u0026nbsp;5 with selected bond distances given in the caption. The coordination sphere of the seven-coordinate Zr(IV) center may be described as a distorted pentagonal bipyramidal geometry.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cb\u003eFigure 5.\u003c/b\u003e Structural view of [Zr(PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003ePr\u003c/sup\u003e)(Br)\u003csub\u003e4\u003c/sub\u003e][NH\u003csub\u003e2\u003c/sub\u003eMe\u003csub\u003e2\u003c/sub\u003e]\u0026sdot;CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e (\u003cb\u003e12\u003c/b\u003e\u0026sdot;CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e) showing 50% thermal ellipsoids (H atoms, the [NH\u003csub\u003e2\u003c/sub\u003eMe\u003csub\u003e2\u003c/sub\u003e]\u003csup\u003e+\u003c/sup\u003e cation and CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e are omitted for clarity). Selected bond lengths (\u0026Aring;) and bond angles (deg): Zr1-N1 2.251(4), Zr1-Br1 2.7763(7), Zr1-Br2 2.7352(7), Zr1-Br3 2.5865(7), Zr1-Br4 2.6323(7), Zr1-P1 2.772(1), Zr1-P2 2.785(1), Br3-Zr1-Br4 177.53(3), N1-Zr1-Br1 139.68(9), N1-Zr1-Br2 142.48(9), N1-Zr1-Br3 94.6(1) N1-Zr1-Br4 87.6(1) P1-Zr1-P2 135.33(4), Br2-Zr1-P1 148.96(3), Br1-Zr1-P2 150.87(3).\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eIn sum, we described the synthesis and reactivity of several new group 4 metal complexes containing a central anionic pyrrole moiety connected \u003cem\u003evia\u003c/em\u003e CH\u003csub\u003e2\u003c/sub\u003e-linkers to two \u003cem\u003ei\u003c/em\u003ePr donors. As starting materials [MCl\u003csub\u003e4\u003c/sub\u003e(THF)\u003csub\u003e2\u003c/sub\u003e] (M\u0026thinsp;=\u0026thinsp;Zr, Hf) and [M(NMe\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e] (M\u0026thinsp;=\u0026thinsp;Ti, Zr) as well as [Hf(NEt\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e] were utilized. Treatment of [P(NH)P-\u003cem\u003ei\u003c/em\u003ePr] with in the presence of base to yields the dimeric complexes [M(PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003ePr\u003c/sup\u003e)(\u0026micro;-Cl)(Cl)\u003csub\u003e2\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003e (M\u0026thinsp;=\u0026thinsp;Zr, Hf) featuring bridging chloride ligands. These dimeric complexes are precursors for several monomeric group 4 complexes including [M(PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003ePr\u003c/sup\u003e)(η\u003csup\u003e5\u003c/sup\u003e-Cp)(Cl)\u003csub\u003e2\u003c/sub\u003e] and [M(PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003ePr\u003c/sup\u003e)(I)\u003csub\u003e3\u003c/sub\u003e]. The latter react with MeMgBr to give trialkyl complexes of the type [M(PNP\u003csup\u003eiPr\u003c/sup\u003e)(Me)\u003csub\u003e3\u003c/sub\u003e]. Interestingly, if [P(NH)P-\u003cem\u003ei\u003c/em\u003ePr] is reacted with [M(NMe\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e] (M\u0026thinsp;=\u0026thinsp;Ti, Zr) and [Hf(NEt\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e] complexes of the type [M(PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003ePr\u003c/sup\u003e)(NMe\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e3\u003c/sub\u003e] and [Hf(PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003ePr\u003c/sup\u003e)(NEt\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e3\u003c/sub\u003e] were obtained. DFT calculations revealed that the most stable species is [Ti(κ\u003csup\u003e1\u003c/sup\u003e\u003cem\u003eN\u003c/em\u003e- PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003ePr\u003c/sup\u003e)(NMe\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e3\u003c/sub\u003e] featuring a κ\u003csup\u003e1\u003c/sup\u003e\u003cem\u003eN\u003c/em\u003e-bound PNP ligand. In solution, there is a fast equilibrium between complexes where the PNP ligand is coordinated in κ\u003csup\u003e1\u003c/sup\u003e\u003cem\u003eN\u003c/em\u003e- and κ\u003csup\u003e2\u003c/sup\u003e\u003cem\u003ePN\u003c/em\u003e-fashion. The formation of a species where the PNP ligand is coordinated in κ\u003csup\u003e3\u003c/sup\u003e\u003cem\u003ePNP-\u003c/em\u003efashion seems unlikely. On the other hand, in the case of Zr and Hf, the energies of all three species are similar and may thus be in equilibrium with one another. Finally, if a solution of [P(NH)P-\u003cem\u003ei\u003c/em\u003ePr] and [Zr(NMe\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e] was treated with SiMe\u003csub\u003e3\u003c/sub\u003eBr the anionic seven-coordinate tetrabromo complex [Zr(PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003ePr\u003c/sup\u003e)(Br)\u003csub\u003e4\u003c/sub\u003e][H\u003csub\u003e2\u003c/sub\u003eNMe\u003csub\u003e2\u003c/sub\u003e]. The corresponding hafnium complex [Hf(PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003ePr\u003c/sup\u003e)(Br)\u003csub\u003e4\u003c/sub\u003e][H\u003csub\u003e2\u003c/sub\u003eNEt\u003csub\u003e2\u003c/sub\u003e] was obtained in similar fashion by utilizing [Hf(NEt\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e] as metal precursor.\u003c/p\u003e "},{"header":"EXPERIMENTAL","content":"\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003cp\u003eAll manipulations were performed under an inert atmosphere of argon by using Schlenk techniques or in an MBraun inert-gas glovebox. The solvents were purified according to standard procedures [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e] The deuterated solvents were purchased from Eurisotop SAS and dried over 4 \u0026Aring; molecular sieves. The ligand precursor [P(NH)P-\u003cem\u003ei\u003c/em\u003ePr] (\u003cb\u003e1\u003c/b\u003e) (2,5-Bis[[bis(1-methylethyl)phosphino]methyl]-1\u003cem\u003eH\u003c/em\u003e-pyrrole) was prepared according to the literature [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. All other starting materials are known compounds and were used as obtained from commercial sources. \u003csup\u003e1\u003c/sup\u003eH, \u003csup\u003e13\u003c/sup\u003eC{\u003csup\u003e1\u003c/sup\u003eH}, and \u003csup\u003e31\u003c/sup\u003eP{\u003csup\u003e1\u003c/sup\u003eH} NMR spectra were recorded on Bruker AVANCE-250, AVANCE-400 and AVANCE-600 spectrometers. \u003csup\u003e1\u003c/sup\u003eH and \u003csup\u003e13\u003c/sup\u003eC{\u003csup\u003e1\u003c/sup\u003eH} NMR spectra were referenced internally to residual protio-solvent and solvent resonances, respectively, and are reported relative to tetramethylsilane (δ\u0026thinsp;=\u0026thinsp;0 ppm). \u003csup\u003e31\u003c/sup\u003eP{\u003csup\u003e1\u003c/sup\u003eH} NMR spectra were referenced externally to H\u003csub\u003e3\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e (85%) (δ\u0026thinsp;=\u0026thinsp;0 ppm).\u003c/p\u003e \u003cp\u003e \u003cb\u003eSynthesis of Bis-[2,5-bis[[bis(1-methylethyl)phosphino-κ\u003c/b\u003e \u003csup\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sup\u003e \u003cb\u003eP\u003c/b\u003e \u003cb\u003e]methyl]-1\u003c/b\u003e \u003cb\u003eH\u003c/b\u003e \u003cb\u003e-pyrrolato-κ\u003c/b\u003e \u003cb\u003eN\u003c/b\u003e \u003cb\u003e](\u0026micro;-chloro)(dichloro)zirconium(IV)], [Zr(PNP\u003c/b\u003e \u003csup\u003e \u003cb\u003ei\u003c/b\u003e \u003cb\u003ePr\u003c/b\u003e \u003c/sup\u003e \u003cb\u003e)(\u0026micro;-Cl)(Cl)\u003c/b\u003e \u003csub\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sub\u003e \u003cb\u003e]\u003c/b\u003e \u003csub\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sub\u003e \u003cb\u003e(2, C\u003c/b\u003e\u003csub\u003e\u003cb\u003e36\u003c/b\u003e\u003c/sub\u003e\u003cb\u003eH\u003c/b\u003e\u003csub\u003e\u003cb\u003e68\u003c/b\u003e\u003c/sub\u003e\u003cb\u003eCl\u003c/b\u003e\u003csub\u003e\u003cb\u003e6\u003c/b\u003e\u003c/sub\u003e\u003cb\u003eN\u003c/b\u003e\u003csub\u003e\u003cb\u003e2\u003c/b\u003e\u003c/sub\u003e\u003cb\u003eP\u003c/b\u003e\u003csub\u003e\u003cb\u003e4\u003c/b\u003e\u003c/sub\u003e\u003cb\u003eZr\u003c/b\u003e\u003csub\u003e\u003cb\u003e2\u003c/b\u003e\u003c/sub\u003e\u003cb\u003e)\u003c/b\u003e A solution of [P(NH)P-\u003cem\u003ei\u003c/em\u003ePr] (\u003cb\u003e1\u003c/b\u003e) (200 mg, 0.61 mmol) in THF (8 cm\u003csup\u003e3\u003c/sup\u003e) was treated with \u003cem\u003en\u003c/em\u003eBuLi (419 \u0026micro;L, 1.6 M in \u003cem\u003en\u003c/em\u003e-hexane, 0.67 mmol, 1.1 equiv.) at -78\u0026deg;C. After stirring for 30 min at this temperature the reaction mixture was allowed to reach room temperature and stirred for further 30 min and [ZrCl\u003csub\u003e4\u003c/sub\u003e(THF)\u003csub\u003e2\u003c/sub\u003e] (219 mg, 0.58 mmol, 0.95 equiv.) was added. Upon stirring for 1 h, all volatiles were removed under reduced pressure and the orange oily residue was redissolved in toluene (10 cm\u003csup\u003e3\u003c/sup\u003e). The orange solution was filtered through a syringe filter (PTFE, 0.2 \u0026micro;m), which was washed with toluene (2 x 8 cm\u003csup\u003e3\u003c/sup\u003e). After evaporation of the solvent, the residue was washed with \u003cem\u003en\u003c/em\u003e-pentane (3 x 10 cm\u003csup\u003e3\u003c/sup\u003e) until the washing phase was colorless. The product was obtained as beige powder. Yield: 230 mg ( 76%). \u003csup\u003e1\u003c/sup\u003eH NMR (400 MHz, CD\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e, 25\u0026deg;C) δ\u0026thinsp;=\u0026thinsp;5.85 (s, 2H, Pyr\u003csup\u003e3,4\u003c/sup\u003e), 3.29\u0026ndash;3.22 (m, 4H, CH\u003csub\u003e2\u003c/sub\u003e), 2.40\u0026ndash;2.24 (m, 4H, C\u003cem\u003eH\u003c/em\u003eCH\u003csub\u003e3\u003c/sub\u003e), 1.42\u0026ndash;1.28 (m, 12H, CHC\u003cem\u003eH\u003c/em\u003e\u003csub\u003e\u003cem\u003e3\u003c/em\u003e\u003c/sub\u003e), 1.23\u0026ndash;1.09 (m, 12H, CHC\u003cem\u003eH\u003c/em\u003e\u003csub\u003e\u003cem\u003e3\u003c/em\u003e\u003c/sub\u003e).\u003csup\u003e13\u003c/sup\u003eC{\u003csup\u003e1\u003c/sup\u003eH} NMR (101 MHz, CD\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e, 25\u0026deg;C) δ\u0026thinsp;=\u0026thinsp;138.3 (C\u003csub\u003eq\u003c/sub\u003e, Pyr\u003csup\u003e2,5\u003c/sup\u003e), 107.2 (Pyr\u003csup\u003e3,4\u003c/sup\u003e), 25.0 (CH\u003csub\u003e2\u003c/sub\u003e), 19.2 (\u003cem\u003eC\u003c/em\u003eHCH\u003csub\u003e3\u003c/sub\u003e), 18.3 (CH\u003cem\u003eC\u003c/em\u003eH\u003csub\u003e3\u003c/sub\u003e). \u003csup\u003e31\u003c/sup\u003eP{\u003csup\u003e1\u003c/sup\u003eH} NMR (162 MHz, CD\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e, 25\u0026deg;C) δ\u0026thinsp;=\u0026thinsp;40.2. Anal. Calcd for C\u003csub\u003e36\u003c/sub\u003eH\u003csub\u003e68\u003c/sub\u003eCl\u003csub\u003e6\u003c/sub\u003eN\u003csub\u003e2\u003c/sub\u003eP\u003csub\u003e4\u003c/sub\u003eZr\u003csub\u003e2\u003c/sub\u003e: C, 41.26; H, 6.54; N, 2.67. Found: C, 41.40; H, 6.46; N, 2.82.\u003c/p\u003e \u003cp\u003e \u003cb\u003eSynthesis of Bis-[2,5-bis[[bis(1-methylethyl)phosphino-κ\u003c/b\u003e \u003csup\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sup\u003e \u003cb\u003eP\u003c/b\u003e \u003cb\u003e]methyl]-1\u003c/b\u003e \u003cb\u003eH\u003c/b\u003e \u003cb\u003e-pyrrolato-κ\u003c/b\u003e \u003cb\u003eN\u003c/b\u003e \u003cb\u003e](\u0026micro;-chloro)(dichloro)hafnium(IV)], [Hf(PNP\u003c/b\u003e \u003csup\u003e \u003cb\u003ei\u003c/b\u003e \u003cb\u003ePr\u003c/b\u003e \u003c/sup\u003e \u003cb\u003e)(\u0026micro;-Cl)(Cl)\u003c/b\u003e \u003csub\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sub\u003e \u003cb\u003e]\u003c/b\u003e \u003csub\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sub\u003e \u003cb\u003e(3, C\u003c/b\u003e\u003csub\u003e\u003cb\u003e36\u003c/b\u003e\u003c/sub\u003e\u003cb\u003eH\u003c/b\u003e\u003csub\u003e\u003cb\u003e68\u003c/b\u003e\u003c/sub\u003e\u003cb\u003eCl\u003c/b\u003e\u003csub\u003e\u003cb\u003e6\u003c/b\u003e\u003c/sub\u003e\u003cb\u003eN\u003c/b\u003e\u003csub\u003e\u003cb\u003e2\u003c/b\u003e\u003c/sub\u003e\u003cb\u003eP\u003c/b\u003e\u003csub\u003e\u003cb\u003e4\u003c/b\u003e\u003c/sub\u003e\u003cb\u003eHf\u003c/b\u003e\u003csub\u003e\u003cb\u003e2\u003c/b\u003e\u003c/sub\u003e\u003cb\u003e)\u003c/b\u003e This complex was prepared analogously to \u003cb\u003e2\u003c/b\u003e with [P(NH)P-\u003cem\u003ei\u003c/em\u003ePr] (\u003cb\u003e1\u003c/b\u003e) (200 mg, 0.61 mmol), \u003cem\u003en\u003c/em\u003eBuLi (419 \u0026micro;L, 1.6 M in hexane, 0.67 mmol, 1.1 equiv.) and [HfCl\u003csub\u003e4\u003c/sub\u003e(THF)\u003csub\u003e2\u003c/sub\u003e] (283 mg, 0.58 mmol, 0.95 equiv.) as starting materials. Yield: 298 mg (80%). Single crystals for X-Ray diffraction measurement were obtained by layering a saturated CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e solution with \u003cem\u003en\u003c/em\u003e-pentane. \u003csup\u003e1\u003c/sup\u003eH NMR (600 MHz, CD\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e, 25\u0026deg;C) δ\u0026thinsp;=\u0026thinsp;5.86 (s, 2H), 3.28 (s, 4H), 2.34 (bs, 4H), 1.39\u0026ndash;1.31 (m, 12H), 1.18 (bs, 12H). \u003csup\u003e13\u003c/sup\u003eC{\u003csup\u003e1\u003c/sup\u003eH} NMR (151 MHz, CD\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e, 25\u0026deg;C) δ\u0026thinsp;=\u0026thinsp;137.9 (C\u003csub\u003eq\u003c/sub\u003e, Pyr\u003csup\u003e2,5\u003c/sup\u003e), 107.7 (Pyr\u003csup\u003e3,4\u003c/sup\u003e), 24.9 (\u003cem\u003eC\u003c/em\u003eHCH\u003csub\u003e3\u003c/sub\u003e), 21.0 (CH\u003csub\u003e2\u003c/sub\u003e), 19.3 (CH\u003cem\u003eC\u003c/em\u003eH\u003csub\u003e3\u003c/sub\u003e), 18.4 (CH\u003cem\u003eC\u003c/em\u003eH\u003csub\u003e3\u003c/sub\u003e). \u003csup\u003e31\u003c/sup\u003eP{\u003csup\u003e1\u003c/sup\u003eH} NMR (243 MHz, CD\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e, 25\u0026deg;C) δ\u0026thinsp;=\u0026thinsp;42.8. Anal. Calcd for C\u003csub\u003e36\u003c/sub\u003eH\u003csub\u003e68\u003c/sub\u003eCl\u003csub\u003e6\u003c/sub\u003eN\u003csub\u003e2\u003c/sub\u003eP\u003csub\u003e4\u003c/sub\u003eHf\u003csub\u003e2\u003c/sub\u003e: C, 35.37; H, 5.61; N, 2.29. Found: C, 35.20; H, 5.78; N, 2.35.\u003c/p\u003e \u003cp\u003e \u003cb\u003eSynthesis of [2,5-bis[[bis(1-methylethyl)phosphino-κ\u003c/b\u003e \u003csup\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sup\u003e \u003cb\u003eP\u003c/b\u003e \u003cb\u003e]methyl]-1\u003c/b\u003e \u003cb\u003eH\u003c/b\u003e \u003cb\u003e-pyrrolato-κ\u003c/b\u003e \u003cb\u003eN\u003c/b\u003e \u003cb\u003e](η\u003c/b\u003e \u003csup\u003e \u003cb\u003e5\u003c/b\u003e \u003c/sup\u003e \u003cb\u003e-cyclopentadienyl)(dichloro)zirconium(IV)], [Zr(PNP\u003c/b\u003e \u003csup\u003e \u003cb\u003ei\u003c/b\u003e \u003cb\u003ePr\u003c/b\u003e \u003c/sup\u003e \u003cb\u003e)(η\u003c/b\u003e \u003csup\u003e \u003cb\u003e5\u003c/b\u003e \u003c/sup\u003e \u003cb\u003e-Cp)(Cl)\u003c/b\u003e \u003csub\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sub\u003e \u003cb\u003e] (4, C\u003c/b\u003e \u003csub\u003e \u003cb\u003e23\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eH\u003c/b\u003e \u003csub\u003e \u003cb\u003e39\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eCl\u003c/b\u003e \u003csub\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eNP\u003c/b\u003e \u003csub\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eZr)\u003c/b\u003e To a solution of \u003cb\u003e2\u003c/b\u003e (100 mg, 0.095 mmol) in THF (6 cm\u003csup\u003e3\u003c/sup\u003e) NaCp (79.5 \u0026micro;L, 2.4 M in THF, 0.19 mmol, 2 equiv.) was added at room temperature whereupon the solution became immediately dark red. Upon stirring for 1 h, the solvent was evaporated and the residue was redissolved in toluene (10 cm\u003csup\u003e3\u003c/sup\u003e). The solution was filtered through a syringe filter (PTFE, 0.2 \u0026micro;m). Upon evaporation of the solvent and washing of the residue with \u003cem\u003en\u003c/em\u003e-pentane (2 x 10 cm\u003csup\u003e3\u003c/sup\u003e) the product was obtained as brown powder. Yield: 95 mg ( 90%).\u003csup\u003e1\u003c/sup\u003eH NMR (600 MHz, CD\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e, 25\u0026deg;C) δ\u0026thinsp;=\u0026thinsp;6.70 (t, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;1.2 Hz, 5H, Cp), 5.78 (s, 2H, Pyr\u003csup\u003e3,4\u003c/sup\u003e), 3.20\u0026ndash;3.14 (m, 4H, CH\u003csub\u003e2\u003c/sub\u003e), 2.34\u0026ndash;2.26 (m, 4H, C\u003cem\u003eH\u003c/em\u003eCH\u003csub\u003e3\u003c/sub\u003e), 1.32\u0026ndash;1.28 (m, 12H, CHC\u003cem\u003eH\u003c/em\u003e\u003csub\u003e\u003cem\u003e3\u003c/em\u003e\u003c/sub\u003e), 1.28\u0026ndash;1.23 (m, 12H, CHC\u003cem\u003eH\u003c/em\u003e\u003csub\u003e\u003cem\u003e3\u003c/em\u003e\u003c/sub\u003e). \u003csup\u003e13\u003c/sup\u003eC{\u003csup\u003e1\u003c/sup\u003eH} NMR (151 MHz, CD\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e 25\u0026deg;C) δ\u0026thinsp;=\u0026thinsp;135.0 (t, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;4.3 Hz, C\u003csub\u003eq\u003c/sub\u003e, Pyr\u003csup\u003e2,5\u003c/sup\u003e), 115.6 (Cp), 105.8 (t, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;4.5 Hz, Pyr\u003csup\u003e3,4\u003c/sup\u003e), 25.5 (t, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;5.9 Hz, C\u003cem\u003eH\u003c/em\u003eCH\u003csub\u003e3\u003c/sub\u003e), 25.3 (dd, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;9.5, 8.0 Hz, CH\u003csub\u003e2\u003c/sub\u003e), 19.6 (d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;7.9 Hz, CH\u003cem\u003eC\u003c/em\u003eH\u003csub\u003e3\u003c/sub\u003e). \u003csup\u003e31\u003c/sup\u003eP{\u003csup\u003e1\u003c/sup\u003eH} NMR (243 MHz, CD\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e, 25\u0026deg;C) δ\u0026thinsp;=\u0026thinsp;36.2. Anal. Calcd for C\u003csub\u003e23\u003c/sub\u003eH\u003csub\u003e39\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003eNP\u003csub\u003e2\u003c/sub\u003eZr: C, 49.90: H, 7.10; N, 2.53. Found: C, 50.10; H, 7.26; N, 2.22.\u003c/p\u003e \u003cp\u003e \u003cb\u003eSynthesis of [2,5-bis[[bis(1-methylethyl)phosphino-κ\u003c/b\u003e \u003csup\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sup\u003e \u003cb\u003eP\u003c/b\u003e \u003cb\u003e]methyl]-1\u003c/b\u003e \u003cb\u003eH\u003c/b\u003e \u003cb\u003e-pyrrolato-κ\u003c/b\u003e \u003cb\u003eN\u003c/b\u003e \u003cb\u003e](η\u003c/b\u003e \u003csup\u003e \u003cb\u003e5\u003c/b\u003e \u003c/sup\u003e \u003cb\u003e-cyclopentadienyl)(dichloro)hafnium(IV)], [Hf(PNP\u003c/b\u003e \u003csup\u003e \u003cb\u003ei\u003c/b\u003e \u003cb\u003ePr\u003c/b\u003e \u003c/sup\u003e \u003cb\u003e)(η\u003c/b\u003e \u003csup\u003e \u003cb\u003e5\u003c/b\u003e \u003c/sup\u003e \u003cb\u003e-Cp)(Cl)\u003c/b\u003e \u003csub\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sub\u003e \u003cb\u003e] (5, C\u003c/b\u003e \u003csub\u003e \u003cb\u003e23\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eH\u003c/b\u003e \u003csub\u003e \u003cb\u003e39\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eCl\u003c/b\u003e \u003csub\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eNP\u003c/b\u003e \u003csub\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eHf)\u003c/b\u003e This complex was prepared analogously to \u003cb\u003e4\u003c/b\u003e with \u003cb\u003e3\u003c/b\u003e (250 mg, 0.20 mmol) and NaCp (170 \u0026micro;L, 2.4 M in THF, 0.40 mmol, 2 equiv) as starting materials. Yield: 243 mg (93%). Single crystals for X-Ray diffraction measurements were obtained by layering a saturated CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e solution with \u003cem\u003en\u003c/em\u003e-pentane. \u003csup\u003e1\u003c/sup\u003eH NMR (600 MHz, CD\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e, 25\u0026deg;C) δ\u0026thinsp;=\u0026thinsp;6.40 (t, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;1.1 Hz, 5H, Cp), 5.64 (s, 2H, Pyr\u003csup\u003e3,4\u003c/sup\u003e), 3.11\u0026ndash;3.00 (m, 4H, CH\u003csub\u003e2\u003c/sub\u003e), 2.25\u0026ndash;2.16 (m, 4H, C\u003cem\u003eH\u003c/em\u003eCH\u003csub\u003e2\u003c/sub\u003e), 1.19\u0026ndash;1.15 (m, 12H, CHC\u003cem\u003eH\u003c/em\u003e\u003csub\u003e\u003cem\u003e3\u003c/em\u003e\u003c/sub\u003e), 1.15\u0026ndash;1.11 (m, 12H, CHC\u003cem\u003eH\u003c/em\u003e\u003csub\u003e\u003cem\u003e3\u003c/em\u003e\u003c/sub\u003e).\u003csup\u003e13\u003c/sup\u003eC{\u003csup\u003e1\u003c/sup\u003eH} NMR (151 MHz, CD\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e, 25\u0026deg;C) δ\u0026thinsp;=\u0026thinsp;134.9 (t, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;4.2 Hz, C\u003csub\u003eq\u003c/sub\u003e, Pyr\u003csup\u003e2,5\u003c/sup\u003e), 114.0 (Cp), 106.2 (t, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;4.4 Hz, Pyr\u003csup\u003e3,4\u003c/sup\u003e), 25.5 (t, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;6.8 Hz, \u003cem\u003eC\u003c/em\u003eHCH\u003csub\u003e3\u003c/sub\u003e), 25.1 (d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;8.9 Hz, CH\u003csub\u003e2\u003c/sub\u003e), 25.0 (d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;9.0 Hz, CH\u003csub\u003e2\u003c/sub\u003e), 24.2 (d, 13.5 Hz, CH\u003cem\u003eC\u003c/em\u003eH\u003csub\u003e3\u003c/sub\u003e), 19.6 (CH\u003cem\u003eC\u003c/em\u003eH\u003csub\u003e3\u003c/sub\u003e).\u003csup\u003e31\u003c/sup\u003eP{\u003csup\u003e1\u003c/sup\u003eH} NMR (243 MHz, CD\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e, 25\u0026deg;C) δ\u0026thinsp;=\u0026thinsp;37.8. Anal. Calcd for C\u003csub\u003e23\u003c/sub\u003eH\u003csub\u003e39\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003eNP\u003csub\u003e2\u003c/sub\u003eHf: C, 41.10: H, 6.13; N, 2.19. Found: C, 41.20; H, 6.26; N, 2.02.\u003c/p\u003e \u003cp\u003e \u003cb\u003eSynthesis of [2,5-bis[[bis(1-methylethyl)phosphino-κ\u003c/b\u003e \u003csup\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sup\u003e \u003cb\u003eP\u003c/b\u003e \u003cb\u003e]methyl]-1\u003c/b\u003e \u003cb\u003eH\u003c/b\u003e \u003cb\u003e-pyrrolato-κ\u003c/b\u003e \u003cb\u003eN\u003c/b\u003e \u003cb\u003e](triiodo)zirconium(IV)], [Zr(PNP\u003c/b\u003e \u003csup\u003e \u003cb\u003ei\u003c/b\u003e \u003cb\u003ePr\u003c/b\u003e \u003c/sup\u003e \u003cb\u003e)(I)\u003c/b\u003e \u003csub\u003e \u003cb\u003e3\u003c/b\u003e \u003c/sub\u003e \u003cb\u003e] (6, C\u003c/b\u003e \u003csub\u003e \u003cb\u003e18\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eH\u003c/b\u003e \u003csub\u003e \u003cb\u003e34\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eI\u003c/b\u003e \u003csub\u003e \u003cb\u003e3\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eNP\u003c/b\u003e \u003csub\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eZr)\u003c/b\u003e To a solution of \u003cb\u003e2\u003c/b\u003e (100 mg, 0.095 mmol) in toluene (10 cm\u003csup\u003e3\u003c/sup\u003e) SiMe\u003csub\u003e3\u003c/sub\u003eI (407 \u0026micro;L, 2.86 mmol, 30 equiv.) was added at room temperature and stirred for 1 h. During addition of SiMe\u003csub\u003e3\u003c/sub\u003eI the solution became orange and a precipitate was formed. The solution was decanted and the remaining residue was extracted three times with toluene (10 cm\u003csup\u003e3\u003c/sup\u003e). The organic layers were combined and all volatiles were removed under reduced pressure. The orange residue was washed with \u003cem\u003en\u003c/em\u003e-pentane (3 x 10 cm\u003csup\u003e3\u003c/sup\u003e) affording \u003cb\u003e6\u003c/b\u003e as orange powder. Yield: 120 mg (78%). \u003csup\u003e1\u003c/sup\u003eH NMR (400 MHz, CD\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e, 25\u0026deg;C) δ\u0026thinsp;=\u0026thinsp;5.88 (s, 2H, Pyr\u003csup\u003e3,4\u003c/sup\u003e), 3.48\u0026ndash;3.32 (m, 4H, CH\u003csub\u003e2\u003c/sub\u003e), 2.63\u0026ndash;2.48 (m, 4H, C\u003cem\u003eH\u003c/em\u003eCH\u003csub\u003e3\u003c/sub\u003e), 1.45\u0026ndash;1.18 (m, 24H, CHC\u003cem\u003eH\u003c/em\u003e\u003csub\u003e\u003cem\u003e3\u003c/em\u003e\u003c/sub\u003e). \u003csup\u003e13\u003c/sup\u003eC{\u003csup\u003e1\u003c/sup\u003eH} NMR (101 MHz, CD\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e, 25\u0026deg;C) δ\u0026thinsp;=\u0026thinsp;139.1 (t, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;5.3 Hz, Pyr\u003csup\u003e2,5\u003c/sup\u003e), 108.6 (t, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;4.3 Hz, Pyr\u003csup\u003e3,4\u003c/sup\u003e), 27.2 (t, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;7.0 Hz, \u003cem\u003eC\u003c/em\u003eHCH\u003csub\u003e3\u003c/sub\u003e), 26.7 (t, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;9.9 Hz, CH\u003csub\u003e2\u003c/sub\u003e), 20.1 (CH\u003cem\u003eC\u003c/em\u003eH\u003csub\u003e3\u003c/sub\u003e), 19.7 (CH\u003cem\u003eC\u003c/em\u003eH\u003csub\u003e3\u003c/sub\u003e). \u003csup\u003e31\u003c/sup\u003eP{\u003csup\u003e1\u003c/sup\u003eH} NMR (162 MHz, CD\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e, 25\u0026deg;C) δ\u0026thinsp;=\u0026thinsp;56.5. Anal. Calcd for C\u003csub\u003e18\u003c/sub\u003eH\u003csub\u003e34\u003c/sub\u003eI\u003csub\u003e3\u003c/sub\u003eNP\u003csub\u003e2\u003c/sub\u003eZr: C, 27.08; H, 4.29; N, 1.75. Found: C, 27.30; H, 4.18; N, 1.32.\u003c/p\u003e \u003cp\u003e \u003cb\u003eSynthesis of [2,5-bis[[bis(1-methylethyl)phosphino-κ\u003c/b\u003e \u003csup\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sup\u003e \u003cb\u003eP\u003c/b\u003e \u003cb\u003e]methyl]-1\u003c/b\u003e \u003cb\u003eH\u003c/b\u003e \u003cb\u003e-pyrrolato-κ\u003c/b\u003e \u003cb\u003eN\u003c/b\u003e \u003cb\u003e](triiodo)hafnium(IV)], [Hf(PNP\u003c/b\u003e \u003csup\u003e \u003cb\u003ei\u003c/b\u003e \u003cb\u003ePr\u003c/b\u003e \u003c/sup\u003e \u003cb\u003e)(I)\u003c/b\u003e \u003csub\u003e \u003cb\u003e3\u003c/b\u003e \u003c/sub\u003e \u003cb\u003e] (7, C\u003c/b\u003e \u003csub\u003e \u003cb\u003e18\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eH\u003c/b\u003e \u003csub\u003e \u003cb\u003e34\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eI\u003c/b\u003e \u003csub\u003e \u003cb\u003e3\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eNP\u003c/b\u003e \u003csub\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eHf)\u003c/b\u003e This complex was prepared analogously to \u003cb\u003e6\u003c/b\u003e with \u003cb\u003e3\u003c/b\u003e (100 mg, 0.082 mmol) and SiMe\u003csub\u003e3\u003c/sub\u003eI (249 \u0026micro;L, 2.5 mmol, 30 equiv.) as starting materials. Yield: 57 mg (87%). Single crystals for X-Ray measurements were obtained by layering a saturated CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e solution with \u003cem\u003en-\u003c/em\u003epentane. \u003csup\u003e1\u003c/sup\u003eH NMR (400 MHz, CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e, 25\u0026deg;C) δ\u0026thinsp;=\u0026thinsp;5.84 (s, 2H, Pyr\u003csup\u003e3,4\u003c/sup\u003e), 3.56\u0026ndash;3.40 (m, 4H, CH\u003csub\u003e2\u003c/sub\u003e), 2.73\u0026ndash;2.49 (m, 4H, CHC\u003cem\u003eH\u003c/em\u003e\u003csub\u003e\u003cem\u003e3\u003c/em\u003e\u003c/sub\u003e), 1.38 (ddt, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;10.2, 7.1, 3.6 Hz, 24H, CHC\u003cem\u003eH\u003c/em\u003e\u003csub\u003e\u003cem\u003e3\u003c/em\u003e\u003c/sub\u003e). \u003csup\u003e13\u003c/sup\u003eC{\u003csup\u003e1\u003c/sup\u003eH} NMR (101 MHz, CD\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e, 25\u0026deg;C) δ\u0026thinsp;=\u0026thinsp;139.0 (t, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;4.8 Hz, Pyr\u003csup\u003e2,5\u003c/sup\u003e, C\u003csub\u003eq\u003c/sub\u003e, Pyr\u003csup\u003e2,5\u003c/sup\u003e), 109.4 (t, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;4.3 Hz, Pyr\u003csup\u003e3,4\u003c/sup\u003e), 27.5 (t, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;9.9 Hz, CH\u003csub\u003e2\u003c/sub\u003e), 27.2 (t, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;8.2 Hz, \u003cem\u003eC\u003c/em\u003eHCH\u003csub\u003e3\u003c/sub\u003e), 20.1 (d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;6.4 Hz, CH\u003cem\u003eC\u003c/em\u003eH\u003csub\u003e3\u003c/sub\u003e).\u003csup\u003e31\u003c/sup\u003eP{\u003csup\u003e1\u003c/sup\u003eH} NMR (162 MHz, CD\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e, 25\u0026deg;C) δ\u0026thinsp;=\u0026thinsp;62.3. Anal. Calcd for C\u003csub\u003e18\u003c/sub\u003eH\u003csub\u003e34\u003c/sub\u003eI\u003csub\u003e3\u003c/sub\u003eNP\u003csub\u003e2\u003c/sub\u003eHf: C, 24.41; H, 3.87; N, 1.58. Found: C, 24.52; H, 3.93; N, 3.77.\u003c/p\u003e \u003cp\u003e \u003cb\u003eSynthesis of [2,5-bis[[bis(1-methylethyl)phosphino-κ\u003c/b\u003e \u003csup\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sup\u003e \u003cb\u003eP\u003c/b\u003e \u003cb\u003e]methyl]-1\u003c/b\u003e \u003cb\u003eH\u003c/b\u003e \u003cb\u003e-pyrrolato-κ\u003c/b\u003e \u003cb\u003eN\u003c/b\u003e \u003cb\u003e](trimethyl)zirconium(IV)], [Zr(PNP\u003c/b\u003e \u003csup\u003e \u003cb\u003ei\u003c/b\u003e \u003cb\u003ePr\u003c/b\u003e \u003c/sup\u003e \u003cb\u003e)(Me)\u003c/b\u003e \u003csub\u003e \u003cb\u003e3\u003c/b\u003e \u003c/sub\u003e \u003cb\u003e] (8, C\u003c/b\u003e \u003csub\u003e \u003cb\u003e21\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eH\u003c/b\u003e \u003csub\u003e \u003cb\u003e43\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eNP\u003c/b\u003e \u003csub\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eZr)\u003c/b\u003e A suspension of \u003cb\u003e6\u003c/b\u003e (60 mg, 0.075 mmol) in toluene (5 cm\u003csup\u003e3\u003c/sup\u003e) was treated with MeMgBr (0.23 mmol, 161 \u0026micro;L, 1.4 M, 3 equiv) in THF/toluene (1:4) at room temperature. During the addition of MeMgBr a clear solution was formed. Dioxane (116 \u0026micro;L, 1.35 mmol, 6 equiv) was added for precipitation of magnesia salts. Upon stirring for 1 h, all volatiles were evaporated under reduced pressure and the white residue was redissolved in \u003cem\u003en\u003c/em\u003e-pentane (5 cm\u003csup\u003e3\u003c/sup\u003e). The reaction mixture was filtered through a syringe filter (PTFE, 0.2 \u0026micro;L) to afford a pale orange solution. After evaporation of the solvent the product was obtained as orange oil. Yield: 28 mg (80%). \u003csup\u003e1\u003c/sup\u003eH NMR (400 MHz, C\u003csub\u003e6\u003c/sub\u003eD\u003csub\u003e6\u003c/sub\u003e, 25\u0026deg;C) δ\u0026thinsp;=\u0026thinsp;6.26 (d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.9 Hz, 2H, Pyr\u003csup\u003e3,4\u003c/sup\u003e), 2.90 (d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;6.1 Hz, 4H, CH\u003csub\u003e2\u003c/sub\u003e), 1.94 (dq, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;14.4, 7.2 Hz, 2H, C\u003cem\u003eH\u003c/em\u003eCH\u003csub\u003e3\u003c/sub\u003e), 1.04 (t, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;3.8 Hz, 9H, Zr-CH\u003csub\u003e3\u003c/sub\u003e), 0.99 (dd, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;13.6, 7.1 Hz, 12H, CHC\u003cem\u003eH\u003c/em\u003e\u003csub\u003e\u003cem\u003e3\u003c/em\u003e\u003c/sub\u003e), 0.92 (dd, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;12.8, 7.1 Hz, 12H, CHC\u003cem\u003eH\u003c/em\u003e\u003csub\u003e\u003cem\u003e3\u003c/em\u003e\u003c/sub\u003e). \u003csup\u003e13\u003c/sup\u003eC{\u003csup\u003e1\u003c/sup\u003eH} NMR (101 MHz, C\u003csub\u003e6\u003c/sub\u003eD\u003csub\u003e6\u003c/sub\u003e) δ 136.6 (t, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;6.3 Hz, C\u003csub\u003eq\u003c/sub\u003e, Pyr\u003csup\u003e4,5\u003c/sup\u003e), 107.0 (t, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;4.3 Hz, Pyr\u003csup\u003e3,4\u003c/sup\u003e), 51.7 (Zr-CH\u003csub\u003e3\u003c/sub\u003e), 23.9\u0026ndash;23.4 (m, CH\u003csub\u003e2\u003c/sub\u003e), 23.3\u0026ndash;23.0 (m, \u003cem\u003eC\u003c/em\u003eHCH\u003csub\u003e3\u003c/sub\u003e), 18.3 (d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;7.4 Hz, CH\u003cem\u003eC\u003c/em\u003eH\u003csub\u003e3\u003c/sub\u003e). \u003csup\u003e31\u003c/sup\u003eP{\u003csup\u003e1\u003c/sup\u003eH} NMR (162 MHz, C\u003csub\u003e6\u003c/sub\u003eD\u003csub\u003e6\u003c/sub\u003e, 25\u0026deg;C) δ\u0026thinsp;=\u0026thinsp;27.9. Anal. Calcd for C\u003csub\u003e21\u003c/sub\u003eH\u003csub\u003e43\u003c/sub\u003eNP\u003csub\u003e2\u003c/sub\u003eZr: C, 54.51; H, 9.37; N, 3.03. Found: C, 54.40; H, 9.13 6; N, 3.18.\u003c/p\u003e \u003cp\u003e \u003cb\u003eSynthesis of [2,5-bis[[bis(1-methylethyl)phosphino-κ\u003c/b\u003e \u003csup\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sup\u003e \u003cb\u003eP\u003c/b\u003e \u003cb\u003e]methyl]-1\u003c/b\u003e \u003cb\u003eH\u003c/b\u003e \u003cb\u003e-pyrrolato-κ\u003c/b\u003e \u003cb\u003eN\u003c/b\u003e \u003cb\u003e](trimethyl)hafnium(IV)], [Hf(PNP\u003c/b\u003e \u003csup\u003e \u003cb\u003ei\u003c/b\u003e \u003cb\u003ePr\u003c/b\u003e \u003c/sup\u003e \u003cb\u003e)(Me)\u003c/b\u003e \u003csub\u003e \u003cb\u003e3\u003c/b\u003e \u003c/sub\u003e \u003cb\u003e] (9, C\u003c/b\u003e \u003csub\u003e \u003cb\u003e21\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eH\u003c/b\u003e \u003csub\u003e \u003cb\u003e43\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eNP\u003c/b\u003e \u003csub\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eHf)\u003c/b\u003e This complex was prepared analogously to \u003cb\u003e8\u003c/b\u003e with \u003cb\u003e7\u003c/b\u003e (60 mg, 0.067 mmol) and MeMgBr (0.20 mmol, 145 \u0026micro;L, 1.4 M, 3.5 equiv) as starting materials. Yield: 31 mg (82%). \u003csup\u003e1\u003c/sup\u003eH NMR (400 MHz, C\u003csub\u003e6\u003c/sub\u003eD\u003csub\u003e6\u003c/sub\u003e, 25\u0026deg;C) δ\u0026thinsp;=\u0026thinsp;6.24 (s, 2H, Pyr\u003csup\u003e3,4\u003c/sup\u003e), 2.93 (d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;5.6 Hz, 4H, CH\u003csub\u003e2\u003c/sub\u003e), 2.05\u0026ndash;1.88 (m, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;7.2 Hz, 4H, C\u003cem\u003eH\u003c/em\u003eCH\u003csub\u003e3\u003c/sub\u003e), 1.02\u0026ndash;0.86 (m, 24H, CHC\u003cem\u003eH\u003c/em\u003e\u003csub\u003e\u003cem\u003e3\u003c/em\u003e\u003c/sub\u003e), 0.74 (t, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;3.9 Hz, 9H, Hf-CH\u003csub\u003e3\u003c/sub\u003e).\u003csup\u003e13\u003c/sup\u003eC{\u003csup\u003e1\u003c/sup\u003eH} NMR (101 MHz, C\u003csub\u003e6\u003c/sub\u003eD\u003csub\u003e6\u003c/sub\u003e, 25\u0026deg;C) δ\u0026thinsp;=\u0026thinsp;136.5\u0026ndash;136.1 (m, Pyr\u003csup\u003e2,5\u003c/sup\u003e), 106.8\u0026ndash;106.6 (m, Pyr\u003csup\u003e3,4\u003c/sup\u003e), 59.4 (t, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;6.4 Hz, Hf-CH\u003csub\u003e3\u003c/sub\u003e), 22.6 (d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;7.1 Hz, CH\u003csub\u003e2\u003c/sub\u003e), 22.3 (d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;10.1 Hz, C\u003cem\u003eH\u003c/em\u003eCH\u003csub\u003e3\u003c/sub\u003e), 17.6 (dt, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;18.1, 1.2 Hz, CH\u003cem\u003eC\u003c/em\u003eH\u003csub\u003e3\u003c/sub\u003e). \u003csup\u003e31\u003c/sup\u003eP{\u003csup\u003e1\u003c/sup\u003eH} NMR (162 MHz, C\u003csub\u003e6\u003c/sub\u003eD\u003csub\u003e6\u003c/sub\u003e, 25\u0026deg;C) δ\u0026thinsp;=\u0026thinsp;30.8. Anal. Calcd for C\u003csub\u003e21\u003c/sub\u003eH\u003csub\u003e43\u003c/sub\u003eNP\u003csub\u003e2\u003c/sub\u003eHf: C, 45.86; H, 7.88; N, 2.55. Found: C, 45.98; H, 8.06; N, 2.69.\u003c/p\u003e \u003cp\u003e \u003cb\u003eReaction of Tetrakis(dimethylamido)titanium(IV), ([Ti(NMe\u003c/b\u003e \u003csub\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sub\u003e \u003cb\u003e)\u003c/b\u003e \u003csub\u003e \u003cb\u003e4\u003c/b\u003e \u003c/sub\u003e \u003cb\u003e]), with (2,5-Bis[[bis(1-methylethyl)phosphino]methyl]-1\u003c/b\u003e \u003cb\u003eH\u003c/b\u003e \u003cb\u003e-pyrrole), [P(NH)P-\u003c/b\u003e \u003cb\u003ei\u003c/b\u003e \u003cb\u003ePr] (1). Formation of [2,5-bis[[bis(1-methylethyl)phosphino]methyl]-1\u003c/b\u003e \u003cb\u003eH\u003c/b\u003e \u003cb\u003e-pyrrolato]tris-(dimethylamido)titanium(IV)], [Ti(PNP\u003c/b\u003e \u003csup\u003e \u003cb\u003eiPr\u003c/b\u003e \u003c/sup\u003e \u003cb\u003e)(NMe\u003c/b\u003e \u003csub\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sub\u003e \u003cb\u003e)\u003c/b\u003e \u003csub\u003e \u003cb\u003e3\u003c/b\u003e \u003c/sub\u003e \u003cb\u003e] (10)\u003c/b\u003e A solution of [P(NH)P-\u003cem\u003ei\u003c/em\u003ePr] (\u003cb\u003e1\u003c/b\u003e) (100 mg, 0.31 mmol) and [Ti(NMe\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e] (71 \u0026micro;L, 0.31 mmol) in toluene (4 cm\u003csup\u003e3\u003c/sup\u003e) was stirred for 2 days at 80\u0026deg;C. After removing of all volatiles under reduced pressure, \u003cb\u003e10\u003c/b\u003e was obtained as red oil. \u003csup\u003e1\u003c/sup\u003eH NMR (400 MHz, C\u003csub\u003e6\u003c/sub\u003eD\u003csub\u003e6\u003c/sub\u003e, 25\u0026deg;C) δ\u0026thinsp;=\u0026thinsp;6.42 (s, 2H, Pyr\u003csup\u003e3,4\u003c/sup\u003e), 3.14 (s, 18H, NCH\u003csub\u003e3\u003c/sub\u003e), 2.82\u0026ndash;2.77 (m, 4H, CH\u003csub\u003e2\u003c/sub\u003e) 1.90\u0026ndash;1.64 (m, 4H, C\u003cem\u003eH\u003c/em\u003eCH\u003csub\u003e3\u003c/sub\u003e), 1.08 (dd, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;7.1, 3.6 Hz, 12H, CHC\u003cem\u003eH\u003c/em\u003e\u003csub\u003e\u003cem\u003e3\u003c/em\u003e\u003c/sub\u003e), 1.05 (dd, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;7.1, 2.3 Hz, 12H, CHC\u003cem\u003eH\u003c/em\u003e\u003csub\u003e\u003cem\u003e3\u003c/em\u003e\u003c/sub\u003e). \u003csup\u003e13\u003c/sup\u003eC{\u003csup\u003e1\u003c/sup\u003eH} NMR (101 MHz, C\u003csub\u003e6\u003c/sub\u003eD\u003csub\u003e6\u003c/sub\u003e, 25\u0026deg;C) δ\u0026thinsp;=\u0026thinsp;136.7 (d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;12.4 Hz, C\u003csub\u003eq\u003c/sub\u003e, Pyr\u003csup\u003e2,5\u003c/sup\u003e), 107.7 (d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;4.9 Hz, Pyr\u003csup\u003e3,4\u003c/sup\u003e), 44.6 (CH\u003csub\u003e3\u003c/sub\u003e), 24.8 (d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;11.7 Hz, CH\u003csub\u003e2\u003c/sub\u003e), 24.3 (d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;14.8 Hz, \u003cem\u003eC\u003c/em\u003eHCH\u003csub\u003e3\u003c/sub\u003e), 20.4 (d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;14.8 Hz, CH\u003cem\u003eC\u003c/em\u003eH\u003csub\u003e3\u003c/sub\u003e), 19.5 (d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;10.6 Hz, CH\u003cem\u003eC\u003c/em\u003eH\u003csub\u003e3\u003c/sub\u003e). \u003csup\u003e31\u003c/sup\u003eP{\u003csup\u003e1\u003c/sup\u003eH} NMR (162 MHz, C\u003csub\u003e6\u003c/sub\u003eD\u003csub\u003e6\u003c/sub\u003e, 25\u0026deg;C) δ\u0026thinsp;=\u0026thinsp;6.2.\u003c/p\u003e \u003cp\u003e \u003cb\u003eSynthesis of [2,5-bis[[bis(1-methylethyl)phosphino-κ\u003c/b\u003e \u003csup\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sup\u003e \u003cb\u003eP\u003c/b\u003e \u003cb\u003e]methyl]-1\u003c/b\u003e \u003cb\u003eH\u003c/b\u003e \u003cb\u003e-pyrrolato-κ\u003c/b\u003e \u003cb\u003eN\u003c/b\u003e \u003cb\u003e](dichloro)(dimethylamido)titanium(IV)], [Ti(PNP\u003c/b\u003e \u003csup\u003e \u003cb\u003ei\u003c/b\u003e \u003cb\u003ePr\u003c/b\u003e \u003c/sup\u003e \u003cb\u003e)(Cl)\u003c/b\u003e \u003csub\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sub\u003e \u003cb\u003e(NMe\u003c/b\u003e \u003csub\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sub\u003e \u003cb\u003e)] (11, C\u003c/b\u003e \u003csub\u003e \u003cb\u003e20\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eH\u003c/b\u003e \u003csub\u003e \u003cb\u003e40\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eCl\u003c/b\u003e \u003csub\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eN\u003c/b\u003e \u003csub\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eP\u003c/b\u003e \u003csub\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eTi)\u003c/b\u003e A solution of [P(NH)P-\u003cem\u003ei\u003c/em\u003ePr] (\u003cb\u003e1\u003c/b\u003e) (100 mg, 0.31 mmol) and [Ti(NMe\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e] (142 \u0026micro;L, 0.62 mmol, 2 equiv.) in CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e (5 cm\u003csup\u003e3\u003c/sup\u003e) was stirred for 12 h at room temperature. After removing of all volatiles under reduced pressure, the product was obtained as brown solid. Yield: 140 mg (92%). Single crystals for X-ray diffraction measurements could be obtained from a saturated \u003cem\u003en\u003c/em\u003e-pentane solution at -20\u0026deg;C. \u003csup\u003e1\u003c/sup\u003eH NMR (400 MHz, CD\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e, 25\u0026deg;C) δ\u0026thinsp;=\u0026thinsp;6.40 (Pyr\u003csup\u003e3,4\u003c/sup\u003e) 3.13\u0026ndash;3.04 (m, 4H, CH\u003csub\u003e2\u003c/sub\u003e), 2.50 (s, 6H, NC\u003cem\u003eH\u003c/em\u003e\u003csub\u003e\u003cem\u003e3\u003c/em\u003e\u003c/sub\u003e), 1.88\u0026ndash;1.60 (m, 4H, C\u003cem\u003eH\u003c/em\u003eCH\u003csub\u003e3\u003c/sub\u003e), 1.45\u0026ndash;1.15 (m, 24H, CHC\u003cem\u003eH\u003c/em\u003e\u003csub\u003e\u003cem\u003e3\u003c/em\u003e\u003c/sub\u003e). \u003csup\u003e13\u003c/sup\u003eC{\u003csup\u003e1\u003c/sup\u003eH} NMR (101 MHz, CD\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e, 25\u0026deg;C) δ\u0026thinsp;=\u0026thinsp;135.2 (Pyr\u003csup\u003e2,5\u003c/sup\u003e), 105.9 (Pyr\u003csup\u003e3,4\u003c/sup\u003e), 44.5 (CH\u003csub\u003e3\u003c/sub\u003e), 24.8 (CH\u003csub\u003e2\u003c/sub\u003e), 20.2 (CH\u003cem\u003eC\u003c/em\u003eH\u003csub\u003e3\u003c/sub\u003e), 18.4 (CH\u003cem\u003eC\u003c/em\u003eH\u003csub\u003e3\u003c/sub\u003e). \u003csup\u003e31\u003c/sup\u003eP{\u003csup\u003e1\u003c/sup\u003eH} NMR (162 MHz, C\u003csub\u003e6\u003c/sub\u003eD\u003csub\u003e6\u003c/sub\u003e, 25\u0026deg;C) δ\u0026thinsp;=\u0026thinsp;54.0. Anal. Calcd for C\u003csub\u003e20\u003c/sub\u003eH\u003csub\u003e40\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003eN\u003csub\u003e2\u003c/sub\u003eP\u003csub\u003e2\u003c/sub\u003eTi: C, 49.10; H, 8.24; N, 5.73. Found: C, 48.95; H, 8.39; N, 5.82.\u003c/p\u003e \u003cp\u003e \u003cb\u003eSynthesis of Dimethylammonium[2,5-bis[[bis(1-methylethyl)phosphino-κ\u003c/b\u003e \u003csup\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sup\u003e \u003cb\u003eP\u003c/b\u003e \u003cb\u003e]methyl]-1\u003c/b\u003e \u003cb\u003eH\u003c/b\u003e \u003cb\u003e-pyrrolato-κ\u003c/b\u003e \u003cb\u003eN\u003c/b\u003e \u003cb\u003e](tetrabromo)zirconium(IV)], [Zr(PNP\u003c/b\u003e \u003csup\u003e \u003cb\u003ei\u003c/b\u003e \u003cb\u003ePr\u003c/b\u003e \u003c/sup\u003e \u003cb\u003e)(Br)\u003c/b\u003e \u003csub\u003e \u003cb\u003e4\u003c/b\u003e \u003c/sub\u003e \u003cb\u003e] [NH\u003c/b\u003e \u003csub\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eMe\u003c/b\u003e \u003csub\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sub\u003e \u003cb\u003e] (12, C\u003c/b\u003e \u003csub\u003e \u003cb\u003e20\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eH\u003c/b\u003e \u003csub\u003e \u003cb\u003e42\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eBr\u003c/b\u003e \u003csub\u003e \u003cb\u003e4\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eN\u003c/b\u003e \u003csub\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eP\u003c/b\u003e \u003csub\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eZr)\u003c/b\u003e A solution of [P(NH)P-\u003cem\u003ei\u003c/em\u003ePr] (\u003cb\u003e1\u003c/b\u003e) (200 mg, 0.61 mmol) and [Zr(NMe\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e] (163 mg, 0.61 mmol) in toluene (5 cm\u003csup\u003e3\u003c/sup\u003e) was stirred at 120\u0026deg;C for 72 h. The reaction mixture was then allowed to reach room temperature and SiMe\u003csub\u003e3\u003c/sub\u003eBr (282 \u0026micro;L, 2.1 mmol, 3.5 equiv) was added. After 5 min an orange precipitate was formed. All volatiles were removed under reduced pressure and the residue was washed with \u003cem\u003en\u003c/em\u003e-pentane (4 x 10 cm\u003csup\u003e3\u003c/sup\u003e). The product was obtained as orange powder. Yield: 383 mg (80%). Single crystals for X-Ray diffraction measurement were obtained by layering a saturated CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e solution with \u003cem\u003en\u003c/em\u003e-pentane. \u003csup\u003e1\u003c/sup\u003eH NMR (400 MHz, CD\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e, 25\u0026deg;C) δ\u0026thinsp;=\u0026thinsp;7.64 (bs, 2H, \u003cem\u003eH\u003c/em\u003e\u003csub\u003e2\u003c/sub\u003eNMe\u003csub\u003e2\u003c/sub\u003e), 5.90 (s, 2H, Pyr\u003csup\u003e3,4\u003c/sup\u003e), 3.27 (d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;6.4 Hz, 4H, CH\u003csub\u003e2\u003c/sub\u003e), 2.94 (s, 6H, Zr-N-CH\u003csub\u003e3\u003c/sub\u003e), 2.58\u0026ndash;2.40 (m, 4H, C\u003cem\u003eH\u003c/em\u003eCH\u003csub\u003e3\u003c/sub\u003e), 1.34 (dd, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;13.5, 7.2 Hz, 12H, CHC\u003cem\u003eH\u003c/em\u003e\u003csub\u003e\u003cem\u003e3\u003c/em\u003e\u003c/sub\u003e), 1.24 (dd, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;12.0, 7.1 Hz, 12H, CHC\u003cem\u003eH\u003c/em\u003e\u003csub\u003e\u003cem\u003e3\u003c/em\u003e\u003c/sub\u003e).\u003csup\u003e13\u003c/sup\u003eC{\u003csup\u003e1\u003c/sup\u003eH} NMR (101 MHz, CD\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e, 25\u0026deg;C) δ\u0026thinsp;=\u0026thinsp;137.6 (t, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;5.6 Hz, C\u003csub\u003eq\u003c/sub\u003e, Pyr\u003csup\u003e2,5\u003c/sup\u003e), 106.3 (Pyr\u003csup\u003e3,4\u003c/sup\u003e), 36.2 (Zr-N-CH\u003csub\u003e3\u003c/sub\u003e), 24.9 (t, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;5.2 Hz), 21.4 (\u003cem\u003eC\u003c/em\u003eHCH\u003csub\u003e3\u003c/sub\u003e), 18.9 (CH\u003cem\u003eC\u003c/em\u003eH\u003csub\u003e3\u003c/sub\u003e), 18.0 (CH\u003cem\u003eC\u003c/em\u003eH\u003csub\u003e3\u003c/sub\u003e).\u003csup\u003e31\u003c/sup\u003eP{\u003csup\u003e1\u003c/sup\u003eH} NMR (162 MHz, CD\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e, 25\u0026deg;C) δ\u0026thinsp;=\u0026thinsp;39.7.\u003c/p\u003e \u003cp\u003eAnal. Calcd for C\u003csub\u003e20\u003c/sub\u003eH\u003csub\u003e42\u003c/sub\u003eBr\u003csub\u003e4\u003c/sub\u003eN\u003csub\u003e2\u003c/sub\u003eP\u003csub\u003e2\u003c/sub\u003eZr: C, 30.67; H, 5.40; N, 3.58. Found: C, 30.88; H, 5.24; N, 3.72.\u003c/p\u003e \u003cp\u003e \u003cb\u003eSynthesis of Diethylammonium[2,5-bis[[bis(1-methylethyl)phosphino-κ\u003c/b\u003e \u003csup\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sup\u003e \u003cb\u003eP\u003c/b\u003e \u003cb\u003e]methyl]-1\u003c/b\u003e \u003cb\u003eH\u003c/b\u003e \u003cb\u003e-pyrrolato-κ\u003c/b\u003e \u003cb\u003eN\u003c/b\u003e \u003cb\u003e](tetrabromo)hafnium(IV)], [Hf(PNP\u003c/b\u003e \u003csup\u003e \u003cb\u003ei\u003c/b\u003e \u003cb\u003ePr\u003c/b\u003e \u003c/sup\u003e \u003cb\u003e)(Br)\u003c/b\u003e \u003csub\u003e \u003cb\u003e4\u003c/b\u003e \u003c/sub\u003e \u003cb\u003e][NH\u003c/b\u003e \u003csub\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eEt\u003c/b\u003e \u003csub\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sub\u003e \u003cb\u003e] (13, C\u003c/b\u003e \u003csub\u003e \u003cb\u003e22\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eH\u003c/b\u003e \u003csub\u003e \u003cb\u003e46\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eBr\u003c/b\u003e \u003csub\u003e \u003cb\u003e4\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eN\u003c/b\u003e \u003csub\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eP\u003c/b\u003e \u003csub\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sub\u003e \u003cb\u003eHf)\u003c/b\u003e A solution of [P(NH)P-\u003cem\u003ei\u003c/em\u003ePr] (\u003cb\u003e1\u003c/b\u003e) (200 mg, 0.61 mmol) and [Hf(NEt\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e] (228 \u0026micro;L, 0.61 mmol) in toluene (5 cm\u003csup\u003e3\u003c/sup\u003e) was stirred at 120\u0026deg;C for 48 h. The reaction mixture was allowed to reach room temperature and SiMe\u003csub\u003e3\u003c/sub\u003eBr (282 \u0026micro;L, 2.12 mmol, 3.5 equiv.) was added. After stirring for 1 h the precipitate was filtered through a syringe filter (PTFE, 0.2 \u0026micro;l) and washed with toluene (3 x 10 cm\u003csup\u003e3\u003c/sup\u003e). All volatiles were removed under reduced pressure. After washing of the residue with \u003cem\u003en\u003c/em\u003e-pentane (10 cm\u003csup\u003e3\u003c/sup\u003e) the product was obtained as orange powder. Yield: 390 mg (81%). \u003csup\u003e1\u003c/sup\u003eH NMR (400 MHz, CD\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e, 25\u0026deg;C) δ\u0026thinsp;=\u0026thinsp;7.66 (bs, 2H, \u003cem\u003eH\u003c/em\u003e\u003csub\u003e2\u003c/sub\u003eNEt\u003csub\u003e2\u003c/sub\u003e) 5.86 (s, 2H, Pyr\u003csup\u003e3,4\u003c/sup\u003e), 3.38\u0026ndash;3.34 (m, 2H, CH\u003csub\u003e2\u003c/sub\u003eP), 3.30 (q, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;7.4 Hz, 4H, NC\u003cem\u003eH\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003eCH\u003csub\u003e3\u003c/sub\u003e), 2.59\u0026ndash;2.44 (m, 4H, C\u003cem\u003eH\u003c/em\u003eCH\u003csub\u003e3\u003c/sub\u003e), 1.46 (t, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;7.3 Hz, 6H, NCH\u003csub\u003e2\u003c/sub\u003eC\u003cem\u003eH\u003c/em\u003e\u003csub\u003e\u003cem\u003e3\u003c/em\u003e\u003c/sub\u003e), 1.39\u0026ndash;1.22 (m, 24H, CHC\u003cem\u003eH\u003c/em\u003e\u003csub\u003e\u003cem\u003e3\u003c/em\u003e\u003c/sub\u003e).\u003csup\u003e13\u003c/sup\u003eC{\u003csup\u003e1\u003c/sup\u003eH} NMR (101 MHz, CD\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e, 25\u0026deg;C) δ\u0026thinsp;=\u0026thinsp;138.4 (C\u003csub\u003eq\u003c/sub\u003e, Pyr\u003csup\u003e2,5\u003c/sup\u003e), 108.2 (Pyr\u003csup\u003e3,3\u003c/sup\u003e), 42.5 (N\u003cem\u003eC\u003c/em\u003eH\u003csub\u003e2\u003c/sub\u003eCH\u003csub\u003e3\u003c/sub\u003e), 25.8 (t, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;7.6 Hz, \u003cem\u003eC\u003c/em\u003eHCH\u003csub\u003e3\u003c/sub\u003e), 24.7 (\u003cem\u003eC\u003c/em\u003eH\u003csub\u003e2\u003c/sub\u003eP), 19.7 (CH\u003cem\u003eC\u003c/em\u003eH\u003csub\u003e3\u003c/sub\u003e), 19.3 (CH\u003cem\u003eC\u003c/em\u003eH\u003csub\u003e3\u003c/sub\u003e), 11.5 (NCH\u003csub\u003e2\u003c/sub\u003e\u003cem\u003eC\u003c/em\u003eH\u003csub\u003e3\u003c/sub\u003e).\u003csup\u003e31\u003c/sup\u003eP{\u003csup\u003e1\u003c/sup\u003eH} NMR (162 MHz, CD\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e, 25\u0026deg;C) δ\u0026thinsp;=\u0026thinsp;49.9. Anal. Calcd for C\u003csub\u003e22\u003c/sub\u003eH\u003csub\u003e46\u003c/sub\u003eBr\u003csub\u003e4\u003c/sub\u003eN\u003csub\u003e2\u003c/sub\u003eP\u003csub\u003e2\u003c/sub\u003eHf: C, 29.40; H, 5.16; N, 3.12. Found: C, 29.81; H, 5.32; N, 3.02.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eX-ray Structure Determination\u003c/h2\u003e \u003cp\u003eX-ray diffraction data of \u003cb\u003e5\u003c/b\u003e, \u003cb\u003e7\u003c/b\u003e, \u003cb\u003e11\u003c/b\u003e and \u003cb\u003e12\u003c/b\u003e\u0026sdot;CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e (CCDC 2301968, 2301969, 2301970, and 2301972) were collected at \u003cem\u003eT\u003c/em\u003e\u0026thinsp;=\u0026thinsp;100 K in a dry stream of nitrogen on a Bruker Kappa APEX II diffractometer system using graphite-monochromatized Mo-\u003cem\u003eK\u003c/em\u003eα radiation (λ\u0026thinsp;=\u0026thinsp;0.71073 \u0026Aring;) and fine sliced \u003cem\u003eφ\u003c/em\u003e- and \u003cem\u003eω\u003c/em\u003e-scans. Data were reduced to intensity values with SAINT and a correction for absorption effects was applied with the multi-scan approach followed by a spherical absorption correction using SADABS or TWINABS [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]. The structures were solved by the dual-space approach implemented in SHELXT [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e] and refined against \u003cem\u003eF\u003c/em\u003e\u003csup\u003e2\u003c/sup\u003e with SHELXL [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]. Non-hydrogen atoms were refined with anisotropic displacement parameters. H atoms attached to C were placed in calculated positions and thereafter refined as riding on the parent atoms. The positions of the ammonium hydrogen atoms in \u003cb\u003e12\u003c/b\u003e were refined freely. Crystals of \u003cb\u003e5\u003c/b\u003e were systematically twinned by reflection at (1\u0026ndash;10) owing to local pseudo-symmetry. Molecular graphics were generated with the program MERCURY [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e].\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eComputational Details\u003c/h2\u003e \u003cp\u003eThe computational results presented have been achieved in part using the Vienna Scientific Cluster (VSC). Calculations were performed using the Gaussian 09 software package [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e] with the PBE0 functionals without symmetry constraints, the Stuttgart/Dresden ECP (SDD) basis set to describe the electrons of titanium, zirconium and hafnium and a standard 6-31G** basis for all other atoms as already described previously [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e].\u003c/p\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003ch2\u003eFunding\u003c/h2\u003e \u003cp\u003eOpen access funding provided by Austrian Science Fund (FWF).\u003c/p\u003e\u003ch2\u003eAcknowledgements\u003c/h2\u003e \u003cp\u003eFinancial support by the Austrian Science Fund (FWF) is gratefully acknowledged (Project P 32570-N). The X-Ray center of the Vienna University of Technology is acknowledged for financial support and for providing access to the single-crystal diffractometer.\u003c/p\u003e\u003ch2\u003eData availability\u003c/h2\u003e \u003cp\u003eAll relevant data are included in the manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eGossage RA, van de Kuil LA, van Koten G (1998) ) Acc Chem Res 31:423\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAlbrecht M, van Koten G (2001) Angew Chem Int Ed 40:3750\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003evan der Boom ME, Milstein D (2003) Chem Rev 103:1759\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSingleton JT (2003) Tetrahedron 59:1837\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiang LC (2006) Coord Chem Rev 250:1152\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMorales-Morales D, Jensen CM (2007) The Chemistry of Pincer Compounds. 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Gaussian Inc., Wallingford.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"},{"header":"Scheme ","content":"\u003cp\u003eSchemes 1-7 are available in the Supplementary Files section.\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":true,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"monatshefte-fur-chemie-chemical-monthly","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"mccm","sideBox":"Learn more about [Monatshefte für Chemie - Chemical Monthly](https://www.springer.com/journal/706)","snPcode":"706","submissionUrl":"https://www.editorialmanager.com/mccm/","title":"Monatshefte für Chemie - Chemical Monthly","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Pincer Complexes, Pyrrole, Titanium, Zirconium, Hafnium","lastPublishedDoi":"10.21203/rs.3.rs-3517952/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-3517952/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe synthesis, characterization and reactivity of several group 4 metal complexes featuring a central anionic pyrrole moiety connected \u003cem\u003evia\u003c/em\u003e CH\u003csub\u003e2\u003c/sub\u003e linkers to two phosphine donors is described. Treatment of [P(NH)P-\u003cem\u003ei\u003c/em\u003ePr] with [MCl\u003csub\u003e4\u003c/sub\u003e(THF)\u003csub\u003e2\u003c/sub\u003e] (M\u0026thinsp;=\u0026thinsp;Zr, Hf) in the presence of base yields the dimeric complexes [M(PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003ePr\u003c/sup\u003e)(\u0026micro;-Cl)(Cl)\u003csub\u003e2\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003e featuring two bridging chloride ligands. These complexes react with sodium cyclopentadienyl and SiMe\u003csub\u003e3\u003c/sub\u003eI to give the mononuclear complexes [M(PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003ePr\u003c/sup\u003e)(η\u003csup\u003e5\u003c/sup\u003e-Cp)(Cl)\u003csub\u003e2\u003c/sub\u003e] and [M(PNP\u003csup\u003eiPr\u003c/sup\u003e)(I)\u003csub\u003e3\u003c/sub\u003e], respectively. The latter react with MeMgBr to form the trialkyl complexes [M(PNP\u003csup\u003eiPr\u003c/sup\u003e)(Me)\u003csub\u003e3\u003c/sub\u003e]. Upon treatment of [Ti(NMe\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e] with [P(NH)P-\u003cem\u003ei\u003c/em\u003ePr] a complex with the general formula [Ti(PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003ePr\u003c/sup\u003e)(NMe\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e3\u003c/sub\u003e] is obtained. DFT calculations revealed that the most stable species is [Ti(κ\u003csup\u003e1\u003c/sup\u003e\u003cem\u003eN\u003c/em\u003e- PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003ePr\u003c/sup\u003e)(NMe\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e3\u003c/sub\u003e] featuring a κ\u003csup\u003e1\u003c/sup\u003e\u003cem\u003eN\u003c/em\u003e-bound PNP ligand. When [P(NH)P-\u003cem\u003ei\u003c/em\u003ePr] is reacted with [Ti(NMe\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e] in CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e complex [Ti(PNP\u003csup\u003eiPr\u003c/sup\u003e)(Cl)\u003csub\u003e2\u003c/sub\u003e(NMe\u003csub\u003e2\u003c/sub\u003e)] is formed. Treatment of a solution of [P(NH)P-\u003cem\u003ei\u003c/em\u003ePr] (\u003cb\u003e1\u003c/b\u003e) and [Zr(NMe\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e] with SiMe\u003csub\u003e3\u003c/sub\u003eBr affords the anionic seven-coordinate tetrabromo complex [Zr(PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003ePr\u003c/sup\u003e)(Br)\u003csub\u003e4\u003c/sub\u003e][H\u003csub\u003e2\u003c/sub\u003eNMe\u003csub\u003e2\u003c/sub\u003e]. The corresponding hafnium complex [Hf(PNP\u003csup\u003e\u003cem\u003ei\u003c/em\u003ePr\u003c/sup\u003e)(Br)\u003csub\u003e4\u003c/sub\u003e][H\u003csub\u003e2\u003c/sub\u003eNEt\u003csub\u003e2\u003c/sub\u003e] is obtained in similar fashion by utilizing [Hf(NEt\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e] as metal precursor. All complexes are characterized by means of NMR spectroscopy. Representative complexes were also characterized by X-ray crystallography.\u003c/p\u003e","manuscriptTitle":"Synthesis and characterization of pyrrole-based group 4 PNP pincer complexes","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2023-11-09 16:23:47","doi":"10.21203/rs.3.rs-3517952/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewersInvited","content":"","date":"2023-11-02T15:35:19+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2023-11-02T10:42:59+00:00","index":"","fulltext":""},{"type":"submitted","content":"Monatshefte für Chemie - Chemical Monthly","date":"2023-11-01T15:23:29+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"monatshefte-fur-chemie-chemical-monthly","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"mccm","sideBox":"Learn more about [Monatshefte für Chemie - Chemical Monthly](https://www.springer.com/journal/706)","snPcode":"706","submissionUrl":"https://www.editorialmanager.com/mccm/","title":"Monatshefte für Chemie - Chemical Monthly","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"6a8d6282-f4c4-4129-b7ac-7cd72773c8c6","owner":[],"postedDate":"November 9th, 2023","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2024-02-12T15:12:04+00:00","versionOfRecord":{"articleIdentity":"rs-3517952","link":"https://doi.org/10.1007/s00706-024-03171-x","journal":{"identity":"monatshefte-fur-chemie-chemical-monthly","isVorOnly":false,"title":"Monatshefte für Chemie - Chemical Monthly"},"publishedOn":"2024-02-09 15:01:37","publishedOnDateReadable":"February 9th, 2024"},"versionCreatedAt":"2023-11-09 16:23:47","video":"","vorDoi":"10.1007/s00706-024-03171-x","vorDoiUrl":"https://doi.org/10.1007/s00706-024-03171-x","workflowStages":[]},"version":"v1","identity":"rs-3517952","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-3517952","identity":"rs-3517952","version":["v1"]},"buildId":"ApUGefWb6u5IBVtyqm6d5","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}