Eightfold Electrophilic Methylation of Octacyanotungstate [W(CN)8]4−/3−: Preparation of Homoleptic, Eight-coordinate Methylisocyanide Complexes [W(CNMe)8]4+/5+

Homoleptic eight-fold coordinated methylisocyanide complexes of W(IV) and W(V) have been prepared for the first time. The reaction of [NBu4]4[W(CN)8] with methyl triflate MeOTf gives [W(CNMe)8][OTf]4. The even stronger methylating mixture of methyl fluoride MeF and arsenic pentafluoride AsF5 in liquid sulfur dioxide SO2 is able to fully alkylate both [NBu4]4[W(CN)8] and [NBu4]3[W(CN)8]. The paramagnetic octakis(methylisocyanide)- tungsten(V) [W(CNMe)8][AsF6]5 is thermally highly unstable above −30 °C. All compounds have been characterized via single-crystal X-ray diffraction, IR and Raman, as well as NMR or EPR spectroscopy