Designing Stability into Thermally Reactive Plumbylenes

We complete the picture of thermally stable and volatile N- heterocyclic metallylenes with the synthesis, structural analysis, and thermal characterization of rac - N 2 , N 3 -di- tert -butylbutane-2,3-diamido lead(II) ( 1Pb ). Transamination of bis[bis(trimethylsilyl)amido] lead(II) with the free diamino ligand yields 1Pb in high yield, whereas salt-metathesis leads to oxidative cleavage of the butane backbone and production of acetaldehyde- tert- butylimine. 1Pb itself undergoes [2+2+1] cycloreversion at 150 °C to the same imine, but with a vapour pressure of 1 Torr at 94 °C a wide thermal window is available for use as a vapour deposition precursor. We contrast this with the the extreme instability of its sisters N 2 , N 3 -di- tert -butylethane-2,3-diamido lead(II) ( 2Pb ) and N 2 , N 3 -di- tert -butylethylene-2,3-diamido lead(II) ( 3Pb ), which both reductively eliminate Pb(0) at or below room temperature. This is also in start contrast to the stability of the lighter Si, Ge and Sn congeners.