Unsymmetrical Carbene Homologues: Isolable Pyrido[ b ]‐1,3,2 λ 2 ‐diazasilole, ‐germole and ‐stannole and Quantum‐Chemical Comparison with Unstable Pyrido[ c ] Isomers

The first isolable electronically unsymmetrical silylene, dineopentylpyrido[b]-1,3,2λ2-diazasilol, and the analogous germylene and stannylene (right) are presented and characterized by NMR and photoelectron spectroscopy. In contrast to nonisolable analogous pyrido[c] derivatives, the pyrido[b] derivatives possess a symmetrical π charge density distribution in the HOMO from a nodal plane through the pyrido nitrogen atom.