Synthesis, Structure, and Reactivity of a Pyridine-Stabilized Germanone

摘要

The first isolable pyridine-stabilized germanone has been prepared and its reactivity toward trimethylaluminum has been investigated. The germanone adduct results from a stepwise conversion that starts from 4-dimethylaminopyridine (DMAP) and the ylide-like N-heterocyclic germylene LGe: (L=CH{(CCH₂)(CMe)[N(aryl)]₂}, aryl=2,6-iPr₂C₆H₃) (1) at room temperature, and gives the corresponding germylene–pyridine adduct L(DMAP)Ge: (2) in 91 % yield. The latter reacts with N₂O at room temperature to form the desired germanone complex L(DMAP)GeO (3) in 73 % yield. The GeO distance of 1.646(2) Å in 3 is the shortest hitherto reported for a GeO species. The reaction of 3 with trimethylaluminum leads solely to the addition product LGe(Me)O[Al(DMAP)Me₂] (4). The latter results from insertion of the GeO subunit into an AlMe bond of AlMe₃ and concomitant migration of the DMAP ligand from germanium to the aluminum atom. Compounds 2–4 have been fully characterized by analytical and spectroscopic methods. Their molecular structures have been established by single-crystal X-ray crystallographic analysis.