A multiply functionalized base-coordinated Ge(II) compound and its reversible dimerization to the digermene

Abstract

Stable compounds with a GeGe bond are usually prepared under relatively harsh reaction conditions that are incompatible with many functional groups. In particular, unsaturated functionalities are not tolerated owing to their facile reaction with low-coordinate germanium compounds. We now report the synthesis of an imino-functionalized germanium(II) species, stabilized by coordination of an N-heterocyclic carbene (NHC), by reaction of an isonitrile with a heavier NHC-coordinated vinylidene. Removal of the NHC by a Lewis acid results in dimerization to the corresponding digermene with a GeGe bond. The reversibility of this process is demonstrated by addition of two equivalents of NHC to the isolated digermene.

Keywords: Lewis acid; digermene; germanium; insertion; low-valent compounds.