Using N-Heterocyclic Vinyl Ligands to Access Stable Divinylgermylenes and a Germylium Cation.

Two efficient methods are presented to install σ- and π-electron-donating N-heterocyclic vinyl groups onto main-group elements (E): halosilane elimination and base-induced E-C bond formation. Placement of two NHC=CH- ligands (NHC=N-heterocyclic carbene) onto a GeII center affords a two-coordinate germylene, a heavy congener of the elusive divinyl carbenes. The π-donating ability of this vinylic ligand scaffold was further demonstrated by the synthesis of a three-coordinate germylium cation R3 Ge+ .