Isolation and Reactivity of Chlorotetryliumylidenes Using a Bidentate Bis(N-heterocyclic imine) Ligand

By use of the ethylene-bridged bidentate bis-NHI (NHI = N-heterocyclic imine) ligand 1 toward the complexation of ECl₂·(dioxane) (E = Ge, Sn) the synthesis of the first bis-NHI-stabilized chlorogermyliumylidene 2a[GeCl₃] and chlorostannyliumylidene 2b[SnCl₃] by Lewis base mediated autoionization was achieved. Using additional TMSOTf enabled the isolation of the corresponding triflate salts 2a[OTf] and 2b[OTf] in moderate yields. The obtained tetryliumylidene ions were fully characterized, including single-crystal X-ray diffraction analysis, and additionally investigated by density functional theory calculations. Reaction of 2a[OTf] with NaBH₄led to the formation of a push-pull-stabilized hydridogermyliumylidene complex by Cl/H exchange. The same reaction with the stannyliumylidene led to transmetalation, yielding the corresponding dihydroboronium complex. Also, reactions with LiAlH₄in both cases afforded the transmetalation product.