Preparation of Stable Low-Oxidation-State Group 14 Element Amidohydrides and Hydride-Mediated Ring-Expansion Chemistry of N-Heterocyclic Carbenes

Various low oxidation state (+2) group 14 element amidohydride adducts, IPr center dot EH(BH3)NHDipp (E=Si or Ge; IPr=[(HCNDipp)2C:], Dipp=2,6-iPr2C6H3), were synthesized. Thermolysis of the reported adducts was investigated as a potential route to Si- and Ge-based clusters; however, unexpected transmetallation chemistry occurred to yield the carbeneborane adduct, IPr center dot BH2NHDipp. When a solution of IPr center dot BH2NHDipp in toluene was heated to 100 degrees C, a rare C-N bond-activation/ring-expansion reaction involving the bound N-heterocyclic carbene donor (IPr) transpired.