Subvalent group 13 molecules by carbene-induced hydrogen abstraction.

The -Heterocyclic Carbene (NHC) alane and gallane adducts (NHC)·CpAlH (NHC = MeIm5, iPrIm6, DippIm 7) and (NHC)·CpGaH (NHC = MeIm8, iPrIm9, DippIm 10; RIm = 1,3-di-organyl-imidazolin-2-ylidene; Dipp = 2,6 diisopropylphenyl; MeIm = 1,3,4,5-tetra-methyl-imidazolin-2-ylidene; Cp* = CMe) were prepared either the reaction of (AlHCp*)1 with the NHC or by the treatment of (NHC)·GaHI (NHC = MeIm2, iPrIm3, DippIm 4) with KCp*. The reaction of (AlHCp*)1 with the backbone saturated NHC DippIm led to NHC ring expansion instead with the formation of (RER-DippImH)AlCp* 12. Heating solutions of the gallium compounds 8-10 triggered reductive elimination of CpH and afforded CpGa16. The reaction of the alane adduct (MeIm)·CpAlH5 with cAAC led to the insertion of cAAC into the Al-H bond with the formation of the compound -(MeIm)·AlHCp(cAACH) -14. Heating a solution of -14 led to irreversible isomerisation with the formation of (MeIm)·AlHCp*(cAACH) 14. The alane adducts (iPrIm)·CpAlH6 and (DippIm)·CpAlH7 react with cAAC with the release of the NHC and formation of the exceptionally stable oxidative addition product (cAACH)AlHCp* 15. Reactions of the gallane adducts 8-10 with cAAC led to reductive elimination of cAAC-H and the formation of Cp*Ga16.