Subvalent group 13 molecules by carbene-induced hydrogen abstraction.

The N -Heterocyclic Carbene (NHC) alane and gallane adducts (NHC)·Cp*AlH 2 (NHC = Me 2 Im Me 5, iPr 2 Im Me 6, Dipp 2 Im 7) and (NHC)·Cp*GaH 2 (NHC = Me 2 Im Me 8, iPr 2 Im Me 9, Dipp 2 Im 10; R 2 Im = 1,3-di-organyl-imidazolin-2-ylidene; Dipp = 2,6 diisopropylphenyl; Me 2 Im Me = 1,3,4,5-tetra-methyl-imidazolin-2-ylidene; Cp* = C 5 Me 5 ) were prepared either via the reaction of (AlH 2 Cp*) 3 1 with the NHC or by the treatment of (NHC)·GaH 2 I (NHC = Me 2 Im Me 2, iPr 2 Im Me 3, Dipp 2 Im 4) with KCp*. The reaction of (AlH 2 Cp*) 3 1 with the backbone saturated NHC Dipp 2 Im H led to NHC ring expansion instead with the formation of (RER-Dipp 2 Im H H 2 )AlCp* 12. Heating solutions of the gallium compounds 8-10 triggered reductive elimination of Cp*H and afforded Cp*Ga I 16. The reaction of the alane adduct (Me 2 Im Me )·Cp*AlH 2 5 with cAAC Me led to the insertion of cAAC Me into the Al-H bond with the formation of the compound rac -(Me 2 Im Me )·AlHCp*(cAAC Me H) rac -14. Heating a solution of rac -14 led to irreversible isomerisation with the formation of (Me 2 Im Me )·AlHCp*(cAAC Me H) meso - 14. The alane adducts (iPr 2 Im Me )·Cp*AlH 2 6 and (Dipp 2 Im)·Cp*AlH 2 7 react with cAAC Me with the release of the NHC and formation of the exceptionally stable oxidative addition product (cAAC Me H)AlHCp* 15. Reactions of the gallane adducts 8-10 with cAAC Me led to reductive elimination of cAAC Me -H 2 and the formation of Cp*Ga I 16.