Subvalent Group 13 Molecules by Carbene-Induced Hydrogen Abstraction.

The N-Heterocyclic Carbene (NHC) alane and gallane adducts (NHC)center dot Cp*AlH2 (NHC = Me(2)Im(Me) 5, iPr(2)Im(Me) 6, Dipp(2)Im 7) and (NHC)center dot Cp*GaH2 (NHC = Me(2)Im(Me) 8, iPr(2)Im(Me) 9, Dipp(2)Im 10; R(2)Im = 1,3-diorganyl-imidazolin-2-ylidene; Dipp = 2,6 diisopropylphenyl; Me(2)Im(Me) = 1,3,4,5-tetra-methyl-imidazolin-2-ylidene; Cp* = C5Me5) were prepared either via the reaction of (AlH2Cp*)(3) 1 with the NHC or by the treatment of (NHC)center dot GaH2I (NHC = Me(2)Im(Me) 2, iPr(2)Im(Me) 3, Dipp(2)Im 4) with KCp*. The reaction of (AlH2Cp*)(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)) center dot Cp*AlH2 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))center dot AlHCp*(cAAC(Me)H) rac-14. Heating a solution of rac-14 led to irreversible isomerisation with the formation of (Me(2)Im(Me))center dot AlHCp*(cAAC(Me)H) meso-14. The alane adducts (iPr(2)Im(Me)) center dot Cp*AlH2 6 and (Dipp(2)Im)center dot Cp*AlH2 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.