Coordination and Activation of AlH and GaH Bonds

The modes of interaction of donor‐stabilized Group 13 hydrides (E=Al, Ga) were investigated towards 14‐ and 16‐electron transition‐metal fragments. More electron‐rich N‐heterocyclic carbene‐stabilized alanes/gallanes of the type NHC⋅EH 3 (E=Al or Ga) exclusively generate κ 2 complexes of the type [M(CO) 4 (κ 2 ‐H 3 E⋅NHC)] with [M(CO) 4 (COD)] (M=Cr, Mo), including the first κ 2 σ‐gallane complexes. β‐Diketiminato (′nacnac′)‐stabilized systems, {HC(MeCNDipp) 2 }EH 2 , show more diverse reactivity towards Group 6 carbonyl reagents. For {HC(MeCNDipp) 2 }AlH 2 , both κ 1 and κ 2 complexes were isolated, while [Cr(CO) 4 (κ 2 ‐H 2 Ga{(NDippCMe) 2 CH})] is the only simple κ 2 adduct of the nacnac‐stabilized gallane which can be trapped, albeit as a co‐crystallite with the (dehydrogenated) gallylene system [Cr(CO) 5 (Ga{(NDippCMe) 2 CH})]. Reaction of [Co 2 (CO) 8 ] with {HC(MeCDippN) 2 }AlH 2 generates [(OC) 3 Co(μ‐H) 2 Al{(NdippCme) 2 CH}][Co(CO) 4 ] ( 12 ), which while retaining direct AlH interactions, features a hitherto unprecedented degree of bond activation in a σ‐alane complex.