“…Thus, a range of κ 2 -gallane complexes of the type M(CO) 4 (κ 2 -H 3 GaÁNHC) (where M ¼ Cr, Mo, and NHC ¼ 6-Dipp, 6-Mes) can be synthesized from M(CO) 4 (cod) in a manner analogous to the corresponding alanes and (like their aluminium counterparts) can be shown to be inert toward loss of H 2 (see Scheme 18). 49d By contrast, the reactions of the β-diketiminato-stabilized gallium dihydride {HC(MeCDippN) 2 }GaH 2 with a range of mono-and dinuclear metal carbonyl reagents demonstrate, perhaps more clearly than any other systems, the propensity for gallanes to lose dihydrogen and form 18 From a spectroscopic viewpoint, σ-complex 84 displays two CO stretching bands (1951/1886 cm À1 ), similar to those reported for 70 (1947/1879 cm À1 ), implying similar donor characteristics for the alane and gallane ligand (a finding also reflected in the very similar geometric structures of the two systems). 18,49a The corresponding bands for 85 are markedly red-shifted (1903/1837 cm À1 ), however, consistent with the stronger σ-donor capabilities of the gallylene ligand.…”