Stable Dihydrogen Complexes of Cobalt(-I) Suggest an Inverse trans-Influence of Lewis Acidic Group 13 Metalloligands.

A triad of d10 cobalt dihydrogen complexes was synthesized by utilizing Lewis acidic group 13 metalloligands, M[N((o-C6H4)NCH2PiPr2)3], where M = Al, Ga, and In. These complexes have formal Co(-I) oxidation states, representing the only coordination complexes in which dihydrogen is bound to a subvalent transition metal center. Single-crystal X-ray diffraction and NMR studies support the assignment of these complexes as nonclassical dihydrogen adducts of Co(-I).