A triad of d(10) cobalt dihydrogen complexes was synthesized by utilizing Lewis acidic group 13 metalloligands, M[N((o-C6H4)(NCH2PPr2)-Pr-i)(3)], where M = Al, Ga, and In. These coinplexes 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).