Reductive Disproportionation of CO₂ Mediated by Bimetallic Nickelate(–I)/Group 13 Complexes

The reactivity of bimetallic nickel(–I)/group 13 complexes towards carbon dioxide is presented. Reaction of the anionic [NiML]^– complexes, where M is Al or Ga, and L is {N[(o-C₆H₄)NCH₂PiPr₂]₃}^3–, with CO₂ (1 atm) results in reductive disproportion of CO₂ to afford CO₃^2–, NiML, and the mono-carbonyl adducts, (CO)NiML. The (CO)NiML complexes, where M is Al, Ga, or In, were independently synthesized and characterized. The extent of CO activation varies slightly across the different group 13 ions, where the CO stretching frequency increases for M = Al < Ga < In.