Room-Temperature Aerobic C-CN Bond Activation in Nickel(II) Cyanomethyl Dicarboranyl Complex

Wereport the synthesis and characterization of a nickel(II) complexof the dicarboranyl CNC dianionic pincer ligand, which activates acetonitrileby C-C bond cleavage. Deprotonation of the relatively acidicC-H bond of the coordinated acetonitrile with potassium t-butoxide led to the formation of the C-bound cyanomethylene ligand at the metal center. Unlike most previouslycharacterized Ni(II) cyanoalkyls, the resulting complex exhibitedquick transformation under aerobic conditions at room temperatureto afford CNC-ligated nickel(II) cyanide, indicating facile cleavageof the C-CN bond. The cyanoalkyl and cyanide complexes wereisolated in excellent yields and characterized by NMR spectroscopyand single-crystal X-ray diffraction. Carbon-containing products ofthe aerobic C-CN bond activation are hydroxyacetonitrile, formaldehyde,cyanomethyl formate, and carbon dioxide.