Isolation and Characterization of a Trinuclear Cobalt Complex Containing Trigonal-Prismatic Cobalt in Secondary Alcohol Aerobic Oxidation

An unusual trinuclear cobalt complex was successfully isolated and characterized in the Co(OAc)(2)center dot 4H(2)O-catalyzed aerobic oxidation of pyridine-based secondary alcohols. In this complex, a cobalt ion (the one in the middle, labeled Co-2) has a novel trigonal-prismatic structure coordinated with six oxygen atoms from the substrate. The molecular oxygen present in air plays a major role in enabling this transformation to be catalytic. This aerobic catalytic reaction is very selective to pyridine-based secondary alcohols over primary alcohols.