Synthesis, Characterization, and Reactivity of Hydroxycyclopentadienyl Cobalt Complexes

The reaction of tetraphenylcyclopentadienone with Co2­(CO)8 generates the mixed-valence tricobalt complex [Ph4C4­CO]­Co­(CO)2]2­[μ-Co­(MeCN)2]. In contrast to the conventional Pauson–Khand reaction to generate cyclopentadienone-ligated cobalt complexes, this method benefits from both mild reaction conditions and high yields. Treatment of this tricobalt complex with proton sources such as water or alcohols yields the monomeric hydroxytetraphenylcyclopentadienyl cobalt complex [Ph4­Cp­OH]­Co­(CO)2. Phosphite substituted monomeric cobalt complexes [Ph4­CpOH]­Co­(CO)­[P­(OR)3] were also synthesized, and protonation of these complexes transiently formed cobalt hydride species