Facile Transformations of a Binuclear Cp*Co(II) Diamidonaphthalene Complex to Mixed-Valent Co(II)Co(III), Co(III)(μ-H)Co(III), and Co(III)(μ-OH)Co(III) Derivatives

A diamido-bridged dicobalt complex supported by a diamidonaphthalene ligand, Cp*2Co2(μ-1,8-C10H8(NH)2) (1), was synthesized, and the reactivity relevant to redox transformations of the Co2N2 core was investigated. It was found that the Co(II)-Co(II) bond allows for protonation by [HPPh3][BF4] resulting in a bridging hydride, [1H]+, with pKa ∼ 7.6 in CH2Cl2. The diamidonaphthalene ligand can stabilize the binuclear system in the Co(II)Co(III) mixed-valent state (1+), which is capable of binding CO to afford [1-CO]+. Surprisingly, the mixed-valent complex also activates H2O to furnish a Co(III)Co(III) hydroxy complex [1-OH]+ accompanied by release of H2. The hydroxy ligand in [1-OH]+ is exchangeable, as demonstrated by 18O-labeling experiments on [1-OH]+ with H218O that led to the heavier isotopolog [1-18OH]+.