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* 2 Co 2 (μ-1,8-C 10 H 8 (NH) 2 ) ( 1 ), was synthesized, and the reactivity relevant to redox transformations of the Co 2 N 2 core was investigated. It was found that the Co(II)-Co(II) bond allows for protonation by [HPPh 3 ][BF 4 ] resulting in a bridging hydride, [ 1 H] + , with p K a ∼ 7.6 in CH 2 Cl 2 . 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 H 2 O to furnish a Co(III)Co(III) hydroxy complex [ 1 -OH] + accompanied by release of H 2 . The hydroxy ligand in [ 1 -OH] + is exchangeable, as demonstrated by 18 O-labeling experiments on [ 1 -OH] + with H 2 18 O that led to the heavier isotopolog [ 1 - 18 OH] + .