Characterization of a μ-η²:η²-Peroxo Dinuclear Cobalt(II) Complex

Abstract

A novel dicobalt(II) μ-peroxo complex (3) is formed by the reaction of a dicobalt(II) bis(μ-hydroxo) complex, [Co(HB(3,5-iPr2pz)3)]2(OH)2 (2), with a stoichiometric amount of H2O2. Unusual and characteristic spectroscopic properties [(1) existence of two O22- to metal charge transfer absorption bands; (2) low ν(O−O) vibration in the resonance Raman spectrum; (3) antiferromagnetic coupling between the two Co(II) ions] suggest that the peroxo ligand coordinates in the planar μ-η2:η2 binding mode as found in the oxyhemocyanin and the dicopper(II) peroxo model complexes. Warming of a pentane solution of 3 induces aliphatic C−H bond activation concomitant with O−O bond cleavage to yield the novel μ-alkoxo−μ-hydroxo complex 4, Co2(μ-OH)[HB(μ-3-OCMe2-5-iPrpz)(3,5-iPr2pz)2][HB(3,5-iPr2pz)3], and the bis(μ-hydroxo) complex 2.