Di- and Trinuclear Mixed-Valence Copper Amidinate Complexes from Reduction of Iodine

摘要

Molecular examples of mixed-valence copper complexes through chemical oxidation are rare but invoked in the mechanism of substrate activation, especially oxygen, in copper-containing enzymes. To examine the cooperative chemistry between two metals in close proximity to each other we have begun to study the reactivity of a dinuclear Cu(I) amidinate complex. The reaction of [(2,6-Me2C6H3N)2C(H)]2Cu2, >1, with I2 in THF, CH3CN, and toluene affords three new mixed-valence copper complexes, [(2,6-Me2C6H3N)2C(H)]2Cu2(μ2-I3)(THF)₂, >2, [(2,6-Me₂C₆H₃N)₂C(H)]₂Cu₂(μ₂-I)(NCMe)₂, >3, and [(2,6-Me₂C₆H₃N)₂C(H)]₃Cu₃(μ₃-I)₂, >4, respectively. The first two compounds have been characterized by UV-Vis and EPR spectroscopy and their molecular structure determined by X-ray crystallography. Both di- and trinuclear mixed-valence intermediates have been characterized for the reaction of compound >1 to compound >4 and the molecular structure of >4 has been determined by X-ray crystallography. The electronic structure of each of these complexes has also been investigated using density functional theory.