Copper(II) is harder than copper(I): a novel mixed-valence example from alkoxide chemistry

Partial oxidation or disproportionation of tetrameric 2-allyl-6-methylphenoxocopper( I) leads to the formation of a novel trinuclear mixed-valence Cu(I) / Cu(II) alkoxide: [Cu-3 {OC6H3 (CH3) [CH2C(H) = CH2]}(4)], in which the central copper( II) atom is coordinated in a distorted square-planar configuration by four oxide ligands, whereas the peripheral copper( I) centres are each bonded to two C = C linkages and to two oxide ligands in a tetrahedral arrangement.