A paramagnetic copper(III) complex containing an octahedral Cu(III)S₆ coordination polyhedron

Only the second octahedral, paramagnetic copper(III) complex (S=1) has now been synthesized and characterized. Six thiolato bridging ligands in the heterotrinuclear species [LCo(III)Cu(III)Co(III)L]-(ClO₄)₃·2Me₂CO (L = 1,4,7-tris(4-tert-butyl-2-sulfidobenzyl)-1,4,7-triazacyclononane) stabilize this rare electron configuration. A section of the structure of the reduced form (Cu(II), S = 1/2 ) is shown. XAS, EXAFS, and EPR spectroscopy prove unambiguously that the one-electron oxidation to the copper(III) is metal- rather than ligand-centered.