Copper( 11) acetate reacts with triphenylphosphine, in ethanol solution, in a manner depending on the concentration of Cu(O,CMe),, the molar ratio of PPh, to Cull, and temperature, to form the copper(i) complex [CU(O,CM~)(PP~,)~] ( n = 2 or 3), the copper(ii) complex [Cu,(O,CMe),( PPh,),], and the mixed-valence copper(i,ii) complex [Cu,(O,CMe),( PPh,),]. The pale blue-green complex [Cu,( O,CMe),( PPh,),]has been characterized by microanalysis, electronic, i.r., and e.s.r. spectra, and magnetic susceptibility measurements. The crystal and molecular structure of [ Cu,( O,CMe),( PPh,),] has been determined from X-ray diffractometer data by the heavy-atom method and refined by full-matrix least-squares methods to R = 0.0565 for 2 227 reflections. Crystals are triclinic, space group PT, with a = 10.898( 8), b = 12.850(4), c = 19.877(8) A, x = 121.03(2), j3 = 90.14(5), y = 11 7.98(4)", and Z = 1. The crystal structure comprises centrosymmetrical molecules of [Cu,( O,CMe),( PPh,),].Each molecule consists of a Cu,(O,CMe), dimeric unit in the axial positions t o which two molecular Cu(O,CMe)(PPh,), ligands are co-ordinated through the oxygen atom of each acetate group.Reduction of copper(I1) to copper(1) by triphenyphosphine'-6 leading to the formation of relatively stable complexes has been used frequently for the synthesis of copper(1) triphenylphosphine complexes.' The copper(1) complexes [CuY(PPh,),] (n = 2 or 3, Y = carboxylate anion or half dicarboxylate anion) were prepared in accordance with that procedure., In spite of the reducing influence of PPh, the copper(i1) complexes [Cu-(O,CR), (PPh,)] [R = CH,CHCH2,' CH2CH(CH2)2,7 B u ' , ~ or Me9] and [CuY(PPh,)] [Y = 2,9-bis(methoxymethy1)-2,9dimethyl-4,7-dioxadecanedioate(2 -)'"] could also be prepared.By reaction of copper(r1) acetate with PPh, under various reaction conditions we have recently synthesized' ' acetato copper(i1) and mixed-valence acetato copper(1,rr) complexes with PPh,