Binuclear copper(<scp>I</scp>) complexes containing bis(diphenylphosphino)methane bridging ligands: crystal structure of [Cu₂(µ-dppm)₂(MeCN)₄][ClO₄]₂

Abstract

Novel binuclear copper(I) complexes of the types [Cu2(µ-dppm)2(MeCN)n]X2(n= 2 or 4) and [Cu2(µ-dppm)3]X2(X = BF4 or ClO4, dppm = Ph2PCH2PPh2) have been prepared. Proton and 31P-{1H} n.m.r. studies at room temperature show that they undergo ligand-dissociation processes in solution. The crystal structure of [Cu2(µ-dppm)2(MeCN)4][ClO4]2 has been determined by X-ray methods. Crystals are monoclinic, space group C2/c with Z= 4 in a unit cell of dimensions a= 22.407(9), b= 13.052(6), c= 21.522(8)Å, and β= 108.69(3)°. The structure has been solved from diffractometer data by Patterson and Fourier methods and refined by full-matrix least squares to R= 0.079 for 3 907 observed reflections [I > 3σ(I)]. The structure consists of [Cu2(µ-dppm)2(MeCN)4]2+ cations and of disordered perchlorate anions. In the cations the two copper atoms are bridged by dppm ligands to give eight-membered Cu2P4C2 rings. The tetrahedral co-ordination around the copper is completed by two nitrogen atoms from acetonitrile ligands.