A thiocyanato-bridged layer structure composed of symmetrical, dithiocyanato(N,S)-bridged dimers of heterotrinuclear alkoxo-bridged Cu,Pb units; synthesis from zerovalent copper, structural, spectroscopic and magnetic studies

A novel mixed-metal compound [{Cu2Pb(SCN)(3)L-3}(2)] has been prepared from zerovalent copper and lead thiocyanate in an acetonitrile solution of 2-dimethylaminoethanol (HL). The compound, which crystallizes in the monoclinic space group P2(1)/c with a = 14.5786(1), b = 17.4145(2), c = 10.5194(1) Angstrom, beta = 105.11(1)degrees and Z = 4, has been characterized by a range of spectroscopic methods. The crystal structure contains symmetrical dimers of heterotrinuclear alkoxo-bridged Cu2Pb units in which dimerization has occurred through bridging of NCS via the axial positions on the copper ions. The so-formed hexanuclear units are linked by Pb ... S interactions between adjacent units to form layered supramolecular assemblies along the b axis of the crystal. The magnetic behaviour can be understood on the basis of the structure, and corresponds to that of a weakly antiferromagnetically coupled dinuclear unit. The small value of the antiferromagnetic coupling can be explained by the roof-shaped CuO2Cu unit, which prevents the magnetic orbitals from undergoing significant overlap.