Synthesis, crystal structure and magnetic properties of catena-poly[(2,2 '-bipyridylcopper)-di-mu-thiocyanato] and bis(2,2 '-bipyridyl)thiocyanatocopper(II) perchlorate

The reaction of ethanolic solutions of CuX2 (X = NO3-, ClO4-), with bidenta te amine, 2,2'-bipyridyl (bipy) and ammonium thiocyanate, leads to the high -yield formation of {catena-[Cu(bipy)(mu(N,S)-NCS)(2)]} (1) and [Cu(NCS)(bi py)(2)]ClO4. 1/2CH(3)CN (2). The crystal structure of 1 and 2 were determin ed. Complex 1 crystallises in the monoclinic system, space group C2/c with a = 8.125(4) Angstrom, b = 15.557(6) Angstrom, c = 10.536(3) Angstrom, beta = 95.32(3)degrees and Z = 4. The crystal structure consists of neutral Cu( NCS)(2)(bipy) units which are bridged by sulfur atoms of the thiocyanate gr oups to yield a 1D chain. Complex 2 crystallises in the monoclinic system, space group C2/c with a = 12.694(4) Angstrom, b = 25.007(11) Angstrom, c = 15.479(11) Angstrom, beta = 106.85(4)degrees and Z = 8. The crystal structu re consists of a [Cu(NCS)(bipy)(2)](+) cation, ClO4-, anion and CH,CN. The cations show a quasi-trigonal bipyramidal coordination. A variable temperat ure magnetic susceptibility study was performed on 1 at a temperature range of 2-300 K. The compound shows a very weak antiferromagnetic coupling (J = -0.13 cm(-1)) and the magnetic susceptibility data were analysed by the ex pression for the magnetic susceptibility of isotropically coupled S = 1/2 i ons in antiferromagnetic chains. The single crystal EPR spectra of 2 presen ts rhombic g values and the direction of the highest g value lies in the eq uatorial plane near the Cu-N-eq direction; therefore, this is a distorted t rigonal bipyramidal structure. (C) 1999 Elsevier Science S.A. All rights re served.