Synthesis, structure and magnetic properties of a trinuclear cyano-bridged complex [Cu(bappz)(mu-NC)Ni(CN)(2)(mu-CN)Cu(bappz)](ClO4)(2) {bappz=1,4-bis(3-aminopropyl)piperazine}

The bimetallic trinuclear complex [Cu(bappz)(mu-NC)Ni(CN)(2)(mu-CN)Cu(bappz)](ClO4)(2) (bappz = 1,4-bis(3-aminopropyl)piperazine) has been prepared from the reaction of [Cu(bappz)](ClO4)(2) and K-2[Ni(CN)(4)] in water and its crystal and molecular structure has been determined. The structure consists of a trinuclear [Cu(bappz)(mu-NC)Ni(CN)(2)(mu-CN)Cu(bappz)](2+) cation and two perchlorate anions. The bridging [Ni(CN)(4)](2-) anion is coordinated by two [Cu(bappz)](2+) cations through two cyano groups, providing a novel trinuclear structure with the Cu-(NC)-Ni-(CN)-Cu linkage. The nickel(II) ion is four-coordinated by carbon atoms from four cyano groups (two of them, in trans position, form a bridge) in a square planar arrangement, whereas both the copper(II) ions are five-coordinated by four bappz nitrogens and one cyanide nitrogen in a distorted square pyramidal geometry. The temperature dependence of magnetic susceptibility was measured for this compound over the range of 2-300 K. The magnetic investigation showed the presence of a very weak antiferromagnetic interaction (superexchange interaction parameter J = -0.54 cm(-1)) between the copper atoms through the diamagnetic [Ni(CN)(4)](2-) ion. (C) 2003 Elsevier B.V. All rights reserved.