EXCHANGE COUPLING ACROSS MULTIPLE-ATOM BRIDGES - CRYSTAL-STRUCTURE AND MAGNETIC-PROPERTIES OF A CHLORANILATE BRIDGED DICOPPER(II) COMPLEX

A dinuclear copper(II) complex, [L2Cu2(mu-ClA)](ClO4)(2) (1), with a c hloranilate dianion (ClA(2-)) as the bridging ligand and 1,4,7-trimeth yl-1,4,7-triazacyclononane (L) as the capping ligands is reported. 1 C rystallizes in the monoclinic space group P2(1)/n with the cell consta nts a = 9.540(1), b = 13.572(2), c = 13.544(2) Angstrom, beta = 96.31( 1)degrees, V = 1743.0(4) Angstrom(3) and Z = 2. The structure of the c ation in 1 consists of a planar chloranilate unit bridging two five-co ordinated square-pyramidal Cu(II) centres and resulting in the intramo lecular Cu ... Cu separation of 7.679 Angstrom. Variable temperature ( 4.2-300 K) magnetic susceptibility data yield a moderate antiferromagn etic interaction between the copper centres in 1 with an exchange coup ling constant of J = -12.3 cm(-1) based on H = -2JS(1) . S-2. (C) 1998 Elsevier Science S.A. All rights reserved.