SYNTHESIS, CRYSTAL-STRUCTURE AND MAGNETIC-PROPERTIES OF AN ISOPHTHALATE-BRIDGED MANGANESE(II) CHAIN COMPLEX

An isophthalate-bridged manganese(II) chain complex of the formula [Mn -2(bipy)(4)(m-phth)](n)[ClO4](2n). 4nH(2)O, where bipy is 2,2'-bipyrid ine and m-phth is isophthalate (dianion of benzene-1,3-dicarboxylic ac id), has been prepared and characterized by X-ray crystallography and magnetic measurements. The structure consists of cationic isophthalate -bridged [Mn-2(bipy)(4)(m-phth)](2+) chains, non-coordinated perchlora te anions and water molecules of crystallization. Each isophthalate li gand is bound to four manganese atoms through carboxylate oxygens with the syn-syn bridging mode, affording manganese(II) pairs that are lin ked by the isophthalate group to yield a one-dimensional chain running along the c-axis. The manganese(II) ion displays a distorted octahedr al coordination being linked to four nitrogen atoms of two bipy ligand s and two oxygen atoms of two carboxylate groups from two isophthalate ligands. The variable temperature magnetic susceptibility of the titl e complex in the temperature range 4-300 K has been interpreted in ter ms of a Mn-II dimer with a molecular field approximation, and the valu es obtained for J, g(fixed) and zJ' being -0.98 cm(-1), 2.00 and -0.03 cm(-1), respectively, indicating a weakly antiferromagnetic exchange coupling between the Mn-II ions. (C) 1997 Elsevier Science Ltd.