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'-bipyridine and m-phth is isophthalate (dianion of benzene-1,3-dicarboxylic acid), 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 perchlorate anions and water molecules of crystallization. Each isophthalate ligand is bound to four manganese atoms through carboxylate oxygens with the syn-syn bridging mode, affording manganese(II) pairs that are linked by the isophthalate group to yield a one-dimensional chain running along the c-axis. The manganese(II) ion displays a distorted octahedral coordination being linked to four nitrogen atoms of two bipy ligands and two oxygen atoms of two carboxylate groups from two isophthalate ligands. The variable temperature magnetic susceptibility of the title complex in the temperature range 4-300 K has been interpreted in terms of a Mn-II dimer with a molecular field approximation, and the values 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.