Synthesis, crystal structure and magnetic properties of an isophthalate-bridged manganese(II) chain complex

Abstract

An isophthalate-bridged manganese(II) chain complex of [Mn 2(phen) 4( m-phth)] n [ClO 4] 2 n ·2 nH 2O, where phen is 1,10- phenanthroline and m-phth is isophthalate (dianion of benzene-1,3-dicarboxylic acid), has been prepared and characterized by X-ray crystallography and magnetic measurements. It crystallizes in the triclinic system, space group P 1 ̄ , with a=14.651(1), b=16.679(7), c=13.561(4) Å, α=101.46(3), β=113.91(2), δ=65.52(3)° and Z=2. The structure consists of cationic isophthalate-bridged [Mn 2(phen) 4( m-phth)] 2+ chains, non-coordinated perchlorate anions and crystallized water molecules. Each isophthalate is bound to four manganese atoms through carboxylate oxygens with the syn–syn bridging mode, affording manganese(II) pairs which are linked by the isophthalate group to yield a one-dimensional chain running along the a axis. The intrachain Mn⋯Mn separations are 4.86 and 4.66 Å (through the double carboxylate bridges) and 7.16 Å (the shortest distance through the bridging isophthalate), respectively. The manganese(II) ion displays a distorted octahedral coordination being linked to four nitrogen atoms of two phen 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 1.5–300 K has been interpreted in terms of an Mn(II) dimer with a molecular field approximation, the values obtained for J, g(fixed) and z J′ being 3.23 cm −1, 2.00 and −0.35 cm −1, respectively, indicating a weakly ferromagnetic exchange coupling within the Mn(II) dimer with double carboxylates in syn–syn conformation.