Synthesis, crystal structure and magnetic properties of a one-dimensional Mn2+ complex constructed from (+)-dibenzoyltartaric acid and 2,2′-bipyridine

The self-assembly reaction of (+)-dibenzoyltartaric acid (D-H(2)DBTA) with 2,2'-bipyridine (bpy) and Mn(CH3CO2)(2)center dot 4H(2)O yielded a new coordination polymer, namely, catena-poly[[[diaqua(2,2'-bipyridine-kappa N-2,N')manganese(II)]-mu-2,3-bis-(benzoyloxy)butanedioato-kappa O-2(2):O-3] dihydrate], {[Mn(C18H12O8)(C10H8N2)(H2O)(2)]center dot 2H(2)O}(n) or {[Mn(DBTA)(bpy)(H2O)(2)]center dot 2H(2)O}(n), (I). Complex (I) has been characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis (TGA) and single-crystal and powder X-ray diffraction. It crystallizes in the orthorhombic space group P2(1)2(1)2(1). In the complex, the Mn2+ cation displays a distorted octahedral {MnO4N2} geometry, formed from two carboxylate O atoms of two DBTA(2-) ligands, two cis-oriented N atoms from one chelating 2,2'-bipyridine ligand and two trans-oriented O atoms from coordinated water molecules. The polymer displays a 1D chain with an Mn center dot center dot center dot Mn distance of 9.428 (1) angstrom. Due to the presence of flexible polycarboxylate and rigid bipyridyl ligands in the molecular structure, a high thermal stability of the complex is attained. The magnetic properties of (I) were analyzed based on the mononuclear Mn2+ model due to the long intramolecular Mn center dot center dot center dot Mn distance. The zero field splitting (ZFS) contribution in the high-spinMn(2+) cation is almost negligible and there are weak antiferromagnetic couplings between 1D chains [zJ' = -0.062 (5) cm(-1)], corresponding to an intermolecular Mn center dot center dot center dot Mn distance of 7.860 (2) angstrom.