Structure of a polymeric benzenetetracarboxylato complex of Mn(II) with imidazole

A novel polymeric mu -BTC complex of Mn(II) with imidazole has been synthesized, where BTC is the 1,2,4,5-benzenetetracarboxylato tetravalent anion, and its crystal structure has been determined by X-ray diffraction methods. The complex crystallizes in the monoclinic space-group P2(1)/n with a = 11.184(5), b = 9.177(2), c = 18.243(1) Angstrom and beta = 107.84(1)degrees. Each BTC ligand, located around the crystallographic inversion centre, bridges four Mn(II) atoms through four carboxyl groups to form a three dimensional polymeric structure. The carboxyl groups in the ortho-position of BTC bridges Mn(II) atoms related by the crystallographic screw axis to form helical complex chains along the b axis. Coordination around the Mn(II) atom is distorted octahedral; two BTC anions coordinate to Mn(II), one in unidentate fashion and the other as a chelate. The coordination distance of the unidentate ligand is much shorter than in the chelated ligand.