Poly[tetraaqua(mu(6)-9,10-dioxo-9,10dihydroanthracene-1,4,5,8-tetra- carboxylato)dimanganese(11)]

The title complex, [Mn-2(Ci(8)H(4)O(10))(H2O)41, was synthesized from manganese(II) chloride tetrahydrate and 9,10-dioxo9,10-dihydroanthr acene-1,4,5,8-tetracarboxylic acid (H4AQTC) in water. The anthraquinone unit is located about a crystallographic center of inversion. Each asymmetric unit therefore contains one Mn-II atom, two water ligands and one half AQTC(4-)anion. The Mn-II atom is coordinated in a distorted octahedral geometry by four O atoms from three AQTC(4-) ligands and two water O atoms. Two of the carboxylate groups coordinate one Mn-II atom in a chelating mode, whereas the others each coordinate two Mn-II atoms. Each AQTC(4-) tetra-anion therefore coordinates six different Mn-II ions and, as a result, a three-dimensional coordination polymer is formed. O-H center dot center dot center dot O hydrogen bonds, some of them bifurcated, between water ligands and neighboring water or anthraquinone ligands are observed in the crystal structure.