catena-Poly[[hexakis(1H-benzimidazole)-bis(μ2-5-sulfonatosalicylato)tricopper(II)]octahydrate]

The crystal structure of the title compound, {[Cu-3(C7H3O6S)(2-)(C7H6N2) 6] (.) 8H(2)O}(n), is built of trinuclear complexes [Cu-3(bz)(6)(ssal)(2)] (bz = benzimidazole and ssal = 5-sulfonatosalicylate trianion) and uncoordinated water molecules. The molecule of the complex occupies a special position on a crystallographic inversion centre. The Cu atom located on the inversion centre has a square planar coordination made up of the two N atoms of monodentate benzimidazole ligands and the O atoms of two bridging salicylates. The other crystallographically independent Cu atom has a square pyramidal environment formed by the N atoms of two more monodentate benzimidazole ligands, two chelate O atoms of the bridging salicylate and the sulfonate O atom of the sulfonatosalicylate ligand belonging to the neighbouring trimetallic complex. The latter coordination links the molecules of the complex into infinite chains running along the a axis. These chains are further connected by O-H (...) O and N-H O-... hydrogen bonding into a three-dimensional network.