catena-Poly[[di-μ2-aqua-hexaaquabis(μ3-4-oxidopyridine-2,6-dicarboxylato)trimanganese(II)] trihydrate]: a new one-dimensional coordination polymer based on a trinuclear MnII complex of chelidamic acid

4-Hydroxypyridine-2,6-dicarboxylic acid (chelidamic acid, hypydc([H])H(2)) reacts with MnCl2 center dot 2H(2)O in the presence of piperazine in water to afford the title complex, {[Mn-3(C7H2NO5)(2)(H2O)(8)]center dot 3H(2)O}(n) or {[Mn-3(hypydc)(2)(H2O)(8)]center dot 3H(2)O}(n). This compound is a one-dimensional coordination polymer, with the twofold symmetric repeat unit containing three metal centres. Two different coordination geometries are observed for the two independent Mn-II metal centres, viz. a distorted pentagonal bipyramid and a distorted octahedron. The 4-oxidopyridine-2,6-dicarboxylate anions and two of the water molecules act as bridging ligands. The zigzag-like geometry of the coordination polymer is stabilized by hydrogen bonds. O-H center dot center dot center dot O and C-H center dot center dot center dot O hydrogen bonds and water clusters consolidate the three-dimensional network structure.