Poly[[diaqua-μ3-malonatoiron(II)] monohydrate]

The title coordination polymer, [[Fe(C4H4O5)(H2O)2]·H2O] n , was obtained by the hydro-thermal reaction of FeSO4 with malic acid in alkaline aqueous solution. Each FeII atom is coordinated by four O atoms from three malate ligands and two water mol-ecules, and displays a distorted octa-hedral geometry. The polychelated malate ligands bridge Fe ions to form corrugated layers; these layers are further assembled by inter-molecular O - H⋯O hydrogen-bonding inter-actions to form a three-dimensional supra-molecular network, with channels running along the b axis in which the uncoordinated water mol-ecules are located. The solvent water mol-ecule is disordered over two positions, with occupancy ratios of 0.78/0.22. © International Union of Crystallography 2007.