Triclinic modification of diaqua­bis­(5-carb­oxy-1H-imidazole-4-carboxyl­ato-κ(2) N (3),O (4))iron(II)

The title compound, [Fe(C(5)H(3)N(2)O(4))(2)(H(2)O)(2)], is a triclinic modification of a monoclinic form recently reported by Du et al. [Acta Cryst. (2011) ▶, E67, m997]. The Fe(II) ion lies at an inversion center and is coordinated by two N and two O atoms from two 5-carb­oxy-1H-imidazole-4-carboxyl­ate ligands in trans positions, together with two water mol­ecules, completing a slightly distorted octahedral coordination. Inter­molecular N—H⋯O hydrogen bonding between the N—H group of the imidazole ring and the deprotonated carboxyl­ate group builds a chain of 5-carb­oxy-1H-imidazole-4-carboxyl­ate anions along the [101] direction. The water molecules form intermolecular hydrogen bonds to O—C and O=C sites of the carboxylate group in adjacent layers.