Triclinic modification of diaquabis(5-carboxy-1H-imidazole-4-carboxylato-κ2N3,O4)iron(II)

Abstract

The title compound, [Fe(C5H3N2O4)2(H2O)2], is a triclinic modification of a monoclinic form recently reported by Du et al. [Acta Cryst. (2011), E67, m997]. The FeII 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.