Bis-(µ-pyridine-2,3-dicarboxyl-ato)bis-[aqua-(3-carb-oxy-pyridine-2-carboxyl-ato)indium(III)] tetra-hydrate.

In the binuclear centrosymmetric title compound, [In(2)(C(7)H(3)NO(4))(2)(C(7)H(4)NO(4))(2)(H(2)O)(2)]·4H(2)O, which contains both pyridine-2,3-dicarboxyl-ate and 3-carb-oxy-pyridine-2-carboxyl-ate ligands, the In(III) atom is six-coordinated in a distorted octa-hedral geometry. One pyridine ligand is N,O-chelated while the other is N,O-chelated and at the same time bridging to the other via the second carboxyl group. In the crystal, an extensive O-H⋯O hydrogen-bonding network, involving the coordinated and lattice water mol-ecules and the carboxyl groups of the ligands, together with C-H⋯O and π-π inter-actions [centroid-centroid distance = 3.793 (1) Å], leads to the formation of a three-dimensional structure.