(4-Oxido-2-oxo-1,2-dihydro-pyrimidine-5-carboxyl-ato-κO,O)(4-oxido-2-oxo-1,2-dihydro-pyrimidin-3-ium-5-carboxyl-ato-κO,O)bis-(1,10-phenanthroline-κN,N')gadolinium(III) dihydrate.

The title compound, [Gd(C(5)H(2)N(2)O(4))(C(5)H(3)N(2)O(4))(C(12)H(8)N(2))(2)]·2H(2)O, was obtained from a solvothermal reaction of 2,4-dihydroxy-pyrimidine-5-carboxylic acid (H(3)iso), GdCl(3)·6H(2)O and 1,10-phenanthroline (phen). The Gd(III) ion is located on a twofold rotation axis and is coordinated by four N atoms from two chelating phen ligands and four O atoms (5-carboxyl-ate and 4-oxido O atoms) from H(2)iso(-) and Hiso(2-) ligands. The mol-ecules are linked into a three-dimensional network by N-H⋯O, N-H⋯N and O-H⋯O hydrogen bonds. The H atom involved in an N-H⋯N hydrogen bond is disordered around a twofold rotation axis with half occupancy.