Poly[hexa­aqua­bis­(μ4-pyrimidine-4,6-dicarboxyl­ato)tetra­lithium]

The asymmetric unit of the title compound, [Li(4)(C(6)H(2)N(2)O(4))(2)(H(2)O)(6)](n), comprises two Li(+) ions bridged by a completely deprotonated pyrimidine-3,6-dicarboxyl-ate ligand and coordinated by two water mol-ecules; the asymmetric units related by an inversion operation create a structural unit which forms part of a two-dimensional polymeric structure parallel to (10-1). One of the Li(+) ions shows a distorted tetra-hedral arrangement involving two symmetry-related coordinating water mol-ecules and two carboxyl-ate O atoms. The other Li(+) ion is in distorted trigonal-bipyramidal geometry defined by N and O atoms of the ligands and a water mol-ecule. Water O atoms are proton donors to carboxyl-ate O atoms forming hydrogen bonds.