Crystal structure of a heterometallic coordination polymer: catena-poly[[[tetra-aquacobalt(II)]-mu-pyridine-2,6-dicarboxylato-calcium(II)-mu-pyridine-2,6-dicarboxylato] dihydrate]

In the crystal of the title polymeric complex, {[CoCa(C7H3NO4)(2)(H2O)(4)]center dot 2H(2)O}(n) (1), the Co-II ion is N,O,O'-chelated by two pyridine-2,6-dicarboxylate anions in a distorted N2O4 octahedral geometry, and two carboxylate O-atoms of pyridine-2,6-dicarboxylate anions bridge tetraaquacalcium(II) units to form polymeric chains propagating along the b-axis direction. In the crystal, O-H center dot center dot center dot O O and C-H center dot center dot center dot O hydrogen bonds, and offset pi-pi stacking interactions [intercentroid distances = 3.551 (1) and 3.746 (1) angstrom] involving inversion-related pyridine rings link the polymeric chains and lattice water molecules to form a supramolecular three-dimensional framework.