Poly[[bis-[μ(2)-8-ethyl-5-oxo-2-(piperazin-1-yl)-5,8-dihydro-pyrido[2,3-d]pyrimidine-6-carboxyl-ato]cobalt(II)] dihydrate].

The title compound, {[Co(C(14)H(16)N(5)O(3))(2)]·2H(2)O}(n) or [Co(ppa)(2)]·2H(2)O}(n), where ppa denotes the 8-ethyl-5-oxo-2-(piperazin-1-yl)-5,8-dihydro-pyrido[2,3-d]pyrimidine-6-carb-ox-yl-ate anion, was synthesized under hydro-thermal conditions. The Co(II) atom (site symmetry ) exhibits a distorted trans-CoN(2)O(4) octa-hedral geometry defined by two monodentate N-bonded and two bidentate O,O'-bonded ppa anions. The extended two-dimensional structure is a square grid, which is consolidated by N-H⋯O hydrogen bonds. The disordered uncoordinated water mol-ecules occupy cavities within the grid.