catena-Poly[[diaqua-bis-(3-methyl-pyridine-κN)cobalt(II)]-μ-sulfato-κO:O'].

The environment of the Co(II) ion in the title compound, Co(SO(4))(C(6)H(7)N)(2)(H(2)O)(2), exhibits an octa-hedral configuration with the two 3-methyl-pyridine ligands lying in cis positions with respect to each other and trans to the two coordinated water mol-ecules. The axial positions are occupied by O atoms of the sulfate ions. Co and S atoms occupy special positions (twofold axis, Wyckoff position 4c). Neighboring Co(II) ions are covalently connected with each other through the sulfate ions, thus creating infinite polymeric chains that run along the c axis. The water mol-ecules are connected with neighboring sulfate ions through strong O-H⋯O hydrogen bonds. Intra-molecular hydrogen bonds parallel to the propagation direction of the chains stabilize the polymeric chains, and inter-molecular hydrogen bonds between chains connect neighboring chains with each other, thus leading to polymeric double chains.