Tetraaquabis(pyridine)metal(II) saccharinate tetrahydrate, [M(H2O)(4)(py)(2)](sac)(2)center dot 4H(2)O; M = Co, Ni. Crystal structure determination

The crystal structure determination of the title compounds showed that they are isomorphous, revealing the general formula [M(H2O)(4)(py)(2)](sac)(2). 4H(2)O. Their structures are built up of [M(H2O)(4)(py)(2)](2+) cations, sa ccharinato anions and non-coordinated water molecules. The metal atom lies on the inversion center and is octahedrally coordinated by four water oxyge ns and two pyridine nitrogen atoms. The crystal structure packing is achiev ed through the hydrogen bonds of O-w...O-w, O-w...O and O-w...N type. Coord inated water molecules are hydrogen bonded to non-coordinated ones at the s ame time participating in hydrogen bonding with carbonyl oxygen and nitroge n atom from the saccharinato anions. Non-coordinated water molecules partic ipate in hydrogen bonding with the oxygen atoms belonging to the saccharina to CO and SO2 groups. The hydrogen bond network between the oxygen atoms be longing to the SO2 group of the saccharinato anions and one of the non-coor dinated water molecules (OW3) constructs the centrosymmetric cavity in the structure.