Tetraaquabis[3-(2-pyridylsulfanyl)propionato N-oxide]nickel(II)

In the centrosymmetric title compound, [Ni(C8H8NO3S)2(H2O)4], the NiII ion, which lies on an inversion centre, is six coordinated by four water molecules and two propionate O atoms from two 2-pyridylsulfanylpropionate N-oxide ligands, forming a slightly distorted octahedral geometry. An intramolecular O—H⋯O hydrogen bond stabilizes the molecular conformation. The crystal packing is consolidated by intermolecular O—H⋯O and C—H⋯O hydrogen bonding.

In the centrosymmetric title compound, [Ni(C 8 H 8 N-O 3 S) 2 (H 2 O) 4 ], the Ni II ion, which lies on an inversion centre, is six coordinated by four water molecules and two propionate O atoms from two 2-pyridylsulfanylpropionate N-oxide ligands, forming a slightly distorted octahedral geometry. An intramolecular O-HÁ Á ÁO hydrogen bond stabilizes the molecular conformation. The crystal packing is consolidated by intermolecular O-HÁ Á ÁO and C-HÁ Á ÁO hydrogen bonding.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: BT2915).   (Lobana & Bhatia, 1989;Symons & West, 1985). These compounds are also found to be involved in DNA strand scission under physiological conditions (Katsuyuki et al., 1991;Bovin et al., 1992). Pyridine N-oxides bearing a sulfur group in position two display significant antimicrobial activity (Leonard et al., 1955). In view of the importance of N-oxides, we have previously reported the crystal structures of N-oxide derivatives (Jebas et al., 2005;Ravindran et al., 2008). As an extension of our work on N-oxide derivatives, we report here the crystal structure of the title compound.

Structure Reports Online
The asymmetric unit comprises of half molecule of the title compound, the other half is symmetry generated [symmetry code: -x + 1,-y + 1,-z + 1]. The Ni II ion which lies on an inversion centre is six coordinated by four water molecules and two propianoto oxygen atoms from two 2-pyridylsulfanylpropionato N-oxide ligands forming a slightly distorted octahedral

Experimental
A mixture of the potassium salt of 3(1-oxo-pyridinine-2-sulfanyl)propionic acid (0.237 g,1 mmol) and Nickel (II) chloride (0.13 g, 0.5 mmol), in water (20 ml) was heated at 333k with continous stirring for one hour. The solution was kept aside for slow evaporation. After two weeks, green colored crystals were obtained.

Refinement
After checking their presence in the Fourier map, all the hydrogen atoms were fixed on the calculated positions and allowed to ride on their parent atoms with the C-H = 0.95 Å (aromatic), C-H = 0.99 Å (methylene) and O-H = 0.81-0.82 Å (water) with U iso (C) in the range of 1.2U eq (C) and 1.5U eq (O). Fig. 1. The molecular structure of the title compound, showing 50% probability displacement ellipsoids and the atom numbering scheme. Symmetry code: -x + 1,-y + 1,-z + 1. Crystal data [Ni(C 8 H 8