Tetraaquabis{2-[4-(4-pyridyl)pyrimidin-2-ylsulfanyl]acetato}zinc

In the title compound, [Zn(C11H8N3O2S)2(H2O)4], the ZnII ion lies on an inversion centre and is coordinated by four water molecules and two N atoms from two 2-[4-(4-pyridyl)pyrimidin-2-ylsulfanyl]acetate (L) ligands in a distorted octahedral geometry. In L, the pyridine and pyrimidine rings are twisted at an angle of 11.2 (1)°. The coordinated water molecules and the acetate groups are involved in the formation of a three-dimensional hydrogen-bonded network, which consolidates the crystal packing.

In the title compound, [Zn(C 11 H 8 N 3 O 2 S) 2 (H 2 O) 4 ], the Zn II ion lies on an inversion centre and is coordinated by four water molecules and two N atoms from two 2-[4-(4-pyridyl)pyrimidin-2-ylsulfanyl]acetate (L) ligands in a distorted octahedral geometry. In L, the pyridine and pyrimidine rings are twisted at an angle of 11.2 (1) . The coordinated water molecules and the acetate groups are involved in the formation of a three-dimensional hydrogen-bonded network, which consolidates the crystal packing.

Related literature
For a related structure, see: Zhu et al. (2009).
Similar to the reported Mn(II) coordination compound (Zhu et al., 2009), the Zn(II) center in the title compound also adopts an octahedral coordination geometry defined by four water O atoms in equatorial positions and two N atoms in apical positions ( Fig. 1). The Zn-O bond lengths vary from 2.070 (2) to 2.137 (2)Å, and the Zn-N bond length is 2.176 (2) Å.

Experimental
The mixture of Zn(NO 3 ) 2 (0.1 mmol), L (0.2 mmol) and NaOH (0.2 mmol) in 10 ml of H 2 O was stirred for 30 min at room temperature. After filtration, the mother liquid was stood for three weeks to give yellow crystals suitable for X-ray diffraction analysis.

Refinement
C-bound H atoms were positioned geometrically (C-H = 0.93 Å) and allowed to ride on their parent atoms, with U iso (H) = 1.2 U eq (C). The positions of the water H atoms were found from a difference Fourier map and refined with restraint O-H = 0.82 (2) Å using a riding model, with U iso (H) = 1.2 U eq (O). Fig. 1. The coordination environment around Zn(II) in the title complex with the atom-labeling scheme [symmetry code: (A) -x, -y + 1, -z + 1]. Displacement ellipsoids for non-hydrogen atoms are drawn at the 50% probability level.