Diaqua(2,5-di-4-pyridyl-1,3,4-thiadiazole-κN 2)bis(thiocyanato-κN)nickel(II) dihydrate

In the title mononuclear complex, [Ni(NCS)2(C12H8N4S)2(H2O)2]·2H2O, the NiII atom is located on an inversion center and is octahedrally coordinated by four N atoms from two 2,5-di-4-pyridyl-1,3,4-thiadiazole (bpt) ligands and two thiocyanate molecules forming the equatorial plane; the axial positions are occupied by two O atoms of coordinated water molecules. O—H⋯O, O—H⋯N and O—H⋯S hydrogen bonds, involving the uncoordinated water molecules, result in the formation of a sheet structure developing parallel to (021).

In the title mononuclear complex, [Ni(NCS) 2 (C 12 H 8 N 4 S) 2 -(H 2 O) 2 ]Á2H 2 O, the Ni II atom is located on an inversion center and is octahedrally coordinated by four N atoms from two 2,5di-4-pyridyl-1,3,4-thiadiazole (bpt) ligands and two thiocyanate molecules forming the equatorial plane; the axial positions are occupied by two O atoms of coordinated water molecules. O-HÁ Á ÁO, O-HÁ Á ÁN and O-HÁ Á ÁS hydrogen bonds, involving the uncoordinated water molecules, result in the formation of a sheet structure developing parallel to (021).
the nickel(II) atom located on an inversion center is octahedrally coordinated by four N atoms from two bpt ligands and two thiocyanate molecules forming the equatorial plane, whereas axial positions are occupied by two O atoms of coordinated water molecules (Fig.1). The Ni-N distances are similar with related complexes (Du et al., 2002;Ma & Yang, 2008).

The occurence of O-H···O, O-H···N and O-H···S results in the formation of a two-dimensional sheet structure
developping parallel to the (0 2 1) plane (Table 1, Fig.2). The guest water molecule acts as acceptor and donor.

S2. Experimental
Bpt (21 mg,0.6 mmol), NiCl2 (28 mg, 0.9 mmol) and NH4SCN (23 mg,0.8 mmol) were added in methanol. The mixture was heated for one hour under refluxing and stirring. The resulting solution was then cooled to room temperature, and some single crystals were obtained five weeks later.

S3. Refinement
The hydrgen atoms of water molecule were located from difference Fourier maps and their coordinates were initially refined using restraints (O-H= 0.85 (1)Å and H···H = 1.39 (2)     where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.39 e Å −3 Δρ min = −0.51 e Å −3 Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.