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

In the title compound, [Cu(NCS)2(C12H8N4S)2(H2O)2]·2H2O, the Cu atom is located on an inversion center and displays an octahedral geometry. Two N atoms of two different 2,5-di-4-pyridyl-1,3,4-thiadiazole ligands and two N atoms from two separate thiocyanate molecules form the equatorial plane, while two coordinated water molecules are in axial positions. The crystal structure is consolidated by extensive hydrogen bonding, forming a two-dimensional network.

In the title compound, [Cu(NCS) 2 (C 12 H 8 N 4 S) 2 (H 2 O) 2 ]Á2H 2 O, the Cu atom is located on an inversion center and displays an octahedral geometry. Two N atoms of two different 2,5-di-4pyridyl-1,3,4-thiadiazole ligands and two N atoms from two separate thiocyanate molecules form the equatorial plane, while two coordinated water molecules are in axial positions. The crystal structure is consolidated by extensive hydrogen bonding, forming a two-dimensional network.
The Cu atom is located on an inversion center and displays octahedral geometry (Fig. 1). Two nitrogen atoms of two different 2,5-di-4-pyridyl-1,3,4-thiadiazole ligands and two nitrogen atoms from two separated thiocyanate molecules form the basal plane, while two coordinated water molecules hold in axis position. The bond and angle are similar with others complexes with L ligand (Zhang et al., 2005). These monuclear units are held together by means of H bonds involving the coordinated water molecules, sulfur atoms of thiocyanate, lattice water molecules and N atoms of pyridyl rings from L ligands, which further assemble into a 2-D supramolecular sheet (Fig.2, Table 1).

S2. Experimental
Cu(NCS) 2 (0.025 g, 0.13 mmol), L(0.031 g, 0.21 mmol), and NaOH (0.08 g, 0.2 mmol). were added in a solvent of methanol, the mixture was heated for ten hours under reflux. During the process stirring and influx were required. The resultant was then filtered to give a pure solution which was infiltrated by diethyl ether freely in a closed vessel, Four weeks later some single crystals of the size suitable for X-Ray diffraction analysis.

S3. Refinement
All H atoms attached to C atoms were fixed geometrically and treated as riding with C-H = 0.93 Å (methyl) and U iso (H) = 1.2U eq (C or N). H atoms of water molecule were located in difference Fourier maps and included in the subsequent refinement using restraints (O-H= 0.82 (1)Å and H···H= 1.38 (2)Å) with U iso (H) = 1.5U eq (O). In the last stage of refinement they were treated as riding on their parent O atoms.     Diaquabis(2,5-di-4-pyridyl-1,3,4-thiadiazole-κN 2 )bis(thiocyanato-κN) where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.44 e Å −3 Δρ min = −0.69 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq