Aquabis[2,5-bis(pyridin-2-yl)-1,3,4-thiadiazole-κ2 N 2,N 3](trifluoromethanesulfonato-κO)copper(II) trifluoromethanesulfonate

2,5-Bis(pyridin-2-yl)-1,3,4-thiadiazole (denoted L) has been found to act as a bidentate ligand in the monomeric title complex, [Cu(CF3O3S)(C12H8N4S)2(H2O)](CF3O3S). The complex shows a distorted octahedrally coordinated copper(II) cation which is linked to two thiadiazole ligands, one water molecule and one trifluoromethanesulfonate anion. The second trifluoromethanesulfonate anion does not coordinate the copper(II) cation. Each thiadiazole ligand uses one pyridyl and one thiadiazole N atom for the coordination of copper. The N atom of the second non-coordinating pyridyl substituent is found on the same side of the 1,3,4-thiadiazole ring as the S atom. The trifluoromethanesulfonate ions are involved in a three-dimensional network of O—H⋯O hydrogen bonds. C—H⋯N interactions also occur.

2,5-Bis(pyridin-2-yl)-1,3,4-thiadiazole (denoted L) has been found to act as a bidentate ligand in the monomeric title complex, [Cu(CF 3 O 3 S)(C 12 H 8 N 4 S) 2 (H 2 O)](CF 3 O 3 S). The complex shows a distorted octahedrally coordinated copper(II) cation which is linked to two thiadiazole ligands, one water molecule and one trifluoromethanesulfonate anion. The second trifluoromethanesulfonate anion does not coordinate the copper(II) cation. Each thiadiazole ligand uses one pyridyl and one thiadiazole N atom for the coordination of copper. The N atom of the second non-coordinating pyridyl substituent is found on the same side of the 1,3,4-thiadiazole ring as the S atom. The trifluoromethanesulfonate ions are involved in a three-dimensional network of O-HÁ Á ÁO hydrogen bonds. C-HÁ Á ÁN interactions also occur.
In the new monomeric title complex, the Cu atom is no longer situated on a center of symmetry: its octahedral coordination sphere is built from two crystallographically independent molecules L and two O atoms of different chemical entities: O1 is from a water molecule with Cu1-O1 = 2.259 (2) Å and O4 from one trifluoromethanesulfonate anion with a very long distance Cu1-O4 = 2.540 (3)Å (Fig.1). The axial distortion of the octahedron corresponds to the Jahn-Teller effect typical for Cu 2+ . While N-Cu-O1 angles range from 88.18 (9)° (N2-Cu-O1) to 94.74 (9)° (N1-Cu-O1), keeping O1 at the axial position on one side of the distorted equatorial plane, the bonded O4 trifluoromethanesulfonate end is located in the opposite axial position, with N-Cu-O4 angles ranging from 85.90 (9)° (N5-Cu-O4) to 89.47 (9)° (N6-Cu-O4).
Cu(O 3 SCF 3 ) 2 (1.5 mmol, 0.54 g) in 8 ml of water was added to (0.42 mmol, 0.1 g) of L (bptd ligand) dissolved in 8 ml of ethanol. The solution was filtered and after 24 h, the blue compound crystallized at room temperature. Yield: 63%.

Refinement
H atoms were located in a difference map and treated as riding with C-H = 0.95 Å for the aromatic CH, with U iso (H) = 1.2 U eq (C). The O-bound H atoms were initially also located in a difference map and refined with O-H distance restraints of 0.86 (1). In a the last cycle they were refined using the riding model approximation with U iso (H) set to 1.2U eq (O). Plot of the unit cell showing a packing diagram. Hydrogen bonds are depicted as dashed lines.

Aquabis[2,5-bis(pyridin-2-yl)-1,3,4-thiadiazole-κ 2 N 2 ,N 3 ](trifluoromethanesulfonato-κO)copper(II)
trifluoromethanesulfonate where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max = 0.001 Δρ max = 1.39 e Å −3 Δρ min = −0.41 e Å −3 Special details Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'s 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 > 2σ(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.