Bis[benzyl N′-(3-phenylprop-2-enylidene)hydrazinecarbodithioato-κ2 N′,S]copper(II)

The CuII atom of the title complex, [Cu(C17H15N2S2)2], lies on a twofold rotation axis, and is in a distorted tetrahedral geometry with the two bidentate N2S2 Schiff bases. In the crystal structure, the molecules are interconnected into chains along the c axis by weak C—H⋯S intermolecular interactions. The crystal packing is further stabilized by C—H⋯π interactions.

The Cu II atom of the title complex, [Cu(C 17 H 15 N 2 S 2 ) 2 ], lies on a twofold rotation axis, and is in a distorted tetrahedral geometry with the two bidentate N 2 S 2 Schiff bases. In the crystal structure, the molecules are interconnected into chains along the c axis by weak C-HÁ Á ÁS intermolecular interactions. The crystal packing is further stabilized by C-HÁ Á Á interactions.
Cg1 is the centroid of the C1-C6 phenyl ring. Data collection: APEX2 (Bruker, 2005); cell refinement: APEX2; data reduction: SAINT (Bruker, 2005); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2003 & Tarafder, 1977) and crystal structure (Shanmuga Sundara Raj et al., 2000) of S-benzyldithiocarbazate (SBDTC) have been reported. We have been greatly involved in the chemistry of Schiff bases derived from SBDTC, and also on their metal complexes because of their interesting physico-chemical properties and potentially useful biological activities (Ali et al., 2002(Ali et al., , 2008Tarafder et al., 2001Tarafder et al., , 2002. In continuation of our interests, we report herein the syntheses of the cinnamaldehyde Schiff base of SBDTC and its copper complex, along with the x-ray structural analysis of the fourcoordinated Cu II complex. The Cu II atom of the title complex, lies on a twofold rotation axis and the asymmetric unit therefore contains one-half of a molecule ( Fig. 1). Based on other thiosemicarbazones (Ali et al., 2002;Tarafder et al., 2001Tarafder et al., , 2002, the coordination mode of the Cu II complex is as expected, i.e bis-chelated through the two azomethine nitrogen atoms and the two thiolate sulfur atoms. The Cu II center is in a distorted tetrahedral geometry with the N 2 S 2 donor atoms of the two Schiff base ligands ( Fig. 1). Both nitrogen atoms (N1 and N1A) and sulfur atoms (S1 and S1A) from the two ligands are coordinated at opposite positions. The N-Cu-N and S-Cu-S bond angles are 104.29 (5)° and 134.452 (14)°, respectively, and reflective of the elongation of the Cu-S bond length [ca 0.19 Å] over the Cu-N bond length. The Cu1-N1 and Cu1-S1 distances of 2.0663 (10) Å and 2.2648 (3) Å, respectively, are in the same range as those in other four coordination Cu II complexes of the related Schiff base ligands (Ali et al., 2008;Castiñeiras et al., 1998;Goswami & Eichhorn, 2000). The Cu II -bidentate rings are slightly non-planar. The Cu1-S1-N1A-N2A-C10 ring has a maximum deviation of 0.085 (1) Å for the N1A atom.
Bond lengths and angles observed in the Schiff base ligand are of normal values (Allen et al., 1987).
In the crystal packing (Fig. 2), the molecules are interconnected by weak C-H···S intermolecular interactions (Table   1) into chains along the c axis. The crystal structure is further stabilized by C-H···π interactions (Table 2) involving the C1-C6 benzene ring (centroid Cg1).

Experimental
The Schiff base ligand was prepared by adding cinamaldehyde (1.32 g, 10 mmol) to a hot solution of S-benzyldithiocarbazate (SBDTC) (1.98 g, 10 mmol) in absolute ethanol (40 ml), as reported previously (Ali & Tarafder, 1977). The mixture was refluxed for 10 min. The yellow precipitate which formed was isolated and washed with hot ethanol. The yellow solid product was recrystallized from absolute ethanol (yield: 1.52 g, 46%). The copper complex was synthesized by adding the copper nitrate trihydrate (0.31 g, 0.5 mmol) in ethanol (10 ml) to a hot solution of the above Schiff base ligand (0.31 g, 1 mmol) in ethanol (80 ml) and the reaction mixture was refluxed for 5 min when a brownish precipitate was formed. The supplementary materials sup-2 product was separated and washed with hot ethanol (yield: 0.32 g, 74%). Green single crystals of the title complex were recrystallized from a chloroform-absolute ethanol (10:3 V/V) solution after 20 d at room temperature.

Refinement
All H atoms were positioned geometrically and allowed to ride on their parent atoms, with C-H distances in the range 0.93-0.97 Å. The U iso values were constrained to be 1.2U eq of the carrier atom. The highest residual density peak is located 0.38 Å from Cu1 and the deepest hole is located 0.46 Å from S2. Fig. 1. The molecular structure of the title compound, showing 50% probability displacement ellipsoids. Atoms labelled with the suffix A are generated by the symmetry operation (-x, y, 3/ 2 -z).

Special details
Experimental. The low-temparture data was collected with the Oxford Cyrosystem Cobra low-temperature attachment. 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 Rfactors(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.