Bis{benzyl 2-[4-(4-methoxyphenyl)butan-2-ylidene]hydrazinecarbodithioato-κ2 N 2,S}nickel(II)

The complete molecule of the title complex, [Ni(C19H21N2OS2)2], is generated by the application of twofold symmetry. The NiII atom is N,S-chelated by two hydrazinecarbodithioate ligands, which provide an N2S2 donor set that defines a distorted square-planar geometry, the S atoms being approximately cis. The conformation of the chelate ring is an envelope with the NiII atom being the flap atom. The dihedral angle between the least-squares planes through the chelate rings = 30.10 (6)°. Supramolecular chains propagated by glide symmetry along the c axis and mediated by C—H⋯N contacts feature in the crystal packing.


Comment
In our on-going investigations to expand the scope of hydrazinecarbodithioate derivatives, their coordination chemistry and bio-activities (Khoo et al., 2005;Chan et al., 2008;Manan et al., 2012), the title complex, (I), was synthesized and characterized crystallographically.
In (I), Fig. 1, the Ni II atom exists within a distorted square planar cis-N 2 S 2 donor set defined by two N,S-chelating hydrazinecarbodithioate ligands, Table 1. The five-membered chelate ring in non-planar (r.m.s. = 0.239 Å) but has an envelope conformation with the Ni atom being the flap atom. A measure of the distortion from the ideal square planar geometry is the dihedral angle of 30.10 (6)° formed between the least-squares planes through the chelate rings. The coordination geometry in (I) resembles that seen in a closely related analogue (Chan et al., 2008).
The hydrazinecarbodithioate ligand is twisted about the N1-N2 bond with the C1-N1-N2-C9 torsion angle being 146.88 (14)°. The dihedral angle between the terminal benzene and phenyl rings is 89.37 (8)°, indicating an almost orthogonal relationship. The methoxy group is co-planar with the benzene ring to which it is connected as seen in the value of the C19-O1-C16-C15 torsion angle of -1.9 (3)°.
The most prominent feature of the crystal packing is the formation of supramolecular chains mediated by C-H···N contacts, Fig. 2 and Table 1. The chains are propagated by glide symmetry along the c axis.
The mixture was heated (~340 K) while being stirred for half an hour and then cooled to room temperature. The Schiff base thus formed was filtered and dried in vacuo over anhydrous silica gel. A combination of hot absolute ethanol solutions of the Schiff base (0.36 g, 10 mmol, in 30 ml) and nickel(II) acetate tetrahydrate (0.12 g, 5 mmol, in 10 ml) was stirred at ~340 K for half an hour. The mixture was cooled to room temperature and a green precipitate formed. Darkgreen crystals were obtained from its acetonitrile solution after one week. Yield 66%, M.pt: 417 K.

Refinement
Carbon-bound H-atoms were placed in calculated positions (C-H = 0.95 to 0.99 Å) and were included in the refinement in the riding model approximation with U iso (H) set to 1.2 to 1.5U equiv (C).

Figure 1
The molecular structure of (I) showing the atom-labelling scheme and displacement ellipsoids at the 50% probability level.

Figure 2
A view of the supramolecular chain in (I) mediated by C-H···N interactions, shown as blue dashed lines. Hydrogen atoms not involved in these interactions are omitted.

Bis{benzyl 2-[4-(4-methoxyphenyl)butan-2-ylidene]hydrazinecarbodithioato-\ κ 2 N 2 ,S}nickel(II)
Crystal data [Ni(C 19  where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max = 0.001 Δρ max = 0.80 e Å −3 Δρ min = −0.45 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.