Crystal structure of bis(acetophenone 4-benzoylthiosemicarbazonato-κ2 N 1,S)nickel(II)

In [Ni(C16H14N3OS)2], the nickel ion is tetracoordinated in a square-planar geometry by two independent molecules of the ligand which act as mononegative bidentate N,S-donors and form two five-membered chelate rings. Close approach of hydrogen atoms to Ni2+ suggests anagostic interactions (Ni⋯H—C) are present.


Chemical context
Thiosemicarbazones containing N and S donor atoms have been widely used in metal coordination chemistry due to their structural flexibility and versatility (Pelosi et al., 2010;Yousef et al., 2013;Jagadeesh et al., 2015). The chemistry of transition metal complexes of thiosemicarbazones has gained significant attention due to their potential medicinal applications (Pelosi et al., 2010;Li et al., 2012;Manikandan et al., 2014). The variable mode of binding of thiosemicarbazone towards nickel has encouraged us to explore its coordination chemistry further since nickel has the ability to take up different coordination environments. Nickel complexes are known to catalyse carbon-carbon cross-coupling and other reactions (Suganthy et al., 2013;Wang et al., 2014). ISSN 2056-9890

Figure 2
Two anagostic interactions (dashed lines) between the nickel(II) ion and the aromatic C-H groups. Table 2 Hydrogen-bond geometry (Å , ).

Synthesis and crystallization
The title complex was prepared by adding a solution of acetophenone-4-benzoyl-3-thiosemicarbazone (75 mg; 0.25 mmol) in dichloromethane (10 mL) dropwise to a stirred solution of nickel(II) nitrate hexahydrate (47.5 mg; 0.26 mmol) in 2-propanol (10 mL) in a small beaker. The resulting mixture solution was stirred continuously for 1 h at 318-323 K. The resultant green precipitate was separated by vacuum filtration, washed with 2-propanol and then with ether, and dried in a vacuum desiccator over dry silica gel. Single crystals suitable for X-ray analysis were obtained after slow evaporation of a dichloromethane solution saturated   Table 2). H atoms not involved in the hydrogen bonding have been omitted for clarity.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 3. The H atoms attached to nitrogen were located in difference Fourier maps and freely refined.

Bis(acetophenone 4-benzoylthiosemicarbazonato-κ 2 N 1 ,S)nickel(II)
Crystal data [Ni(C 16  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.