{N′-[(E)-1-(5-Bromo-2-oxidophenyl)ethylidene-κO]-4-methylbenzohydrazidato-κ2 N′,O}(pyridine-κN)nickel(II)

The central NiII atom in the title complex, [Ni(C16H13BrN2O2)(C5H5N)], is in a square-planar trans-N2O2 environment defined by the NO2 donor atoms of the tridentate hydrazone ligand and the monodentate pyridine ligand. The pyridine molecule forms a dihedral angle of 9.99 (11)° with the least-squares plane through the NiN2O2 atoms.

The central Ni II atom in the title complex, [Ni(C 16 H 13 Br-N 2 O 2 )(C 5 H 5 N)], is in a square-planar trans-N 2 O 2 environment defined by the NO 2 donor atoms of the tridentate hydrazone ligand and the monodentate pyridine ligand. The pyridine molecule forms a dihedral angle of 9.99 (11) with the leastsquares plane through the NiN 2 O 2 atoms.

Comment
Hydrazones are an important class of Schiff bases compounds which has attracted much attention because of their biological activities (Carcelli et al., 1995) such as antimicrobial, antifungal, antitumor and as herbicides (El-Masry et al., 2000;Singh & Dash, 1988;Desai et al., 2001), and strong tendency to chelate to transition metals (Ali et al., 2004;Cheng et al., 1996).
As an extension of our work on the structural characterization of aroylhydrazone derivatives (Zheng et al., 2008), the title compound was synthesized and its crystal structure is reported here.
The coordination polyhedron about the nickel ion in the title complex is essentially planar, Fig. 1. The coordination environment of nickel is comprised of one pyridine ligand and one hydrazone ligand (two O atoms, one N atom) so that the central nickel atom is four-coordinated, Table 1.
Experimental p-Methyl ethylbenzoate (8.21 g, 0.05 mol) was dissolved in ethanol (50 ml) at room temperature and heated at 363 K, followed by the addition of hydrazine hydrate (3.00 g, 0.060 mol). Subsequently, the mixture was refluxed for 10 h, and then cooled to room temperature. The crystals were precipitated and collected by filtration. The product was recrystallized from ethanol and dried under reduced pressure to give 4-methylbenzohydrazide.
4-methylbenzohydrazide (3.75 g, 0.025 mol) was dissolved in ethanol (50 ml) at room temperature and heated at 363 K, followed by the addition of 5-bromo-2-hydroxyphenyl ethyl ketone (5.38 g, 0.025 mol). Subsequently, the mixture was refluxed for 9 h, and then cooled to room temperature. The crystals were precipitated and collected by filtration. The product was recrystallized from ethanol and dried under reduced pressure to give compound N'- NiCl 2 .6H 2 O (0.024 g, 0.10 mmol), pyridine (0.0079 g, 0.10 mmol), and H 2 O (5.00 ml), several drops of acetone was placed in a Parr Teflon-lined stainless steel vessel (25 ml). The vessel was sealed and heated at 393 K for 3 d. After the mixture was slowly cooled to room temperature, red crystals were obtained (yield 41%).

Refinement
All H atoms were positioned geometrically and treated as riding on their parent atoms,with C-H(methyl) = 0.96 Å, C-H(aromatic) = 0.93 Å, and with U iso (H) =1.5U eq (C methyl ) and 1.2U eq (C aromatic ).
supplementary materials sup-2 Figures Fig. 1. The molecular structure of the title compound, showing displacement ellipsoids drawn at the 30% probability level. H atoms are presented as a small spheres of arbitrary radius.