trans-Bis[acetone (2-hydroxybenzoyl)hydrazonato-κ2 N′,O]bis(pyridine-κN)zinc(II)

In the title compound, [Zn(C10H11N2O2)2(C5H5N)2], the ZnII atom lies on an inversion centre, and is coordinated in a distorted octahedral geometry by two carbonyl O atoms and two imino N atoms from two anionic bidentate acetone (2-hydroxybenzoyl)hydrazone ligands and by two N atoms from two pyridine molecules. The hydroxyl group acts as a donor, forming an intramolecular O—H⋯N hydrogen bond.

In the title compound, [Zn(C 10 H 11 N 2 O 2 ) 2 (C 5 H 5 N) 2 ], the Zn II atom lies on an inversion centre, and is coordinated in a distorted octahedral geometry by two carbonyl O atoms and two imino N atoms from two anionic bidentate acetone (2hydroxybenzoyl)hydrazone ligands and by two N atoms from two pyridine molecules. The hydroxyl group acts as a donor, forming an intramolecular O-HÁ Á ÁN hydrogen bond.

Comment
Hydrazones have been attracting much attention by chemists in recent years because of their biological activities, chemical and industrial versatility, and strong tendency to chelate transition metals (Bai et al., 2006;Grove et al., 2004), lanthanide metals (Ma et al., 1989) and main group metals (Gao et al., 1998;Liu & Gao, 1998). In particular, salicyloylhydrazone can be very flexible and finely tuned at the molecular level to take versatile bonding modes. It can act as a bi-, tri-, tetra-and even pentadentate ligand. A number of zinc(II) complexes with salicyloylhydrazone ligands have been studied (Hu et al., 2006;Hu et al., 2007;Li et al., 2006;Samanta et al., 2007;Wu et al., 2006). As an extension of the work on the structural characterization of salicyloylhydrazone complexes, the preparation and crystal structure of the title zinc(II) complex are reported here.
The molecular structure of the title compound is shown in Fig. 1. The Zn II atom lies on an inversion centre and has an axially elongated octahedral coordination geometry. The two carbonyl O atoms and the two imino N atoms make up the equatorial plane and the two N atoms of two pyridine molecules occupy the axial positions at longer distances (Table 1).
The resulting red solution was stirred for 20 min and then filtered. After standing for 5 d, yellow crystals were separated from the filtrate.

Refinement
H atoms bonded to C atoms were positioned geometrically and refined as riding atoms, with C-H = 0.93 (aromatic) and 0.96 (CH 3 ) Å and with U iso (H) = xU eq (C), where x=1.2 for aromatic and 1.5 for methyl H atoms. H atom of the hydroxyl group was located in difference Fourier map and refined isotropically with its coordinates fixed. Fig. 1