Bis{5-methoxy-2-[(1H-pyrrol-2-yl)methyliminomethyl]phenolato}zinc(II)

The title compound, [Zn(C13H13N2O2)2], contains a Zn(II) centre, located on a twofold rotation axis, that is coordinated by two O atoms and two N atoms from two salicylal Schiff base molecules. The crystal structure is stabilized by intermolecular C—H⋯O hydrogen bonds.

The title compound, [Zn(C 13 H 13 N 2 O 2 ) 2 ], contains a Zn(II) centre, located on a twofold rotation axis, that is coordinated by two O atoms and two N atoms from two salicylal Schiff base molecules. The crystal structure is stabilized by intermolecular C-HÁ Á ÁO hydrogen bonds.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: HG2551).

Comment
Zinc derivatives are particularly interesting owing to their essential importance in several biological processes Xiao et al., 2007;Chen et al., 2007). We have reported the structures of a few zinc(II) complexes (You & Zhu, 2006;Qiu et al., 2004;Zhu et al., 2004). As an extension of our work on the structural characterization of zinc compounds, we report the crystal structure of the title compound, (I), which has been determined in an attempt to understand the structural behaviour of nitrogen containing ligands.
The present X-ray single-crystal diffraction study reveals that compound (I), Bis(4-methoxysalicylidene(1H-pyrrol-2yl)methanaminato)zinc(II), consists of a Zn(II) atom and two bidentate salicylal Schiff base ligands. As shown in Fig. 1, The central Zn atom exhibits 4-coordination by two N atoms from imine moieties and two O-anions from salicylal groups, forming a slightly distorted tetrahedron. The distortion arises from the difference between O-Zn and Zn-N ( Table 1).
The hydrogen-bonding interactions occur between the C-H in the CH 2 group as donors and O in the salicylal moiety as acceptors (Table 1). These intermolecular hydrogen bonds construct an infinite ribbon. Interactions between the ribbons are van der Waals forces. Experimental 0.5 mmol of zinc oxide, 1 mmol of 4-methoxysalicylaldehyde and 1 mmol of (1H-pyrrol-2-yl)methanamine were dissolved in 10 ml methanol. After 3 ml ammonia was added, the result solution was then heated to 423 K for 12 h. The reactor was cooled to room temperature at a rate of 10 K h -1 . The mixture was filtered and held at room temperature for 12 d. Colorless block crystals were isolated in 41% yield.

Refinement
All H atoms were placed in geometrically idealized positions and constrained to ride on their parent atoms. U iso (H) values were set at 1.2 times U eq (C, N) for aromatic C and N in pyrrole ring groups and 1.5 times U eq (C) for CH 3 groups.
supplementary materials sup-2 Figures Fig. 1. The independent components of (I), showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level.