Structural Chemistry & Crystallography Communication

Keywords

Chirality; Schiff base; Zinc (II) complex; Molecular structure

Introduction

We have studied on organic/inorganic hybrid materials of chiral Schiff base metal complexes and photochromic dyes such as azobenzene in polymer films to investigate molecular orientation control by irradiation of polarized UV light [1-3]. In this kind of materials, not only molecular structures of metal complexes but also intra- or inter-molecular interaction are important. Since crystal structure of the title compound (Scheme 1), which may be expected π-π stacking and hydrogen bonds, has not been determined yet [4], we report it herein.

Scheme 1: The molecular structure of the title compound.

Experimental

Synthesis

Synthesis of the title compound was published in our previous paper [4]. Yellow prismatic crystals of (I) were obtained from reaction solution by solvent diffusion method with water in sample tube at 278 K over 7 days.

Data collection

X-ray diffraction intensity data were collected on Bruker Kappa Apex II single crystal X-ray diffractometer equipped with graphite monochromated MoKα (λ=0.71073 Å) radiation and CCD detector. Crystal of suitable size was mounted on a glass fiber after determination of the unit cell parameters, the intensity data were collected with an average fourfold redundancy per reflection and optimum resolution. The intensity data collection, frames integration, Lorentz and polarization correction and decay correction were done using SAINT software [5]. Empirical absorption correction (multi-scan) was performed using SADABS program [5].

Results and Discussion

Structure solving and refinement

Crystal structure was solved by direct methods using SHELXS-97 [6]. All the non-hydrogen atoms were located automatically. The structure was then refined by full-matrix least-squares method using SHELXL- 97 [6]. The model of non-hydrogen atoms was refined using by anisotropic thermal parameters. Hydrogen atoms were positioned geometrically C–H=0.93–0.98 Å and allowed to ride on their parent atoms, with Uiso(H)=1.5 Ueq(C) for methyl H 1.2 Ueq(C) for other H atoms mainly. The relevant crystallographic data are listed in Table 1.

Table 1: Crystal data for the title compound.

The molecular structure (ORTEP diagram) of the title compound is shown in Figure 1. Selected bond lengths and angles are listed in Table 2. The title zinc(II) complex affords a four-coordinated tetrahedral coordination geometry and umbrella conformation affected in which both ligands bend towards the same side, with Zn₁-N₁ and Zn₁-O₁ bond distances being 2.034(5) and 1.940(4) Å, respectively. Because of symmetric center, coordination bond angles are O₁-Zn₁-N₁=94.00(19)°, O₁-Zn₁-N₁’=109.07(19)°, O₁- Zn₁-O₁’=131.1(3)°, and N₁-Zn₁-N₁’=122.8(3)° (‘denotes symmetry code: 1-x, y, 1-z). The values are within common range of the related complexes [7-11]. Benzene rings of ligands, parts of (R)- (−)-2-phenylglycinol and 3, 5-dibromosalicylaldehyde, formed weak intramolecular π-π stacking structure, affecting its umbrella conformation. Contrary to our expectation, there are no relevant hydrogen bonds within 3.3 Å.

Figure 1: The molecular structure of the title compound, showing the atomic numbering (for asymmetric unit) and displacement ellipsoids drawn at the 30% probability level.

Table 2: Selected bond lengths (Å) and angles (Å) (‘denotes symmetry code: 1-x, y, 1-z).

Additional Information

Crystallographic data for the structures reported here have been deposited with CCDC Deposition No CCDC 1482903. These data can be obtained free of charge from the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK, Fax: +441223336033; E-mail: deposit@ccdc.cam.ac.uk.

References

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2. Akitsu T, YamazakiA, Takanashi T,Aritake Y (2011)Polarized spectroscopy and hybrid materials of chiral Schiff base Ni(II), Cu(II), Zn(II) complexes with included or separated azo-groups.Polyhedron30: 886-894.
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