Chiral crystallization of a zinc(II) complex.

Shabana Noor,Tomoyuki Haraguchi,Fehmeeda Khatoon,Shintaro Suda,Takashiro Akitsu

doi:10.1107/s2056989021003650

Abstract

The compound, {6,6'-dimeth-oxy-2,2'-[(4-azaheptane-1,7-di-yl)bis-(nitrilo-meth-an-yl-idyne)]diphenolato}zinc(II) methanol monosolvate, [Zn(C22H27N3O4)]·CH3OH, at 298 K crystallizes in the ortho-rhom-bic space group Pna21. The Zn atom is coordinated by a penta-dentate Schiff base ligand in a distorted trigonal-bipyramidal N3O2 geometry. The equatorial plane is formed by the two phenolic O and one amine N atom. The axial positions are occupied by two amine N atoms. The distorted bipyramidal geometry is also supported by the trigonality index (τ), which is found to be 0.85 for the mol-ecule. In the crystal, methanol solvent mol-ecule is connected to the complex mol-ecule by an O-H⋯O hydrogen bond and the complex mol-ecules are connected by weak supra-molecular inter-actions, so achiral mol-ecules generate a chiral crystal. The Hirshfeld surface analysis suggests that H⋯H contacts account for the largest percentage of all inter-actions.

Highlights

The compound, {6,60-dimethoxy-2,20-[(4-azaheptane-1,7-diyl)bis(nitrilomethanylidyne)]diphenolato}zinc(II) methanol monosolvate, [Zn(C22H27N3O4)]ÁCH3OH, at 298 K crystallizes in the orthorhombic space group Pna21
The Zn atom is coordinated by a pentadentate Schiff base ligand in a distorted trigonal– bipyramidal N3O2 geometry
Methanol solvent molecule is connected to the complex molecule by an O—HÁ Á ÁO hydrogen bond and the complex molecules are connected by weak supramolecular interactions, so achiral molecules generate a chiral crystal

Summary

Chemical context

Schiff bases and their coordination compounds play an important role in metal coordination chemistry owing to their thermal stability, relevant biological properties and high synthesis flexibility (Bartyzel, 2018; Siddiqui et al, 2006; Sacconi, 1966). These ligands are able to coordinate a wide variety of metal ions and to stabilize them in various oxidation states. For Zn, = O2—Zn—O3 = 122.87 (10) and = N1—Zn—N3 = 173.91 (12) so the trigonality index is 0.85 According to this value, the coordination geometry around the zinc ion is best described as distorted trigonal–bipyramidal. This molecule has neither an asymmetric carbon nor a helical structure, so it is an achiral compound

Structural commentary

Database survey

Synthesis and crystallization

Findings

Refinement