2-{(1E)-[(E)-2-(2,6-Di-chloro-benzyl-idene)hydrazin-1-yl-idene]meth-yl}phenol: crystal structure, Hirshfeld surface analysis and computational study

Crystal structures of two dis-symmetric di-Schiff base compounds: 2-({(E)-2-[(E)-2,6-di-chloro-benzyl-idene]hydrazin-1-yl-idene}meth-yl)-6-meth-oxy-phenol and 4-bromo-2-({(E)-2-[(E)-2,6-di-chloro-benzyl-idene]hydrazin-1-yl-idene}meth-yl)phenol

Each of the title dis-symmetric di-Schiff base compounds, C15H12Cl2N2O2 (I) and C14H9BrCl2N2O (II), features a central azo-N-N bond connecting two imine groups, each with an E-configuration. One imine bond in each mol-ecule connects to a 2,6-di-chloro-benzene substituent while the other links a 2-hydroxyl-3-meth-oxy-substituted benzene ring in (I) or a 2-hydroxyl-4-bromo benzene ring in (II). Each mol-ecule features an intra-molecular hydroxyl-O-H⋯N(imine) hydrogen bond. The C-N-N-C torsion angles of -151.0 (3)° for (I) and 177.8 (6)° (II) indicates a significant twist in the former. The common feature of the mol-ecular packing is the formation of supra-molecular chains. In (I), the linear chains are aligned along the a-axis direction and the mol-ecules are linked by meth-oxy-C-H⋯O(meth-oxy) and chloro-benzene-C-Cl⋯π(chlorobenzene) inter-actions. The chain in (II) is also aligned along the a axis but, has a zigzag topology and is sustained by Br⋯O [3.132 (4) Å] secondary bonding inter-actions. In each crystal, the chains pack without directional inter-actions between them. The non-covalent inter-actions are delineated in the study of the calculated Hirshfeld surfaces. Dispersion forces make the most significant contributions to the identified inter-molecular inter-actions in each of (I) and (II).

Crystal structure, Hirshfeld surface analysis and computational study of bis-(2-{[(2,6-di-chloro-benzyl-idene)hydrazinyl-idene]meth-yl}phenolato)cobalt(II) and of the copper(II) analogue

The title homoleptic Schiff base complexes, [M(C14H9Cl2N2O)2], for M = CoII, (I), and CuII, (II), present distinct coordination geometries despite the Schiff base dianion coordinating via the phenolato-O and imine-N atoms in each case. For (I), the coordination geometry is based on a trigonal bipyramid whereas for (II), a square-planar geometry is found (Cu site symmetry ). In the crystal of (I), discernible supra-molecular layers in the ac plane are sustained by chloro-benzene-C-H⋯O(coordinated), chloro-benzene-C-H⋯π(fused-benzene ring) as well as π(fused-benzene, chloro-benzene)-π(chloro-benzene) inter-actions [inter-centroid separations = 3.6460 (17) and 3.6580 (16) Å, respectively]. The layers inter-digitate along the b-axis direction and are linked by di-chloro-benzene-C-H⋯π(fused-benzene ring) and π-π inter-actions between fused-benzene rings and between chloro-benzene rings [inter-centroid separations = 3.6916 (16) and 3.7968 (19) Å, respectively] . Flat, supra-molecular layers are also found in the crystal of (II), being stabilized by π-π inter-actions formed between fused-benzene rings and between chloro-benzene rings [inter-centroid separations = 3.8889 (15) and 3.8889 (15) Å, respectively]; these stack parallel to [10] without directional inter-actions between them. The analysis of the respective calculated Hirshfeld surfaces indicate diminished roles for H⋯H contacts [26.2% (I) and 30.5% (II)] owing to significant contributions by Cl⋯H/H⋯Cl contacts [25.8% (I) and 24.9% (II)]. Minor contributions by Cl⋯Cl [2.2%] and Cu⋯Cl [1.9%] contacts are indicated in the crystals of (I) and (II), respectively. The inter-action energies largely arise from dispersion terms; the aforementioned Cu⋯Cl contact in (II) gives rise to the most stabilizing inter-action in the crystal of (II).