Crystal structure, Hirshfeld surface analysis and computational study of bis(2-{[(2,6-dichlorobenzylidene)hydrazinylidene]methyl}phenolato)cobalt(II) and of the copper(II) analogue

The title homoleptic Schiff base complexes, [M(C14H9C12N2O)2], for M = Con (I), and Cu", (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 1). In the crystal of (I), discernible supramolecular layers in the ac plane are sustained by chlorobenzene-C H- center dot center dot center dot-pi (coordinated), chlorobenzene-C H center dot center dot center dot-pi r(fusedbenzene ring) as well as rr(fused-benzene, chlorobenzene) z(chlorobenzene) interactions [inter-centroid separations = 3.6460 (17) and 3.6580 (16) A, respectively]. The layers inter-digitate along the b -axis direction and are linked by dichlorobenzene-C H center dot center dot center dot pi r(fused-benzene ring) and 7r rr interactions between fused-benzene rings and between chlorobenzene rings [inter-centroid separations = 3.6916 (16) and 3.7968 (19) A, respectively]. Flat, supramolecular layers are also found in the crystal of (II), being stabilized by 7r rr interactions formed between fused -benzene rings and between chlorobenzene rings [intercentroid separations = 3.8889 (15) and 3.8889 (15) A, respectively]; these stack parallel to [101] without directional interactions between them. The analysis of the respective calculated Hirshfeld surfaces indicate diminished roles for H center dot center dot center dot H contacts [26.2% (I) and 30.5% (II)] owing to significant contributions by Cl- center dot center dot center dot H-H center dot center dot center dot Cl contacts [25.8% (I) and 24.9% (II)]. Minor contributions by Cl-center dot center dot center dot Cl [2.2%] and Cu center dot center dot center dot Cl [1.9%] contacts are indicated in the crystals of (I) and (II), respectively. The interaction energies largely arise from dispersion terms; the aforementioned Cu center dot center dot center dot Cl contact in (II) gives rise to the most stabilizing interaction in the crystal of (II).