Bis(N'-{(E)-[(2E)-1,3-di-phenyl-prop-2-en-1-yl-idene]amino}-N-ethyl-carbamimido-thio-ato-κ2N',S)zinc(II): crystal structure and Hirshfeld surface analysis.

Ming Yueh Tan,Edward R T Tiekink,Thahira B S A Ravoof,Karen A Crouse,Mukesh M Jotani

doi:10.1107/s2056989017008064

Abstract

The title ZnII complex, [Zn(C18H18N3S)2], (I), features two independent but chemically equivalent mol-ecules in the asymmetric unit. In each, the thio-semicarbazonate monoanion coordinates the ZnII atom via the thiol-ate-S and imine-N atoms, with the resulting N2S2 donor set defining a distorted tetra-hedral geometry. The five-membered ZnSCN2 chelate rings adopt distinct conformations in each independent mol-ecule, i.e. one ring is almost planar while the other is twisted about the Zn-S bond. In the crystal, the two mol-ecules comprising the asymmetric unit are linked by amine-N-H⋯N(imine) and amine-N-H⋯S(thiol-ate) hydrogen bonds via an eight-membered heterosynthon, {⋯HNCN⋯HNCS}. The dimeric aggregates are further consolidated by benzene-C-H⋯S(thiol-ate) inter-actions and are linked into a zigzag supra-molecular chain along the c axis via amine-N-H⋯S(thiol-ate) hydrogen bonds. The chains are connected into a three-dimensional architecture via phenyl-C-H⋯π(phen-yl) and π-π inter-actions, the latter occurring between chelate and phenyl rings [inter-centroid separation = 3.6873 (11) Å]. The analysis of the Hirshfeld surfaces calculated for (I) emphasizes the different inter-actions formed by the independent mol-ecules in the crystal and the impact of the π-π inter-actions between chelate and phenyl rings.

Highlights

The title ZnII complex, [Zn(C18H18N3S)2], (I), features two independent but chemically equivalent molecules in the asymmetric unit
The five-membered ZnSCN2 chelate rings adopt distinct conformations in each independent molecule, i.e. one ring is almost planar while the other is twisted about the Zn—S bond
The two molecules comprising the asymmetric unit are linked by amine-N—HÁ Á ÁN(imine) and amine-N—HÁ Á ÁS(thiolate) hydrogen bonds via an eight-membered heterosynthon, {Á Á ÁHNCNÁ Á ÁHNCS}

Summary

Chemical context

Thiosemicarbazone molecules, derived from thiosemicarbazide, H2N—NH—C( S)—NH2, constitute an important class of mixed hard–soft, nitrogen–sulfur donor ligands which have been extensively investigated in their coordination chemistry towards both transition metals (Lobana et al, 2009) and main group elements (Casas et al, 2000). The interesting properties of their metal complexes, such as structural diversity, accessible redox activities, the ability to fine-tune ligand substitution, access to radical species, catalytic properties, distinct spectroscopic properties, etc. The presence of additional, suitably positioned donor atoms can increase their coordination ability/denticity, giving rise to different coordination geometries, such as tetrahedral, octahedral and pentagonal-bipyramidal. The thiosemicarbazone ligands chelate the ZnII atoms to form five-membered ZnSCN2 rings. The chelate rings adopt different conformations in each independent molecule.

Structural commentary

Supramolecular features

Analysis of the Hirshfeld surfaces

Database survey

Findings

Synthesis and crystallization