Copper(II) thiocyanate complexes of 2-(2-pyridinyl)-benzthiazole: synthesis, structure, redox behavior, thermal aspects, and DFT calculations

Abstract

Reaction of 2-(2-pyridinyl)-benzthiazole (Pbt), KSCN, and copper(II)perchlorate hexahydrate in 1 : 2 : 1 molar proportion in dimethyl sulfoxide gives monomeric [Cu(Pbt)(SCN)₂DMSO] (1a). In another run, identical proportions of the same reactants in methanol generates a symmetric thiocyanate bridged dimeric copper(II) compound, [Cu₂(Pbt)₂(SCN)₂] (2a), in 72% yield. Both 1a and 2a have been characterized by C, H, and N microanalyses, copper estimation, FTIR, UV–vis spectra, and room temperature magnetic susceptibility measurements. The X-ray crystal structures of 1a and 2a have been determined. Electrochemical studies of 1a and 2a show Cu(II) to Cu(III) oxidation in solution. The thermal behaviors of 1a and 2a have been studied. Bond valence sum method of analysis was performed to assign the oxidation state for each copper center in 1a and 2a. Geometry optimization of 1a, 2a, and their linkage isomers has also been performed at the level of the density functional theory to show that 1a and 2a are the most stable congeners. These results corroborate our experimental findings.

Keywords:

• Copper
• Thiocyanate
• Electrochemistry
• Thermal behavior
• DFT calculation

Acknowledgments

Financial support [F. No. SR/FT/CS-75/2010] received from the SERC under Department of Science and Technology (DST), India, is gratefully acknowledged. J.P.N. gratefully acknowledges the University Grants Commission (UGC), New Delhi, India, for financial support [F. No. 41-220/2012 (SR)].