Physico-chemical Characterization of Some Metal Complexes Formed by Substituted Thiourea

In view of unique physico-chemical observations affecting the geometry and various properties of the substituted thiourea complexes in literature along with several biological activities, N-(hydroxy)-N,N-diphenyl thiourea was taken up for study. Complexes with geometries of high spin octahedral for iron(II), cobalt(II); tetrahedral & square planar for nickel(II); and dimeric square planar for copper chloride, copper perchlorate, copper acetate and distorted octahedral for copper nitrate were synthesized and characterized based on magnetic moments, visible spectra, diffuse reflectance spectra, electron spin resonance, infrared spectral studies, and thermal analysis.

Interestingly, the nature of anion influenced the geometry, the complex from copper nitrate salt resulted in a distorted octahedral structure and complexes formed from copper chloride, copper perchlorate, copper acetate exhibited sub-normal magnetic moments, highly insoluble in the most common organic solvents and water. Based on these and spectral data, polymeric or square-planar dimeric geometry with sulfur bridging between copper atoms is proposed. It was confirmed by the application of Bleaney-Bower’s equation for magnetic susceptibility, applicable to dimeric copper complexes.

The overall thermal behavior of the ligand and complexes were observed and the detailed calculations interestingly lead to confirmation of the above proposed geometrical structures.