Kinetics and mechanism of thermal decomposition of cadmium(II) complexes with substituted thioureas

Abstract

From the thermal decomposition curves of cadmium(II) complexes with substituted thioureas (methyl-, dimethyl-, ethyl-, diethyl-, butyl-, dibutyl-, phenyl-, diphenyl-, acetyl-and benzoylphenylthiourea), the kinetic parameters of the thermal decompositions of these complexes were determined and a decomposition mechanism was suggested. The following thermal stability sequence is given for the Cd(I1) complexes: complexes with alkylthioureas < complexes with phenylthioureas < complexes with acylthioureas.Systematic studies on chemical and physical changes brought about by heating in chemical compounds provide information on the mechanisms and steps of their decomposition, and permit determination of the kinetic parameters of the reactions [1][2][3].The metal compounds of thioureas comprise an extensive series of sulfur-bonded complexes. Thermal decomposition studies here have been concerned with a few nickel(II) thiourea compounds [4], and acetylthiourea complexes of molybdenum [5] and Cd(II) [6]. The thermal decompositions Of methylthiourea and dimethylthiourea complexes of several transition metals, and of cadmium complexes containing various thioureas, have been studied by thermogravimetry in air and in vacuum. In vacuum, the dimethylthiourea complexes decomposed to a mixture of metal chloride and sulfide. The organic products included dimethylthiourea, methyl isothiocyanate, HC1 and polymerized material. In air, intermediates were formed in which part of the organic ligand was retained, followed by complete decomposition to inorganic salts at higher temperatures. While the overall pattern of decomposition was generally similar to that of thiourea itself, coordination

Synthesis, characterisation and thermal degradation behaviour of some coordination polymers by using TG–DTG and DTA techniques

“…The nanoscale particles of transition metal coordination polymers have huge thermal stability and tremendous potential applications [1,2]. Various studies have been reported on thermal stability, synthesis, morphological and applications of transition metal organic coordination polymers with derivative of dicarboxylic [3][4][5][6][7], amines [8], aromatic mono/dicarboxylic acid [9,10], substituted thiourea salt and bidentate ligand [11][12][13]. Actually, the supramolecular skeleton of coordination polymer is formed due to the polydentate ligand.…”

Thermal decomposition and mass spectra of mixed ligand copper(II) complexes of 1,10-phenanthroline and coumarin derivatives

“…In studies on the physical and chemical properties and the structures of solid complexes of transition metal ions with organic ligands, it is customary to investigate the thermal decomposition of these complexes so as to obtain useful data on the metal-ligand bonds [2][3][4] and stability trends. The thermal investigations on some derivatives of amines [5], sulfonamides [6], substituted thiourea salts [7], and complexes of bidentate ligands and others [8][9][10][11][12][13], have already been published.…”

Thermal analysis of thione compounds

“…In spite of literature reports on the thermal analysis investigations of thioureametal ion complexes, publications on the thermal behaviour of these individual materials are very scarce [6][7][8][9].…”