PREPARATION AND THERMAL STUDIES OF SOME NEW OXORHENIUM(V) COMPLEXES WITH 2-AMINO-5-METHYL-1,3,4-THIADIAZOLE

Abstract

ABSTRACT A new series of oxorhenium(V) complexes were prepared by the reaction of 2-amino-5-methyl-1,3,4-thiadiazole (L), alone or with addition of NaSCN, with H2[ReOCl5]. Mononuclear complexes of various types, [ReOLCl3- (OH2)], [ReOL2Cl2(OH2)]Cl, [ReOLCl(SCN)2(OH2)], [ReOL2Cl3] and [ReOLCl2(SCN) (OH2)], along with binuclear complexes, Re2O2(µ-L)Cl6(OH2)2·2H2O and [Re2O3(µ-L)Cl4]·2H2O, were obtained depending on the metal:ligand molar ratio and the concentration of hydrochloric acid containing the dissolved parent rhenium complex. Thermal studies on these complexes showed the possibility of obtaining new complexes pyrolytically, where the complexes decompose through several isolable as well as non-isolable, intermediates during heating. [Re2O3L4Cl4], [Re2O3(µ-L)2(SCN)4], [Re2O2(µ-L)(µ-Cl)2Cl4] and [Re2O3(µ-L)2(SCN)2Cl2, were synthesized pyrolytically in the solid state from the respective precursor rhenium complexes. All of the prepared complexes and their thermal products have octahedral configurations. The ligand (L) behaves in these complexes either as a neutral monodentate or bidentate ligand towards oxorhenium ions. The structures of all complexes and the corresponding thermal products were elucidated by elemental analyses, conductance, IR and electronic absorption spectra, magnetic moments, 1H NMR and TG-DSC measurements.