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

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.

Acknowledgments