Di- and triorganotin(IV) derivatives of 5-amino-3H-1,3,4-thiadiazole-2-thione as precursors for SnS/SnO 2: Thermal studies and related kinetic parameters

Abstract

Thermogravimetric analysis (TGA) with simultaneous differential thermal analysis (DTA) of R 2SnL 2 (R = methyl ( 1), n-butyl ( 2), n-octyl ( 3) and phenyl ( 4)) and R 3SnL (R = methyl ( 5), n-propyl ( 6), n-butyl ( 7) and phenyl ( 8); L = anion of 5-amino-3H-1,3,4-thiadiazole-2-thione) show that in air and nitrogen, diorganotin(IV) thiadiazolates decompose in a different manner, whereas triorganotin(IV) thiadiazolates decompose in a similar way. The decomposition of di- and triorganotin(IV) thiadiazolates occur in two or three steps. The first step of decomposition corresponds to the loss of a ligand/a part of ligand moiety, which is followed by the loss of remaining ligand moiety (in case of diorganotin(IV) thiadiazolates) and the organic groups attached to tin. In case of compounds ( 3) and ( 5), tin is partially lost to the gas phase due to sublimation. The residues obtained by thermal decomposition of these compounds are SnS and/or Sn in nitrogen and SnO 2 in air, which are characterized by infrared (IR), far-infrared (far-IR), X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). Mathematical analysis of thermogravimetric analysis data shows that the first step of decomposition in compounds ( 4), ( 6) and ( 8) in both air and nitrogen follows first order kinetics. Kinetic and thermodynamic data, such as energy of activation ( E *), pre-exponential factor ( A), entropy of activation ( S *), free energy of activation ( G *) and enthalpy of activation ( H *) of the first step of decomposition have also been calculated.