Online coupled TG-FTIR and TG/DTA-MS analyses of the evolved gases from dichloro(thiourea) tin(II)

Identification and monitoring of gaseous species released during thermal decomposition of title compound 1, dichloro(thiourea) tin(II), Sn(tU)Cl-2, [thiourea (tu), (NH2)(2)C=S] in flowing air atmosphere have been carried out by both online coupled TG-FTIR and simultaneous TG/DTA - MS evolved gas -analysis (EGA) instruments. The first gaseous products of 1, evolved from 170 degreesC, are cyanamide (NH2CN), carbonyl sulphide (COS), carbon disulfide (CS2) and water (H2O). At 240 degreesC isothiocyanic acid (HNCS) becomes the main product, accompanied by CS2, hydrogen cyanide (HCN) and traces of hydrogen chloride (HCI) according to EGA-FTIR analysis. Ammonia (NH3) occurs first only above 250 degreesC, while sulfur dioxide (SO2) formation is not observed till 400 degreesC. Air oxidation products of tin sulphides and organic residues, such as SO2, carbon dioxide (CO2) and NH2CN, occur suddenly at 425 degreesC together with a very sharp exothermic heat effect. All species identified by FTIR gas cells are confirmed by mass spectrometry, except HNCS. Evolution of H2S has not been observed at any stage of the degradation of 1 by either of the EGA methods. (C) 2004 Elsevier B.V. All rights reserved.