Introduction Studies on supramolecular chemistry of lanthanide com- plexes are an area of increasing interest due to the wide range of applications for these compounds, as solid-state lasers, luminescent probes, NMR shift reagents, electro- luminescent devices, catalytic processes and other uses [1]. Complexes of lanthanide picrates and sulfoxide ligands are under investigation in our laboratories. Stud- ies on the synthesis and characterization, structural de- termination, spectroscopy and thermal decomposition were previously reported [2–10]. In this paper the ther- mal behavior of complexes of lanthanide picrates with cis-DTSO 2 ligand and the volatile products liberated from thermal decomposition using TG/DTG, DSC and TG/DTA-GC/MS techniques are presented. Experimental The oxidation of 1,3-dithiane-1-oxide with m-chloro- peroxybenzoic acid results in the isomers trans- and cis-1,3-dithiane-1,3-dioxide. The insoluble cis-isomer (Fig. 1) was separated and purified from the soluble trans-isomer by ethanolic treatment [9]. Hydrated lanthanide picrates were prepared by reaction of lanthanide hydroxycarbonates and picric acid in aque- ous solution [6]. The complexes were prepared by re- action of the lanthanide picrates dissolved in absolute ethanol and treatment with a warm ligand solution in the same solvent (molar ratio 1:4). The yellow crystals formed were separated and dried under vacuum over anhydrous calcium chloride. The characterization of the complexes by micro- analytical procedures, infrared absorption spectros- copy, emission and absorption spectroscopy and crys- tal structure determination by X-ray was described elsewhere [9]. Thermal behavior studies of complexes were made by TG/DTG and DSC analysis. A small amount of material (1–1.5 mg) was used, due to the easy explo- sion of picrates. TG/DTG experiments have been per- formed in a TGA-50 Shimadzu instrument under dy- namic air atmosphere (50 mL min –1 ) at a heating rate of 10 K min –1 up to 900°C. DSC measurements were performed in a dynamic nitrogen atmosphere (50 mL min –1 ) at a heating rate of 10 K min –1 up to 600°C, using a DSC-50 cell (Shimadzu). The DSC cell was calibrated with indium (m.p. 156.6°C; DH fus =28.54 J g –1 ) and zinc (m.p. 419.6°C). The final products of the thermal decomposition were character- ized by CHN microanalytical (Perkin Elmer 240 in- strument) and IR spectra (Nicolet FTIR-8100 spec- trometer) using KBr pellets. 1388–6150/$20.00 Akadémiai Kiadó, Budapest, Hungary © 2005 Akadémiai Kiadó, Budapest Springer, Dordrecht, The Netherlands Journal of Thermal Analysis and Calorimetry, Vol. 79 (2005) 305–308 THERMAL DECOMPOSITION OF LANTHANIDE COMPLEXES WITH SULFOXID LIGAND AND STUDY OF VOLATILE PRODUCTS LIBERATED P. Miranda Jr. 1* , L. P. Mercuri 2 , J. R. Matos 3 , M. F. Máduar 4 and J. Zukerman-Schpector 5 1 Centro Universitário – Fundaç±o Santo André (SP), Brazil 2 Centro CETEC – Universidade Cruzeiro do Sul – UNICSUL, S±o Paulo (SP), Brazil 3 Departamento de Química Fundamental – LATIG - IQ - Universidade de S ±o Paulo (SP), Brazil 4 Centro de Metrologia das Radiações – CMR, IPEN-CNEN (SP), Brazil 5 Departamento de Química, Universidade Federal de S±o Carlos (SP), Brazil Thermal behavior studies on complexes [Ln(cis-DTSO 2 ) 4 (H 2 O) 2 ](pic) 3 (Ln=Pr–Lu, Y; cis-DTSO 2 =cis-1,3-dithiane-1,3-dioxide and pic=picrate) were done by TG/DTG and DSC analysis. The volatiles liberated from thermal decomposition were separated by chromatographic packed column (Tenax 60–80 mesh) and detected by mass spectrometry using TG/DTA-GC/MS combined analytical technique. The retention times of volatile products liberated in the chromatographic column were 4.25 min for SO 2 and 21.05 min for methyl-propyl-sulfoxide. Keywords: cis-1,3-dithiane-1,3-dioxide, lanthanide, thermal decomposition Fig. 1 Structure formula of cis-DTSO 2 ligand * Author for correspondence: p.miranda.jr@globo.com