Thermal analysis of Fe(III) complexes with salicylaldehyde semi-, thiosemi- and S-methylisothiosemi-carbazones

The paper describes the results of differential thermal analysis of the oct ahedral Fe(III) complexes of the general formula [Fe(HLn)(2)]Cl and Fe(HL3) L-3, as well as of the corresponding ligands H2Ln (H2Ln - tridentate salicy laldehyde semi thiosemi- and S-methylisothiosemi-carabazones with n=1, 2 an d 3 respectively). The decomposition of the complexes involving sulphur-con taining ligands (H2L2 and H2L3) starts with sulphur elimination. In case of the complexes [Fe(HL2)]Cl and [Fe(HL3)]Cl sulphur evolves independently, w hereas with Fe(HL3)L-3 it is eliminated within the SCH3 group. In the forme r case, sulphur elimination takes place at the same temperature for both co mplexes. The change in the coordination mode, being a consequence of the re placement of O by S, has no essential effect on thermal stability of the co ordination polyhedron. The complexes involving ONN coordination, realized w ith the H2L3 ligand, exhibit a comparatively highest thermal stability of t he coordination polyhedron.