Synthesis and thermal properties of IIB group derived ε-caprolactam-3-dithiocarboxylic acid complexes
Zn(II), Cd(II) and Hg(II) ε-caprolactam-3-dithiocarboxylic acid complexes were synthesized by reacting the ε-caprolactam-3-carbothioic sodium salt with the respective metal salt. Samples were characterized by X-ray powder diffraction, EDS elemental analysis, UV-visible, FT-IR, 1H NMR and EPR spectroscopy. Thermal properties were determined using thermogravimetry and differential scanning calorimetric analysis. M-ε-caprolactam-3-dithiocarboxylic acid complexes showed intense electronic delocalization due to the charge transfer (420 nm) induced from the metal to the dithiolate group reaching different stages into the V unit (350 nm) of the dithiocarboxylate ring with a "n → " (310 nm) transition. This transition was also observed by EPR which showed 3 parallel and 3 perpendicular signals. The complexes are stabilized by the electro-attraction of the amidic and carbonyl groups; the stability trend is Zn > Cd > Hg. Thermal decomposition shows a multi-step fragmentation process that suggests lactamic chain rupture.
Keywords: DSC; Dithiocarboxylates complexes; EPR, V-unit; TGA
Document Type: Research Article
Affiliations: 1: Facultad de Química de la UAEM, Departamento de Química Inorgánica, CP 50140, México 2: Departamento de Física, Instituto Nacional de Investigaciones Nucleares, La Marquesa Edo de México, CP 52750, México
Publication date: 01 January 2007
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