The coordination behavior of thiosemicarbazide and its thiosemicarbazones towards Bi(III) is the main goal of this investigation. The structure of the isolated complexes has been proved by microanalysis, thermal, spectra (electronic, IR and ms) and voltammetric measurements. The ligands act as neutral or mononegative molecules and the coordination donors were found to be S for HTS; NN for HBTS; NS for HATS and H 2 STS and NNS or NSO for H 2 DMTS in the complexes. The complexes show thermal decomposition steps ending at 800°C with a stable fragment. The redox properties of the complexes toward oxidation waves are strongly dependent on =N thio substituents. At pH 1.5 and excess of iodide, Bi 3+ forms an orange-yellow [BiI 4 ] ) complex which associated with tricaprylylmethylammonium chloride (TCMAC) forming [TCMA] + [BiI 4 ] ) easily extracted into the CHCl 3 layer. The colored organic layer containing the ion pair is determined spectrophotometrically at 490 nm and represents the second goal.

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