Spectral, thermal, electrochemical and analytical studies on Cd(II) and Hg(II) thiosemicarbazone complexes

The coordination characteristic of the investigated thiosemicarbazones towards hazard pollutants, Cd(II) and Hg(II), becomes the first goal. Their complexes have been studied by microanalysis, thermal, electrochemical and spectral (electronic, IR and MS) studies. The substitutent (salicylaldehyde, acetophenone, benzophenone, o-hydroxy-p-methoxybenzophenone or diacetylmonoxime) plays an important role in the complex formation. The coordination sites were the S for thiosemicarbazide (HTS); NN for benzophenone thiosemicarbazone (HBTS): NS for acetophenone thiosemicarbazone (HATS) and salicylaldehyde thiosemicarbazone (H2STS); NNS or NSO for diacetylmonoxime thiosemicarbazone (H2DMTS). The stability constants of Hg(II) complexes were higher than Cd(II). The kinetic and thermodynamic parameters for the different thermal decomposition steps in the complexes have been evaluated. The activation energy values of the first step ordered the complexes as: [Cd(H2STS)Cl-2]H2O > [Cd(H(2)DAMTS)Cl-2] > [Cd(HBTS)(2)Cl-2]2H(2)O > [Cd(HATS)(2)Cl-2]. The CV of [Cd(H2STS)Cl-2]H2O and [Hg(HBTS)Cl-2] were recorded. The use of H2DMTS as a new reagent for the separation and determination of Cd(II) ions from water and some synthetic samples using flotation technique is aimed to be discussed. (C) 2007 Elsevier B.V. All rights reserved.