Kinetic Analyis of TG Data: XXXV. Spectroscopic and thermal studies of some cobalt(III) chelates with ethylenediamine

Authors: Zsakó, J.; Pokol, G.; Novák, Cs.; Várhelyi, Cs.; Dobó, A.; Liptay, G.

Source: Journal of Thermal Analysis and Calorimetry, Volume 64, Number 2, May 2001 , pp. 843-856(14)

Publisher: Springer

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Abstract:

A number of 30 [Co(en)₃]Y₃, [Co(en)₂X₂]Y and [Co(en)₂X(amine)]Y₂ type complexes (X=Cl, Br; Y=Cl, Br, I, NCO, NCS, NO₃, ClO₄, etc.; amine=aromatic and alkylamines) were obtained from trans-[Co(en)₂Cl₂]Cl by double decomposition and by substitution reactions, respectively. The structure of the complexes was proved by means of far and middle FTIR spectra. The thermal decomposition was studied by TG, DTA and DSC measurements. Mass spectra were also recorded. In the case of [Co(en)₃]Y₃ complexes the nitrate, perchlorate and dimesoperiodates decompose suddenly, frequently explosion like. The halides and thiocyanates seem to substitute an ethylenediamine ligand, yielding a rather unstable intermediate. The pyrolysis of [Co(en)₂X₂]Y type derivatives yields no relatively stable intermediates, but the decomposition temperatures may be correlated with the nature of Y and with the cis or trans configuration of the compound. With the [Co(en)₂X(amine)]Y₂ type complexes one observes the formation of [Co(en)₂XY]Y as intermediate product. From the TG curves kinetic parameters were derived for some dehydration and deamination processes, by using the nomogram method. The validity of a nonlinear kinetic compensation law was observed.

Keywords: cobalt(III) complexes; DSC; DTA; kinetics; FTIR and IR spectra of Co(III) complexes; TG

Document Type: Research article

DOI: http://dx.doi.org/10.1023/A:1011577319016

Publication date: 2001-05-01