Kinetic analyis of TG data - XXXV. Spectroscopic and thermal studies of some cobalt(III) chelates with ethylenediamine

A number of 30 [Co(en)(3)]Y-3, [Co(en)(2)X-2]Y and [Co(en)(2)X(amine)]Y-2 t ype complexes (X=Cl, Br; Y=Cl, Br, I, NCO, NCS, NO3, ClO4, etc.; amine=arom atic and alkylamines) were obtained from trans-[Co(en)(2)Cl-2]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 ther mal decomposition was studied by TG, DTA and DSC measurements. Mass spectra were also recorded. In the case of [Co(en)(3)]Y-3 complexes the nitrate, p erchlorate and dimesoperiodates decompose suddenly, frequently explosion li ke. The halides and thiocyanates seem to substitute an ethylenediamine liga nd, yielding a rather unstable intermediate. The pyrolysis of [Co(en)(2)X-2 ]Y type derivatives yields no relatively stable intermediates, but the deco mposition temperatures may be correlated with the nature of Y and with the cis or trans configuration of the compound. With the [Co(en)(2)X(amine)]Y-2 type complexes one observes the formation of [Co(en)(2)XY]Y as intermediat e product. From the TG curves kinetic parameters were derived for some dehy dration and deamination processes, by using the nomogram method. The validi ty of a non-linear kinetic compensation law was observed.