[Zurück]

K. Misra, I. Mitra, G. Ghosh, S. Mukherjee, B. Misini, W. Linert, S. Moi:
"Kinetics and mechanism of biphasic substitution reactions of a platinum(II) complex with thioglycollic acid and 4-methyl-3-thiosemicarbazide in aqueous solution";
Transition Metal Chemistry, 39 (2014), S. 789 - 796.

The kinetics of interaction between cis-diaqua(2-aminomethylpyridine)platinum(II) perchlorate (1) [Pt(pic)(OH2)2](ClO4)2, thioglycollic acid (TGA), and 4-Methyl-3- thiosemicarbazide (MTSC) have been studied spectrophotometrically in aqueous medium as a function of the [complex (1)] as well as [TGA] or [MTSC], pH and temperature at constant ionic strength. The observed pseudo-first-order rate constants were proportional to [TGA] or [MTSC]. At pH 4.0, the interactions of (1) with both TGA and MTSC separately show two distinct consecutive steps; the first step is dependent and second independent of [TGA] / [MTSC]. The association equilibrium constant (KE) for the outer sphere complex formation has been evaluated, along with the rate constants for the two steps. The first step is assigned toligand-assisted anation and the second to chelation of TGA or MTSC. The activation parameters for both the steps were evaluated using Eyring´s equation. On the basis of the kinetic observations and evaluated activation parameters, an associative mechanism is proposed for both the reactions.

Kinetics and mechanism. 2-Aminomethylpyridine. Thioglycollic acid. 4-Methyl-3- thiosemicarbazide. Associative mechanism.

http://dx.doi.org/10.1007/s11243-014-9861-6