Articles written in Journal of Chemical Sciences
Volume 124 Issue 4 July 2012 pp 791-799
The kinetics of the reaction of HOBt with [Rh(H2O)5(OH)]2+ has been studied spectrophotometrically in aqueous medium as a function of [Rh(H2O)5OH2+], [HOBt], pH and temperature. At pH 4.3, the reaction proceeds via a rapid outer sphere association complex formation step followed by two consecutive steps. The first of these involves ligand-assisted anation, while the second involves chelation as the second aqua ligand is displaced. The association equilibrium constant for the outer sphere complex formation has been evaluated together with the rate constants for the two subsequent steps. The activation parameters for both steps have been evaluated using Eyrings equation. Thermodynamic parameters calculated from the temperature dependence of the outer sphere association equilibrium constants are also consistent with an associative mode of activation. The product of the reaction has been characterized by IR and ESI-mass spectroscopic analysis.
Volume 124 Issue 4 July 2012 pp 801-807
The kinetics of interaction between
Volume 128 Issue 8 August 2016 pp 1327-1335 Regular Article
A brief overview of mechanistic studies of the reactions of Pd(II)-bipy-malonate complex with different set of ligands, viz., (N, S), (S, O) and (S) donor molecules is reported here. The kinetics of complex formation reactions of three sulphur containing bio-relevant ligands thioglycolic acid[L₁],thiourea[L₂] andthiosemicarbazide [L₃] were studied with innermetallic [Pd(bipy)(malonate)] complex at physiological condition. The effect of the nucleophilicity of the chosen nucleophiles was studied for the reactant complex under pseudo-first order conditions as a function of nucleophile concentration and temperature using stopped-flow technique. This article describes the results obtained for substitution reactions of bi-functional Pd(II) complex with different biomolecules, under varying experimental conditions. The kinetic studies showed that the malonate ring departs from the coordination zone of palladium centre via two-step mechanism. The first step depends on the concentration of the incoming ligand for all the ligands. But in the second step thiourea is ligand dependent where as other two are independent of the ligand concentration. Hence, it can be concluded that the second step is the chelation step for L₁ and L₃. The mechanism for the substitution of the coordinated malonate molecule is associative, as demonstrated by the negative values of ∆S=. Such type of complexes are less toxic than chloro-, which in turn hydrolyses to aqua or aqua complexes as they are prevented from oligomer formation at physiological pH.
Volume 130 Issue 9 September 2018 Article ID 0124
The reactivity of
Volume 135, 2023
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