Kinetics of aquation of Co(III) complex in binary aqueous mixtures and effect of multiparameters of the solvent on the reaction rate

Abstract

Kinetics and solvent effects of the aquation of trans 4 Cl 2 ] + have been studied in ethanol + water ranging from 0 to 60% (v/v) and urea + water of various solvent compositions up to 40% (w/w) of organic solvent. Thermodynamic activation parameters were computed and discussed in terms of the solvation effect. Isokinetic temperature within the experimental range revealed that the existence of the compensation effect arising from the solute-solvent interaction. Nonlinear plots of log k with D −1 suggest that changes in the solvent structure are an important factor that influences these rates. The influence of the added cosolvent on reactivity was analyzed in light of various simple and multiple regression equations using Kirkwood, E T (30), and Kamlet-Taft parameters. The obtained results showed that the solvation phenomenon plays a dominant role in the aquation. C 2011 Wiley Periodicals, Inc. Int J Chem Kinet 43: [230][231][232][233][234][235][236][237] 2011

Kinetics and mechanism of aquation of bromopentammine cobalt(III) cation assisted by ion-pairing succinate anion in ethane-2-diol-water mixtures

“…The log A/k versus Eb/log (C/D) gives a good straight line passing through origin with a slope equal to 0.0520, which is in consistent with the theoretical one (0.0522). As shown in Figure 5, the plot was found to be non linear in accordance with the general observations found in the aquation of a large number of other cobalt(III) complexes [19][20][21][22][23][24][25] in water-cosolvent mixtures, which led to a conclusion, that the contribution of the non electrostatic part of solvent effect, overcomes the electrostatic component part. Also log kip was plotted against reciprocal of the dielectric constant D at different temperatures, where the dielectric constant values of different compositions are obtained from Akerlöf data [18].…”

Studies on ion-pairing effects of the kinetics of aquation of bromopentaammine cobalt(III) complex in malonate media

“…Figure 10 depicts the variation of the values of the left hand side of the Equation (36) at 25 °C as a function of mole fraction of the co-solvent from which the differential solvating behavior of different malonate buffer for the initial and transition state is clearly evident. All the values on the left hand side of Equation (36) are negative as found for the aquation of a wide range of cobalt(III) complexes in a mixture of water with different co-solvents [31][32][33]. In all these cases, the effect of changing solvent structure on the pentacoordinatedcobalt cation in the transition state dominate the effect on the hexacoordinatedcobalt(III) cation in the initial state.…”

Reactivity Tracers of the Hydrolysis of Fe(II)‐Bis(salicylidene) Complexes: Initial–Transition States Analysis and Enhanced Impact of Tensides on the Kinetic Trends

“…The nonlinear plots obtained on plotting log k obs against 1/ D (Figs. ) suggest the effect of degree of the solvation of both IS and TS on the rate constant of the reaction .…”