Kinetics of the solvolysis of [Co(3Rpy)₄Cl₂]⁺ (R = Me or Et) in water + propan‐2‐ol mixtures

Abstract

Rates of solvolysis of complex ions [C0(3Rpy)~Cl~]+ with R = Me and Et have been determined in mixtures of water with the hydrophobic co-solvent propan-2-01 for a range of temperatures. The variations of the enthalpies and entropies of activation with the solvent composition have been correlated with the physical properties of the solvent and it has been shown that the linear plot found for AH* against AS* in water + propan-2-01 is coincident with that found for water + methanol mixtures. A free energy cycle has been applied to the dissociative-type process of initial state (C"') going to the transition state (M("+')'. . . . . It is concluded that, using values for AGp(Cl-) from either source, the stabilizing influence of changes in solvent structure is greater on the cation in the transition state than on the cation in the initial state for the solvolyses of complexes [ C~( R p y )~C l~+ l and [CoenzLCl]"'.As part of our continuing investigation of the kinetics of hydrolytic reactions involving inorganic complexes with varying hydrocarbon content on the surface of their molecules in mixtures of water with co-solvents of varying hydrophilic [l] Propan-2-01 has been chosen as the co-solvent as properties of its mixtures with water, such as the deviation of the extremum in the excess enthalpy of

Kinetic Studies of Solute-Solvent Interactions in the Solvolysis of Trans- [Co (4-Teri-Butylpyri Dine)4C12)Clo4 in Organic-Aqueous Mixtures

“…The same observations were made using methanol, isopropanol, tert-butanol and urea as cosolvents with water used for the same complex [15,25]. Moreover, the same behaviour was observed for the solvolysis of trans-[Co(R-py) 4 Cl 2 ] þ ions (R ¼ H, 3-Et or 4-Me) in different cosolvents added to water [10,12,26].…”

Influence of solvent structure on the aquation of trans-[Ru(3-MePy)4Cl2] complex in mixed aqueous solvents

“…On the other hand, the observed variations in the solvolysis rate in media of different relative permittivity suggest that the rate determining step of the reaction depends to some extent on the ionizing power of the medium. Plots of log k versus the interpolated [18,19] were also non-linear as shown in Figure 2. This non-linearity may arise from the differential effects in solvent structure and solvation with changes in solvent composition between the initial and transition states.…”

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

“…The aquation of metal complexes has been the subject of extensive studies [1][2][3][4][5][6][7][8][9][10]. The study of the influence of solvent on the reactions of cobalt(III) complexes in mixed-solvent media is a matter of current and growing interest.…”