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Kinetics of the solvolysis of [Co(3Rpy) 4 Cl 2 ] + ions (R = Me or Et ) in Water + t ‐butyl alcohol mixtures
Author(s) -
ElSubruiti Gehan M.,
Wells Cecil F.,
Sidahmed Ibrahim M.
Publication year - 1992
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.550240606
Subject(s) - solvolysis , chemistry , alcohol , enthalpy , solvent , cobalt , ion , entropy of activation , inorganic chemistry , kinetics , reaction rate constant , thermodynamics , organic chemistry , hydrolysis , physics , quantum mechanics
Rates of solvolysis of complex ions [Co(3Rpy) 4 Cl 2 ] + with R = Me and Et have been determined in mixtures of water with t ‐butyl alcohol over a range of temperatures. Extrema found in the enthalpy Δ H * and entropy Δ S * of activation are correlated with the physical properties of the solvent mixtures which are influenced by changes in the solvent structure and these extrema are compared with those found for the solvolysis of related complexes in water + alcohol mixtures. Isokinetic plots over wide ranges of Δ H * and Δ S * are compared for the solvolysis of Co III complexed to a variety of ligands. The application of a free energy cycle shows that the emergent cobalt (III) cation in the transition state becomes increasingly stabilized in water‐rich mixtures relative to the cobalt (III) cation in the initial state as the mol fraction of t ‐butyl alcohol increases.