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Effect of solvent and structure on the kinetics and mechanism of the aquation of bromopentaamine cobalt(III) complex in binary aqueous mixtures
Author(s) -
ElSubruiti Gehan M.,
Younes Ghassan O.,
Zeitouni Farah S.,
Amira Mohamed F.
Publication year - 2004
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.20021
Subject(s) - aquation , chemistry , solvation , cobalt , solvent , reaction rate constant , aqueous solution , acetonitrile , inorganic chemistry , solvent effects , enthalpy , kinetics , dimethyl sulfoxide , organic chemistry , thermodynamics , physics , quantum mechanics
The kinetics of aquation of bromopentaamine cobalt(III) complex have been investigated spectrophotometrically in aqueous‐organic solvent media using acetonitrile, urea, and dimethyl sulfoxide as co‐solvents at 45 ≤ T (°C) ≤ 65. The logarithms of rate constant of the aquation reaction vary nonlinearly with the reciprocal of the dielectric constant for all cosolvent mixtures, indicating a specific solute–solvent interaction. Also, the rate constants are correlated with the total number of moles of water and the organic solvents. However, the solvent effects on the solvation components of the enthalpy of activation, Δ H ‡ , and the entropy of activation, Δ S ‡ , have been studied. Analysis of the solvent effect confirmed a common I d mechanism for the aquation of the cobalt(III) complex. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36:494–499, 2004