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oai:ojs.www.eurjchem.com:article/440 2011-12-31T08:09:40Z eurjchem:ART driver

Studies on ion-pairing effects of the kinetics of aquation of bromopentaammine cobalt(III) complex in malonate media Zeitouni, Farah Samih El-Subruiti, Gehan Moustafa Younes, Ghassan Omar Amira, Mohammad Fawzi Ion-pair Aquation Solvent effect Cobalt(III) complex Dicarboxylic acid Tert-butanol The aquation of bromopentaamminecobalt(III) ion in the presence of ion-pairing malonate anion in mixed solvent media of water with tert-butanol (10%-50%) v/v have been investigated spectrophotometrically at different temperatures (30-60 oC). Nonlinear plots of Log (kip) ion-pair rate constants against the reciprocal of the dielectric constant D, Log of water concentration and Grunwald-Winstein Y values were found. The thermodynamic and extrathermodynamic analyses of the kinetic data have been discussed in terms of solvent effect on the ion-pair aquation reactions. The obtained isokinetic temperatures of these systems indicate the existence of compensation effect arising from solute-solvent interaction. The extrema found in the change of ∆Hip* and ∆Sip*with the mole fraction of the co-solvent can be attributed to the change of the physical properties of the solvent-water mixture with the solvent structure. Application of a free energy cycle is performed to compare between the stability of the initial and the transition state of the complex. However, small changes in ∆Gip*with the mole fraction of the co-solvent was found, indicating a compensating effects between ∆Hip* and ∆Sip* Atlanta Publishing House LLC 2011-12-31 info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion application/pdf https://www.eurjchem.com/index.php/eurjchem/article/view/440 10.5155/eurjchem.2.4.489-494.440 European Journal of Chemistry; Vol. 2 No. 4 (2011): December 2011; 489-494 2153-2257 2153-2249 eng https://www.eurjchem.com/index.php/eurjchem/article/view/440/PDF