%0 Journal Article
%T Studies on ion-pairing effects of the kinetics of aquation of bromopentaammine cobalt(III) complex in malonate media
%A Farah Samih Zeitouni
%A Gehan Moustafa El-Subruiti
%A Ghassan Omar Younes
%A Mohammad Fawzi Amira
%J European Journal of Chemistry
%D 2011
%I 
%R 10.5155/eurjchem.2.4.489-494.440
%X 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*
%K Ion-pair
%K Aquation
%K Solvent effect
%K Cobalt(III) complex
%K Dicarboxylic acid
%K Tert-butanol
%U http://www.eurjchem.com/index.php/eurjchem/article/view/440