The reaction of nickel(II) with 2,2′-bipyridyl in methanol- and in dimethyl sulphoxide-water mixtures: Solvent effects on reactivity

Summary Enthalpies of solution (298 K) are reported for NiCl₂ · 6H₂O, CoCl₂ · 6H₂O, and FeCl₂ · 4H₂O in aqueous methanol (0–40% methanol) and for NiCl₂ · 6H₂O, 2,2-bipyridyl, and water in aqueous dimethyl sulphoxide (0–60% DMSO). Solubilities (298 K) of 2,2-bipyridyl are reported for aqueous dimethyl sulphoxide (0–60% DMSO). From these, from appropriate published thermodynamic data, and from published rate constants and activation enthalpies, we have analysed solvent effects on reactivities ( and H) into initial state and transition state contributions (the latter are in fact composite ion-association and interchange quantities). In all systems examined the observed kinetic trends represent small differences between large and almost identical solvent effects on the respective initial and transition states.     

Transfer chemical potentials for iron(II)-diimine complexes from water into aqueous methanol

Summary Solubilities of perchlorate and thiocyanate salts of several iron(II)-diimine complexes of Schiff base ligands in methanolwater mixtures are reported. From these results and published values for transfer chemical potentials of the perchlorate and thiocyanate anions, transfer chemical potentials for the complex cations are calculated. Trends with solvent composition suggest that preferential solvation varies from negligible to very strongly by methanol, depending on the size and hydrophilic-hydrophobic character of the complex.On leave from the Faculty of Science, Sohag, Egypt.