SOLUBILITIES IN AQUEOUS MIXTURES OF T-BUTANOL AND TRANS-DICHLOROTETRA(3-ALKYLPYRIDINE) COBALT(III) HEXACHLORORHENATE(IV) - GIBBS ENERGIES OF TRANSFER OF THE COMPLEX CATIONS

The solubilities of the hexachlororhenate(IV) salts of the complex cations trans-[Co(3Mepy)4Cl2]+ and trans-[Co(3Etpy)4Cl2]+ have been determined in water + t-butyl alcohol mixtures. By reference to the solubilities of Cs2ReCl6 and the Gibbs energies of transfer of Cs+ from water into water + t-butyl alcohol mixtures, DELTAG(t)-degrees(Cs+), DELTAG(t)-degrees[Co(3Mepy)4Cl2+] and DELTAG(t)-degrees [Co(3Etpy)4Cl2+] are calculated. These latter values, when introduced into the equation for a free energy cycle applied to the process of the initial state going to the transition state for the solvolyses of these two cations, produces values for DELTAG(t)-degrees[Co(3Mepy)4Cl2+*] and DELTAG(t)-degrees[Co(3Etpy)4Cl2+*] for the Co3+ cations in the transition state. These values are compared with (DELTAG(t)-degrees(i) for i = [Co(RPY)4Cl2]+, [Co(Rpy)4Cl]2+*, [Coen2XCl]+ and [Coen2X]2+* to investigate the influence of the hydrophobicity of the surface of the complex on its stability in the mixtures. DELTAG(t)-degrees(i) (solvent sorting) are compared with DELTAG(t)-degrees(i) (TATB).