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 cat ions trans-[Co(3Mepy)4Cl2]+ and trans-[Co(3Etpy)4Cl2]+ have been deter mined in water + t-butyl alcohol mixtures. By reference to the solubil ities 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 fo r a free energy cycle applied to the process of the initial state goin g to the transition state for the solvolyses of these two cations, pro duces values for DELTAG(t)-degrees[Co(3Mepy)4Cl2+] and DELTAG(t)-degr ees[Co(3Etpy)4Cl2+] for the Co3+ cations in the transition state. The se values are compared with (DELTAG(t)-degrees(i) for i = [Co(RPY)4Cl2 ]+, [Co(Rpy)4Cl]2+, [Coen2XCl]+ and [Coen2X]2+* to investigate the in fluence of the hydrophobicity of the surface of the complex on its sta bility in the mixtures. DELTAG(t)-degrees(i) (solvent sorting) are com pared with DELTAG(t)-degrees(i) (TATB).