Solubilities of several complex salts at ambient temperature and pressure are reported for aqueous solutions and for solutions in binary aqueous organic mixtures. The organic cosolvents are ethanol and propan-2-01. These and earlier published solubilities are analysed using the TATB assumption which sets the transfer chemical potentials of Ph,As+ ions equal to those of Ph,B-ions. The calculations yield transfer parameters for various ions including complex metal ions. Derived transfer parameters for ions are compared for a range of solvent systems comprising binary aqueous mixtures, including those systems where the organic cosolvents are methanol, ethanol, propan-2-01 and acetone. These transfer parameters are used in an analysis of kinetic data describing chemical reaction between hydroxide ions and iron(rr) complex cations, [Fe(phen),I2+ in aqueous solutions. Definitions of standard state chemical potentials for solutes and solvents are considered with reference to descriptions of composition of these systems using the mole fraction scale.

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The dependence of rate constants for base hydrolysis on solvent composition for several iron(ii)-diimine complexes has been established for aqueous ethane-l,2-diol (ethylene glycol) and aqueous propane-1,2,3-triol (glycerol) mixtures, and for aqueous sucrose solutions. These dependences are compared with analogous reactivity trends for binary aqueous solvent mixtures containing monohydroxylic alcohols. Transfer chemical potentials for iron(ii)-diimine complexes, and for simple cations and anions, have been estimated on the TATB assumption for transfer to aqueous ethane-l,2-diol and aqueous propane-l,2,3-triol. These transfer chemical potentials allow resolution of the observed reactivity trends into initial-state and transition-state contributions for the aqueous ethane-1,2-diol mixtures. Such information on the role of solvation in this type of reaction is complented by the determination of activation volumes for base hydrolysis for four iron(ii)-diimine complexes in aqueous ethane-l,2-diol.

Solubilities of the perchlorate salt of the iron(II) complex of the tripodal ligand derived from tris(2-aminoethyl)amine and pyridine 2-carboxaldehyde, [Fe(fpyHg 3 tren)](ClO 4 ) 2 , have been determined in MeOH-, i-PrOH-, t-BuOH-, and DMSO-H 2 O mixtures. Solubilities of [Fe(fpyMeg 3 tren)](ClO 4 ) 2 and of [Fe(fpyPhg 3 tren)](ClO 4 ) 2 , analogues derived from 2-acetylpyridine and 2-benzoylpyridine, respectively, have been determined in MeOH-H 2 O mixtures. Transfer chemical potentials for the three complexes have been calculated from these solubilities, and solvation trends for these complexes discussed in relation to the overall pattern for iron(II)-diimine complexes in binary aqueous solvent mixtures. The crystal structure of [Fe(fpyHg 3 tren)](ClO 4 ) 2 has been determined.