Solvation and reactivity of inorganic complexes: F vs. H and CF3vs. CH3

Abstract

We are currently examining the effects of the replacement of H by F, and of CH3 by CF3, in the ligands of selected inorganic complexes on solvation and on reactivity. We are also comparing CF3CH2OH with CH3CH2OH, and CF3CH(OH)CF3 as solvents for inorganic complexes.Solute-solvent interactions are being probed through transfer chemical potentials and through solvatochromism. We shall compare transfer chemical potential trends for complexes M(acac)3, M(tfac)3, and M(hfac)3, and for some iron (II) complexes of diimine ligands and their fluoro-analogues, in binary aqueous solvent mixtures. The trends which are emerging show that replacement of H by F results in a significant increase in hydrophilicity, with the determined transfer chemical potentials giving a quantitative measure of differences. The solvatochromic properties of ternary iron(II)-diimine-cyanide give an alternative means of comparing solute-solvent interactions, both in relation to fluorine substitution in the diimine ligands and in respect of the solvating properties of the fluoroalcohols mentioned above.Replacement of H by F, or of CH3 by CF3, in iron(II) complexes of Schiff bases derived from appropriate results in much faster rate constants for base hydrolysis. It is hoped to present an initial state-transition state analysis of reactivity trends in methanol-water mixtures in order to establish precisely how solvation changes affect reactivities in this type of reaction.