SOLVATION AND REACTIVITY OF IRON(II) DIIMINE COMPLEXES IN DIMETHYL-SULFOXIDE WATER MIXTURES

Kinetics of the base hydrolysis of several iron(II)-diimine complexes, including two with terdentate ligands and one with an encapsulating ligand, and of the peroxodisulfate oxidation of three ternary iron(II)-diimine-cyanide complexes, are reported for reaction in dimethyl sulfoxide (DMSO)-water mixtures at 298.15 K. Solubilities of simple and complex salts have been determined in these mixtures, both to extend the range of simple and complex ion-transfer chemical potentials and to provide the basis for initial-state/transition-state analyses of reactivity trends for several of the base hydrolysis and peroxodisulfate oxidations. Cases are identified where the destabilisation of hydroxide ions, OH- (aq), by added DMSO increases the rate of base hydrolysis. We also identify cases where compensation effects result in only a small change in rate constant for oxidation by peroxodisulfate where DMSO is added.