Solvation and Reactivity of Iron(l1)-Diimine Complexes in Dimethyl Sulfoxide-Water Mixtures

Kinetics of the base hydrolysis of several iron(ik)4iimine complexes, including two with terdentate ligands and one with an encapsulating ligand. and of the peroxodisulfate oxidation of three ternary i ron(11)4i imine-cyanide complexes. are reported for reactlon in dimethyl sulfoxide (DMS0)-water mixtures at 298.15 K. Solublilties of simple and complex salts have been determined in these mixtures, both to extend the range 01 simple and complex ion-transfer chemical potentials and to provide the basis lor initial-state/transilion-state analyses 01 reactivity trends for several of the base hydrolysis and peroxodisulfate oxidations. Cases are identified where the deslabilisalion of hydroxide ions, OH(aq1, by added DMSO increases the rate of base hydrolysis. We also identify cases where compensation ettects result in only a small change in rate constant lor oxidation by per-oxodisulfate where DMSO is added. I-or m:my years we have heen interested in rz;ictivity trends Sor substitution;~nd redox reactions 01 inorganic complexes i n hinary aqueous solvent mixtures. ' More recently, we have established trendi i n transler chemical potentials lor a variety ill inorganic i o n and complexcs in several series o l hinary aqueous mixtures, with particular concern to use these dat