Kinetics of the reaction of tris(2,2'-bipyridyl)iron(II) with cyanide and with hydroxide ions in binary aqueous solvent mixtures

Rates of reaction of [Fe(bipy)₃]²⁺ with cyanide ion in binary aqueous solvent mixtures containing ethylene glycol glycerol, acetonitrile, dimethyl sulphoxide (dmso), or tris (dimethylamino)phosph ine oxide (tdpo), and with hydroxide ion in binary aqueous solvent mixtures containing t-butyl alcohol, dmso, or tdpo, are reported. Reactivity trends in the various solvent mixtures are discussed and, in the case of the reaction with hydroxide in aqueous dmso, compared with reactivity trends for similar inorganic and organic reactions. Where the existence of the required thermodynamic data on Gibbs free energies of transfer of single ions permits, it is shown that the effect of solvation, and thence chemical-potential, changes for cyanide and hydroxide ions is dominant in determining reactivies in their reactions with [Fe(bipy)₃]²⁺.