Analysis of the effects of solvent on the initial and transition states in the kinetics of reaction between tris(1,10-phenanthroline)iron(II) cation and hydroxide ions in methanol– and acetone–water mixtures

Abstract

Rate constants at 298 K are reported for the reaction of [Fe(phen)₃]²⁺(phen = 1,10-phenanthroline) with hydroxide ion in methanol–water and acetone–water mixtures. From known solubilities of naphthalene in these mixtures, and using the method of Van Meter and Neumann, the effect of added solvent on the solvation of this iron complex has been calculated. Thence, the kinetic results have been split into the effects of solvent on the initial and transition states. The treatment of Van Meter and Neumann has been extended to an analysis of the effect of solvent on the transition state, using solubility data obtained from 2-naphthol in methanol–water mixtures. The results support a mechanism in which hydroxide attacks initially at the 2(9) position of the co-ordinated phen; considerable interaction between this carbon-bonded hydroxyl group and the central iron atom is indicated.