The Kinetics and Mechanism of Oxidation of the N-Substituted Urea-Titanium (III) Complexes by Iodine (AS I-3) in Ethanol and Acetonitrile

The oxidation of complexes of Ti(III), (TiL6)3+ (L=ur, Meur, DMeur, DEture, N-Bu-ur, and Phur), by iodine as I3- in ethanol and acetonitrile solutions, appears to proceed as a second order reaction and is much faster in ethanol solution (where solvolysis occurs) than in acetonitrile. The enthalpy of activation appears to decrease as ligand's size increases which suggest that the kinetic stability of these compounds is not just because of steric hindrance; but electronic effect of the ligand must be more important.The mechanism of the reaction is suggested to be an inner redox reaction in which an electron transfers through a bridge which is formed by bonding I3- to the complex ion.