Electron transfer. Part 166 . Reactions of Ti(II)(aq) with oxidants having strongly positive potentials

Titanium(II) solutions, prepared by dissolving titanium metal in triflic acid+HF, react readily with chelated complexes of Ag(III), nickel(IV) and copper(III). Reactions with excess Ti(II) yield Ti(III) and are strongly catalyzed by added Ti(IV), but stoichiometry is unaffected. Rapid reactions of Ti(II) with nonchelated oxidants, VO2+, View the MathML sourceUO22+ and View the MathML sourceMnO4- do not exhibit catalysis by Ti(IV). Reductions by Ti(III) are unaffected by Ti(IV). The Ag(III)–Ti(II) reaction, as catalyzed by Ti(IV), is subject to kinetic saturation with an association quotient 4 × 102 M−1 for the Ti(IV)-activated species. It is proposed that the catalyzed reductions of the Ag(III) and Ni(IV) oxidants are initiated by 1e− steps, but that the initially formed cation pairs undergo geminate follow-up reactions to give the observed stable products.