Electrophilicities of Acceptor‐Substituted Tritylium Ions

Abstract

Abstract Rates of hydride transfers from triphenylsilane to a series of substituted tritylium ions in dichloromethane solution at 20 °C have been determined spectrophotometrically. The obtained kinetic data have been used to evaluate electrophilicity parameters ( E ) for acceptor‐substituted tritylium ions according to the linear free energy relationship log k = s N ( N + E ), thus extending the previously established electrophilicity scale of differently substituted tritylium ions to more reactive systems. The rates of attack of water at meta ‐fluoro‐substituted tritylium ions in aqueous acetonitrile solution have been determined by laser‐flash techniques. Hydroxide and methyl anion affinities of fluoro‐substituted tritylium ions have been calculated at the MP2(FC)/6‐31+ G(2d,p)//B3LYP/6‐31G(d,p) level of theory. Rate‐equilibrium relationships are discussed.