Aromatic radical-ion formation using lewis acid catalysts

Abstract

The formation of radical ions from interactions between organic compounds with transition metal chlorides (Pt, Pd, Rh, Ru, Ir), their potassium salts, and other Lewis acid catalysts has been studied by electron spin resonance. The possible importance of these e.s.r. active species in catalytic reactions such as self-activation in isotopic hydrogen exchange and Friedel-Crafts processes has been investigated. A number of organic donors have been examined including polycyclic aromatic hydrocarbons, aromatic mines, alkenes, chloropromazine, and phenothiazine. Effect of water of crystallization, oxygen, ultraviolet radiation, and methyl substituents on the e.s.r. has been evaluated. A study has been made of the factors affecting the formation of these e.s.r. species in solution when compared with solid state interactions using as acceptors iodine, and the halides of iron, cadmium, boron, tellurium, and titanium. The results have been interpreted in terms of the formation of radical ions. It is proposed that in the solid state, the transferred electrons are weakly coupled as in a diradicaloid triplet state.