Electrophilic phosphonium cations (EPCs) with perchlorinated-aryl substituents: towards air-stable phosphorus-based Lewis acid catalysts

Abstract

A series of phosphines incorporating (C₆Cl₅) substituents, Ph₂P(C₆Cl₅) 1, PhP(C₆Cl₅)₂2, P(C₆Cl₅)₃3 and (C₆F₅)P(C₆Cl₅)₂4 were prepared. In the case of 1, 2 and 4, these were converted to the corresponding aryl-difluorophosphoranes 5–7via reaction with XeF₂, whereas reaction of 3 with XeF₂ afforded only an inseparable mixture of products. The compounds 5–7 were converted to the fluorophosphonium cations 8–10, whereas the reaction of 3 with Selectfluor afforded (C₆Cl₅)₂POF and (C₆Cl₅)₂. The fluorophosphonium salts showed evidence of improved air stability as well as Lewis acid catalytic activity in hydrodefluorination, hydrosilylation, deoxygenation and dehydrocoupling chemistry.