Electrophilic bis-fluorophosphonium dications: Lewis acid catalysts from diphosphines.

Stepwise oxidation of 1,8-bis(diphenylphosphino)naphthalene and a series of (oligo)methylene-linked diphosphines with XeF followed by fluoride abstraction yields a family of compounds featuring phosphine, phosphonium and phosphorane moieties in close proximity. The bisphosphonium ions [(CH)(PhPF)] () and [CH(PhPF)] () exhibit remarkable Lewis acidity arising from the proximity of the phosphonium centers. The effectiveness of bisphosphonium dications (, ) is examined in a series of Lewis acid catalysed transformations.