Interaction of difluoromethylene phosphobetaine with heteroatom-centered electrophiles

A series of difluorinated phosphonium salts were obtained by reaction of difluoromethylene phosphobetaine with halogenating reagents, as well as arylsulfenyl and arylselenyl chlorides. The reaction proceeds via decarboxylation of the phosphobetaine followed by trapping of the difluorinated phosphorus ylide by heteroatomcentered electrophiles. The crystal structures of the phosphonium salts were studied by X-ray diffraction analysis. For the salt containing the CF2I group and iodide counterion, the I center dot center dot center dot I interaction was identified in the solid state. The nature of this halogen bond was evaluated by quantum chemical calculations.