Phosphorus–Carbon Bond Forming Reactions of Diphenylphosphenium and Diphenylphosphine Triflate Complexes of Tungsten

The complex [W(CO)5{PClPh2}] reacts with AlCl3 to form a mixture of the phosphenium complex [W(CO)5{PPh2}][AlCl4] and an isocarbonyl, with GaCl3 to form [W(CO)5{PPh2}][GaCl4], and with silver trifluoromethanesulfonate to form [W(CO)5{P(OSO2CF3)Ph2}].All three complexes react as strong P electrophiles, undergoing electrophilic substitution reactions with aromatic and heteroaromatic compounds, alkenes, and alkynes, to form aromatic and heteroaromatic phosphines, allyl phosphines, and alkynyl phosphines, respectively. Alkenes lacking cleavable γ-H atoms and internal alkynes undergo tandem electrophilic addition/substitution reactions, adding between the P and one of the phenyl rings to form fused P heterocycles. The newly formed phosphines can be removed from the tungsten complex by photolysis in the presence of bis(diphenylphosphino)ethane.