Phosphonium salts derived from α-ferrocenylvinyl cation in situ generated in sc-CO2 from ethynylferrocene by Nafion film

•Protonation of ethynylferrocene with Nafion film in sc-CO2.•Preparations of phosphonium salts from ferrocenylvinyl cation and phosphines.•(Ferrocenylvinyl)phosphonium salts: “green” and mild preparation.•A convenient method for generation and trapping of labile carbocations.

A protonation of ethynylferrocene by nafion in sc-CO2 in the presence of triphenylphosphine (PPh3) or 1,2-bis(diphenylphosphino)ethane (DPPE) leads to a formation of novel (1-ferrocenylvinyl)phosphonium or ferrocenyl substituted bisphosphonium salt isolated as tetrafluoroborates 3 and 4, respectively. Ferrocenyl substituted bisphosphonium tetrafluoroborate 4 undergoes the hydrolytic cleavage of the P+-C(Fc) bond in the presence of Al2O3 at 25 °C to form ferrocenyl substituted phosphinyl phosphonium tetrafluoroborate 5. Complexes 3-5 were completely characterized by NMR spectra and their molecular structures elucidated by X-ray studies.

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