Intramolecular dehydrofluorinative coupling of η⁶-arene and fluoroarylphosphine ligands in ruthenium complexes

Abstract

NMR studies of reactions between a series of arene ruthenium(II) fluoroarylphosphine complexes and Proton Sponge have revealed the necessary conditions for intramolecular dehydrofluorinative ligand coupling. The complex must be cationic, and the phosphine need have only one fluoroaryl substituent. The reaction is rapid and clean for [(η⁶-toluene)RuCl(dfppe)]BF₄, [(η⁶-mesitylene)RuCl{(C₆F₅)₂PC₆H₄SMe}]BF₄ and the diastereomer of [(η⁶-toluene)RuCl{Ph₂PC₂H₄PPh(C₅F₄N-4)}]BF₄ in which the tetrafluoropyridyl substituent is close to the η6-arene. [(η⁶-p-cymene)RuCl(dfppe)]BF₄ reacts in the presence of Proton Sponge to give a mixture of unidentified compounds. The neutral complex [(η⁶-toluene)RuCl₂{Ph₂P(C₆F₅)}] and the diastereomer of [(η⁶-toluene)RuCl{Ph₂PC₂H₄PPh(C₅F₄N-4)}]BF₄ in which the tetrafluoropyridyl substituent is distant to the η⁶-arene do not undergo reaction.