Fluoride Abstraction Induced by Tris(pentafluoroethyl)difluorophosphorane: A Convenient Way to Synthesize Cationic N -Heterocyclic Carbene- and Cyclic (Alkyl)(amino)carbene-Ligated Copper Alkyne and Arene Complexes.

We herein report the convenient synthesis of different N -heterocyclic carbene (NHC)- and cyclic (alkyl)(amino)carbene (cAAC)-ligated copper cations using the weakly coordinating tris(pentafluoroethyl)trifluorophosphate counterion ( FAP anion, [(C2 F5 )3 PF3 ]- ). The reaction of the fluorido complexes [(carbene)CuF] (carbene = NHC, cAACMe ) 2a - 2f and the tris(pentafluoroethyl)difluorophosphorane (C2 F5 )3 PF2 in the presence of alkynes or arenes led to fluoride transfer from Cu to the phosphorane with formation of the cationic transition metal complexes [(carbene)Cu( L )]+ and the weakly coordinating counteranion [(C2 F5 )3 PF3 ]- ( FAP ). Using this method, the complexes [(IDipp)Cu( L )]+ FAP - (IDipp = 1,3-bis(2,6-di- iso -propylphenyl)-imidazolin-2-ylidene; L = PhC≡CPh, 4d ; PhC≡CMe, 5d ), [(cAACMe )Cu( L )]+ FAP - (cAACMe = 1-(2,6-di- iso -propylphenyl)-3,3,5,5-tetramethyl-pyrrolidin-2-ylidene; L = PhC≡CPh, 4f ; PhC≡CMe, 5f ), [(SIDipp)Cu(C6 Me6 )]+ FAP - ( 6e ), (SIDipp = 1,3-bis(2,6-di- iso -propylphenyl)-imidazolidine-2-ylidene), and [(cAACMe )Cu(C6 Me6 )]+ FAP - ( 6f ) have been synthesized and characterized. The complexes [(IDipp)Cu(C6 Me6 )]+ FAP - ( 6d ) and [(cAACMe )Cu(C6 Me6 )]+ FAP - ( 6f ) have been used as catalysts for the copper(I)-catalyzed cycloaddition of benzyl azide to terminal alkynes.