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, [(C 2 F 5 ) 3 PF 3 ] - ). The reaction of the fluorido complexes [(carbene)CuF] (carbene = NHC, cAAC Me ) 2a - 2f and the tris(pentafluoroethyl)difluorophosphorane (C 2 F 5 ) 3 PF 2 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 [(C 2 F 5 ) 3 PF 3 ] - ( 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 ), [(cAAC Me )Cu( L )] + FAP - (cAAC Me = 1-(2,6-di- iso -propylphenyl)-3,3,5,5-tetramethyl-pyrrolidin-2-ylidene; L = PhC≡CPh, 4f ; PhC≡CMe, 5f ), [(SIDipp)Cu(C 6 Me 6 )] + FAP - ( 6e ), (SIDipp = 1,3-bis(2,6-di- iso -propylphenyl)-imidazolidine-2-ylidene), and [(cAAC Me )Cu(C 6 Me 6 )] + FAP - ( 6f ) have been synthesized and characterized. The complexes [(IDipp)Cu(C 6 Me 6 )] + FAP - ( 6d ) and [(cAAC Me )Cu(C 6 Me 6 )] + FAP - ( 6f ) have been used as catalysts for the copper(I)-catalyzed cycloaddition of benzyl azide to terminal alkynes.