Silylpalladium Cations Enable the Cleavage of Nitrile C–CN Bonds

The stoichiometric addition of aryl
and alkyl nitriles to the silylpalladium
cation [(PCy3)2Pd–SiMe2Et+]­[(C6F5)4B–] (1) resulted in the cleavage of the nitrile C–CN
bond and the formation of palladium–aryl and palladium–alkyl
cations. Low-temperature experiments support a mechanism where silylpalladium
cation 1 transfers silylium to nitrile, generating a
silylnitrilium cation and the reduced, zerovalent complex Pd­(PCy3)2. These two intermediates readily recombine at
low temperatures to generate palladium–(N-silyl)­iminoacyl
complexes, which upon warming can undergo aryl/alkyl group migration
from the iminoacyl ligand to the metal. Additional experiments show
that palladium–(N-silyl)­iminoacyl cations
are potent sources of silylium, capable of cleaving the methyl C–O
bond of an ether, while DFT calculations confirm the electrophilicity
of the silyl moiety.