C–CN Bond Cleavage Using Palladium Supported by a Dippe Ligand

The (dippe)­palladium(0) fragment
generated from [(dippe)­Pd­(μ-H)]2 (1) has been shown to form an intermediate η2-nitrile
complex with acetonitrile (dippe)­Pd­(η2-C,N-CH3CN-BEt3) (2a) in
the presence of BEt3 [(dippe = bis-diisopropyl­phos­phino)­ethane)].
On introducing a solution
of 2a to 1 equiv of BPh3, rapid formation
of (dippe)­Pd­(η2-C,N-CH3CN­BPh3) (2a′) is observed. Heating 2a′ at 100 °C in THF-d8 results in
the C–CN activation product 3a′, (dippe)­Pd­(CH3)­(CNBPh3). Reaction of 1 with
benzonitrile in the presence of BEt3 gives the C–CN
activation product (dippe)­Pd­(Ph)­(CN-BEt3) (3b) exclusively. The complexes 2a, 2a′, 3a′, and 3b were characterized
by 1H, 31P­{1H}, and 13C­{1H} NMR spectroscopy, elemental analysis, IR spectroscopy,
and X-ray diffraction.