Mechanism of the Reaction of Vinyl Chloride with (α-diimine)PdMe+ Species

The reaction of vinyl chloride (VC) with (alpha-diimine)PdMe+ species yields (alpha-diimine)PdCl-(propene)(+) Isotope labeling experiments using the deuterium-labeled vinyl chlorides 1-VC-d(1) and Z-VC-d(1) combined with DFT computations establish that this reaction proceeds by 2,1-insertion of VC to produce beta-H agostic (alpha-diimine)Pd(CHClCH2Me)(+), chain-walking isomerization to generate beta-Cl dative (alpha-diimine)Pd(CHMeCH2Cl)(+) and syn beta-Cl elimination. The labeling experiments rule out mechanisms involving initial 1,2-insertion or C-Cl oxidative addition. The computational results and the observation of small amounts of propene-d(2) argue against mechanisms involving 2,1-insertion followed by alpha-Cl elimination and a 1,2 H-shift.