β-Heteroatom versus β-Hydrogen Elimination: A Theoretical Study

This is the authors' abstract. We don't add key points for this paper.

β-Heteroatom and β-hydrogen eliminations of the model complexes [L 2 PdCH 2 CH 2 X] + (L 2 = H 2 PCH 2 CH 2 PH 2; X = halides, OMe, OH, OAc) were studied using density function theory calculations at the B3LYP level. Our calculations indicate that for the complexes where X = Cl, Br, and I β-heteroatom eliminations are thermodynamically and kinetically more favorable. For the complexes where X = F, OH, OMe, and OAc, β-hydrogen elimination is kinetically more favorable than β-heteroatom elimination. However, the products (hydride-olefin complexes) formed from the kinetically favorable β-hydrogen elimination are thermodynamically unstable relative to the pre-eliminated species (Pd-alkyl containing a β-X to metal dative bond). Implications of these results on the palladium-catalyzed reactions have been discussed.