Reductive elimination rates density

Often Lewis acids are added to the system as a cocatalyst. It could be envisaged that Lewis acids enhance the cationic nature of the nickel species and increase the rate of reductive elimination. Indeed, the Lewis acidity mainly determines the activity of the catalyst. It may influence the regioselectivity of the catalyst in such a way as to give more linear product, but this seems not to be the case. Lewis acids are particularly important in the addition of the second molecule of HCN to molecules 2 and 4. Stoichiometrically, Lewis acids (boron compounds, triethyl aluminium) accelerate reductive elimination of RCN (R=CH2Si(CH3)3) from palladium complexes P2Pd(R)(CN) (P2= e g. dppp) [7], This may involve complexation of the Lewis acid to the cyanide anion, thus decreasing the electron density at the metal and accelerating the reductive elimination. 

The reaction pathways of conjugate addition of Me2CuLi and Me2CuLi LiCl have been studied for acrolein [79] and cydohexenone [80] with the aid of density functional methods, and fit favorably with the NMR properties of intermediates, kinetic isotope effects [81], and the diastereofacial selectivity. A similar mechanism also operates in this reaction, as summarized in Scheme 10.5. The rate-determining step of the reaction (TScc) is the C-C bond formation caused by reductive elimination from Cu " to give Cu. ... 

Equations 8.56-8.58 display several examples of reductive eliminations to form carbon-heteroatom bonds from Pt(IV). Reductive elimination of phenyl iodide occurs from a Pt(IV) diphenyl diiodide complex (Equation 8.56). - This reaction is preceded by dissociation of iodide to generate a cationic Pt(IV) intermediate, as shown by inhibition of the reaction rate by added iodide. Elimination after dissociation of the iodide is favored by the five-coordinate geometry and by the reduced electron density on the cationic metal center. 

Aikyi group increases electron density at P. Large R favors [LiPd(0)] Increases rate of oxidative addition and reductive elimination... 

Due to the strong Ti-acceptor properties of phosphinines and their preference to stabilize late-transition metals in low oxidation states, successful applications of these ligands might be anticipated in reactions in which the rate determining step leads to an increase in the electron density at the metal center. This has been explored in the Ni-catalyzed intramolecular [4 + 2] cycloaddition of dieneynes, in which the reductive elimination of the product from the metal center is most likely the rate determining step (Scheme 6.13) [24]. 

---