Insights into Amine Binding to Biaryl Phosphine Palladium Oxidative Addition Complexes and Reductive Elimination from Biaryl Phosphine Arylpalladium Amido Complexes via Density Functional Theory

2007 ◽  
Vol 129 (39) ◽  
pp. 12003-12010 ◽  
Author(s):  
Timothy E. Barder ◽  
Stephen L. Buchwald
2019 ◽  
Vol 9 (3) ◽  
pp. 646-651 ◽  
Author(s):  
Zhaoyuan Yu ◽  
Tao Zhang ◽  
Ruopeng Bai ◽  
Yu Lan

Density functional theory (DFT) calculations indicate that favorable oxidative addition/reductive elimination process from arylrhodium complex determines the enantioselectivity.


2009 ◽  
Vol 87 (1) ◽  
pp. 151-160 ◽  
Author(s):  
Hui Huang ◽  
N Raluca Hurubeanu ◽  
Cheryl J Bourgeois ◽  
Sue-Mei Cheah ◽  
Jian Yuan ◽  
...  

Oxidative addition of primary, secondary, or benzylic perfluoroalkyl iodides (RF–I) to the phosphine free Ir(I) precursor Ir(acac)(CO)2 1 (acac = 2,4-pentanedionato) proceeds smoothly to afford octahedral Ir(III) products Ir(acac)(I)(RF)(CO)2, A combination of X-ray crystallographic studies and solution spectroscopy shows that these products are the result of overall trans-addition of the C–I bond to iridium, probably a result of thermodynamic control; evidence for a kinetic product resulting from net cis-addition is obtained in one case. Treatment of the Ir(III) compounds with AgOTf (Tf = CF3SO3) illustrates that the iodo ligand is replaced by triflate with retention of stereochemistry at Ir. The resulting triflate complexes are inert to displacement by H2O or H2. The Ir(III) products exhibit very high CO stretching frequencies in the IR, indicating that the CO ligands may be non-classical. A quantitative estimation of the degree of backbonding to the CO ligands in these compounds, and a comparison of the π-acceptor properties of CO and fluoroalkyl ligands, is made using an approach based on Density Functional Theory (DFT) and Natural Bond Orbital analyses.Key words: iridium, fluoroalkyl, oxidation, carbonyl, DFT.


2016 ◽  
Vol 94 (12) ◽  
pp. 1028-1037 ◽  
Author(s):  
Zhe Li ◽  
Miaoren Xia ◽  
Russell J. Boyd

The mechanism of the iridium-catalyzed functionalization of a primary C–H bond at the γ position of an alcohol 5 is investigated by density functional theory (DFT) calculations. A new IrIII–IrV mechanism is found to be more feasible than the previously reported IrI–IrIII mechanism. 10 In the IrIII–IrV mechanism, the reaction begins with the initial formation of (Me4phen)IrIII(H)[Si(OR)Et2]2 from the catalyst precursor, [Ir(cod)OMe]2 (cod = 1,5-cyclooctadiene). The catalytic cycle includes five steps: (1) the insertion of norbornene into the Ir–H bond to produce (Me4phen)IrIII(norbornyl)[Si(OR)Et2]2 (R = –CH(C2H5)C3H7); (2) the Si–H oxidative addition of HSi(OR)Et2 to form (Me4phen)IrVH(norbornyl)[Si(OR)Et2]3; (3) the reductive elimination of norbornane to furnish (Me4phen)IrIII[Si(OR)Et2]3; (4) the intramolecular C–H activation of the primary C–H bond at the γ position; and (5) the Si–C reductive elimination to produce the final product and regenerate the catalyst. The highest barrier in the IrIII–IrV mechanism is 7.3 kcal/mol lower than that of the IrI–IrIII mechanism. In addition, the regioselectivity of the C–H activation predicted by this new IrIII–IrV mechanism is consistent with experimental observation.


2009 ◽  
Vol 87 (7) ◽  
pp. 832-837 ◽  
Author(s):  
Peter H.M. Budzelaar

Catalytic ethene trimerization at a chromium(I) indolate-AlR2Cl centre has been studied by density functional theory (DFT) methods. The reaction is found to follow the standard metallacycle mechanism. At most stages of the reaction, coordination of Cr to the pyrrole ring of the indolate is preferred. In all 13-e intermediates, coordination of the Al-bound chloride to Cr provides additional stabilization: the chloride behaves as a hemilabile ligand. Benzene is found to compete with ethene for coordination to CrI. The final hexene-forming step involves direct Cβ → Cα′ hydrogen transfer; reductive elimination from a possible (hydride)(hexenyl) intermediate is more difficult. The kinetic isotope effect calculated for the direct hydrogen transfer (4.1) agrees well with the experimental value for a bis(phosphino)amide chromium catalyst. Side products obtained in such systems (methylenecyclopentane, methylcyclopentane) can plausibly be explained through routes not involving any (hydride)(alkyl) reductive elimination. Our results indicate that a CrI/CrIII trimerization cycle is possible for some chromium trimerization catalysts, and also suggest that direct hydrogen transfer is most likely a general feature of trimerization at Cr centres.


2021 ◽  
Author(s):  
Jing Zhang ◽  
Shihan Liu ◽  
Tao Zhang ◽  
Tao Liu ◽  
Yu Lan

Density functional theory (DFT) calculation has been used to reveal the mechanism of Pd-catalyzed disilylation reaction of aryl halide. The DFT calculations indicate that the reaction starts with oxidative addition...


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