Use of Ligand Steric Properties to Control the Thermodynamics and Kinetics of Oxidative Addition and Reductive Elimination with Pincer-Ligated Rh Complexes
| العنوان: | Use of Ligand Steric Properties to Control the Thermodynamics and Kinetics of Oxidative Addition and Reductive Elimination with Pincer-Ligated Rh Complexes |
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| المؤلفون: | Shunyan Gu, Diane A. Dickie, Robert J. Nielsen, Kathleen H. Taylor, Junqi Chen, T. Brent Gunnoe, William A. Goddard, George C. Fortman |
| المصدر: | Organometallics. 39:1917-1933 |
| بيانات النشر: | American Chemical Society (ACS), 2020. |
| سنة النشر: | 2020 |
| مصطلحات موضوعية: | Inorganic Chemistry, Steric effects, Ligand, Chemistry, Organic Chemistry, Kinetics, Reaction intermediate, Physical and Theoretical Chemistry, Combinatorial chemistry, Oxidative addition, Reductive elimination, Catalysis, Pincer movement |
| الوصف: | Oxidative addition and reductive elimination reactions are central steps in many catalytic processes, and controlling the energetics of reaction intermediates is key to enabling efficient catalysis. A series of oxidative addition and reductive elimination reactions using (RPNP)RhX complexes (R = tert-butyl, isopropyl, mesityl, phenyl; X = Cl, I) was studied to deduce the effect of the size of the phosphine substituents. Using (^RPNP)RhCl as the starting material, oxidative addition of MeI was observed to produce (^RPNP)Rh(Me)(I)Cl, which was followed by reductive elimination of MeCl to form (^RPNP)RhI. The thermodynamics and kinetics vary with the identity of the substituent R on phosphorus of the PNP ligand. The presence of large steric bulk (e.g., R = tert-butyl, mesityl) on the phosphine favors Rh(I) in comparison to the presence of two smaller substituents (e.g., R = isopropyl, phenyl). An Eyring plot for the oxidative addition of MeI to (^(tBu)PNP)RhCl in THF-d₈ is consistent with a polar two-step reaction pathway, and the formation of [(^(tBu)PNP)Rh(Me)I]I is also consistent with this mechanism. DFT calculations show that the steric bulk affects the reaction energies of addition reactions which generate six-coordinate complexes by tens of kcal mol⁻¹. The ligand steric bulk is calculated to have a reduced effect (a few kcal mol⁻¹) on S_N2 addition barriers, which only require access to one side of the square plane. |
| وصف الملف: | application/pdf |
| تدمد: | 1520-6041 0276-7333 |
| URL الوصول: | https://explore.openaire.eu/search/publication?articleId=doi_dedup___::51c5f8d4cd9dec8904f0856723186c15 https://doi.org/10.1021/acs.organomet.0c00122 |
| حقوق: | OPEN |
| رقم الأكسشن: | edsair.doi.dedup.....51c5f8d4cd9dec8904f0856723186c15 |
| قاعدة البيانات: | OpenAIRE |
Find this issue from the American Chemical Society | تدمد: | 15206041 02767333 |
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