| Titre : | Etude théorique des réactions de transfert d’hydrogène catalysées aux métaux de transition |
| Auteurs : | Yazid Meftah, Auteur ; Youcef Boumedjane, Directeur de thèse |
| Type de document : | Thése doctorat |
| Editeur : | Biskra [Algérie] : Faculté des Sciences Exactes et des Sciences de la Nature et de la Vie, Université Mohamed Khider, 2016 |
| Format : | 1 vol. (108 p.) / couv. ill. en coul / 30 cm |
| Langues: | Français |
| Langues originales: | Français |
| Résumé : |
Firstly, the effects of several functionals in the prediction of the geometrical parameters of four diastereomeric half-sandwich Ru (II) cationic complexes containing amino amide ligands were investigated. Four Ruthenium complexes were used to evaluate the performance of fifteen density functionals. The standard 6-31G (d,p) basis set was used for all light elements, while pseudo potential LANL2DZ was used for the Ruthenium atom. The best bond lengths, bond angles and bond dihedrals were obtained using (PBE-GD3BJ), (TPSS-GD3BJ) and (BP86- GD3BJ) functionals respectively. The energy difference of the two diastereomeric halfsandwich Ru (II) cationic complexes (Ru(S)) and (Ru(R)) containing the phenyl alanine amide ligand has been calculated using the fifteen density functionals in other side the enantioselectivity in ATH of acetophenone catalyzed by Ru(II) complexes containing amino amide ligands were also investigated by defferents functionals,The best overall performance is observed for (PBE-GD3BJ) , because this functional gives good results both for the geometry and the energetics and is not too costly in terms of computation time. For the solvent system, we have chosen PCM. Secondly The origin of enantioselectivity in the reaction of chiral Ru amino amide complexes in asymmetric transfer hydrogenation of acetophenone was investigated with DFT calculation. The roles of the chirality of the ruthenium in Ru amino amide complexes was analyzed by considering foor tested cases: 1) Ru(S)C(S) phenyl alanine amide , 2) Ru(R)C(S) phenyl alanine amide, 3) Ru(S)C(S) proline amide and, 4) Ru(R)C(S) proline amide. We succeeded in reproducing the experimentally observed enantioselectivity for the foor studied Ru amino amide complexes, For each of these, the full free energy profile for the reaction is calculated according to the concerted hydrogen transfer mechanism. Our results indicated that high enantioselectivity explained by stabilizing CH–π interaction exists between the phenyl group of acetophenone and the cymene ring of the catalyst. This is in line with the explanations provided by Noyori et al. Hence, ours results show that rotation of p-cymene play a significant role in selectivity. finaly our results showed that important insights can be obtained with such a theoretical approach, particularly the origin of the reaction asymmetry. This can help experimentalists to design new catalysts that will ensure good enantioselectivity. Finally a proline amide/amine derived amino acid has been experimentally employed as an effective chiral catalytic precursor in the ruthenium-mediated asymmetric reduction of prochiral ketones in water to produce the corresponding secondary alcohols, which provides the products in 80% ee. We show that transition state modeling according to the outer spher reactionp. IVmechanism at the PBE-GD3BJ/LANL2DZ/6-31G (d,p) level of theory can accurately model enantioselectivity for various proline-catalyzed asymmetric transfer hydrogenation in water |
| Sommaire : |
Chapter 1 General Introduction………………………………………………… 1 1.1 Introduction………………………………………………………………….. 2 1.2 Structure of the thesis………………………………………………………... 4 1.3 References…………………………………………………………………… 5 Chapter 2 Asymmetric Transfer Hydrogenation (ATH) of ketones…………… 7 2.1. Catalysis…………………………………………………………………….. 8 2.2. Asymmetric catalysis………………………………………………………... 8 2.3. Transition Metal Catalysed Asymmetric Transfer Hydrogenation of Ketones. 11 2.3.1. A Short History of Asymmetric Transfer Hydrogenation………………….. 11 2.3.2. Ligands with NH Functionality……………………………………………. 12 2.4 Prediction of enantiomeric excess (ee)………………………………………. 13 2.5. Computational studies……………………………………………………….. 15 2.5.1 Introduction………………………………………………………………... 15 2.5.2 Hydrogenation of a Carbonyl Group……………………………………… 17 2.5.3 Conclusions………………………………………………………………... 21 2.6. References…………………………………………………………………... 22 Chapter 3 Computational Methodology………………………………………... 25 3.1. Electronic structure theory…………………………………………………. 26 3.1.1. The Born-Oppenheimer approximation…………………………………... 27 3.2. The Hartree and Hartree-Fock Approximations…………………………… 28 3.3. Density functional theory (DFT)……………………………………………. 29 3.3.1. Thomas-Fermi theory……………………………………………………... 29 3.3.2. Hohenberg-Kohn theorems……………………………………………….. 30 3.3.3. Kohn-Sham equations…………………………………………………….. 31 3.4. Exchange-correlation functionals………………………………………….. 32 3.4.1. Local Density Approximation (LDA)…………………………………….. 32 3.4.2. Generalised Gradient Approximation (GGA)…………………………..... 33 3.4.3. Hybrid Functionals……………………………………………………….. 33 3.5. Dispersion in density functional theory (DFT-D)…………………………... 34 3.6. Basis sets……………………………………………………………………. 35 3.7. Pseudopotentials……………………………………………………………. 36 3.7.1. Pseudopotentials applied in this thesis…………………………………… 36 LANL (Los Alamos National Laboratory) ECPs………………………………... 36 3.8. Optimisation………………………………………………………………… 37 3.8.1. Minimisation………………………………………………………………. 37 3.8.2. Methods of locating transition state structures………………………….... 37 3.8.2.1. Constrained optimisation (CO) method……………………………….... 37 3.8.2.2. Synchronous transit-guided quasi-Newton (STQN) method……………. 37 3.9. Modelling Solvation……………………………………………………….... 38 3.9.1. The Polarisable Continuum Model (PCM)……………………………….. 38 3.10. References…………………………………………………………………. 40 Chapter 4 Application I: The Choice of Density Functional………………….. 41 4.1. Introduction ………………………………………………………………… 42 4.2. Experimental section………………………………………………………... 43 4.2.1. Computational details…………………………………………………….. 43 4.3. Results and discussion………………………………………………………. 44 4.3.1. Geometries………………………………………………………………… 44 4.3.1.1. Bond distances…………………………………………………………... 61 4.3.1.2. Bond angles……………………………………………………………... 62 4.3.1.3. Dihedral angles…………………………………………………………. 62 4.3.2. Energetics…………………………………………………………………. 63 4.3.2.1. Diastereoisomer energy difference……………………………………… 63 4.3.2.2. Activation energies……………………………………………………… 64 4.4. Conclusion…………………………………………………………………... 69 4.5. References…………………………………………………………………… 70 Chapter 5 Application II : Theoretical Study of the enantioselective reduction of prochiral ketones promoted by amino amide ruthenium Complexes……….. 73 5.1. Introduction…………………………………………………………………. 74 5.2. Computational Methods…………………………………………………….. 77 5.3. Results and Discussion……………………………………………………… 77 5.3.1. Formation of the active catalyst…………………………………………... 78 5.3.2. Formation of the bi-functional ruthenium complex………………………. 80 5.3.2.1. With the (N, N) Phenylalanine………………………………………….. 81 Precatalyst S diastereoisomer of {(ɳ6-arene) Ru [(Ϗ2N, N) phenyl alanine amide] Cl+ }PF6…………………………………………………………………. 81 Precatalyst R diastereoisomer of {(ɳ6-arene) Ru [(Ϗ2N, N) phenylalanine amide] Cl+} PF6................................................. 81 5.3.2.2. With the (N, N) proline amide………………………………………….. 82 precatalyst S diastereoisomer of {Ru[(ɳ6- arene) proline amide]Cl}PF6……… 82 5.3.3. Asymmetric transfer hydrogenation of acetophenone……………………. 84 Precatalyst S diastereoisomer of {(ɳ6-arene) Ru [(Ϗ2N, N) phenyl alanine amide] Cl+ }PF6…………………………………………………………………. 84 Precatalyst R diastereoisomer of {(ɳ6-arene) Ru [(Ϗ2N, N) phenylalanine amide] Cl+} PF6…………………………………………………………………. 85 precatalyst S diastereoisomer of {Ru[(ɳ6- arene) proline amide]Cl}PF6………. 88 5.4. Conclusion…………………………………………………………………... 89 5.5. References…………………………………………………………………… 90 Chapter 6 Application III : DFT modeling of the enantiomeric excess for Asymmetric transfer hydrogenation reaction of prochiral ketones in water promoted by chiral proline (amide/amine) ruthenium (II) complexes………… 93 6.1. Introduction....................... 94 6.2. Experimental section………………………………………………………... 96 6.2.1. Computational Details……………………………………………………. 96 6.3. Results and discussion………………………………………………………. 96 6.3.1. Stereoselectivity with Ligand 1, 2 (proline amide/amine)………………… 97 6.3.2. Stereoselectivity with Ligand 3, 4 (proline amide/amine)………………… 99 6.4. Conclusion…………………………………………………………………... 100 6.5. References…………………………………………………………………… 102 Chapter 7 General Conclusion…………………………………………………... 104 7.1. General Conclusion………………………………………………………….. 105 Appendix………………………………………………………………………….. 106 |
| Type de document : | Thése doctorat |
| En ligne : | http://thesis.univ-biskra.dz/5483/1/these%20doctorat%20meftah%20yazid.pdf |
Disponibilité (1)
| Cote | Support | Localisation | Statut |
|---|---|---|---|
| TCH/88 | Théses de doctorat | bibliothèque sciences exactes | Consultable |
