Berlin, Humboldt-Univ., Diss., 2003. / Computerdatei im Fernzugriff.

Berlin, Humboldt-Univ., Diss., 2003. / Computerdatei im Fernzugriff.

Berlin, Humboldt-University, Diss., 2003.

No description available.

The bidentate ligand 1,2-bis(ditertbutylphosphinomethyl)benzene has been shown to be a very efficient catalyst for operating the alkoxycarbonylation of alkenes and unsaturated esters and carboxylic acids giving a very high selectivity to the linear product with very few exceptions to this general rule. Due to the increasing prices of petroleum feedstock and petroleum-derived chemicals, the preparation of chemicals starting from renewable resources and waste products from the industry becomes an interesting alternative. Fatty acids and fatty esters, due to the existence of one or more unsaturation in their alkyl chain are subjected to the alkoxycarbonylation reactions in presence of 1,2-bis(ditertbutylphosphinomethyl)benzene, palladium, methane sulfonic acid, carbon monoxide and methanol, yielding diesters with a long carbon chain (up to 19 carbon atoms). The diesters are shown to be readily prepared from unpurified olive, rapeseed or sunflower oils as well as from tall oil. In the last case triesters are also formed. The diesters are subjected to hydrogenation in the presence of 1,1,1-tris(diphenylphosphinomethyl)ethane, ruthenium and hydrogen, in a mixture of dioxane and water at high temperature, yielding the corresponding diols. The resulting products of the reactions are monomers for preparing polyesters having the potential to replace some existing petroleum-based polymers (for instance polyethylene). The aminocarboxylation reaction in the presence of the same palladium/1,2-bis(ditertbutylphosphinomethyl) benzene catalyst, in the presence of aniline, 2{naphthol and potassium iodide in diethylether, is employed for preparing esteramides, which are subjected to hydrogenation. Aromatic polyamides are prepared by melting together an aromatic diamine and diacids obtained from methoxycarbonylation. Finally, N-Heterocyclic Carbene (NHC) ligands are employed for preparing new palladium complexes which are used in the Suzuki-Miyaura cross-coupling reaction in a water/isopropanol mixture. Other complexes based on copper are employed for developing an inexpensive transmetallation reaction for transferring a NHC ligand from copper to palladium and gold.

More attention has been paid to find new type renewable energy sources because of increasing concern about the environmental problems arising from the combustion of fossil fuels as energy sources. The development of new storage materials will facilitate the use of hydrogen as a major energy carrier. Several possibilities exist for &lsquo / &lsquo / solid-state&rsquo / &rsquo / storage: the hydrogen can be trapped in metal organic frameworks, carbon nanotubes and certain alloys / or one can use materials in which hydrogen is already present in the composition (e.g., chemical hydrides). The latter option seems to be the most promising since it permits a higher mass ratio of hydrogen. Recently, ammonia-borane complex (NH3BH3, AB) has been considered as solid hydrogen storage material since it possess one of the highest hydrogen contents (19.6 wt. %) and high stability under the moderate conditions. Hydrolysis and methanolysis are the two reactions liberating hydrogen from AB. However, a catalyst is needed for hydrogen generation from methanolysis of AB. In this context, we aim to develop PVP-stabilized palladium(0) and ruthenium(0) nanoclusters as catalyst for the methanolysis of AB. The PVP-stabilized palladium(0) and ruthenium(0) nanoclusters were prepared from the in-situ reduction of palladium(II) acetylacetonate and ruthenium(III) chloride respectively in the methanolysis of AB. The prepared palladium(0) nanoclusters were isolated as solid materials by removing the volatile in vacuum and characterized by using TEM, SAED, XPS, FT-IR, XRD and UV-visible electronic absorption spectroscopy techniques while and ruthenium(0) nanoclusters were characterized by TEM, XPS, XRD, FT-IR and UV-visible electronic absorption spectroscopy techniques. The kinetics of methanolysis of AB catalyzed by palladium(0) and ruthenium(0) nanoclusters were studied depending on the catalyst concentration, substrate concentration and temperature. The activation parameters of the catalytic methanolysis reaction obtained from the evaluation of kinetic data.

Die vorliegende Dissertation beschäftigt sich mit der Synthese, der Charakterisierung und der Anwendung neuartiger Phosphane in homogenkatalytischen Reaktionen. Dabei wurden die Ferrocenyl- und Ferrocenylethinylphosphan-Palladium und Ferrocenylethinylphosphan-Ruthenium Komplexe in der Palladium-vermittelten Mizoroki-Heck- und Suzuki-Miyaura-Reaktion sowie der Ruthenium-katalysierten Synthese von β-Oxopropylestern verwendet. Der Schwerpunkt lag dabei auf der Untersuchung des Einflusses der elektronischen und räumlichen Eigenschaften der Phosphanliganden auf die Aktivität und Produktivität der entsprechenden Katalysatoren in den homogenkatalytischen Reaktionen. Weiterhin beschäftigt sich die vorliegende Arbeit mit der Synthese und Charakterisierung von funktionalisierten (Phosphino)Imidazol und (Phosphino)Imidazolium Salzen und deren Anwendung in der Suzuki-Miyaura-Reaktion. Dabei wurde neben der Untersuchung des Einflusses der Position der Phosphanylgruppe und der unterschiedlichen Substituenten ebenfalls die Auswirkung von elektronenziehenden und -schiebenden Gruppen am Phosphanrest untersucht. Die neutralen Mono- und Diphosphane wurden außerdem in der Kreuzkupplung von Arylhalogeniden und in der Synthese räumlich anspruchsvoller Biaryle verwendet. Des Weiteren wurden die (Phosphino)Imidazolium-Salze als Liganden in der Suzuki-Miyaura-Reaktion in ionischen Flüssigkeiten als Reaktionsmedium angewendet, um die Möglichkeit des Recyclings der Katalysatorphase zu untersuchen.:Table of Contents Bibliographische Beschreibung und Referat ii Präambel iii Table of Contents 1 List of Abbreviations 5 A Introduction 9 1 Homogeneous Catalysis 9 2 References 11 B State of Knowledge 13 1 Transition Metal-Catalyzed C,C Cross-Coupling Reactions 13 2 Mizoroki-Heck Reaction 16 3 Suzuki-Miyaura Reaction 23 4 β-Oxopropyl Ester Synthesis 29 5 Ferrocenyl Phosphines in C,C Cross-Coupling Reactions 33 6 Phosphino Imidazoles and their Application in C,C Cross-Coupling Reactions 35 7 Motivation 36 8 References 37 C Metallocenyl Phosphine Palladium Dichlorides: Synthesis, Electrochemistry and their Application in C,C Coupling Reactions 44 1 Introduction 44 2 Results and Discussion 45 2.1 Ligand Synthesis and Properties 45 2.2 Electrochemistry 47 2.3 Single Crystal X-ray Structure Determination 51 2.4 Catalytic Investigations 55 2.4.1 Mizoroki-Heck Catalysis 55 2.4.2 Suzuki-Miyaura Catalysis 56 3 Conclusions 58 4 Experimental Section 60 4.1 General Data 60 4.2 Instruments 60 4.3 Electrochemistry 60 4.4 Spectro-electrochemistry 61 4.5 Materials 61 4.6 General Procedure for the Synthesis of Phosphines 3 and 6 61 4.7 General Procedure for the Synthesis of the Seleno Phosphines 4 and 7 65 4.8 General Procedure for the Synthesis of the Palladium Complexes 9a – e and 10a – d 69 4.9 General Procedure for the Mizoroki-Heck Reaction 72 4.10 General Procedure for the Suzuki-Miyaura Reaction 73 4.11 Crystal Data for 4b 73 5 Supporting Information 73 6 Acknowledgement 77 7 References 77 D Fundamental Study of (Ferrocenylethynyl)phosphines: Correlation of Steric and Electronic Effects in C,C Cross-Coupling Reactions 81 1 Introduction 81 2 Results and Discussion 82 2.1 Synthesis, Reaction Chemistry and Characterization 82 2.2 C,C Cross-Coupling Reactions 95 2.2.1 Suzuki-Miyaura Reaction 95 2.2.2 Mizoroki-Heck Reaction 96 3 Conclusions 97 4 Experimental Section 99 4.1 General Data and Materials 99 4.2 Instruments 99 4.3 Electrochemistry 100 4.4 Spectro-electrochemistry 100 4.5 General Procedure for the Synthesis of Phosphines 3b – f 101 4.6 General Procedure for the Synthesis of Seleno Phosphines 4b – f 104 4.7 General Procedure for the Synthesis of Palladium Complexes 6e, 6f and 7a – f 106 4.8 Synthesis of [PdCl2(P(C≡CFc)(Cy)2)2][B(C6F5)4]2 ([7f][(B(C6F5)4)]2) 110 4.9 General Procedure for the Suzuki-Miyaura Reaction 110 4.10 General Procedure for the Mizoroki-Heck Reaction 110 4.11 Crystal Structure Determination 111 5 Supporting Information 112 6 Acknowledgement 114 7 References 114 E (Ethynylferrocenyl)phosphine Ruthenium Complexes in Catalytic β-Oxopropyl Benzoate Formation 119 1 Introduction 119 2 Experimental Section 120 2.1 General Procedure and Materials 120 2.2 General Procedure for the Synthesis of Ruthenium Complexes 3a – 3e and 10 121 2.3 Synthesis of (Et2N)P(C≡C-PPh2)2 (6) 124 2.4 Synthesis of P(C≡CFc)(C≡CPPh2)2 (9) 124 2.5 Synthesis of (RuCl2(η6-p-cymene))(FcC≡C)P(C≡CPPh2(RuCl2(η6-p-cymene)))2 (10) 125 2.6 General Procedure for the Catalytic Reactions 125 2.7 Crystal Structure Determination 126 3 Results and Discussion 127 4 Conclusions 135 5 Supporting Information 135 6 Acknowledgement 135 7 References 136 F Phosphino Imidazoles and Imidazolium Salts for Suzuki-Miyaura C,C Coupling Reactions 138 1 Introduction 138 2 Results and Discussion 139 2.1 Synthesis 139 2.2 Characterization 143 2.3 Catalysis 148 3 Conclusions 152 4 Experimental Section 154 4.1 General Procedures 154 4.2 Synthesis of 1-(4-iodophenyl)-4,5-dimethyl-1H-imidazole (3b) 155 4.3 Synthesis of 1-(4-ferrocenylphenyl)-1H-imidazole (5) 156 4.4 Synthesis of 1-(4-(ethynylferrocenyl)phenyl)-1H-imidazole (7) 156 4.5 Synthesis of 1-(4-(1,1’-biphenyl))-4,5-dimethyl-1H-imidazole (9) 157 4.6 General Synthesis Procedure for Phosphines 11a – f 157 4.7 General Procedure for the Synthesis of Seleno Phosphines 11a-Se – f-Se 165 4.8 General Procedure for the Synthesis of Imidazolium Salts 16a – 16d 169 4.9 Synthesis of 1-phenyl-2-(diphenylphosphino)-3-n-octyl-4,5-dimethyl-1H-imidazolium hexafluorophosphate (17a) 171 4.10 Synthesis of 1-phenyl-2-(dicyclohexylphosphino)-3-n-octyl-4,5-dimethyl-1H-imidazolium hexafluorophosphate (17b) 172 4.11 Synthesis of [(1-(4-Br-C6H4)-cC3H2N2-3-n-Bu)2PdI2] (19) 173 4.12 Synthesis of 1-(4-(diphenylphosphino)phenyl)-3-n-octyl-4,5-dimethyl-1H-imidazolium hexafluorophosphate (20) 173 4.13 General Procedure for the Suzuki-Miyaura Reaction 174 4.14 General Procedure for the Suzuki-Miyaura Reaction in Ionic Liquids 175 4.16 General Procedure for the Synthesis of Sterically Hindered Biaryls 175 4.17 Crystal Structure Determination 176 5 Supporting Information 177 6 Acknowledgement 180 7 References 180 G Imidazole Phosphines: Synthesis, Reaction Chemistry and Their Use in Suzuki-Miyaura C,C Cross-Coupling Reactions 184 1 Introduction 184 2 Results and Discussion 185 2.1 Synthesis and Characterization of Phosphino Imidazoles and Metallamacrocycles 185 2.2 Suzuki-Miyaura C,C Cross-Coupling Reactions 193 3 Conclusions 196 4 Experimental Section 197 4.1 General Procedures 197 4.2 Synthesis of 1-(4-(diphenylphosphino)phenyl)-4,5-dimethyl-1H-imidazole (4a) 198 4.3 Synthesis of 1-(4-(dicyclohexylphosphino)phenyl)-4,5-dimethyl-1H-imidazole (4b) 199 4.4 General Synthesis Procedure for Phosphines 6a – f 199 4.5 Synthesis of [Pd(1-(4-PPh2-C6H4)-2-PFur2-4,5-Me2-1H-C3N2)Cl2]2 (8) 204 4.6 Synthesis of [Pt(dppf)(C≡C-C6H4-4-PPh2)2] (11) 204 4.7 Synthesis of [Pt(dppf)(C≡C-C6H4-4-PPh2)2PtCl2)]2 (13) 205 4.8 General Procedure for the Suzuki-Miyaura Reaction 205 4.9 General Procedure for the Suzuki-Miyaura Coupling of Aryl Chlorides 206 4.10 General Procedure for the Synthesis of Sterically Hindered Biaryls 206 4.11 Crystal Structure Determination 206 5 Acknowledgement 207 6 Supporting Information 208 7 References 208 H Summary 211 Acknowledgement/Dank 219 Publications, Oral Presentations, Poster 220 Publications 220 Oral Presentations 221 Posters 221 Curriculum Vitae 223 Selbstständigkeitserklärung 224 Appendix 225

Catalysis is a key area of chemistry. Through catalysis it is possible to achieve better synthetic routes, exploit molecules normally considered to be inactive and also attain novel chemical transformations. The development of new catalysts is crucial to furthering chemistry as a field. Computational chemistry, arising from applying the equations of quantum and classical mechanics to solving chemical problems, offers an essential route to investigating the underlying atomistic detail of catalysis. In this thesis calculations have been applied towards studying a number of different catalytic processes. The processing of renewable chemical sources via homogeneous reactions, specifically cardanol from cashew nuts, is discussed. All routes examined for monoreduction of a diene model by [Ru(H)(iPrOH)(Cl)(C₆H₆)] and [Ru(H)(iPrOH)(C₆H₆)]⁺ are energetically costly and would allow for total reduction of the diene if they were operating. While this accounts for the need of high temperatures, further work is required to elucidate the true mechanism of this small but surprisingly complex system. Gold-mediated protodecarboxylation was examined in tandem with experiment to find the subtle steric and electronic effects that dictate CO₂ extrusion from gold N-heterocyclic carbene activated benzene-derived carboxylic acids. The origin of a switch in the rate limiting step from decarboxylation to protodeauration with less activated substrates was also clearly demonstrated. Studies of gold systems are closed with examinations of 1,2-difluorobenzene C–H activation and CO₂ insertion by [Au(IPr)(OH)]. Calculations highlight that the proposed mechanism for oxazole-derived substrates cannot be extended to 1,2-difluorobenzene and instead a digold complex offers more congruent predicted kinetics. The lens of quantum chemistry was turned upon palladium-mediated methoxycarbonylation reactions. An extensive study was undertaken to attempt to understand the bidentate diphosphine ligand dependency on forming either methylpropanoate (MePro) or copolymers. Mechanisms currently suggested in literature are shown to be incongruous with the formation of MePro by Pd(OAc)₂ and bulky diphosphines. A possible alternative route is proposed in this thesis. Four mechanisms for methoxycarbonylation with Pd(2-PyPPh₂)ₙ are detailed. The most accessible route is found to be congruent with experimental reports of selectivity, acid dependency and slight steric modifications. A modification of 2-PyPPh₂ to 2-(4-NMe₂-6-Me)PyPPh₂ is shown to improve both selectivity and turnover, the latter by four orders of magnitude (highest transition state from 22.9 kcal/mol to 16.7 kcal/mol ∆G), and this new second generation in silico designed ligand is studied for its applicability to wider substrate scope and different solvents. The final chapter of this thesis is a mixed quantum mechanics and molecular mechanics (QM/MM) examination of an enzymatic reaction, discussing the need for certain conditions and the role of particular amino acid residues in an S[sub]N2 hydrolysis reaction.