Gold(I) and copper(I) imidazolium complexes were synthesized and probed for use as bulky Lewis acids in frustrated Lewis pairs (FLPs) with bulky phosphines and amines. Their reactivity with small molecules was investigated and the compounds were fully characterized by multinuclear NMR spectroscopy, elemental analysis and X-ray crystallography. Secondly, a new methylene-linked boron-sulfur Lewis acid was synthesized. Its thermodynamic properties were determined and its reactivity with terminal and internal alkynes was demonstrated. Adducts and heterocycles of this boron-sulfur system were fully characterized by multinuclear NMR spectroscopy, elemental analysis and X-ray crystallography. The application of these new systems for the activation of small molecules is described in this thesis.

Gold(I) and copper(I) imidazolium complexes were synthesized and probed for use as bulky Lewis acids in frustrated Lewis pairs (FLPs) with bulky phosphines and amines. Their reactivity with small molecules was investigated and the compounds were fully characterized by multinuclear NMR spectroscopy, elemental analysis and X-ray crystallography. Secondly, a new methylene-linked boron-sulfur Lewis acid was synthesized. Its thermodynamic properties were determined and its reactivity with terminal and internal alkynes was demonstrated. Adducts and heterocycles of this boron-sulfur system were fully characterized by multinuclear NMR spectroscopy, elemental analysis and X-ray crystallography. The application of these new systems for the activation of small molecules is described in this thesis.

While hundreds of papers have been published on frustrated Lewis pairs (FLPs) – the combination of bulky Lewis acids and bases which cannot form adducts – few of these use aluminum-based Lewis acids. The research outlined in this thesis expands the small molecule activation chemistry of FLPs to include Al.Combinations of bulky phosphines and AlX3 (X = halide or C6F5) with CO2 leads to the rapid activation to form the complexes R3P(CO2)(AlX3)2 (R = otol, Mes). Subsequent treatment with ammonia borane (AB) results in the rapid reduction of the CO2 fragment to methanol after water quench. Subsequent reactivity studies have established that AB adducts of AlX3, which react with CO2, are key intermediates in this chemistry. Further studies with Mes3P(CO2)(AlX3)2 revealed that these can reduce exogenous CO2 to CO, along with the generation of Mes3P(C(OAlX2)2O)(AlX3) and [Mes3PX][AlX4]. Detailed experimental and theoretical mechanistic investigations outline a possible mechanism involving direct CO2 insertion into free AlX3, followed by nucleophilic attack by PMes3 resulting in the expulsion of CO. Reactions with olefins were also investigated. While addition products of the type R3P(CH2CH2)AlX3 could be obtained with ethylene, C–H bond activation occurred with bulkier olefins. The resulting allyl species underwent subsequent C–C bond forming reactions with other olefins or CO2. Hydrogen was also activated using PR3/AlX3 FLPs to form species of the general formula, [R3PH][(H)(AlX3)2] (X = I, C6F5). These were found to reduce unactivated olefins, generating the redistributed products [R3PH][AlX4] and RAlX2 (R = alkyl). Attempts to circumvent this redistribution and favour alkyl protonation, thus generating a catalytic hydrogenation catalyst, are also discussed. Finally, the activation of N2O was also examined. While addition products could be formed, unexpected aromatic or benzylic C–H bond activation chemistry occurred in the presence of excess Al. A radical reaction pathway is proposed

Three classes of bifunctional compounds related to frustrated Lewis pair chemistry were studied. The first class, alkynyl-linked phosphonium borates, was strategically synthesized and the corresponding neutral alkynyl-linked phosphine boranes generated in solution. They were reacted with THF, alkenes and alkynes to undergo either ring-opening or multiple bond addition reactions, giving rise to zwitterionic macrocycles. In two select alkynyl-linked phosphonium borates, thermolysis resulted in unique rearrangements transforming the phosphino- and boryl-substituted alkynyl moieties into C4 chains. The alkynyl-linked phosphine boranes were further demonstrated to coordinate as η3-BCC ligands in Ni(0) complexes. The rigid nature of the coordination was confirmed by dimerization without cleavage of the Ni–B interaction upon the addition of acetonitrile or carbon monoxide. Moreover, reactions with Al-, Zn- and B-based Lewis acids prompted hydride transfer within the alkynyl-linked phosphonium borate and interesting functional group transfer reactions. The second class of the bifunctional systems, a series of gem-substituted bis-boranes, was subjected to reactions with tBu3P and CO2. The O-linked bis-borane was shown to coordinate the phosphino-carboxylate moiety with one B, while the methylene-linked bis-boranes were demonstrated to chelate the carboxyl group. The third bifunctional system class, vinyl-group tethered boranes, was examined to elucidate the mechanism of the frustrated Lewis pair addition reaction to olefins. Using a bis(pentafluorophenyl)alkylborane, the close proximity of the olefinic protons and the ortho-fluorine nuclei were evident by both NOE measurements and DFT calculations. Moreover, its reactions with phosphine bases suggested that an initial interaction between the highly electrophilic borane and the olefinic fragment precedes such frustrated Lewis pair addition reaction. Furthermore, a bis(pentafluorophenyl)alkoxyborane was synthesized and reacted with P-, N-, C- and H-based nucleophiles, demonstrating the wide range of Lewis bases that can be applied in olefin addition reactions with complementary regioselectivity.

While hundreds of papers have been published on frustrated Lewis pairs (FLPs) – the combination of bulky Lewis acids and bases which cannot form adducts – few of these use aluminum-based Lewis acids. The research outlined in this thesis expands the small molecule activation chemistry of FLPs to include Al.Combinations of bulky phosphines and AlX3 (X = halide or C6F5) with CO2 leads to the rapid activation to form the complexes R3P(CO2)(AlX3)2 (R = otol, Mes). Subsequent treatment with ammonia borane (AB) results in the rapid reduction of the CO2 fragment to methanol after water quench. Subsequent reactivity studies have established that AB adducts of AlX3, which react with CO2, are key intermediates in this chemistry. Further studies with Mes3P(CO2)(AlX3)2 revealed that these can reduce exogenous CO2 to CO, along with the generation of Mes3P(C(OAlX2)2O)(AlX3) and [Mes3PX][AlX4]. Detailed experimental and theoretical mechanistic investigations outline a possible mechanism involving direct CO2 insertion into free AlX3, followed by nucleophilic attack by PMes3 resulting in the expulsion of CO. Reactions with olefins were also investigated. While addition products of the type R3P(CH2CH2)AlX3 could be obtained with ethylene, C–H bond activation occurred with bulkier olefins. The resulting allyl species underwent subsequent C–C bond forming reactions with other olefins or CO2. Hydrogen was also activated using PR3/AlX3 FLPs to form species of the general formula, [R3PH][(H)(AlX3)2] (X = I, C6F5). These were found to reduce unactivated olefins, generating the redistributed products [R3PH][AlX4] and RAlX2 (R = alkyl). Attempts to circumvent this redistribution and favour alkyl protonation, thus generating a catalytic hydrogenation catalyst, are also discussed. Finally, the activation of N2O was also examined. While addition products could be formed, unexpected aromatic or benzylic C–H bond activation chemistry occurred in the presence of excess Al. A radical reaction pathway is proposed

Industries’ interest in nanomaterials is tremendous and catalysis is one of their applications. Catalysts allow reactions to occur under milder conditions, avoiding committing excessive heat or pressure to foster reactions. The discovery of Frustrated Lewis Pairs (FLP) in 2006 led to a new concept of homogeneous catalysis: metal-free acids and bases preventing from forming an Lewis adduct because their bulkiness create an active clamp that is able to cleave dihydrogen and other small molecules at room temperature. Transferring the FLP concept to the “nano”-world which is more relevant for industrial applications, requires well-designed nanoparticles and rationalization of their interaction with ligands aiming at forming a FLP between nanoparticles and ligands. The following project conducted at LCMCP (Laboratoire de Chimie de la Matière Condensée de Paris) under the supervision of Sophie Carenco aimed at studying the insertion of phosphorus in metallic nanoparticles in order to tune their catalytic activity and demonstrate Frustrated-Lewis Pair catalytic behaviours. To that end, copper nanoparticles and bimetallic core-shell nickel-cobalt nanoparticles were synthesized in colloidal solution. The phosphidation of both nanoparticles was investigated with trioctylphosphine (TOP) as the phosphorous source. Nanoparticles were characterized by X-Ray Diffraction, Transmission Electron Microscopy and X-ray Photoelectron Spectroscopy. Starting from the failure to reproduce a published procedure of copper phosphide nanoparticles synthesis, conditions of the reaction and the washing procedure were successively improved aiming the obtention of copper phosphide nanoparticles. The one-pot synthesis with hot-injection of TOP at the second step (320°C, 1h), allowed to isolate copper phosphide nanoparticles but a longer reaction time did not result in enhanced phosphorus doping. Further work would need to examine the reproducibility problems faced and investigate harsher reaction conditions (eg. higher temperature). Cu3P nanoparticles would be interesting to test as catalysts for hydrosilylation of benzaldehyde or CO2, a model reaction for CO2 hydrogenation. The synthesis of core-shell nickel-cobalt nanoparticles has been previously rationalized by Sophie Carenco’s team. Phosphidation was attempted from this optimized procedure. We started with harsh conditions (> 250°C, > 1h30) which caused reconstruction of the nanoparticles after leaching of the cobalt shell. In such conditions, the core-shell structure is not retained and a NiCoP alloy is obtained. Milder conditions allowed to retain the structure but further studies are required to characterize and locate the phosphorus insertion in the core-shell nanoparticles. NiCoP alloy and phosphidized core-shell Ni@Co will be of great interest to apply in catalysis for water splitting and hydrogenation of nitriles, respectively.

Après avoir pu développer une nouvelle méthode de déracémisation de biphényles iodés permettant, pour la première fois, d’influencer la diastéréosélectivité de la réaction de piégeage du réactif d’Andersen par dédoublement cinétique, nous avons obtenu de nombreuses informations et développé des méthodes permettant de lever différents verrous synthétiques pour accéder à des paires de Lewis frustrées basées sur le squelette biphénylique et portant simultanément ou non un groupement acide de Lewis et une base de Lewis. Par la fonctionnalisation de ces biphényles, nous avons pu accéder à de nouvelles biphénylphosphines énantiopures pouvant jouer le rôle de base de Lewis dans le domaine des paires de Lewis frustrées (FLP) mais aussi d'organocatalyseur nucléophile ou de ligand pour la catalyse organométallique. Différentes méthodes ont ensuite été (re)développées, pour accéder à des acides de Lewis : d'une part la synthèse de boranes par fonctionnalisation de sels d'organotrifluoroborate de potassium comme précurseurs polyvalents d’acides de Lewis chiraux et énantiopurs et d'autre part l’utilisation de silanes électrophiles. L’ensemble des informations et méthodes découlant de ce travail pourront être appliquées à la synthèse de molécules ambiphiles, nouvelles paires de Lewis atropo-frustrées. / After having developed a new method of deracemization of iodinated biphenyls allowing us, for the first time, to influence the diastereoselectivity of the trapping by the Andersen reagent, we have turned our attention to the use of this molecular scaffold in the design of new frustrated Lewis pairs bearing either a Lewis acidic group, a Lewis basic group or simultaneously both groups. We first accessed a new series of enantiopure biphenylphosphines that can find applications as Lewis base (including the field of frustrated Lewis pairs), as nucleophilic organocatalyst or as ligand in organometallic catalysis. Then, various methods were (re)developed to access chiral biphenyl-based Lewis acids: firstly, the functionalization of biphenyltrifluoroborate salts as chiral and enantiopure borane precursors and secondly the use of electrophilic silanes. The whole information and methodologies developed herein may be applied to the synthesis of new ambiphilic compounds as new atropo-frustrated Lewis pairs.

In the first part of this work, a convenient and high yielding synthetic strategy was developed to approach highly electrophilic fluorophosphonium cations as triflate salts. Through in situ electrophilic fluorination of phosphanes with commercially available bench-stable N-fluorobenzenesulfonimide (NFSI), followed by subsequent methylation of the [N(PhSO2)2]- anion with MeOTf, a library of mono-, di- and tri- cationic fluorophosphonium triflates were obtained in excellent yields. The Lewis acidities of all synthesized fluorophosphonium triflates salts were evaluated by both theoretical and experimental methods. These fluorophosphonium triflates have been develop as catalysts for the conversation of formamides into N-sulfonyl formamidines. CHAPTER II of this work focus on developing electrophilic fluorophosphonium cation as Lewis acid pedant in both inter- and intra- molecular FLP systems, as well as exploring their application in small molecular activation and functionalization, such as reversible CO2 sequestration and binding of carbonyls, nitriles and acetylenes. CHAPTER III of this thesis reports on the reaction of electrophilic fluorophosphonium triflates with trimethylsilyl nucleophiles (Me3SiX, X = CN, N3), which selectively yields either pseudohalo-substituted flurophosphoranes or pseudohalo-substituted phosphonium cations.:1. Introduction 1 1.1. Frustrated Lewis Pair chemistry 2 1.2. Phosphorus derivatives as strong Lewis acids 6 2. Objective 11 3. CHAPTER I: Synthesis of fluorophosphonium triflate salts and application as catalyst 15 3.1. Electrophilic fluorination of phosphanes: a convenient approach to electrophilic fluorophosphonium cations 15 3.2. Fluorophilicities and Lewis acidities of the obtained fluorophosphonium derivatives 23 3.2.1. Evaluation of fluorophilicities and Lewis acidities of the obtained fluorophosphonium cations 24 3.2.2. Reactions of fluorophosphonium salts with selected formamides. 27 3.2.3. Reactions of fluorophosphonium salts with selected urea derivatives 31 3.3. Transformation of formamides to N-sulfonyl formamidines using fluorophosphonium triflates as active catalysts 34 4. CHAPTER II: Bifunctional electrophilic fluorophosphonium triflates as intramolecular Frustrated Lewis Pairs 45 5. CHAPTER III: Reaction of fluorophosphonium triflate salts with trimethylsilyl nucleophiles 63 6. Summary 73 7. Perspective 77 8. Experimental section 80 8.1. Materials and methods 80 8.2. Experimental details for CHAPTER I 82 8.2.1. Preparation of imidazoliumyl-substituted phosphanes. 82 8.2.1.1. Preparation of [Ph2LcMeP][OTf] 82 8.2.1.2. Preparation of [Ph2LciPrP][OTf] 83 8.2.1.3. Preparation of [(C6F5)2LcMeP][OTf] 83 8.2.1.4. Preparation of [(C6F5)2LciPrP][OTf] 84 8.2.1.5. Preparation of [PhLcMe2P][OTf]2 85 8.2.1.6. Preparation of [PhLciPr2P][OTf]2 85 8.2.2. Preparation of fluorophosphonium bis(phenylsulfonyl)amide salts 86 8.2.2.1. Preparation of [36(NSI)]. 86 8.2.2.2. Preparation of 58a[NSI] 87 8.2.2.3. Preparation of 58b[N(SO2Ph)2] 88 8.2.3. Preparation of fluorophosphonium triflate salts 88 8.2.3.1. Preparation of 36[OTf] 89 8.2.3.2. Preparation of 36[H(OTf)2] 89 8.2.3.3. Preparation of 58a[OTf] 90 8.2.3.4. Preparation of 58b[OTf] 91 8.2.3.5. Preparation of 58c[OTf] 91 8.2.3.6. Preparation of 59a[OTf] 92 8.2.3.7. Preparation of 59b[OTf] 93 8.2.3.8. Preparation of 60Mea[OTf]2 94 8.2.3.9. Preparation of 60iPra[OTf]2 94 8.2.2.10. Preparation of 60Meb[OTf]2 95 8.2.3.11. Preparation of 60iPrb[OTf]2 96 8.2.3.12. Preparation of 61Me[OTf]3 97 8.2.3.13. Preparation of 61iPr[OTf]3 97 8.2.4. Reaction of fluorophosphonium triflate salts with nucleophiles 98 8.2.4.1. Preparation of 62a[OTf] 98 8.2.4.2. Preparation of 62b[OTf] 99 8.2.4.3. Preparation of 62c[OTf] 100 8.2.4.4. Preparation of 63 100 8.2.4.5. Preparation of 65 101 8.2.4.6. Preparation of 69a[OTf] 102 8.2.4.7. Preparation of 69b[OTf] 103 8.2.5. Synthesis of H[N(SO2R)(SO2Ph)] and corresponding sodium salt 103 8.2.5.1. General procedure for the formation of N-sulfonyl-sulfonamides 103 8.2.5.2. General procedure for the formation of sodium bis(sulfonyl)amides 104 8.2.5.3. Preparation of HN(SO2Ph)2, Na[N(SO2Ph)2] and [nBu4N][N(SO2Ph)2] 104 8.2.5.4. Preparation of 81a and 82a 105 8.2.5.5. Preparation of 81b and 82b 106 8.2.5.6. Preparation of 81c and 82c 106 8.2.5.7. Preparation of 81d and 82d 107 8.2.5.8. Preparation of 81e and 82e 108 8.2.5.9. Preparation of 81f and 82f 108 8.2.5.10. Preparation of 81g and 82g 109 8.2.5.11. Preparation of 81h and 82h 109 8.2.6. Synthesis of N-sulfonyl amidines 110 8.2.6.1. General procedure for the catalytic formation of N-sulfonyl amidines 110 8.2.6.2. Preparation of 64 110 8.2.6.3. Preparation of 72 111 8.2.6.4. Preparation of 73 112 8.2.6.5. Preparation of 74 112 8.2.6.6. Preparation of 75 113 8.2.6.7. Preparation of 76 114 8.2.6.8. Preparation of 77 114 8.2.6.9. Preparation of 78 115 8.2.6.10. Preparation of 79 116 8.2.6.11. Preparation of 80a,b 116 8.2.6.12. Preparation of 83b 117 8.2.6.13. Preparation of 83c 118 8.2.6.14. Preparation of 83d 119 8.2.6.15. Preparation of 83e 119 8.2.6.16. Preparation of 83f 120 8.2.6.17. Preparation of 83g 121 8.2.6.18. Preparation of 83h 122 8.3. Experimental details for CHAPTER II 123 8.3.1. Preparation of N-containing phosphanes 123 8.3.1.1. Preparation of 2-(bis(perfluorophenyl)phosphaneyl)pyridine 123 8.3.1.2. Preparation of 2-(bis(perfluorophenyl)phosphaneyl)-1-methylimidazole 124 8.3.1.3. Preparation of 2-(bis(perfluorophenyl)phosphaneyl)-N,N-dimethylaniline 124 8.3.2. Preparation of N/P Frustrated Lewis Pairs 125 8.3.2.1. General procedure for the synthesis of N/P-Frustrated Lewis pairs 125 8.3.2.2. Preparation of 85[OTf] 126 8.3.2.3. Preparation of 86[OTf] 126 8.3.2.4. Preparation of 87[OTf] 127 8.3.2.5. Preparation of 88[OTf] 128 8.3.2.6. Preparation of 89[OTf] 129 8.3.3. Synthesis of compound 84[OTf] 130 8.3.4. Reaction of N/P FLP with carbonyls, nitriles or acetylenes 131 8.3.4.1. General reaction conditions for the reaction of N/P FLP with carbonyls and nitriles 131 8.3.4.2. Preparation of 90[OTf] 131 8.3.4.3. Preparation of 91[OTf] 132 8.3.4.4. Preparation of 92[OTf] 133 8.3.4.5. Preparation of 93a[OTf] 134 8.3.4.6. Preparation of 93b[OTf] 134 8.3.4.7. Preparation of 94[OTf] 135 8.3.4.8. Preparation of 95[OTf] 136 8.3.4.9. Preparation of 96[OTf] 137 8.3.4.10. Preparation of 97a[OTf] 138 8.3.4.11. Preparation of 97b[OTf] 139 8.3.4.12. Preparation of 99a[OTf]2 140 8.3.4.13 Preparation of 100b[OTf] 141 8.3.5. Reaction of N/P FLPs with CO2 142 8.3.5.1 Reaction of 85[OTf] with CO2 142 8.3.5.2 Reaction of 86[OTf] with CO2 142 8.4. Experimental details for CHAPTER III 144 8.4.1 Synthesis of 105a,b[OTf] and 106c 144 8.4.1.1. General procedure for the reaction of fluorophosphonium triflate with Me3SiCN 144 8.4.1.2. Preparation of 105a[OTf] 144 8.4.1.3. Preparation of 105b[OTf] 145 8.4.1.4. Preparation of 106c 145 8.4.2. Reaction of fluorophosphonium triflate salt with Me3SiN3 146 8.4.2.1. General procedure for preparation of azidofluorophosphorane 146 8.4.2.2. General procedure for preparation of azidofluorophosphonium triflate salts 146 8.4.2.3. Preparation of 107a[OTf] 146 8.4.2.4. Preparation of 107b[OTf] 147 8.4.2.5. Preparation of 107c[OTf] 147 8.4.2.6. Preparation of 108c 148 8.4.2.7. Preparation of 109[OTf] 149 8.4.2.8. Preparation of 110[OTf]2 149 8.4.2.9. Preparation of 113[OTf]3 150 8.4.2.10. Preparation of 114[OTf] 151 8.4.2.11. Preparation of 115[OTf] 151 8.4.2.12. Preparation of 116[OTf] 152 8.4.3 Transformation of azido-fluorophosphorane under heating conditions 153 8.4.3.1 Preparation of 118 153 8.4.3.2 Preparation of 120a,b[OTf] 154 9. Crystallographic details 156 9.1. X-ray Diffraction refinements 156 9.2. Crystallographic details for CHAPTER I 157 9.3. Crystallographic details for CHAPTER II 169 9.4. Crystallographic details for CHAPTER III 176 10. Computational methods 179 11. Abbreviations 181 12. Nomenclature of compounds according to IUPAC recommendations 183 13. References 187 14. Acknowledgment 205 15. Publications and conference contributions 207 15.1. Peer-reviewed publication 207 15.2. Poster presentations 207 Versicherung 209 Erklärung 209

Ce manuscrit aborde plusieurs interactions / réactions chimiques importantes se produisant dans la soluton en utilisant la calorimétrie par titrage isothermique (ITC) et la théorie de la densité fonctionnelle statique (DFT). Cette thèse porte son attention notamment sur : l'association de paires de Lewis (frustrées) ((F)LPs), la migration cis du groupe méthyle au sein du pentaméthylmanganèse induit par les phosphines, l'aminolyse de carbènes de Fischer, l'insertion d'alcynes dans des palladacycles, l'affinité de divers donneurs de Lewis à l’hexafluoroisopropanol. L'ITC s'est révélé être une technique expérimentale puissante pour obtenir des données thermochimiques fiables sur les systèmes étudiés. Les calculs statiques DFT-D ont montré une capacité d’estimation correcte des paramètres de réaction thermodynamique lorsque l’influence de la solvatation n’est pas significative. Autrement, lorsque l’influence du solvant est apparente, les calculs ne permettent pas de reproduire les résultats expérimentaux. En plus, les résultats expérimentaux et théoriques révèlent l’existence d’ensembles moléculaires plus grandes dans la solution de FLP, soulignant le rôle des interactions non covalentes. / This manuscript adressed several important chemical interactions/reactions taking place in solutuon by using Isothermal Titration Calorimetry (ITC) and static Density Functional Theory (DFT). Namely, this thesis dealt with: association of (frustrated) Lewis pairs ((F)LPs), cis-migration of methyl group within pentamethylmanganese induced by phosphines, aminolysis of Fischer carbenes, insertion of alkynes into palladacycles, affinity of various Lewis donors to hexafluoroisopropanol. The ITC proved to be powerful experimental technique for obteining reliable thermochemical data of sutudied systems. The static DFT-D calculations showed capability for proper estiamtion of thermodynamic reaction parameters when an influence of solvation is not sighnificant. Otherwise, when the influence of solvent is not innocent, the calculations moslty failed to reproduce the experimantal results. In addition, Both the experimantal and therortical results revield existance of larger molecular clusters in solution of FLPs emphasising a role of non-covalent interactions.

Protocols for the FLP-mediated transformation of ethers are presented. Distinct reaction pathways involving either C–O or C–H bond activation occur depending on the application of oxophilic B(C6F5)3 or hydridophilic tritylium ions as the Lewis acid.