La réactivité à la phase gazeuse, ou réactivité intrinsèque, a une grande importance puisque l’absence d’interactions avec un solvant peut donner lieu à une réactivité très diffèrent donc, nous permettant d’avoir une meilleure connaissance des propriétés moléculaires. Avec l’émergence en 1900 de nouvelles techniques expérimentales, plus précisément des techniques pour ioniser plus doucement, la chimie des ions en phase gazeuse s’est développée significativement et a supposé en changement dans l’idée de la réactivité chimique. Cet manuscrit est divisé en deux parties chacune d’elles concernant un aspect diffèrent de la réactivité en phase gazeuse.La premier partie, Part I, étude l’acidité intrinsèque d’une série de bases de Lewis du groupe 15 du tableau périodique, l’accent étant mis sur le changements d’acidité ayant lieue après la formation du complexe de Lewis. Divers acides de Lewis appartenant ou groupe 13 on été tenus en compte. Afin d’expliquer l’origine de l’augment d’acidité observé plusieurs méthodes théoriques on été employés. Pour le calcul de l’acidité intrinsèque ont a employé la théorie de la fonctionnelle de la densité (DFT, sigle pour Density Functional Theory) et des méthodes qui sont basées à la fonction d’onde. Pour décrire les variations dans la configuration électronique ayant lieu à la formation du complexe (et qui sont les responsables du changement d’acidité susmentionné) nous avons utilisé des méthodes complémentaires pour l’analyse de la population électronique (AIM, ELF et NBO). Il est important de souligner qu’une partie des résultats présentés dans cet manuscrit on été déjà corroborés par les résultats expérimentaux.La deuxième partie, Part II, est centrée sur l’étude de la réactivité unimoléculaire des ions formamide-M2+ (M = Ca, Sr). Dans ce cas particulier, les ions choisis avaient été déjà étudiés expérimentalement avec la technique de dissociation induite par collision (CID, sigle pour Collision Induced Dissociation). Tout au long de cette deuxième partie, nous avons étudié et caractérisé les différents mécanismes de fragmentation des deux ions, en utilisant diffèrent méthodes théoriques qui sont complémentaires entre eux. Premièrement, ont a évalué divers fonctionnelles afin de trouver le plus approprié pour maintenir le coût computationnelle bas au même temps que d’obtenir des résultats fiables. Ensuite, on a modélisé par moyen de simulations de dynamique la réactivité aux temps courts (< 2.5 femto seconds). En outre, en se servant des données obtenues antérieurement, on a étudié la cinétique de fragmentation avec la théorie statistique RRKM, pour les réactions «lents » (t > 2.5 fs). L’utilisation de cette procédure multi-échelle nous permet de rationaliser l’origine de tous les produits observés expérimentalement ainsi que de donner une explication aux différences entre les deux ions considérés. Pour finir, dans le quatrième chapitre sont énumérés et décrits brièvement les différents méthodes employés au cours de cet travail, tant théorétiques que expérimentaux. / The so-called intrinsic reactivity (gas-phase reactivity) is of great importance since the absence of interaction with a solvent can result in very different reactivity patterns, allowing for a better understanding of molecular properties. With the advent in the 1900s of new experimental techniques, notably soft ionization methods such as electrospray ionization, the gas-phase ion chemistry has significantly developed in the last decades of the 1900s with a concomitant change in our view of chemical reactivity. The present manuscript is divided in two different parts, each one dealing with different aspects of gas-phase reactivity.Part I is concerned with the study of the intrinsic acidity of a series of group 15 Lewis bases. The changes on the aforementioned intrinsic acidity as the Lewis bases form adducts with group 13 Lewis acids is the main subject of this part. Thus, the origin for the acidity enhancement observed upon adduct formation is rationalized by means of different theoretical methods. High-level DFT and ab initio calculation were performed in order to compute theoretical acidities of the molecules under survey. Complementary to this, population analysis techniques such as AIM, ELF, and NBO were used to analyze the changes on the electronic configurations of those molecules and therefore provide with an explanation to the observed acidities. It is worth to stress the fact that part of the results were as well confirmed by means of experimental measurements. Part II focuses in unimolecular reactivity of molecular ions, namely, formamide-M2+ (M = Ca, Sr). In this case, experiments studying the Collision Induced Reactivity (CID) of these ions were already performed and through the second part of this manuscript the fragmentation mechanism of both ions are studied and characterized using different, but complementary, theoretical techniques. It is worth to mention that in a very first-step, an assessment of different methods to perform reliable electronic structure calculations while maintaining the lower possible computational cost. In the one hand, a kinetic study of the fragmentation process using the statistical theory RRKM, to describe the long-time reactivity (> fs). On the other hand, direct dynamics simulations are performed in order to describe the short-time (< 2.5 fs) non-statistical reactivity. This multi-scale approach allowed us to account for all the products observed in the CID experimental spectra of formamide-M2+ ( M = Ca, Sr), as well as the differences between them. In the fourth chapter a summary of the experimental and theoretical procedures used to perform the work presented in this manuscript is provided.

This thesis describes the synthesis and reactivity studies of the actinyl dications [AnO2]2+ in a variety of oxidation states. Chapter one introduces the importance of the chemistry of actinyl cations in nuclear technology and in the environment, and in particular the chemistry of uranyl dication, which is very stable in the higher oxidation state and considered to be chemically-inert. In Chapter two, on the synthesis of the new macrocyclic Pacman complex [UO2(S)(H2L)] is reported and its reactivity with differing amounts of lithium bases evaluated, so providing insight into the single electron reduction of the uranyl dication. Chapter three is focused on the reactions of the lithiated complexes generated in Chapter two towards acid and silyl sources to obtain complexes in which the oxogroup is further functionalised and to provide mechanistic insight into uranyl immobilisation. Chapter four evaluates the reactivity of the uranyl(VI) Pacman complex [UO2(S)(H2L)] with [Zn{N(SiMe3)2}Cl] to obtain another routes to form the complex [(Me3SiO)UO(THF)(ZnCl)2(L)] and the reactivity with different sources of potassium base, and provides a comparison to the analogues Li-base reactions described in Chapter two. The reactivity of the potassiated and lithiated complexes towards a variety of transition metals are described. Chapter five contains a summary and conclusions on this work. Chapter six presents full experimental details and analytical data.

The rac- and meso- forms of “all carbon” 1,2-diphosphonium dications with the naphthalene -1,8-diyl backbone were synthesised in good yields and purity by double alkylation of the parent diphosphine (1,2-diphenyl-1,2-diphosphaacenaphthene) using strong alkylating agents. Pure rac- and meso- forms of 1,2-diphosphoniums were obtained diastereospecifically by using methyl triflate and trimethyloxonium tetrafluoroborate respectively. It was found that the equilibrium between the rac- and meso- forms at room temperature in acetonitrile solutions effectively depends on the anion present. A reaction mechanism which proceeds via a P-pentacoordinated intermediate was proposed for the epimerisation observed between the rac- and meso- forms in the presence of F⁻ donors in the solution. Reactivity of the new 1,2-dications towards a range of compounds (nucleophiles, bases) was examined and a series of new compounds including phosphine-phosphoniums and phosphonium-phosphine oxides were obtained. Cyclic and acyclic compounds belonging to a novel group of phosphine-arsine mixed peri-substituted acenaphthenes were synthesised by introducing arsenic and phosphorus to the acenaphthene ring, using stepwise lithiation and carbon-group 15 element coupling. All new compounds were fully characterised including single crystal X-ray diffraction. The effect of the peri-substitution by phosphorus moieties and mixed arsine-phosphine peri-substitution on the naphthalene ring was studied using the detailed structural data obtained for these systems.

Dicationic diamidines synthesized in the Boykin group a have shown broad range of activity against a wide variety of microbial pathogens such as Cryptosporidium parvum, Leishmania donovani, Plasmodium falciparum, Trypanosoma burcei, and Trichomonas vaginalis. Thiophene based dicationic diamidines have been especially impressive versus Trichomoniasis, and several species of the leishmania parasite. The best compound in vitro against leishmania was 2,5-bis-(4-amidophenyl)thiophene [DB 351]. In an attempt to improve upon antileishmanial activity, several analogs of DB 351 have been synthesized. Previously the central heterocyclic ring has been changed (furan, pyrrole, etc.), and the phenyl has been substituted with a pyridine ring, however, in the thiophene series, the 3 and 4 position of the central thiophene ring has remained unmodified. By modifying the 3 and 4 position of the thiophene ring, and taking advantage of the substituent effect, the pharmacodynamic and distribution properties of DB 351 will altered; hopefully leading to more potent antileishmanial compounds.

Dicationic diamidines synthesized in the Boykin group a have shown broad range of activity against a wide variety of microbial pathogens such as Cryptosporidium parvum, Leishmania donovani, Plasmodium falciparum, Trypanosoma burcei, and Trichomonas vaginalis. Thiophene based dicationic diamidines have been especially impressive versus Trichomoniasis, and several species of the leishmania parasite. The best compound in vitro against leishmania was 2,5-bis-(4-amidophenyl)thiophene [DB 351]. In an attempt to improve upon antileishmanial activity, several analogs of DB 351 have been synthesized. Previously the central heterocyclic ring has been changed (furan, pyrrole, etc.), and the phenyl has been substituted with a pyridine ring, however, in the thiophene series, the 3 and 4 position of the central thiophene ring has remained unmodified. By modifying the 3 and 4 position of the thiophene ring, and taking advantage of the substituent effect, the pharmacodynamic and distribution properties of DB 351 will altered; hopefully leading to more potent antileishmanial compounds.

Studies of gas-phase ionic clusters have become an integral component in understanding microsolvation and catalysis by transition metal cations. Further interest in this field is due to the possibility of bridging the gap between the condensed and gas phases by developing our understanding of clusters and the possibility that small clusters can have unique chemical and catalytic properties. Most gas phase studies have focused on singly charged ions. Electrospray allows for the production of multiply charged ions solvated by a few solvent molecules. Understanding smaller reactive species such as metal centered clusters with well-defined, gas phase conditions also allows for detailed comparison between theory and experiments. In these studies the main focus is to understand bond activation by transition metal cations and solvation of transition metal dications. The gas phase ions of interest are studied using an electrospray-ionization or laser-ablation dual time-of-flight mass spectrometer and are characterized using photofragment spectroscopy in the visible and ultraviolet regions of the spectrum. Photofragment spectroscopy is a powerful method that can be used in gas phase studies to gather a wealth of information on the ions' bond strengths, spectroscopic constants, and dissociation kinetics and dynamics. The study of TiO + (CO 2 ) spectroscopy (Chapter 3) was a result of study of CO 2 bond activation by Ti + that went on to provide a wealth of information on the spectroscopy and dissociation kinetics of this molecule. An electronic transition of the TiO + chromophore was observed, 2 Π[arrow left] 2 Δ, revealing new information about the excited state and the effect of TiO + electronic state on the metal- CO 2 ligand interaction. The photodissociation spectrum of this molecule is well resolved and shows progressions in the covalent Ti-O stretch and metal-ligand stretch and rock. The lifetime of electronically excited TiO + (CO 2 ) was measured, and depends strongly on vibrational energy. Calculations on TiO + and TiO + (CO 2 ) were combined with experimental results on TiO + (CO 2 ) to predict spectroscopic transitions of TiO + , an astrophysically interesting molecule. The photodissociation dynamics of M 2+ (CH 3 CN)n(H 2 O)m where M = Co and Ni, (Chapter 4) is important in understanding the gas phase microsolvation of metal dications. The coordination number and type of solvent affect the dissociation pathways. M 2+ (CH 3 CN)n (n>2) primarily lose a solvent molecule. Electron transfer is a minor channel for n=3 and is the only channel observed for n=2. Mixed clusters M 2+ (CH 3 CN)n(H 2 O)m preferentially lose water. Loss of acetonitrile is a minor channel, as is proton transfer. Water is the proton donor. Replacing acetonitrile with water increases the proton transfer channel. Nickel and cobalt complexes show similar dissociation dynamics, with proton transfer more likely for nickel complexes. Methane activation by transition metal catalysts is industrially important as it can be used to produce gasoline from natural gas. We studied the products and intermediates of the reaction of laser-ablated platinum atoms with methane (Chapter 5). Photoionization efficiency curves were measured for PtCH 2 and the [H-Pt-CH 3 ] insertion intermediate using tunable vacuum ultraviolet light. The resulting ionization energies were combined with bond strengths for the cations to derive bond strengths for the neutrals. These were used to construct a potential energy surface for methane activation by platinum atoms.

Recently, there has been increasing focus toward the development of small molecules designed to target a specific sequences of double stranded DNA for therapeutic purposes1. Minor groove binding compounds have been shown to be capable of selectivity target GC sites in AT tract DNA2. In this research, binding selectivity was investigated using absorption, fluorescence and circular dichroic properties of selected DB minor groove binders in the presence of two unique DNA sequences. Further insight was gained by comparing the electrostatic potential maps and optimized structures of the compounds of interest. Using the results presented, potential selective minor groove binders can be selected for further investigation and kinetic studies.

abstract: Mass spectrometric analysis requires that atoms from the sample be ionized in the gas phase. Secondary ion mass spectrometry achieves this by sputtering samples with an energetic primary ion beam. Several investigations of the sputtering and ionization process have been conducted. Oxygen is commonly used in secondary ion mass spectrometry (SIMS) to increase ion yields, but also can complicate the interpretation of SIMS analyses. An 18O implant in silicon has been used to quantify the oxygen concentration at the surface of sputtered silicon in order to study the dependence on oxygen of several sputtering and depth profile phenomena. The ion yield dependence of trace elements in silicon on the surface oxygen concentration is a function of the ionization potential of the element. The ion yield is high and unaffected by oxygen for elements with low ionization potential and ranges over several orders of magnitude for elements with high ionization potential. Depth resolution in sputter profiles has been shown to be degraded by the presence of oxygen, the mechanism of this effect has been investigated using an 18O implant to quantify oxygen levels and it is shown that the process does not appear to be a consequence of surface oxide formation. Molecular ions are a source of mass interference in SIMS analysis, and multiply charged atomic ion signals might be interference-free due to the possible instability of multiply-charged molecular ions. Sputtered SiH2+, AlH2+, BeH2+, Mo22+ and Mg22+ ions have been observed and appear surprisingly stable. The formation mechanism of some of these species has been explored. / Dissertation/Thesis / Ph.D. Chemistry 2012

Ce travail présente une synthèse des activités de recherche effectuées pendant mon stage post-doctoral à l'Université de Liège (Belgique) et depuis ma nomination en tant que Maître de Conférences à l'Université Lille1. La thèmatique générale est l'application des méthodes de la chimie quantique, essentiellement les techniques d'interactions de configurations et de perturbation, à l'étude des états électroniques excités - notamment avec un rayonnement synchroron - de molécules en phase gazeuse. Dans certains cas, la structure vibrationnelle a aussi été modélisée. Ces travaux se caractérisent par une forte interaction avec des groupes d'expérimentateurs européens (Danemark, Belgique, France, Grande-Bretagne, Serbie), en particulier dans le cadre des programmes européens "RADAM" (Radiation Damage in Biomolecular Systems) et "EIPAM" (Electron Induced Processing At the Molecular Level). Ils s'articulent en trois thèmes : a) Structure et fragmentation de molécules doublement ionisées (dications) Les dications sont métastables avant que la répulsion coulombienne ne les dissocie. Dans les cas de C2H2++ et CH3Cl++, les calculs expliquent quantitativement la présence des fragments observés, en particulier la paire C+/CH2+ provenant d'une isomérisation préalable de C2H2++. b) Spectroscopie en couches de valence (UV et ionisation) Que ce soit pour des molécules d'intérêt atmosphérique (c-C4F8, c-C5F8) ou biologique (tétrahydrofurane, isoprène, limonène, acides gras), la taille du système ne permet pas l'usage des méthodes multiconfigurationnelles. Les seules alternatives sont la fonctionnelle de densité (TD-DFT) ou les techniques "Coupled Cluster". c) Spectroscopie en couches internes Du fait de la nature très excitée des états à calculer, les techniques standard ne sont pas applicables. Nous avons mis au point un protocole qui permet de calculer les spectres en couche K d'atomes légers (C, N, O) avec une excellente précision, y compris pour les états doublement excités. Cela nous a permis d'interpréter ou de ré-interpréter les spectres de molécules organiques telles que des dérivés du benzène (azobenzènes), des furanes, du cyclopropane et plus récemment des acides acétique et propynoïque. Nous envisageons d'appliquer cette méthode à des complexes d'actinides (par exemple UCl62-) au seuil 1s du chlore.

The synthesis of a rigid 4,5-bis(triphenylphosphinimino)-2,7-di-tert-butyl-9,9-dimethylxanthene (Ph3PN)2XT (1) ligand is outlined, along with a modified synthesis for previously reported 1,8-bis(triphenylphosphinimino)naphthalene (Ph3PN)2NAP (3). Reaction of neutral (Ph3PN)2XT with [Y(CH2SiMe3)3(THF)2] resulted in double cyclometallation, yielding the base-free monoalkyl complex, [({Ph2(C6H4)PN}2XT)Y(CH2SiMe3)] (2). Layering a concentrated THF solution of 2 with hexanes at −28 °C afforded THF-coordinated [({Ph2(C6H4)PN}2XT) Y(CH2SiMe3)(THF)]·2THF (2-THF·2THF), with a distorted pentagonal bipyramidal geometry and approximately meridional coordination of the pentadentate {Ph2(C6H4)PN}2XT dianion. Similarly, (Ph3PN)2NAP reacted with [Y(CH2SiMe3)3(THF)2] to afford a THF-coordinated monoalkyl complex, [{(Ph2(C6H4)PN)2NAP}Y(CH2SiMe3)(THF)] (4-THF). Layering a DME solution of 4-THF with hexanes at −28 °C afforded X-ray quality crystals of [{(Ph2(C6H4)PN)2NAP}Y(CH2SiMe3)(κ2-DME)]·hexane (4-DME·hexane), with a highly distorted pentagonal bipyramidal geometry and a facial coordination mode of the tetradentate {Ph2(C6H4)PN}2NAP dianion The synthesis of a rigid 4,5-bis(1,3-diisopropylimidazol-2-imine)-2,7,9,9-tetramethylacridan H(AII2) ligand (5) was achieved via a Buchwald-Hartwig cross-coupling reaction. Reaction of the proligand H(AII2) with [M(CH2SiMe3)3(THF)2] (M = Y(6), Sc(8)) yielded the base free dialkyl complexes [(AII2)Y(CH2SiMe3)2] (6) and [(AII2)Sc(CH2SiMe3)2] (8). The reaction of 6 with one equivalent of [CPh3][B(C6F5)4] yielded [(AII2)Y(CH2SiMe3)][B(C6F5)4] (7) in-situ. Complex 7 proved to be a potent intramolecular hydroamination catalyst for a variety of aminoalkane substrates. The attempted synthesis of 4,5-bis(1,3-diisopropylimidazol-2-imine)-2,7-di-tert-butyl-9,9-dimethylxanthene (XII2) via the Staudinger reaction resulted in the isolation of the triazene intermediate 4,5-bis(1,3-diisopropylimidazol-2-yliedene{triazene})-2,7-di-tert-butyl-9,9-dimethylxanthene XIA2 (9). Reaction of XIA2 with one equivalent of [Y(CH2SiMe3)3(THF)2] led to the isolation of [(XIA2)Y(CH2SiMe3)3] (10). Synthesis of XII2 (11) was achieved via a Buchwald-Hartwig cross-coupling reaction. Reaction of XII2 with one equivalent of YCl3(THF)3.5 resulted in the isolation of [(XII2)YCl3] (12). In contrast, the reaction of XII2 with one equivalent of [Y(CH2SiMe3)3(THF)2] led to several unidentified products. Reaction of XII2 with 1 equivalent of [H(Et2O)2][B(C6F5)4] led to the isolation of the precursor [H(XII)2][B(C6F5)4] (13). The reaction of 13 with 1.1 equivalents of [M(CH2SiMe3)3(THF)2] (M = {Y(14), Sc(15)} led to the isolation of the monocationic [(XII)2M(CH2SiMe3)2][B(C6F5)4] complexes. The reaction of [(XII)2Sc(CH2SiMe3)2][B(C6F5)4] with 1.1 equivalents of B(C6F5)3 led to the abstraction of a methyl anion from the silicon center, with concomitant migration of the remaining alkyl group to the positively charged silicon, forming a new CH2SiMe2CH2SiMe3 alkyl group. This process is accompanied by MeB(C6F5)3 anion formation, forming a contact ion pair to afford the dicationic species [(XII)2Sc(CH2SiMe3)][MeB(C6F5)3][B(C6F5)4] 16. In contrast, the reaction of 15 with 1.3 equivalents of [CPh3][B(C6F5)4] in the presence of 5 equivalents of toluene resulted in the synthesis of [(XII)2Sc(CH2SiMe3)(ɳx-toluene)][B(C6F5)4]2 17 in-situ. Complex 17 is a highly potent ethylene polymerization catalyst with an activity of 868 kg/mol·atm·h. The reaction of 15 with [HNMe2Ph][B(C6F5)4] led to the cyclometallation of the resulting NMe2Ph byproduct to yield [(XII2)Sc(C6H4NMe2)][B(C6F5)4]2 (18) in-situ. The synthesis of a rigid, asymmetric 4-(1,3-diisopropylimidazol-2-imine)-5-(2,6-diisopropylanilido)- 2,7-di-tert-butyl-9,9-dimethylxanthene XAI (19) ligand was achieved by a two step Buchwald-Hartwig cross-coupling reaction with initial cross coupling of 1,3-diisopropylimidazol-2-imine followed by the cross-coupling of 2,6-diisoproylaniline. The reaction of XAI with 1.1 equivalents of [Y(CH2SiMe3)3(THF)2] yielded [(XAI)Y(CH2SiMe3)2] (20). Subsequent reaction of [(XAI)Y(CH2SiMe3)2] with 1 equivalent of [CPh3][B(C6F5)4] in the presence of 10 equivalents of toluene resulted in the synthesis of the toluene coordinated [(XAI)Y(CH2SiMe3)(ɳx-toluene)][B(C6F5)4] (21) complex. Similar to 7, complex 21 was highly active for intramolecular hydroamination of various substrates. / Dissertation / Doctor of Philosophy (PhD) / Cationic group 3 alkyl complexes are underreported in comparison to analogous group 4 complexes. The scarcity of these complexes can be attributed to their propensity to engage in undesirable reactions such as ligand redistribution and cyclometallation. To increase the thermal stability of such complexes, design features, such as carefully positioned steric bulk and ligand rigidity are beneficial. Additionally, such ligands must also have considerable donor ability, in order to stabilize inherently electron deficient cationic metal centers. This work details the synthesis of a variety of neutral and monoanionic ligands that incorporate the aforementioned design features, which were utilized in the successful synthesis of a variety of neutral, monocationic and extremely rare dicationic group 3 alkyl complexes. The cationic monoalkyl complex in this work proved to be a highly potent intramolecular hydroamination catalyst. Furthermore, a rare dicationic scandium complex was highly active for ethylene polymerization