Cette thèse porte sur la synthèse de composés d'Au(III) et de Cu(III) ainsi que sur l'étude de leur stabilité et de leur réactivité vis-à-vis de substrats p. Une approche conjointe expérimentale et théorique a été exploitée afin d'accéder à des complexes capables d'induire des processus d'insertion migratoire. Le premier chapitre aborde de manière globale la chimie organométallique de l'or et du cuivre sur le plan bibliographique. L'importance du degré d'oxydation +III est mis en évidence par la description des principaux exemples ayant contribué à la compréhension des processus associés à l'accès et la réactivité des complexes d'Au(III) et de Cu(III). Le second chapitre traite de la synthèse de deux complexes p-arènes d'Au(III) par insertion migratoire d'oléfines dans la liaison Au-C(sp)2 d'un composé (P,C) cyclométallé. Les interactions entre les systèmes aromatiques et l'or ont été mises en évidence par RMN, DFT et DRX pour un des complexes. Sur la base de cette réactivité, un processus d'arylation directe de l'éthylène a été mis en évidence. Le chapitre trois a pour objet la mise au point d'une réaction d'hydroarylation intermoléculaire d'alcynes catalysée par des complexes de type [(P,C)Au(III)(OAcF)2]. Ces derniers se sont avérés très actifs et robustes en présence d'acide trifluoroacétique. La réaction a pu être généralisée à un large panel de substrats et une étude comparative, notamment avec des complexes (N,C) cyclométallés, a mis en évidence la supériorité des complexes (P,C) pour l'hydroarylation des alcynes. Le quatrième chapitre expose la stratégie envisagée pour le développer d'un processus d'oligomérisation de l'éthylène catalysé par le cuivre. Une approche prédictive basée sur les calculs DFT a permis de mettre en évidence des insertions migratoires plus aisées dans les liaisons Cu(III)-C que dans les Cu(I)-C. Deux stratégies d'accès aux complexes de Cu(III) par addition oxydante de liaisons C-I sur des précurseurs de Cu(I) ont été évaluées théoriquement. Les calculs les plus favorables ont orienté le choix des modèles de ligands envisagés dans les chapitres cinq et six. Le cinquième chapitre aborde l'étude expérimentale associée à la première stratégie d'accès au Cu(III) : l'addition oxydante intramoléculaire dirigée par des ligands naphthylphosphine et naphthylamine peri-iodées. [...] / The present work deals with the synthesis of Au(III) and Cu(III) compounds and the study of their stability and reactivity toward p substrates. An experimental and theoretical approach has been used in order to access complexes capable of undergoing migratory insertion processes. The first chapter delivers a bibliographic overview of the organometallic chemistry of gold and copper. The importance of the high oxidation state +III is highlighted by the description of important examples having contributed to the understanding of processes associated to the access and reactivity of Au(III) and Cu(III) complexes. The second chapter describes the synthesis of two p-arene Au(III) complexes by migratory insertion of olefins in the Au-C(sp)2 bond of a (P,C) cyclometallated complex. Interactions between the metallic center and the aromatic systems have been characterized by NMR, DFT and XRD for one of the complexes. Based on this insertion reactivity, a process of direct arylation of ethylene has been evidenced. The third chapter concerns the development of an intermolecular hydroarylation of alkynes process, catalyzed by [(P,C)Au(III)(OAcF)2] complexes. These have shown great activity and robustness in presence of trifluoroacetic acid. The reaction has been generalized to a broad substrate scope and a comparative study has been carried on, especially with (N,C) cyclometallated complexes, showing the superiority of (P,C) complexes for the hydroarylation of alkynes. The fourth chapter presents the envisioned strategy to develop a copper-catalyzed oligomerization of ethylene process. A predictive approach based on DFT calculations permitted to evidence easier migratory insertions in the Cu(III)-C bond than in the Cu(I)-C bond. Two strategies for the access to Cu(III) species have been theoretically evaluated. The most favourable calculations have oriented the choice of ligand models used in chapters five and six. The fifth chapter deals with the experimental study related to the first strategy of access to Cu(III) species: the directed intramolecular oxidative addition by peri-iodo napthylphosphine and naphthylamine ligands. [...]

Se describe la síntesis de una serie de complejos de Pd(II) con ligandos arilo que contienen en orto los grupos vinilo (CH=CH2), formilo (CHO), acetilo (C(O)Me) y nitrilo (CN), sin sustituyentes adicionales, y se estudia su reactividad frente a moléculas insaturadas: alquinos, isocianuros y monóxido de carbono. De esta forma se obtienen compuestos orgánicos de interés, difíciles de preparar por otros métodos. La tesis contiene un capitulo dedicado a la investigación mediante Resonancia Magnética Nuclear del enlace C-Pd en estos complejos. El último capítulo describe la síntesis del primer ligando pincer derivado del ferroceno, para su uso en catalisis homogénea. / The synthesis of a series of Pd(II) aryl complexes with vinyl (CH=CH2), formyl (CHO), acetyl (C(O)Me) and nitrile (CN) groups in ortho, is described. The reactivity of these complexes towards unsaturated molecules: alkynes, isocyanides and carbon monoxide, is investigated. The formation of interesting and otherwise difficult to obtain organic compounds is described. A chapter is dedicated to the investigation of the C-Pd bond in some of these complexes using Nuclear Magnetic Resonance. The last chapter describes the synthesis of the first ferrocene-derived pincer ligand, of interest in homogeneous catalysis.

The synthesis and reaction chemistry of trans-(PPh3)2Pd(C6H4-4-I)(X) (X = I, OTf) is discussed. Treatment of trans- (PPh3)2Pd(C6H4- 4-I)(OTf) with bidentate Lewis-bases (N)N), such as pz, bipy, C5H4N-4-CN, (C6H4-4-CN)2 or C6H4-1,4-CN produces, depending on N)N, mono- or bimetallic species of type [trans- (PPh3)2Pd(C6H4-4-I)(N)N)]+ or [trans-(Ph3P)2(C6H4- 4-I)Pd N)N Pd- (PPh3)2(C6H4-4-I)]2+. These new complexes rearrange in the solution to give [trans-[(Ph3P)2Pd(C6H4-4-PPh3)(N)N)]2+ (N)N = C4H4N2, C5H4N-4-CN, NaC-4-C5H4N) and [trans-[(Ph3P)2(C6H4-4-PPh3)- Pd N)N Pd(PPh3)2(C6H4-4-PPh3)]4+ (N)N = C6H4-1,4-(CN)2, (C6H4-4- CN)2) along with {[(Ph3P)2(Ph3P-4-C6H4)Pd -(µ-I)]2}2+. The mechanism is elucidated. The latter species are rigid-rod structured. The preparation of mono- and homo-bimetallic palladium complexes of type [(Me(O)CS-4-C6H4)(PPh3)2Pd -(N)N)]+ and {[(Me- (O)CS-4-C6H4)(PPh3)2Pd]2(N)N)} 2+ (N)N = pz, bipy, C5H4N-4-CN, (C6H4-4-CN)2, C6H4-1,4-CN) is reported. The formation of the mono- or bimetallic species depends on the size of the Lewis bases N)N. The use of these molecules as molecular wire is discussed. The synthesis of homo-bimetallic palladium molecular wire complexes of type {[(Me(O)CS-4-C6H4-C6H4)(PPh3)2Pd]2(N)N)}2+ is described. The structural aspects of these complexes in the solid-state by single X-ray crystallography is discussed. The synthesis, characterization and electrochemical properties of a new series of homo-bimetallic palladium and platinum complexes of type [Me(O)CS-NCN-M]2(N)N) (NCN = [C6H2(CH2NMe2)2- 2,6)]-) is described. The effect of the para-substituent of the functionalized thio-acetyl NCN ligand on the electrochemical properties of the incorporated platinum center is discussed. The selective synthesis of acetylene and acyl-thiol endcapped heterobimetallic organometallic pi-tweezer of type {[Ti](µ-sigma,pi-CCR)2}CuS-C6H4-4-R ([Ti] = (eta5-C5H4SiMe3)2Ti; R = SiMe3; R = CCH,R = SC(O)Me) succeeds by the reaction of {[Ti](CCR)2}CuCH3 with equimolar amounts of Me(O)CSC6H4-4-CCH or the dithiol C6H4-1,4-(SC(O)Me)2. Binuclear (µ-RSe)(µ sigma,pi CCPh)Fe2(CO)6 can be prepared by treatment of RSe-CCPh (R = Et, nBu, Ph, 2,4,6-Me3C6H2) with Fe2(CO)9 in tetrahydrofuran at room temperature. In solution two isomers exist, depending on the position of the lone-pair of electrons present at selenium (axial or equatorial, respectively). Nucleophilic addition of P(OiC3H7)3 to (µ-RSe)- (µ -sigma,pi CCPh)Fe2(CO)6 affords vinylidene- and dimetallacylobutene- bridged complexes Fe2(CO)6(µ-Se(2,4,6-Me3C6H2)(µ-eta1C=C(Ph)- (P(OiC3H7)3) and [Fe2(CO)6(µ-Se(2,4,6-Me3C6H2)-(µ -eta1:eta1(Ph)C=C- {P(OiC3H7)3). The isolated complexes were characterized by multinuclear NMR (1H, 13C{1H}, and 31P{1H}, elemental analysis, FT-IR, and single x-ray crystallography. / Ein Ziel der Arbeit war die Synthese von trans-(PPh3)2Pd(C6H4-4-I)(X) (X = I, OTf) und Untersuchungen zu dessen Reaktionsverhalten. Die Zugabe von zweizähnigen Lewis-Basen (N)N), wie z.B. pz, pz, bipy, C5H4N-4-CN, (C6H4-4-CN)2 oder C6H4-1,4-CN ergibt, abhängig von (N)N), mono- oder bimetallische Spezies vom Typ [trans-(PPh3)2Pd(C6H4-4-I)(N)N)]+ oder [trans-(Ph3P)2(C6H4-4-I)Pd N)N Pd-(PPh3)2(C6H4-4-I)]2+. Diese in Lösung instabilen Komplexe reagieren weiter zu [trans-[(Ph3P)2Pd(C6H4-4-PPh3)(N)N)]2+ (N)N = C4H4N2, C5H4N- 4-CN, NC-4-C5H4N) oder [trans-[(Ph3P)2(C6H4-4-PPh3)Pd N)N Pd(PPh3)2-(C6H4-4- PPh3)]4+ (N)N = C6H4-1,4-(CN)2, (C6H4-4-CN)2) zusammen mit {[(Ph3P)2(Ph3P-4- C6H4)Pd(µ-I)]2}2+. Der Mechanismus dieser Reaktionsfolge wurde aufgeklärt. Diese Komplexe besitzen eine starre, lineare Struktur, welche unter anderem mittels Röntgeneinkristallstrukturanalyse ermittelt wurde. Weiterhin wird über die Darstellung von mono- und homobimetallischen Palladium-Komplexen vom Typ [(Me(O)CS-4-C6H4)(PPh3)2Pd(N)N)]+ und {[(Me- (O)CS-4-C6H4)(PPh3)2Pd]2(N)N)}2+ (N)N = pz, bipy, C5H4N-4-CN, (C6H4-4-CN)2, C6H4-1,4-CN) berichtet. Die Bildung von homo- oder bimetallischen Spezies hängt von der Größe der Lewis-Base N)N ab. Die Anwendung dieser Moleküle als molekulare Drähte wird, zusammen mit der Festkörperstruktur zweier dieser Komplexe, diskutiert. Die Synthese von homobimetallischen Pd Komplexen vom Typ {[(Me(O)CS-4- C6H4-C6H4)(PPh3)2Pd]2(N)N)}2+ (molekulare Drähte) wird beschrieben. Die strukturellen Aspekte dieser Komplexe im festen Zustand werden diskutiert Die Synthese, Charakterisierung und elektrochemischen Eigenschaften einer neuen Serie von homobimetallischen Pd und Pt Komplexen vom Typ [Me(O)CSNCN- M]2(N)N) (NCN = [C6H2(CH2NMe2)2-2,6)]-) wird beschrieben. Der Effekt des para-Substituenten der funktionalisierten Thioacetyl-NCN Liganden auf die elektrochemischen Eigenschaften des komplexierten Pt wird diskutiert. Die selektive Synthese von Alkinyl- und Thioacetyl-funkionalisierten heterobimetallischen metallorganischen pi-Pinzetten-Komplexen vom Typ {[Ti](µ-sigma,pi-CCR)2}CuS-C6H4-4-CCH und {[Ti](µ-sigma,pi-CCR)2}CuS-C6H4-4-SC(O)Me ([Ti] = (eta5-C5H4SiMe3)2Ti; R = SiMe3, R = tBu) erfolgt durch die Reaktion von {[Ti](CCR)2}CuCH3 (R = SiMe3, R = tBu) mit äquimolaren Mengen an Me(O)CS-1- C6H4-4-CCH oder des Dithiols C6H4-1,4-(SC(O)Me)2. Im Vorgang dieser Reaktion wird Aceton gebildet. Zweikernige (µ-RSe)(µ sigma,pi CCPh)Fe2(CO)6 Komplexe können durch die Umsetzung von RSe-CCPh (R = Et, nBu, Ph, 2,4,6-Me3C6H2) mit Fe2(CO)9 in Tetrahydrofuran bei 20 °C dargestellt werden. In Lösung liegen, in Abhängigkeit von der Position des freien Elektronenpaares am Selen (axial oder äquatorial), zwei Isomere vor. Addition von P(OiC3H7)3 zu (µ-RSe)(µ sigma,pi CCPh)Fe2-(CO)6 ergibt Vinyliden- Fe2(CO)6(µ-Se(2,4,6-Me3C6H2)-(µ-eta1 C=C-(Ph)(P(OiC3H7)3) und Dimetallacyclobuten- verbrückte Komplexe der Art [Fe2(CO)6(µ-Se(2,4,6-Me3C6H2)-(µ-eta1:eta1- (Ph)C=C{P(OiC3H7)3). Die isolierten Komplexe wurden durch die Elementaranalyse, spektroskopisch (1H, 13C{1H}, 31P{1H} NMR; IR) und die Röntgeneinkristallstrukturanalyse charakterisiert.

Ce travail de thèse porte sur la chimie organométallique des complexes d'or(I) et sur l'étude de leurs réactivités. Plus particulièrement, le travail présenté ici dans ce manuscrit avait pour objectif d'approfondir nos connaissances sur l'impact des ligands utilisés sur la réactivité de l'or vis-à-vis (i) de l'addition oxydante intermoléculaire et (ii) la possibilité de stabiliser des intermédiaires d'or(I) hautement réactifs. Dans la première partie de ce manuscrit, l'addition oxydante intermoléculaire des halogénures d'aryle (iodure et bromure) à des complexes moléculaires d'or(I) a été étudiée en détails. Nous avons pu montrer que cette étape élémentaire de la chimie organométallique, considéré comme impossible avec l'or, était en fait un processus favorable lorsqu'un ligand adéquat est employé, et deux stratégies différentes ont été élaborées. La première consiste à utiliser un ligand bis-phosphine bidenté qui impose une géométrie coudée autour de l'or, tandis que la deuxième stratégie implique l'utilisation d'un ligand hémi-labile bidenté avec des groupements donneurs doux et dur. Les deux stratégies ont été fructueuses, et les complexes d'or(III) issus des réactions d'addition oxydante ont été caractérisés spectroscopiquement et structuralement. Dans la deuxième partie, ayant à notre disposition deux complexes d'or(I) capable d'effectuer l'addition oxydante, nous voulions aller au-delà de cette étape élémentaire. Dans cet objectif, nous avons construit un nouveau cycle catalytique Au(I)/Au(III) impliquant une séquence d'addition oxydante Csp2-X, de Csp2-H auration et d'élimination réductrice, illustrant le premier exemple d'arylation directe d'arènes avec des halogénures d'aryle catalysée à l'or. Enfin, dans la dernière partie, nous avons tenté de stabiliser et de caractériser des intermédiaires d'or(I) très instables, comme le a-oxo carbène d'or(I). Cette espèce hautement électrophile est proposée comme un intermédiaire clés dans des nombreuses transformations catalytiques, mais n'a jamais été isolé ou caractérisé (en solution ou à l'état solide). L'utilisation d'un ligand bis-phosphine bidenté nous a permis de caractériser spectroscopiquement et structuralement le carbène a-oxo d'or(I) pour la première fois. Nous avons ensuite étudié sa réactivité vis-à-vis des réactions d'insertion et de cyclopropanation. / The present work is an organometallic study concerning the chemistry of gold(I) complexes and their reactivity. Of particular interest was to gain further knowledge on the impact of the ligands employed on the reactivity of gold towards (i) the intermolecular oxidative addition of aryl halides and (ii) the possibility of stabilizing high reactive gold(I) intermediates. In the first part of the manuscript, the intermolecular oxidative addition of aryl halides (iodide and bromide) with molecular gold(I) complexes was investigated in detail. We showed that this organometallic elementary step, usually considered to be impossible for gold, is actually a favorable process when an adequate ligand is employed and two different strategies have been elaborated. The first one consists in the use of a bis-phosphine bidentate ligand that forces a bent geometry around gold, whereas the second strategy implicates the use of a hemi-labile bidentate ligand bearing a soft and a hard donor group. Both strategies were found fruitful, and the gold(III) complexes stemming from oxidative addition reactions were characterized by spectroscopic and structural means. In the second part, having in hands two gold(I) complexes that undergo the oxidative addition reaction, we wanted to go beyond this elementary step. In that objective, we constructed a new Au(I)/Au(III) catalytic cycle involving a sequence of Csp2-X oxidative addition, Csp2-H auration and reductive elimination, allowing the first example of gold-catalyzed direct arylation of arenes with aryl halides. Finally, in the last part, we attempted to stabilize and characterize high reactive gold(I) intermediates, like the a-oxo gold(I) carbenes. This electrophilic species is proposed in many catalytic transformations as key intermediates, but has never been isolated or characterized (in solution or in solid state). The use of a bidentate diphosphine ligand allowed the characterization of the a-oxo gold(I) carbene for the first time by means of multinuclear NMR spectroscopy, X-ray diffraction analysis and high resolution mass spectroscopy (ESI+). We then investigated the reactivity of the a-oxo gold(I) carbene towards insertion and cyclopropanation reactions. Interestingly, the reactivity of the generated gold(I) carbenes can be modulated depending on the electronic properties of the aryl ethyl diazoacetate used.

This thesis examines the interaction of hydrides of the group 13 metals aluminium and gallium with transition metal centres. Furthermore, a gallium-based system is developed which activates a wide range of E-H bonds, with the product of H₂ activation found to act as a catalyst for the reduction of CO₂ to a methanol derivative. Chapter 3 details the synthesis of a number of alane and gallane adducts of expanded-ring N-heterocyclic carbene (NHC) ligands, which are more strongly σ-donating and sterically shielding analogues of classical NHCs. These NHC adducts are found to be apposite for the formation of σ-alane and σ-gallane complexes at group 6 metal carbonyl fragments, which has allowed the characterisation of the first κ² σ-gallane complexes. The attempted formation of a terminally coordinated κ³ σ-alane complex leads instead to the isolation of a novel dinuclear cluster featuring both μ:κ¹,κ¹ and μ:κ²,κ² coordination to Mo(CO)₃ units. The work presented in Chapter 4 probes the interaction of the β-diketiminate stabilised gallane Dipp₂NacNacGaH₂ with transition metal carbonyls. Far from simply mimicking the chemistry of the alane congener Dipp₂NacNacAlH₂, which forms simple κ¹ and κ² σ-alane complexes, the gallane shows a marked propensity towards dehydrogenation and formation of direct M-Ga(I) bonds. This represents a rare mode of reactivity among group 13 hydrides, being unprecedented beyond boron chemistry, and provides a new route to M-Ga bond formation. Experimental and computational investigations of the mechanism suggest that initial Ga-H oxidative addition is facile, and is generally followed by rate-limiting loss of H₂. The reaction of Dipp2NacNacAlH2 with Co₂(CO)₂ is shown to yield an unusual alane complex which displays an unprecedented degree of Al-H activation in a σ-alane complex. Chapter 5 represents an extension of the work described in Chapter 5, investigating the interaction of Dipp₂NacNacMH₂ (M = Al, Ga) with cationic group 9 transition metal fragments supported by ancillary phosphine ligands. While attempts to isolate unsupported, cationic σ-alane complexes prove unsuccessful, Dipp₂NacNacGaH₂ readily binds to cationic rhodium and iridium centres, forming the first cationic σ-gallane complexes as well as cationic gallylene complexes resulting from complete Ga-H oxidative addition. The extent of Ga-H bond activation is shown to be markedly dependent on the nature of the phosphine co-ligands. In particular, a series of rhodium complexes is reported which represents snapshots of the oxidative addition process, from a Rh(I) σ-gallane complex to a Rh(III) gallylene dihydride, with two further complexes which are on the cusp of these two oxidation states. Described in Chapter 6 are the synthesis and reactivity studies of an ambiphilic system, Dipp₂NacNac′Ga(^tBu), featuring a three-coordinate gallium centre supported by a deprotonated NacNac ligand. The combination of this electrophilic gallium centre with the highly nucleophilic exocyclic alkene functionality facilitates the cooperative activation of protic, hydridic and apolar E-H bonds. Accordingly, molecules including H₂, NH₃, H₂S and SiH4 may be cleaved under mild conditions. Moreover, the hydride product of H₂ activation is shown to be a competent catalyst in conjunction with HBpin for the reduction of CO₂ to the methanol derivative MeOBpin.

Des ligands hydrides potentiellement bidentes (possédant un donneur N-hétérocyclique (NHC) associé à un groupement donneur éther ou amine) ainsi que des ligands tritopiques de type pinceur (possédant un groupement (NHC) flanqué de deux types de donneurs azotés différents Nimine et Namine) ont été préparés et utilisés pour la coordination de métaux de transition tels que le Ni, Cr, Cu et Ir. L’influence de la longueur de la chaine alkylée -(CH2)2- ou -(CH2)3- reliant le groupe éther ou amine au groupe hétérocyclique (NHC) a été examinée. Dans le but d’accéder aux complexes des métaux de transition différentes méthodologies ont été adoptées : a) déprotonation préalable du sel d’imidazolium suivie de l’addition des précurseurs métalliques correspondants ; b) transmétallation à partir des complexes (NHC) de l’argent correspondants ; c) réaction d’addition oxydante des sels d’imidazolium ou de leurs sels protonés avec du Ni(0). Une série de complexes du Ni(II) et du Cr(III) a été testée dans la réaction catalytique d’oligomérisation de l’éthylène. / Potentially bidentate hybrid ligands (containing a NHC donor associated with an ether or an amine) and tridentate NCN pincer-type ligands (containing a central NHC donor flancked by two chemically-different nitrogen donors (Nimine and Namine)) have been prepared and used for coordination to transition metals, such as Ni, Cr, Cu, Ir. The influence of the length of the alkyl chain, -(CH2)2- or -(CH2)3- connecting the ether or the amine group to the heterocycle NHC was examined. In order to have access to the transition metal complexes, several methodologies were adopted: a) deprotonation of the corresponding imidazolium salts followed by addition of transition metal precursors; b) transmetalation from NHC silver complexes; c) oxidative-addition reaction of Ni(0) with imidazolium salts or the corresponding protonated salts. A series of Ni(II), Cr(III) complexes were tested in the catalytic ethylene oligomerization reaction.

The synthesis and reaction chemistry of trans-(PPh3)2Pd(C6H4-4-I)(X) (X = I, OTf) is discussed. Treatment of trans- (PPh3)2Pd(C6H4- 4-I)(OTf) with bidentate Lewis-bases (N)N), such as pz, bipy, C5H4N-4-CN, (C6H4-4-CN)2 or C6H4-1,4-CN produces, depending on N)N, mono- or bimetallic species of type [trans- (PPh3)2Pd(C6H4-4-I)(N)N)]+ or [trans-(Ph3P)2(C6H4- 4-I)Pd N)N Pd- (PPh3)2(C6H4-4-I)]2+. These new complexes rearrange in the solution to give [trans-[(Ph3P)2Pd(C6H4-4-PPh3)(N)N)]2+ (N)N = C4H4N2, C5H4N-4-CN, NaC-4-C5H4N) and [trans-[(Ph3P)2(C6H4-4-PPh3)- Pd N)N Pd(PPh3)2(C6H4-4-PPh3)]4+ (N)N = C6H4-1,4-(CN)2, (C6H4-4- CN)2) along with {[(Ph3P)2(Ph3P-4-C6H4)Pd -(µ-I)]2}2+. The mechanism is elucidated. The latter species are rigid-rod structured. The preparation of mono- and homo-bimetallic palladium complexes of type [(Me(O)CS-4-C6H4)(PPh3)2Pd -(N)N)]+ and {[(Me- (O)CS-4-C6H4)(PPh3)2Pd]2(N)N)} 2+ (N)N = pz, bipy, C5H4N-4-CN, (C6H4-4-CN)2, C6H4-1,4-CN) is reported. The formation of the mono- or bimetallic species depends on the size of the Lewis bases N)N. The use of these molecules as molecular wire is discussed. The synthesis of homo-bimetallic palladium molecular wire complexes of type {[(Me(O)CS-4-C6H4-C6H4)(PPh3)2Pd]2(N)N)}2+ is described. The structural aspects of these complexes in the solid-state by single X-ray crystallography is discussed. The synthesis, characterization and electrochemical properties of a new series of homo-bimetallic palladium and platinum complexes of type [Me(O)CS-NCN-M]2(N)N) (NCN = [C6H2(CH2NMe2)2- 2,6)]-) is described. The effect of the para-substituent of the functionalized thio-acetyl NCN ligand on the electrochemical properties of the incorporated platinum center is discussed. The selective synthesis of acetylene and acyl-thiol endcapped heterobimetallic organometallic pi-tweezer of type {[Ti](µ-sigma,pi-CCR)2}CuS-C6H4-4-R ([Ti] = (eta5-C5H4SiMe3)2Ti; R = SiMe3; R = CCH,R = SC(O)Me) succeeds by the reaction of {[Ti](CCR)2}CuCH3 with equimolar amounts of Me(O)CSC6H4-4-CCH or the dithiol C6H4-1,4-(SC(O)Me)2. Binuclear (µ-RSe)(µ sigma,pi CCPh)Fe2(CO)6 can be prepared by treatment of RSe-CCPh (R = Et, nBu, Ph, 2,4,6-Me3C6H2) with Fe2(CO)9 in tetrahydrofuran at room temperature. In solution two isomers exist, depending on the position of the lone-pair of electrons present at selenium (axial or equatorial, respectively). Nucleophilic addition of P(OiC3H7)3 to (µ-RSe)- (µ -sigma,pi CCPh)Fe2(CO)6 affords vinylidene- and dimetallacylobutene- bridged complexes Fe2(CO)6(µ-Se(2,4,6-Me3C6H2)(µ-eta1C=C(Ph)- (P(OiC3H7)3) and [Fe2(CO)6(µ-Se(2,4,6-Me3C6H2)-(µ -eta1:eta1(Ph)C=C- {P(OiC3H7)3). The isolated complexes were characterized by multinuclear NMR (1H, 13C{1H}, and 31P{1H}, elemental analysis, FT-IR, and single x-ray crystallography. / Ein Ziel der Arbeit war die Synthese von trans-(PPh3)2Pd(C6H4-4-I)(X) (X = I, OTf) und Untersuchungen zu dessen Reaktionsverhalten. Die Zugabe von zweizähnigen Lewis-Basen (N)N), wie z.B. pz, pz, bipy, C5H4N-4-CN, (C6H4-4-CN)2 oder C6H4-1,4-CN ergibt, abhängig von (N)N), mono- oder bimetallische Spezies vom Typ [trans-(PPh3)2Pd(C6H4-4-I)(N)N)]+ oder [trans-(Ph3P)2(C6H4-4-I)Pd N)N Pd-(PPh3)2(C6H4-4-I)]2+. Diese in Lösung instabilen Komplexe reagieren weiter zu [trans-[(Ph3P)2Pd(C6H4-4-PPh3)(N)N)]2+ (N)N = C4H4N2, C5H4N- 4-CN, NC-4-C5H4N) oder [trans-[(Ph3P)2(C6H4-4-PPh3)Pd N)N Pd(PPh3)2-(C6H4-4- PPh3)]4+ (N)N = C6H4-1,4-(CN)2, (C6H4-4-CN)2) zusammen mit {[(Ph3P)2(Ph3P-4- C6H4)Pd(µ-I)]2}2+. Der Mechanismus dieser Reaktionsfolge wurde aufgeklärt. Diese Komplexe besitzen eine starre, lineare Struktur, welche unter anderem mittels Röntgeneinkristallstrukturanalyse ermittelt wurde. Weiterhin wird über die Darstellung von mono- und homobimetallischen Palladium-Komplexen vom Typ [(Me(O)CS-4-C6H4)(PPh3)2Pd(N)N)]+ und {[(Me- (O)CS-4-C6H4)(PPh3)2Pd]2(N)N)}2+ (N)N = pz, bipy, C5H4N-4-CN, (C6H4-4-CN)2, C6H4-1,4-CN) berichtet. Die Bildung von homo- oder bimetallischen Spezies hängt von der Größe der Lewis-Base N)N ab. Die Anwendung dieser Moleküle als molekulare Drähte wird, zusammen mit der Festkörperstruktur zweier dieser Komplexe, diskutiert. Die Synthese von homobimetallischen Pd Komplexen vom Typ {[(Me(O)CS-4- C6H4-C6H4)(PPh3)2Pd]2(N)N)}2+ (molekulare Drähte) wird beschrieben. Die strukturellen Aspekte dieser Komplexe im festen Zustand werden diskutiert Die Synthese, Charakterisierung und elektrochemischen Eigenschaften einer neuen Serie von homobimetallischen Pd und Pt Komplexen vom Typ [Me(O)CSNCN- M]2(N)N) (NCN = [C6H2(CH2NMe2)2-2,6)]-) wird beschrieben. Der Effekt des para-Substituenten der funktionalisierten Thioacetyl-NCN Liganden auf die elektrochemischen Eigenschaften des komplexierten Pt wird diskutiert. Die selektive Synthese von Alkinyl- und Thioacetyl-funkionalisierten heterobimetallischen metallorganischen pi-Pinzetten-Komplexen vom Typ {[Ti](µ-sigma,pi-CCR)2}CuS-C6H4-4-CCH und {[Ti](µ-sigma,pi-CCR)2}CuS-C6H4-4-SC(O)Me ([Ti] = (eta5-C5H4SiMe3)2Ti; R = SiMe3, R = tBu) erfolgt durch die Reaktion von {[Ti](CCR)2}CuCH3 (R = SiMe3, R = tBu) mit äquimolaren Mengen an Me(O)CS-1- C6H4-4-CCH oder des Dithiols C6H4-1,4-(SC(O)Me)2. Im Vorgang dieser Reaktion wird Aceton gebildet. Zweikernige (µ-RSe)(µ sigma,pi CCPh)Fe2(CO)6 Komplexe können durch die Umsetzung von RSe-CCPh (R = Et, nBu, Ph, 2,4,6-Me3C6H2) mit Fe2(CO)9 in Tetrahydrofuran bei 20 °C dargestellt werden. In Lösung liegen, in Abhängigkeit von der Position des freien Elektronenpaares am Selen (axial oder äquatorial), zwei Isomere vor. Addition von P(OiC3H7)3 zu (µ-RSe)(µ sigma,pi CCPh)Fe2-(CO)6 ergibt Vinyliden- Fe2(CO)6(µ-Se(2,4,6-Me3C6H2)-(µ-eta1 C=C-(Ph)(P(OiC3H7)3) und Dimetallacyclobuten- verbrückte Komplexe der Art [Fe2(CO)6(µ-Se(2,4,6-Me3C6H2)-(µ-eta1:eta1- (Ph)C=C{P(OiC3H7)3). Die isolierten Komplexe wurden durch die Elementaranalyse, spektroskopisch (1H, 13C{1H}, 31P{1H} NMR; IR) und die Röntgeneinkristallstrukturanalyse charakterisiert.

Ce travail est centré sur la synthèse de complexes du rhodium contenant un ligand azoté et leur mise en œuvre dans la réaction catalytique de carbonylation du méthanol en acide acétique. Dans une première partie, nous nous intéressons à la préparation de complexes neutres de formule générale [RhI2(CO)(L)] (L = amines, imidazoles et pyrazoles) et à quelques homologues chlorés. Ces complexes plans carrés manifestent une réactivité directement liée à l’encombrement stérique du ligand azoté L dans la réaction d’addition oxydante de l’iodomethane suivie de la cis-migration du groupement méthyle pour former l’espèce acétyle. Dans une deuxième partie, les complexes précédents ont été engagés dans des essais catalytiques de carbonylation du méthanol dans les conditions du procédé industriel. Comme il s’est avéré que les complexes neutres se transforment en espèce [RhI2(CO)2]- pour laquelle les contre-cations associés sont constitués du ligand azoté protoné ou methylé, nous avons effectué la préparation et la caractérisation des complexes [HNR3][RhI2(CO)2] ou [MeNR3][RhI2(CO)2]. Par IR, RMN et électrochimie, nous nous sommes intéressés aux phénomènes d’appariement d’ions et nous montrons qu’il s’agit dans le meilleur des cas d’interactions hydrogènes. Celles-ci influent la vitesse de la réaction oxydante de CH3I. Dans la dernière partie, nous avons complété une étude, précédemment initiée au laboratoire, sur le mécanisme, qui dans la dernière étape du cycle catalytique permet de passer de l’espèce acétyle [RhI3(COCH3)(CO)2]- à l’espèce active [RhI2(CO)2]- avec production de l’iodure d’acyle. A l’inverse du concept admis d’élimination réductrice de CH3COI suivie de son hydrolyse immédiate en CH3COOH et HI, nous montrons, avec l’appui de calculs théoriques (DFT) qu’en fait un ligand I- est substitué par un ligand acetate pour conduire à l’espèce [RhI2(OAc)(COCH3)(CO)2]-. L’élimination réductrice produit alors l’anhydride acétique qui est hydrolysé en CH3COOH régénérant [RhI2(CO)2]-. Un tel mécanisme opère en présence d’ions acetate dans les milieux faiblement hydratés visés par l’industriel. / This study focuses on the synthesis and reactivity of rhodium complexes bearing N- containing ligands or counter-cations for the [Rh]-catalyzed methanol carbonylation reaction to produce acetic acid under the industrial Celanese Acid Optimization (AO) process conditions. In a first part, full synthesis and characterization of neutral Rh(I) square planar cis- [RhX(CO)2(L)] (X = Cl or I) complexes have been described, for which L is an N-ligand belonging to the amine, imidazole or pyrazole family. For the [RhI(CO)2(L)] complexes, variable-temperature 13C{1H} NMR spectroscopy has put in evidence a fluxional behavior for the different sized L ligands involved. The rate of this fluxional process reveals to be related to both electronic and steric contributions brought by L to the Rh center. These parameters (mainly steric), supported by single-crystal X-ray analyses in the solid state, also influence significantly the kinetics of the methyl iodide oxidative addition reaction followed by rapid CO migratory insertion, the overall being the rate determining step of the [Rh]-catalyzed methanol carbonylation cycle. In absence of CO, this reaction gives rise to the corresponding neutral Rh(III) acetyl complex, which immediately dimerizes to afford [Rh(μ- I)I(COMe)(CO)(L)]2 complex, for which several X-ray crystal structures have been obtained and studied. In addition, the surprising C-H activation in the case of a tBu-pyrazole ligand giving rise to a cyclometalated Rh dimer is reported. In a second part, the reactivity of the latter neutral Rh(I) [RhI(CO)2(L)] complexes as potential precursors has been investigated by batch experiments for the methanol carbonylation reaction. Mechanistic understanding via VT-HP-NMR experiments enabled to detect mainly anionic Rh(I) [RL][RhI2(CO)2] (R = H or CH3 according to the working conditions) complexes formed by decoordination followed by quaternization of the L ligand. Despite this result, the pyrazole family ligands showed better stability under the harsh process conditions. Thus, it cannot be ruled out that equilibrium between neutral and anionic species co-exist in the reaction medium at high temperatures and that [RL]I salt dissociation occurs, restoring the L ligand into the Rh coordination sphere. At this stage we focused on the anionic Rh(I) complex and prepared a series of [XNR3][RhI2(CO)2] (X = H or CH3) species, which have been fully characterized. Infrared, NMR, conductivity experiments and DFT model calculations together put in evidence ion interactions according to the nature of the ammonium counter-cation. Protonated cations significantly impact on the kinetics of the methyl iodide oxidative addition presumably due to H-interactions with the Rh square plane. The final part deals with the mechanism of the reductive elimination reaction, the last step of the [Rh]-catalyzed methanol carbonylation cycle, which from complex [RhI3(COCH3)(CO)2]-, regenerates [RhI2(CO)2]-. In contrast to the classically admitted mechanism of reductive elimination of CH3COI followed by subsequent hydrolysis to form AcOH and HI, we demonstrate from experimental DFT calculation that substitution of an iodo ligand by an acetate ion occurs to give rise to the [RhI2(OAc)(COCH3)(CO)2]- species. Thus, reductive elimination regenerates [RhI2(CO)2]- and produces acetic anhydride, which after hydrolysis affords two molecules of acetic acid. Such a mechanism operates under process conditions at low water content with a significant amount of acetate ions.

The kinetic and mechanistic features of a new series ofplatinum-thallium cyano compounds containing a direct andunsupported by ligands metal-metal bond have been studied insolution, using standard mix–and–measurespectrophotometric technique and stopped–flow method.These reactions are interpreted as oxidative addition of the cspecies to the square planar Pt(CN)42-complex. Each of these processes was found to befirst-order in Pt(CN)42-, the corresponding TIIIIcomplex and a cyanide ion donating species whichacts as a catalyst. Both di- and trinuclear complexes werestudied, and the kinetically significant thallium complexes intheir formation and the catalytically active cyanide sourcesare as follows: [(CN)5PtTl(CN)3]3-: Tl(CN)4–(alkaline region), Tl(CN)3(slightly acidic region) and CN–; [(CN)5Pt–Tl(CN)]–: Tl(CN)2+and Tl(CN)2+; [(CN)5Pt–Tl–Pt(CN)5]3-: [(CN)5Pt–Tl(CN)]–and HCN. Appropriatemechanisms were postulated for the overall reactions in allcases, which include i) metal–metal bond formation stepand ii) coordination of an axial cyanide ion to the platinumcenter. Two experimentally indistinguishable kinetic modelswere proposed for the formation of the dinuclear complexeswhich are different in the sequence of the two steps. In thecase of the trinuclear complex, experimental evidence isavailable to exclude one of the alternative reaction paths, andit was proven that the metal–metal bond formation precedesthe axial cyanide coordination. The cyanide ligands coordinated to TIIIIin the Pt–Tl complexes could be replacedsuccessfully with aminopolycarboxylates e.g.: mimda2-, nta3-, edta4-. The [(CN)5Pt–Tl(edta)]4-complex, with a direct metal–metal bond hasbeen prepared in solution by two different reactions: a)dissolution of [(CN)5Pt–Tl](s) in an aqueous solution of edta, b)directly from Pt(CN)42-and Tl(edta)(CN)2-. The decomposition reaction is greatlyaccelerated by cyanide and significantly inhibited by edta. Itproceeds through the [(CN)5Pt–Tl(CN)3]3-intermediate. The formation of [(CN)5Pt–Tl(edta)]4-can proceed via two different pathways dependingon the ratio of the cyanide to the edta ligand concentrations.The’direct path’at excess of edta means theformation of intermediate[(CN)4Pt···Tl(CN)(edta)]4-, followed by a release of the cyanide from theTl–centre followed by coordination of a cyanide from thebulk to the Pt–centre of the intermediate. The’indirect path’dominates in the absence of extraedta and the formation of the Pt–Tl bond occours betweenPt(CN)42-and Tl(CN)4–. Homoligand MTl(CN)4(M = TlI, K, Na) and, for the first time, Tl(CN)3species have been synthesized in the solid stateand their structures solved by single crystal X–raydiffraction method. Interesting redox processes have been foundbetween TIIIIand CN–in non–aqueous solution and in Tl2O3-CN–aqueous suspension. In the crystal structureof Tl(CN)3·H2O, the thallium(III) ion has a trigonal bypiramidalcoordination geometry with three cyanides in the trigonalplane, while an oxygen atom of the water molecule and anitrogen atom from a cyanide ligand attached to a neighboringthallium complex, form a linear O–Tl–N fragment.Cyanide ligand bridges thallium units forming an infinitezigzag chain structure. Among the thallium(III) tetracyanocompounds, the isostructural M[Tl(CN)4](M = Tl and K) and Na[Tl(CN)4]·3H2O crystallize in different crystal systems, but thethallium(III) ion has in all cases the same tetrahedralgeometry in the [Tl(CN)4]–unit. Three adducts of mercury(II) (isoelectronic with TIIII) (K2PtHg(CN)6·2H2O, Na2PdHg(CN)6·2H2O and K2NiHg(CN)6·2H2O) have been prepared from Hg(CN)2and square planar transition metal cyanides MII(CN)42-and their structure have been studied by singlecrystal X–ray diffraction, XPS and Raman spectroscopy inthe solid state. The structure of (K2PtHg(CN)6·2H2O consists of strictly linear one dimensional wireswith PtIIand HgIIcenters located alternately, dHg–Pt= 3.460 Å. The structure of Na2PdHg(CN)6·2H2O and K2NiHg(CN)6·2H2O can be considered as double salts, the lack ofhetero–metallophilic interaction between both the HgIIand PdIIatoms, dHg–Pd= 4.92 Å, and HgIIand NiIIatoms, dNi–Pd= 4.60 Å, seems obvious. Electronbinding energy values of the metallic centers measured by XPSshow that there is no electron transfer between the metal ionsin all three adducts. In solution, experimental findingsclearly indicate the lack of metal–metal bond formation inall studied HgII–CN-–MII(CN)42-systems (M = Pt, Pd and Ni). It is in contrary tothe platinum–thallium bonded cyanides. KEYWORDS:metal–metal bond, platinum, thallium,kinetics, mechanism, stopped flow, oxidative addition, cyanocomplexes, edta, redox reaction, metal cyanides, X–raydiffraction, Raman, NMR, mercury, palladium, nickel, onedimensional wire

<p>The kinetic and mechanistic features of a new series ofplatinum-thallium cyano compounds containing a direct andunsupported by ligands metal-metal bond have been studied insolution, using standard mix–and–measurespectrophotometric technique and stopped–flow method.These reactions are interpreted as oxidative addition of the cspecies to the square planar Pt(CN)₄^2-complex. Each of these processes was found to befirst-order in Pt(CN)₄^2-, the corresponding TI^IIIcomplex and a cyanide ion donating species whichacts as a catalyst. Both di- and trinuclear complexes werestudied, and the kinetically significant thallium complexes intheir formation and the catalytically active cyanide sourcesare as follows: [(CN)₅PtTl(CN)₃]^3-: Tl(CN)₄^–(alkaline region), Tl(CN)₃(slightly acidic region) and CN^–; [(CN)₅Pt–Tl(CN)]–: Tl(CN)₂⁺and Tl(CN)₂⁺; [(CN)₅Pt–Tl–Pt(CN)₅]^3-: [(CN)₅Pt–Tl(CN)]–and HCN. Appropriatemechanisms were postulated for the overall reactions in allcases, which include i) metal–metal bond formation stepand ii) coordination of an axial cyanide ion to the platinumcenter. Two experimentally indistinguishable kinetic modelswere proposed for the formation of the dinuclear complexeswhich are different in the sequence of the two steps. In thecase of the trinuclear complex, experimental evidence isavailable to exclude one of the alternative reaction paths, andit was proven that the metal–metal bond formation precedesthe axial cyanide coordination.</p><p>The cyanide ligands coordinated to TI^IIIin the Pt–Tl complexes could be replacedsuccessfully with aminopolycarboxylates e.g.: mimda^2-, nta^3-, edta^4-. The [(CN)₅Pt–Tl(edta)]^4-complex, with a direct metal–metal bond hasbeen prepared in solution by two different reactions: a)dissolution of [(CN)₅Pt–Tl](s) in an aqueous solution of edta, b)directly from Pt(CN)₄^2-and Tl(edta)(CN)^2-. The decomposition reaction is greatlyaccelerated by cyanide and significantly inhibited by edta. Itproceeds through the [(CN)₅Pt–Tl(CN)₃]^3-intermediate. The formation of [(CN)₅Pt–Tl(edta)]^4-can proceed via two different pathways dependingon the ratio of the cyanide to the edta ligand concentrations.The’direct path’at excess of edta means theformation of intermediate[(CN)4Pt···Tl(CN)(edta)]^4-, followed by a release of the cyanide from theTl–centre followed by coordination of a cyanide from thebulk to the Pt–centre of the intermediate. The’indirect path’dominates in the absence of extraedta and the formation of the Pt–Tl bond occours betweenPt(CN)₄^2-and Tl(CN)4^–.</p><p>Homoligand MTl(CN)₄(M = Tl^I, K, Na) and, for the first time, Tl(CN)₃species have been synthesized in the solid stateand their structures solved by single crystal X–raydiffraction method. Interesting redox processes have been foundbetween TI^IIIand CN^–in non–aqueous solution and in Tl₂O₃-CN^–aqueous suspension. In the crystal structureof Tl(CN)₃·H₂O, the thallium(III) ion has a trigonal bypiramidalcoordination geometry with three cyanides in the trigonalplane, while an oxygen atom of the water molecule and anitrogen atom from a cyanide ligand attached to a neighboringthallium complex, form a linear O–Tl–N fragment.Cyanide ligand bridges thallium units forming an infinitezigzag chain structure. Among the thallium(III) tetracyanocompounds, the isostructural M[Tl(CN)₄](M = Tl and K) and Na[Tl(CN)₄]·3H₂O crystallize in different crystal systems, but thethallium(III) ion has in all cases the same tetrahedralgeometry in the [Tl(CN)₄]^–unit.</p><p>Three adducts of mercury(II) (isoelectronic with TI^III) (K₂PtHg(CN)₆·2H₂O, Na₂PdHg(CN)₆·2H₂O and K₂NiHg(CN)₆·2H₂O) have been prepared from Hg(CN)₂and square planar transition metal cyanides M^II(CN)₄^2-and their structure have been studied by singlecrystal X–ray diffraction, XPS and Raman spectroscopy inthe solid state. The structure of (K₂PtHg(CN)₆·2H₂O consists of strictly linear one dimensional wireswith Pt^IIand Hg^IIcenters located alternately, d_Hg–Pt= 3.460 Å. The structure of Na₂PdHg(CN)₆·2H₂O and K₂NiHg(CN)₆·2H₂O can be considered as double salts, the lack ofhetero–metallophilic interaction between both the Hg^IIand Pd^IIatoms, d_Hg–Pd= 4.92 Å, and Hg^IIand Ni^IIatoms, d_Ni–Pd= 4.60 Å, seems obvious. Electronbinding energy values of the metallic centers measured by XPSshow that there is no electron transfer between the metal ionsin all three adducts. In solution, experimental findingsclearly indicate the lack of metal–metal bond formation inall studied Hg^II–CN^-–M^II(CN)4^2-systems (M = Pt, Pd and Ni). It is in contrary tothe platinum–thallium bonded cyanides.</p><p><b>KEYWORDS:</b>metal–metal bond, platinum, thallium,kinetics, mechanism, stopped flow, oxidative addition, cyanocomplexes, edta, redox reaction, metal cyanides, X–raydiffraction, Raman, NMR, mercury, palladium, nickel, onedimensional wire</p>