The iridium(III) methyl dlarylphosphido complexes, Ir(CH₃)(PR₂)-[N(SiMe₂CH₂PPh₂)₂] (2a: R = phenyl, 2b: R = meta-tolyl), have been successfully prepared by transmetalation of the iridium(III) methyl iodide complex, Ir(CH₃)(I)[N(SiMe₂CH₂PPh₂)₂], with the corresponding lithium diarylphosphide. Based primarily on a nuclear Overhauser effect difference experiment, these complexes are assigned a stereochemistry intermediate between square pyramidal and trigonal bipyramidal forms. The pyramidal geometry at the phosphido ligand is evident from the ³¹P{¹H} NMR spectral data. The complex 2a affords a mixture of at least three, as yet uncharacterized complexes when heated to 60°C for 5 hours in benzene solution; however, clean formation of the planar iridium(I) methyl-diphenylphosphine complex, Ir(PCH₃Ph₂)[N(SiMe₂CH₂PPh₂)₂], 3a, takes place when 2a is exposed to light for 24 hours in benzene solution. A crossover experiment indicates that the latter reaction involves an intramolecular mechanism. The nucleophilicity of the phosphido ligand is evident from the reaction of 2a with CH₃I; the product afforded in this reaction is Ir(CH₃)(PCH₃Ph₂)(I)[N(SiMe₂CH₂PPh₂)₂], 4. A labelling experiment with CD₃I shows that the reaction is intermolecular as the product observed is Ir(CH₃)(PCD₃Ph₂)(I)[N(SiMe₂CH₂PPh₂)₂]. Exposure of 2a at room temperature to one atmosphere of H₂ produces a mixture of the iridium(III) dihydride Ir(H)₂(PHPh₂)[N(SiMe₂CH₂-PPh₂)₂], 5, and methyl hydride Ir(CH₃)(H)(PHPh₂)[N(SiMe₂CH₂PPh₂)2], 6, in 70 and 30% yields, respectively. The analogous reaction with one atmosphere of D₂ reveals that the formation of the methyl hydride complex involves an intramolecular proton abstraction by the phosphide ligand from the bound methyl group, as the minor product observed in this reaction is Ir(CH₂D)(D)(PHPh₂)[N(SiMe₂CH₂PPh₂)₂]. A mechanism is proposed involving the formation of Ir(=CH₂)(PHPh₂)[N(SiMe₂CH₂PPh₂)₂] followed by trapping with D₂ to give the methyl hydride product. The dihydride complex observed in these reactions is apparently produced by heterolytic cleavage of dihydrogen. Under excess CO, complex 2a is converted to an octahedral carbonyl complex Ir(CH3)(CO)(PPh2)[N(SiMe2CH2PPh2)2], 9; the carbonyl and the phosphide ligands in this complex are in cis arrangement. Upon removing the excess CO from the reaction mixture, another stereoisomer, 10, is produced In which the carbonyl and the phosphide ligands are trans to one another. It is suggested that the carbonyl complex 9 observed under excess CO is the kinetically favoured isomer which rearranges to the more thermodynamically stable isomer, 10, upon removal of the excess CO. Both of the carbonyl Isomers are unstable In solution at room temperature as they convert to the planar iridium(I) complex Ir(CO)[N(SiMe₂CH₂PPh₂)₂] and methyldiphenylphosphine. / Science, Faculty of / Chemistry, Department of / Graduate

Kinetic and spectroscopic studies on solutions of two iridium(I) complexes—trans-chlorocarbonylbis(triphenylphosphine)iridium(I), Ir(CO)Cl(PPh3)2, and μ-dichlorotetrakis (cyclooctene)-di-iridium(I) , [IrCl(C8H,14)2]2—are described, especially for reactions involving activa-tion of molecular H2, molecular O2, and olefins. The studies also illustrate the importance of solvent effects. The catalytic activity of Ir(CO)Cl(PPh3)2 for hydrogenation of maleic acid has been surveyed using a range of solvents—pyridine, dimethylsulfoxide (DMSO), dimethylacetamide (DMA), dimethylformamide (DMF), acetone, sulfolane, acetonitrile, nitromethane and formamide. Where activity is observed, the mechanism appears to involve activation of hydrogen by a square-planar four-coordinate Ir(I) olefin complex. The DMA, DMF and DMSO solvent systems, which are very similar in terms of coordinating ability and dielectric constant, do show catalytic activity and this results from the dissociation of a phosphine molecule from the iridium at some stage to form the required four-coordinate catalyst 1: [series of chemical reactions] The sulfolane system is more active than the DMA, DMF and DMSO systems, but shows much more complicated kinetics. The hydrogenation appears to proceed in part via the phosphine dissociation path outlined in the above scheme, but the major pathway involves a cationic inters mediate Ir (CO) (PPh3)2 (olefin)+, 2, formed via chloride dissociation from the five-coordinate olefin complex. Diethylmaleate is hydrogenated in sulfolane, however, primarily via the phosphine dissociation path. Solvents that are too strongly coordinating (pyridine) or too weakly coordinating (nitromethane) lead to catalytically inactive systems. The catalytic homogeneous hydrogenation of hexene-1, cyclooctene using DMA solutions of [IrCl(C8H14)2]2 involves a monomeric species. The strongly coordinating solvent or the added olefin are thought to cleave the chloride bridge in [IrCl^gH^^J^* The hydrogenation mechanism can be outlined as [series of chemical reactions] where Ir is a complex already containing coordinated olefin. Selective hydrogenation of cyclooctene in a mixture of cyclooctene and hexene-1, the catalytic isomerization of hexene-2 and the catalytic hydrogenolysis of molecular 02 to water, all using [IrCl(C8H 14)2]2 complex in DMA are described and discussed. Molecular 0 is activated by DMA solutions of [IrCl2(C8H14)2]2 containing excess chloride; the major species believed to be present in solution is [IrCl2(C8H14)2]2⁻ . The solution initially absorbs one 02 per iridium. Product characterization proved to be difficult but the solutions catalytically oxidize cumene likely via a hydroperoxide free radical intermediate and the data are discussed in terms of the following equilibria: [series of chemical reactions] During some preliminary studies to investigate possible activation of CO under mild conditions using Ir complexes in aqueous solutions, the iridium(III) dicarbonyl [Ph4As]⁺ [Ir(C0)2C14]⁻•2H20, and a new cluster carbonyl tentatively formulated [Ir(CO)2]n, were synthesized. / Science, Faculty of / Chemistry, Department of / Graduate

Efficient preparative routes to several new rhodium complexes and some iridium compounds containing sulfoxide ligands are described. Chiral sulfoxide complexes of rhodium were tested as possible catalysts for the homogeneous asymmetric hydrogenation of prochiral olefins. Also tested were chiral sulfoxide-iridium complexes as potential catalysts for H2 transfer from isopropanol to prochiral olefins and ketones. The sulfoxides used include: the monodentate ligands dimethyl (DMSO), tetramethylene (TMSO), di-n-propyl (NPSO), methyl phenyl (MPSO), and diphenyl sulfoxide (DPSO); the monodentate chiral ligands (+)-(R)-methyl-p-tolyl sulfoxide (MPTSO), (+)-(R)-t-butyl-p-tolyl sulfoxide (TBPTSO), (-)-(S)-o-tolyl-p-tolyl sulfoxide (OTPTSO), and (+)-(S)-2-methylbutyl-(S,R)-methyl sulfoxide (MBMSO); and the potentially chelating ligands meso-l,2-bis(methyl sulfinyl)ethane (MSE), (R,R)-1,2-bis(p-tolyl sulfinyl)ethane (PTSE), and (-)-(2R,3R)-2,3-0-isopropylidene-2,3-dihydroxy-1,4-bis(methyl sulfinyl)butane (DIOS). Displacement of the labile acetone ligand from [Rh(diene)(PPh₃) (acetone)]A (diene=l,5-cyclooctadiene (COD), norbornadiene (NBD); A=PF₆ ⁻, SbF₆ ⁻ ) allows facile coordination of dialkyl or diaryl sulfoxides, and [Rh(diene)(PPh₃)L]⁺ complexes (L=DMSO,TMSO,NPSO,MBMSO,MPSO,MPTSO, and TBPTSO) have been synthesized; compounds with L=AsPh₃, py and (CO)₂ also form. Diaryl sulfoxides and DIOS coordinate, but no solids were isolated. The upfield shifts of the sulfoxide resonances (¹H nmr), reflecting shielding by the adjacent phenyl groups of PPh₃, and the decrease in v(SO) on coordination, are indicative of O-bonding in all cases. NMR data on the olefinic diene protons suggest the occurrence of some disproportionation of the mixed ligand complexes to [Rh(diene) (PPh₃)₂]⁺ and [Rh(diene)(L)2]⁺ depending on L, and the presence of 3-coordinate, and 5-coordinate (for diene=NBD only) intermediates. The hydrogenation of itaconic acid using catalysts with L=R-MPTSO or DIOS resulted in no asymmetric induction in the a-methyl succinic acid product because of disproportionation and catalysis via the bis(triphenylphosphine) system. Efficient hydroformylation of 1-alkenes is effected using [Rh(diene) (PPh₃)(CO)₂j⁺ as catalyst precursors. Aqueous isopropanol solutions of RhCl₃-3H₂O on treatment with sulfoxides provide an efficient route to RhCl₃L₃ complexes (L=DMSO, R-MPTSO,MPSO,TMSO) that contain in solution, at least for the first three systems, two S-bonded sulfoxides trans to a chloride, and an 0-bonded ligand. The 0-bonded sulfoxide is displaced by amides, amine oxides, and phosphine oxides to give mer- RhCl₃ (DMSO)₂(OL) complexes. The DMSO cis to OL in RhCl₃DMSO)₂(OL) or RhCl₃ (DMSO)₃(OL) can be identified in the nmr by using the ring current shielding effects of OPPh₂Me. RhCl₃L₃ react with H₂ (1:1) in base promoted reactions to yield Rh(I) presumably via undetected Rh(III)-H species. RhCl₃.3H₂O reacts with DPSO in isopropanol to give Rh(I) as the chloride-bridged species [RhCl(DPSO)₂]₂. The reaction with NPSO gives a Rh(I) dimer (indirect evidence) and a Rh(III) product, isolated as [H(NPSO)₂][RhCl₄(NPSO)₂] containing a symmetrical hydrogen-bridged cation. A crystal structure of trans-[H(DMSO)₂] [RhCl₄(DMSO)₂] reveals the short oxygen-oxygen distance (~2.45Å) in the cation expected for strong H-bonds. Such cations display intense v[sub a] (OHO) bands at 1700- 1100 and 900-600 cm⁻¹. The air-sensitive complexes [RhCl(C₈H₁₄)(DPSO)]₂, [RhCl(DMS0)₂]₂, [RhCl(DIOS)₂]₂ and [RhCl(MPSO)(PPh₃)]₂, isolated from [RhCl(cyclooctene)₂]₂/ ligand solutions, contain very labile Rh-S bonds that do not appear to involve Rh(dπ)+S (d-π) backbonding. Attempts at generating hydride complexes by oxidative addition of H₂ or HCl to Rh(I) resulted normally in either metal formation or sulfoxide reduction; even in the presence of prochiral olefins these complications occurred rather than catalytic asymmetric hydrogenation. The compound [Rh(MSE) ₂]PF₆ was isolated from the reaction of H₂ with [Rh(NBD) ₂]PF₆, and 2 MSE in alcohol solutions. The compounds mer-IrCl₂(H)(DMS0)₃ with trans chlorides, and mer-IrCl(H)₂(DMSO)₃ with cis hydrides, were obtained from oxidative addition reactions involving HCl and H₂, respectively, with [IrCl(C₈H₁₄)₂]₂ in DMSO. The former catalyzes the efficient selective reduction of α,β-unsaturated aldehydes to the unsaturated alcohols. Attempts at asymmetric synthesis using as catalysts IrCl₃H₂0/chiral sulfoxide mixtures failed. A simple bent M<-O=L vibrational model is used to estimate from v(M0) and v(S0) the force constants F[sub MO] and F[sub OL] using data for seventy 0-bonded DMSO, DMSO-D₆, and TMSO complexes of several metals. The correlation F[sub OL]=-(1.24±0.12)F[sub MO].+(8.78±0.12) mdyne/Å appears to hold for all metal complexes excepting those of group IVA and VA elements. / Science, Faculty of / Chemistry, Department of / Graduate

Yes / In the past decade, libraries of iridium organometallic arene compounds have expanded rapidly, with the majority of their applications aimed towards effective catalysts and potential anti-cancer drug candidates. Researchers have begun to adapt the traditional “piano-stool” structures to include different bidentate ligands, ancillary ligands and extend the aromaticity and functionality of the arene substituent, all in the hope to optimize their activities and allow the determination of structure activity relationships. Many of the complexes incorporate N- and O-donor ligands, but more recently, these structures have been expanded to include C-donor ligands such as cyclometalated bidentate ligands and N-heterocyclic carbenes. This mini-review highlights the recent and ongoing research in C-donor iridium arene complexes, and discusses their importance as potential anticancer drugs.

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Ici, la conception, la synthèse et la caractérisation et les propriétés optoélectroniques de complexes Ir(III) pour une application dans des dispositifs optiques non linéaires et électroluminescents sont décrits. Le type de complexes varie de ceux de la forme [Ir(C^N)2(N^N)]+ avec des ligands conjugués et non conjugués (où C^N = ligand cyclométallisant et N^N = ligand neutre) à ceux des forment [Ir (C^N^C)(N^N)Cl] (où C^N^C = ligand tripode tridenté). Le chapitre 1 donne une introduction à la photophysique se produisant dans les complexes de métaux de transition et aux applications possibles dans les affichages visuels. Le contexte des propriétés optiques non linéaires (NLO) et l'utilisation de complexes de métaux de transition en tant que chromophores NLO sont décrits. Dans le chapitre 2, l'impact de l'utilisation de ligands de cyclométallation encombrés stériquement sur les propriétés de photoluminescence des complexes cationiques d'iridium(III) et leur performance dans les cellules électrochimiques émettant de la lumière est étudiée. Le chapitre 3 explore l'utilisation de donneurs d'électrons sur le ligand de cyclométallation pour moduler les propriétés NLO des complexes. La combinaison de substituants fortement donneurs d'électrons sur le ligand C^N et de substituants accepteurs d'électrons sur le ligand N^N conduit à une forte activité NLO. Le chapitre 4 résume une nouvelle série de complexes cationiques d'iridium(III) portant benzylpyridinato comme ligands de cyclométallation. L'espaceur méthylène dans les ligands C^N confère de la flexibilité, ce qui donne deux conformères. Des études par RMN combinées à des études de la théorie fonctionnelle de la densité (DFT) montrent comment le comportement fluxionnel est influencé par le choix du ligand auxiliaire. Dans le chapitre 5, des complexes Ir(III) portant un ligand tripode tridentate bis (six-membres) non conjugué inhabituel de la forme [Ir (C^N^C)(N^N)Cl] sont introduits. En fonction des substitutions du ligand C^N^C, une phosphorescence allant du jaune au rouge a été obtenue. La substitution du N^N donne un colorant NIR panchromatique, adapté aux applications DSSC. Au chapitre 6, le concept d'un ligand non conjugué a été étendu au ligand N^N. Une émission bleu-vert et bleu-ciel a été obtenue, démontrant une stratégie pour régler avec succès l'émission au bleu. / Here, the design, synthesis and characterisation and the optoelectronic properties of Ir(III) complexes for application in nonlinear optical and electroluminescent devices are described. The type of complexes varies from those of the form [Ir(C^N)2(N^N)]+ with conjugated and nonconjugated ligands (where C^N = cyclometalating ligand and N^N = neutral ligand) to those of the form [Ir(C^N^C)(N^N)Cl] (where C^N^C = tridentate tripod ligand). Chapter 1 gives an introduction into photophysics occurring in transition metal complexes and possible applications in visual displays. The background of nonlinear optical (NLO) properties and the use of transition metal complexes as NLO chromophores is described. In Chapter 2, the impact of the use of sterically congested cyclometalating ligands on the photoluminescence properties of cationic Iridium(III) complexes and their performance in light-emitting electrochemical cells is investigated. Chapter 3 explores the use of electron donors on the cyclometalating ligand towards modulating the NLO properties of the complexes. Combining strongly electron-donating substituents on the C^N ligand and electron-accepting substituents on the N^N ligand results in strong NLO activity. Chapter 4 summarises a new series of cationic iridium(III) complexes bearing benzylpyridinato as cyclometalating ligands. The methylene spacer in the C^N ligands provides flexibility, resulting in two conformers. NMR studies combined with density functional theory (DFT) studies show how the fluxional behaviour is influenced by the choice of the ancillary ligand. In Chapter 5, Ir(III) complexes bearing an unusual nonconjugated bis(six-membered) tridentate tripod ligand of the form [Ir(C^N^C)(N^N)Cl] are introduced. Depending on the substitutions of the C^N^C ligand phosphorescence ranging from yellow to red was obtained. Substitution of the N^N results in a panchromatic NIR dye, suitable for DSSC applications. In Chapter 6, the concept of a nonconjugated ligand was expanded to the N^N ligand. Blue-green and sky-blue emission was obtained, demonstrating a strategy to successfully tune the emission to the blue.

Le diamant monocristallin est un candidat prometteur pour les applications en électronique de puissance et l'hétéroépitaxie est une alternative crédible à la synthèse de ce matériau. Lors de ce travail de thèse, chacune des étapes de la synthèse de films de diamant hétéroépitaxié sur des pseudo-substrats de Ir/SrTiO₃/Si(001) a été finement étudiée afin de progresser dans la reproductibilité et la qualité cristalline de ces films. Ainsi, un système de réflectométrie laser a été installé sur le bâti d'épitaxie d'iridium afin de caractériser in situ l'épaisseur des films réalisés. Une nouvelle méthode basée sur traitement plasma permettant la recristallisation de l'iridium à des températures comprises entre 800°C et 900°C a été mise au point et brevetée. Ensuite, une caractérisation de la surface de l'iridium après l'étape de nucléation du diamant (BEN) par ellipsométrie spectroscopique a été réalisée en bâtissant un modèle ellipsométrique à partir d'une étude séquentielle en MEB, AFM et XPS. Cette étude démontre que l’ellipsométrie est sensible à la formation des domaines qui contiennent les cristaux de diamant épitaxiés. L'étape de nucléation a été étendue à des pseudo-substrats Ir/SrTiO₃/Si(001) de 10x10 mm². Une stratégie d'épaississement des films de diamant reposant sur deux étapes a été adoptée. La structure cristalline des films épaissis à plusieurs centaines de microns a été caractérisée par DRX et Raman. Des diodes Schottky latérales ont été fabriquées sur l'un des substrats épaissis. Les mesures électriques réalisées démontrent l'homogénéité du substrat de diamant hétéroépitaxié. Afin de mieux contrôler les premiers stades de la croissance, une nouvelle méthode de nucléation sélective a été mise au point et brevetée. Son application permettrait dans l'avenir d'obtenir une croissance latérale (ELO) dès la coalescence des premiers cristaux de diamant. / Single crystal diamond is a promising candidate for power electronics applications and heteroepitaxy is a credible alternative for the synthesis of this material. During this PhD, each step from the synthesis of heteroepitaxial diamond films on Ir/SrTiO₃/Si(001) pseudo-substrates was studied in details to progress in the reproducibility and the crystalline quality of films. Thus, a laser reflectometry system was installed on the iridium epitaxy reactor to characterize in situ the thickness of these films. A new approach based on plasma treatment leading to the iridium recrystallization at temperatures between 800°C and 900°C was developed and patented. Then, a characterization of the iridium surface after diamond nucleation (BEN) by spectroscopic ellipsometry was done by building an ellipsometric model based on a sequential study by SEM, AFM and XPS. Results demonstrate that ellipsometry is sensitive to the formation of domains including epitaxial diamond crystals. The nucleation step was extented to Ir/SrTiO₃/Si(001) pseudo-substrates with a size of 10x10 mm². A strategy for the thickening of diamond films based on two steps was adopted. The crystalline structure of films, few hundreds of microns thick, was characterized by XRD and Raman. Lateral Schottky diodes were built on one of the thick substrates. Electrical measurements demonstrate the homogeneity of the heteroepitaxial diamond substrate. To better control the growth early stages, a new method of selective nucleation was developed and patented. Its application in the future would make possible a lateral growth (ELO) from the coalescence of the first diamond crystals.

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Here, the design, synthesis and characterisation and the optoelectronic properties of Ir(III) complexes for application in nonlinear optical and electroluminescent devices are described. The type of complexes varies from those of the form [Ir(C^N)2(N^N)]+ with conjugated and nonconjugated ligands (where C^N = cyclometalating ligand and N^N = neutral ligand) to those of the form [Ir(C^N^C)(N^N)Cl] (where C^N^C = tridentate tripod ligand). Chapter 1 gives an introduction into photophysics occurring in transition metal complexes and possible applications in visual displays. The background of nonlinear optical (NLO) properties and the use of transition metal complexes as NLO chromophores is described. In Chapter 2, the impact of the use of sterically congested cyclometalating ligands on the photoluminescence properties of cationic iridium(III) complexes and their performance in light-emitting electrochemical cells is investigated. Chapter 3 explores the use of electron donors on the cyclometalating ligand towards modulating the NLO properties of the complexes. Combining strongly electron-donating substituents on the C^N ligand and electron-accepting substituents on the N^N ligand results in strong NLO activity. Chapter 4 summarises a new series of cationic iridium(III) complexes bearing benzylpyridinato as cyclometalating ligands. The methylene spacer in the C^N ligands provides flexibility, resulting in two conformers. NMR studies combined with density functional theory (DFT) studies show how the fluxional behaviour is influenced by the choice of the ancillary ligand. In Chapter 5, Ir(III) complexes bearing an unusual nonconjugated bis(six-membered) tridentate tripod ligand of the form [Ir(C^N^C)(N^N)Cl] are introduced. Depending on the substitutions of the C^N^C ligand phosphorescence ranging from yellow to red was obtained. Substitution of the N^N results in a panchromatic NIR dye, suitable for DSSC applications. In Chapter 6, the concept of a nonconjugated ligand was expanded to the N^N ligand. Blue-green and sky-blue emission was obtained, demonstrating a strategy to successfully tune the emission to the blue.