A series of complexes of the type [(L-L)Pd(alkene)], where (L-L) is a diphosphine ligand and the alkene is dibenzylideneacetone (dba), benzoquinone or tetracyanoethene have been synthesised. These complexes have been evaluated as pre-catalysts in the methoxycarbonylation of ethene (80 C, 10 bar CO/ethene, MeOH, 20 MeSO(_3)H). Where (L-L) is the diphosphine l,2-bis(di-tert-butylphosphinomethyl)benzene and the alkene is dba, rates in excess of 40,000 moles methyl propionate/mole Pd/hr are obtained at 99.6% selectivity. The catalytic activity and selectivity is found to critically depend on the nature of the diphosphine ligand, with l,2-bis(diphenylphosphinomethyl)benzene complexes giving rise to high molecular weight, perfectly alternating CO/ethene co-polymer. Several of the pre-catalyst complexes have been characterised by single crystal X-ray diffraction, and factors common to both methyl propionate selective catalysts and co-polymer selective catalysts have been identified. The phosphine ligands chosen in this study all readily form complexes with Pd(_2)(dba)(_3). The complexes have the formula [(P-P)Pd(dba)] where the bidentate phosphine binds as a chelate ligand to a single palladium atom. The environment around the palladium is essentially trigonal planar, with only small dihedral angles between P(-2)Pd and PdC(_2) planes observed. Detailed studies of the reaction of the complexes [(L-L)Pd(alkene)] with methanesul- phonic acid have been undertaken. The reaction product is shown to depend on the nature of the diphosphine ligand and the alkene. The catalytic activity is discussed with reference to the ability of the reaction products to enter the catalytic cycle. The coordination chemistry of several diphosphines when mixed with Pd(II) salts has been studied. Several complexes have been characterised by X-ray crystallography and the features related to the observed catalytic activity. The reaction chemistry has also been explored and related to the observed catalysis. A mechanism which takes account of all the results reported in this thesis is presented.

No description available.

No description available.

No description available.

Universiẗat, Diss., 2001--Heidelberg.

The tricobalt cluster PhCCo3(CO)9 (1) reacts with the bidentate phosphine ligand 2,3-bis(diphenylphosphino)maleic anhydride (bma) in the presence of added Me3NO to give the diphosphine-substituted cluster PhCCo3(CO)7(bma) (2). Cluster 2 is unstable in solution, readily losing CO to afford Co3(CO)6[(μ2-η2/η1-C(Ph)C=C(PPh2)C(O)OC(O)](μ2-PPh2) (3) as the sole observed product. VT-31P NMR measurements on cluster 2 indicate that the bma ligand functions as both a chelating and a bridging ligand. At -97 °C, 31P NMR analysis of 2 reveals a Keq of 5.7 in favor of the bridging isomer. The bridged bma cluster 2 is the only observed species above -50°C. The solid-state structure of 2 does not correspond to the major bridging isomer observed in solution but rather the minor chelating isomer. The conversion of 2 to 3 followed first-order kinetics, with the reaction rates being independent of the nature of the reaction solvent and strongly suppressed by added CO, supporting a dissociative loss of CO as the rate-determining step. The activation parameters for CO loss were determined to be ΔH≠ = 29.9 ± 2.2 kcal/mol and ΔS≠ = 21.6 ± 6 eu.

This PhD thesis deals with the activation of diorganozinc compounds by asymmetric catalysts in the framework of their enantioselective addition on carbon oxygen and carbon nitrogen double bonds. The properties of several new catalysts systems were investigated. Several chiral sulfonamido alcohols derived from (S)-leucinol and (1S) 3 aminoisoborneol were synthesized to cover a range of electronic and steric properties. These were evaluated in the addition of Et2Zn to N phosphinoyl and N sulfonyl-imines, but they did not provide any acceptable yields or enantioselectivities while used in stoichiometric quantities. Their catalytic properties were also investigated for the addition of Et2Zn to benzaldehyde. Unfortunately, only modest enantiocontrol (max. 47% ee) could be obtained with 10mol% of chiral ligand. We investigated another approach based on the possible activation of the nucleophilicity of dialkylzinc compounds towards benzaldehyde by fluoride anion. The combination of stoichiometric amount of an inorganic fluoride salt and a substoichiometric amount of a phase transfer catalyst (10mol% of crown ether 18 C 6) provided non-negligible rate acceleration. However, an asymmetric version of this catalytic system was not considered. Following our discovery of the activation provided by the fluoride anion, metal fluoride complexes were tapped as potential catalysts. In particular, copper(I) fluoride complex, (Ph3P)3CuF, was shown to accelerate the reaction on benzaldehyde. After screening a range of ligands, the combination of (Ph3P)3CuF and chiral BINAP in catalytic amounts (1mol%) was found to catalyze efficiently the Et2Zn addition on aromatic aldehydes. Yields were good but enantiocontrol was modest (49-63% ee). An improved copper fluoride-based catalyst was developed by combining a copper salt, a fluoride source and a chiral diphosphine ligand. Optimization of this second generation catalyst was carried out (copper source, fluoride source, chiral ligand, relative stoichiometries of catalyst's precursors, catalyst's loading, solvent, temperature) and applied to a range of aldehydes (upto 87% ee). A mechanism was proposed based on literature data and experimental observations. The influence of the counterion was then thoroughly explored by assessing the catalytic potential of various copper complexes in combination with chiral BINAP in the Et2Zn addition to benzaldehyde. Copper(II) diketonates provided good enantiocontrol (upto 88% ee) which could be improved even further by using optically active copper diketonates in a matched combination with chiral BINAP (upto 91% ee). This new system was applied to control the addition of Et2Zn to a range of aldehydes with a low catalyst loading (0.5mol%). A mechanism was proposed to explain a series of experimental observations. / Cette dissertation traite de l'activation de composés diorganozinciques par des catalyseurs asymétriques dans le cadre de leur addition énantiosélective sur des doubles liaisons carbone-oxygène et carbone-azote. Les propriétes de divers catalyseurs originaux ont été investiguées. Plusieurs sulfonamidoalcools chiraux dérivés du (S)-leucinol et du (1S) 3 aminoisoborneol ont été synthétisés pour couvrir un domaine de propriétés électroniques et stériques. Ceux-ci ont été testés lors l'addition du Et2Zn sur les N phosphinoyl et N-sulfonyl-imines, mais ils n'ont pas fourni de rendements et excès énantiomériques intéressants malgré leur utilisation en quantité stoechiométrique. Leurs propriétés catalytiques ont également été examinées dans le cadre de l'addition de Et2Zn au benzaldéhyde. Malheureusement, un faible contrôle de l'énantiosélectivité (max. 47% ee) est obtenu en présence de 10mol% de ligand chiral. Une autre approche abordée concerne l'influence de l'anion fluorure sur la nucléophilie des composés dialkylzincs envers le benzaldehyde. La combinaison de quantités stoechiométriques d'un sel fluoré inorganique et d'une quantités sub stoechiométrique d'un agent de transfert de phase (10mol% éther couronne 18 C 6) conduit à un accroissement non négligeable de la vitesse de réaction. Toutefois, le développement d'une version asymétrique de ce système n'a pas été considéré. A la suite de notre découverte de l'activation due à l'anion fluorure, les complexes métalliques fluorés ont été examinés en tant que catalyseurs potentiels. En particulier, le complexe du cuivre, (Ph3P)3CuF, accélère la réaction d'addition du Et2Zn sur le benzaldéhyde. Après un criblage de divers ligands, la combinaison de (Ph3P)3CuF et de la diphosphine chirale BINAP en quantité catalytique (1mol%) conduit à une catalyse efficace de l'addition du Et2Zn sur des aldéhydes aromatiques. Les rendements obtenus sont bons, par contre l'énantiosélectivité est modeste (49-63% ee). Une version améliorée de catalyseurs cuivre-fluorure a été obtenue en combinant un sel de cuivre, une source de fluorure et une diphosphine chirale. L'optimisation de divers paramètres de réaction a été effectuée (source de cuivre, origine de l'anion fluorure, ligand chiral, stoechiométries relatives des précurseurs du catalyseur, charge de catalyseur, solvant et température). Le catalyseur optimisé a été appliqué à divers aldéhydes (jusqu'à 87% ee). Un mécanisme réactionnel a été proposé sur la base d'arguments de la littérature et d'observations expérimentales. Le rôle du contre-ion a été exploré par un examen attentif de divers complexes du cuivre en combinaison avec la BINAP chirale en tant que catalyseurs de l'addition du Et2Zn sur le benzaldehyde. Les dicétonates du cuivre(II) ont conduit à une bonne énantiosélectivité (jusqu'à 88% ee) qui a pu être améliorée en utilisant des dicétonates du cuivre(II) optiquement actifs assortis avec le bon énantiomère de la BINAP (jusqu'à 91% ee). Ce nouveau système a été appliqué pour l'addition du Et2Zn sur divers aldéhydes avec une charge réduite en catalyseur (0.5mol%). Un mécanisme a été proposé afin de supporter les observations expérimentales.

Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal.

Thermolysis of CoRu(CO)7(m -PPh2) (1) in refluxing 1,2-dichloroethane in the presence of the diphosphine ligands 2,3-bis(diphenylphosphino)maleic anhydride (bma) and 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd) furnishes the new mixed-metal complexes CoRu(CO)4(μ -P-P)(μ -PPh2) [where P-P = bma (3); bpcd (6)], along with trace amounts of the known complex CoRu(CO)6(PPh3)(μ -PPh2) (4). The requisite pentacarbonyl intermediates CoRu(CO)5(μ -P-P)(μ -PPh2) [where P-P = bma (2); bpcd (5)] have been prepared by separate routes and studied for their conversion to CoRu(CO)4(μ -P-P)(μ -PPh2). The complexes 2/3 and 5/6 have been isolated and fully characterized in solution by IR and NMR spectroscopy. The kinetics for the conversion of 2→3 and of 5→6 were measured by IR spectroscopy in chlorobenzene solvent. On the basis of the first-order rate constants, CO inhibition, and the activation parameters, a mechanism involving dissociative CO loss as the rate-limiting step is proposed. The solid-state structure of CoRu(CO)4(μ -bma)(μ -PPh2) (3) reveals that the two PPh2 groups are bound to the ruthenium center while the maleic anhydride π bond is coordinated to the cobalt atom. Thermolysis of the cluster Ru3(CO)12 with the bis(phosphine)hydrazine ligand (MeO)2PN(Me)N(Me)P(OMe)2 (dmpdmh) in toluene at 75°C furnishes the known clusters Ru4(CO)12[μ -N(Me)N(Me)] (9) and Ru3(CO)11[P(OMe)3] (10), in addition to the new cluster Ru3(CO)10(dmpdmh) (8) and the phosphite-tethered cluster Ru3(CO)9[μ -P(OMe)3] (11). The simple substitution product Ru3(CO)10(dmpdmh), a logical intermediate to clusters 9-11, was synthesized by treating Ru3(CO)12 and dmpdmh with Me3NO in CH2Cl2 at room temperature, and independent thermolysis reactions using cluster 8 were shown to yield clusters 9-11. The tetrahedrane cluster FeCo2(CO)9(μ3-S) reacts with the redox-active ligand 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd) to give the disubstituted cluster FeCo2(CO)7(bpcd)(μ3-S) as the sole product. This diphosphine-substituted cluster contains a cobalt-bound, chelating bpcd ligand. The solid-state structure has been unequivocally established by X-ray diffraction analysis. Cyclic voltammetric studies on FeCo2(CO)7(bpcd)(μ3-S) reveal the presence of two quasireversible redox responses assigned to the 0/1- and 1-/2- redox couples. The orbital composition of these redox couples has been examined by carrying out extended Hückel MO calculations on the model complex FeCo2(CO)7(H4-bpcd)(μ3-S), with the results being compared to related cluster compounds.

Les importants aplicacions pràctiques que presenta el cobaltobis(dicarballur), [3,3'-Co(1,2-C2B9H11)2]-, ja sigui com a extractant de radionúclids procedents d'aïgues residuals de centrals nuclears o com a agent dopant de polímers conductors de polipirrol, ens han encoratjat en la recerca d'aquest clúster de bor. Així l'objectiu primordial d'aquest treball és la síntesi i caracterització de nous cobaltocarborans que incorporin substituents tant dels vèrtexs de carboni com en els de bor, per tal d'ésser destinats a aquestes aplicacions. La incorporació de fosfines en els vèrtexs de carboni del cobaltobis(dicarballur) ha estat possible per metal·lació directa d'aquest amb n-BuLi seguida de la reacció amb una clorofosfina (ClPR2: R=Ph, Et, iPr o Cl2PPh). Aquesta reacció ha conduït a la síntesi i separació d'espècies C-difosfinosubstituïdes. La caracterització d'aquestes difosfines per RMN (1H, 13C, 31P i 11B) i difracció de raigs X ha revelat que l'isòmer generat és la mescla racèmica. Únicament s'ha format l'isòmer meso si es duu a terme la mateixa reacció sobre el compost [8,8'-m-C6H4-3,3'-Co(1,2-C2B9H10)2]-. També l'únic cas de mono-C-substitució s'ha observat partint d'aquest compost. Un cop sintetizada tota aquesta nova família de C-fosfino derivats s'han preparat els respectius anàlegs òxids de fosfina per tractament amb H2O2 en acetona. Aquest mètode d'oxidació també s'ha aplicat a closo-carboranildifosfines, en aquests casos però, un cop a tingut lloc l'oxidació dels àtoms de fòsfor té lloc la degradació parcial del clúster closo a nido. Són els òxids de fosfina els que s'han utilitzat en els assaigs d'extracció de radionúclids, en tècniques d'extracció líquid-líquid i en experiments de transport en membranes líquides suportades.La semblança estructural de la cobaltocarboranildifosfina aniònica [3,3'-Co(1-PPh2-1,2-C2B9H10)2]- aquí sintetitzada amb els coneguts lligands BINAP i dppf ens ha motivat a determinar com es comporta aquest cobaltocarborà com a lligand. Per això s'ha complexat amb metalls tals com la Ag, l'Au, el Rh i el Pd. També s'ha dut a terme un anàlisi detallat dels trets geomètrics que diferencien aquests tres lligands tant semblants.Pel que fa a la funcionalització dels vèrtexs de bor, s'ha optimitzat el mètode de síntesi dels derivats iodats [3,3'-Co(8-I-1,2-C2B9H10)(1',2'-C2B9H11)]- i [3,3'-Co(8-I-1,2-C2B9H10)2]- i se n'ha estudiat la seva reactivitat amb reactius de Grignard. La reacció del derivat monoiodat amb magnesians ha permès generar derivats monoalquílics i monoarílics en la posició B8. S'ha estudiat l'efecte del substituent alquil o aril tant experimentalment mitjançant les tècniques de RMN, UV-Visible, voltamperometria cíclica i difracció de raigs X com per càlculs teòrics Extended Hückel i ab initio. D'aquest estudi en resulta el caràcter electroatraient d'un grup alquil quan està enllaçat a bor, i la menor participació dels orbitals d del metall en els orbitals frontera. La reactivitat del derivat diiodat amb magnesians ha generat compostos tant B8,B8'-dialquilsubstituïts com B8-alquil-B8'-hidroxilsubstituïts. A partir del derivat [3,3'-Co(8-Me-1,2-C2B9H10)(8-OH-1',2'-C2B9H10)]- s'ha observat per primer cop en la química dels clústers de bor un procés d'oxodesmetilació. De la reactivitat dels derivats mono i diiodats amb alquins en destaca la reacció del derivat monoiodat amb trimetilsililacetilè la qual ha permès aïllar i caracteritzar els anàlegs en tres dimensions al fenantrè i al 9-vinilfenantrè: [8,8'-m-C2H2-3,3'-Co(1,2-C2B9H10)2]- i [8,8'-m-C4H2(SiMe3)2-3,3'-Co(1,2-C2B9H10)2]-. S'ha proposat un mecanisme basat en etapes d'acoblament B-C, d'hidroboració intramolecular o intermolecular, d'hidrodesililació i "enyne" metàtesis per a explicar la generació d'aquests nous compostos. També s'han sintetitzat nous cobaltocarborans que incorporen cadenes de polièter en la posició B8 per reacció de l'espècie dioxanada [3,3'-Co(8-C4H8O2-1,2-C2B9H10)(1',2'-C2B9H11)] amb alcòxids sòdics. A més a més, per difracció de raigs X s'ha resolt l'estructura cristal·lina de Na[3,3'-Co(8-O(CH2CH2O)2Et-1,2-C2B9H10)(1',2'-C2B9H11)] en la que s'evidencia l'existència d'interaccions B-H◊◊◊Na.Finalment, s'ha polimeritzat electroquímicament el polipirrol amb alguns dels cobaltocarborans B8-substituïts per a avaluar la resistencia a la sobreoxidació del nou material polimèric. / The practical application of cobaltobis(dicarbollide), [3,3'-Co(1,2-C2B9H11)2]-, either as an extractant of radionuclides from nuclear wastes or as a doping agent on conducting organic polymers in particular polypyrrole, has encouraged to research on this boron cluster. The aim of this work has been to synthesize and characterize new cobaltocarborane derivatives with substituents on the carbon vertexes and on the boron vertexes to be used as extractant or doping agents. The incorporation of phosphines in the carbon vertexes of the cobaltobis(dicarbollide) has been possible through direct metallation of the cluster with n-BuLi, followed by reaction with chlorophosphines (ClPR2: R=Ph, Et, iPr or Cl2PPh). This reaction has led to the synthesis and separation of C-diphosphinosubstituted species. Their characterization by NMR spectroscopy (1H, 13C, 31P i 11B) and X-ray diffraction has revealed that among all possible isomers, only the racemic mixture is formed. The meso isomer is only generated if the same reaction is applied to the compound [8,8'-m-C6H4-3,3'-Co(1,2-C2B9H10)2]-. Also the unique case of mono-C-substitution has been observed starting from this compound. After synthesizing all this new family of C-phosphino derivatives, the phosphine oxides analogous has been prepared by treatment with H2O2 in acetone. This oxidation methode has also been applied to closo-carboranyldiphosphines. In this cases, upon oxidation of the phosphorous atoms takes place the partial cluster degradation from closo to nido. The phosphine oxides have been used in radionuclides extraction experiments, liquid-liquid extraction techniques and transport experiments using supporting liquid membranes.The structural similarity of the anionic cobaltocarboranyldiphosphine [3,3'-Co(1-PPh2-1,2-C2B9H10)2]- synthesized here with the well-known BINAP and dppf ligands has motivated to determine how the cobaltocarborane acts as a ligand. In this sense, this has been complexed with metals such as Ag, Au, Rh and Pd. A detailed analysis of the geometrical differences between the three ligands has also been explored.Concerning the functionalization of the boron atoms, the synthetic procedure for the iodated derivatives [3,3'-Co(8-I-1,2-C2B9H10)(1',2'-C2B9H11)]- and [3,3'-Co(8-I-1,2-C2B9H10)2]- as well as their reactivity with Grignard reagents has been studied. The cross-coupling reaction between the monoiodated compound and a Grignard reagent has allowed to generate monoalkylated and monoarylated derivatives on B8 position. The effect of alkyl and aryl substituents has been studied experimentally by NMR, UV/Vis, cyclic voltammetry and X-ray diffraction. Theoretically Extended Hückel and ab initio methods have also been carried out. Experimental and theoretical data agree with the electronwithdrawing character of alkyl groups when bonded to boron, and the less contribution of the metal d orbitals to the frontier orbitals. On the other hand, the reactivity of the diiodated compound with magnesium salts has generated homo-B8,B8'-dialkylsubstituted and hetero-B8-alkyl-B8'-hydroxilsubstituted derivatives. An oxodemethylation process has been observed for the first time in boron cluster chemistry when using [3,3'-Co(8-Me-1,2-C2B9H10)(8-OH-1',2'-C2B9H10)]- in the presence of I2.Remarkable is the reaction between the monoiodated derivative with trimethylsilylacetylene which has permitted the isolation and characterization of the three-dimensional analogous of phenantrene and 9-vinylphenantrene: [8,8'-m-C2H2-3,3'-Co(1,2-C2B9H10)2]- and [8,8'-m-C4H2(SiMe3)2-3,3'-Co(1,2-C2B9H10)2]-. A mechanism based on B-C coupling, intramolecular or intermolecular hydroboration, hydrodesilylation and enyne metathesis reactions has been proposed to explain the formation of these compounds. The synthesis of new cobaltocarboranes that incorporates polyethers chains in B8 vertex has been possible by reaction of the dioxanate species [3,3'-Co(8-C4H8O2-1,2-C2B9H10)(1',2'-C2B9H11)] with sodium alkoxides. Furthermore, through X-ray diffraction has been solved the crystal structure of Na[3,3'-Co(8-O(CH2CH2O)2Et-1,2-C2B9H10)(1',2'-C2B9H11)] that evidenciates the existence of B-H◊◊◊Na interactions. These B8-substituted cobaltocarborane derivatives have been used as doping agents in the electrochemical polymerization of polypyrrol in order to evaluate the overoxidation resistance of the new polymeric materials.