Dissertations / Theses on the topic 'Complexos de rodi'

En aquest treball s'han abordat tres objectius, tots ells relacionats amb la reacció d'hidroformilació i en la seva aplicació a la síntesi de productes d'alt valor afegit.
El primer dels objectius ha estat la síntesi de tres lligands ditioacetat quirals a partir de l'L-(-)-lactat d'etil i diols bicíclics, que en algun cas incorporaven un centre atropoisomèric, per a ser emprats en la reacció d'hidroformilació enantioselectiva catalitzada per complexos tiolat de rodi o bé en altres reaccions asimètriques. Els ditioacetats han pogut ser preparats però no de forma enantiomèricament pura, ja que s'ha observat una racemització del carboni estereogènic clàssic en la darrera de les cinc etapes previstes per la síntesi d'aquests compostos. En aquesta darrera etapa, la basicitat de l'anió tioacetat usat en la substitució nucleofílica dels productes ditosilats ha estat suficient per abstreure el protó a-carbonilic. No s'han trobat precedents d'una reacció similar amb aquest anió.
El segon objectiu del treball ha estat la hidroformilació diastereoselectiva de tres trans-N-1-propeniltartarimides homoquirals. La ruta emprada per sintetitzar-les consisteix, en primer lloc, en la condensació de l'N-al·lilamina i l'àcid L-(-)-tartàric per obtenir l'N?al·liltartarimida. L'esterificació dels grups OH d'aquesta amb els anhídrids apropiats permet obtenir les N-al·liltartarimides funcionalitzades amb grups CH3COO-, (CH3)3COO- i PhCOO-. Finalment, la isomerització d'aquestes imides permet sintetitzar les trans-N-1-propeniltartarimides. Els precedents bibliogràfics indiquen que la isomerització d'imides és una reacció complicada, ja que sovint requereix quantitats elevades de catalitzador així com condicions de reacció dràstiques. En aquest treball s'han assajat diferents complexos metàl·lics de rodi i de ruteni com a catalitzadors d'isomerització. Els millors resultats s'obtenen utilitzant el complex RuClH(CO)(PPh3)3 (1% molar). S'assoleixen conversions properes al 90% en dues hores de reacció amb una regioselectivitat en l'isòmer trans del 90%. Aquests valors representen els millors resultats reportats fins al moment en aquest tipus de reacció. La hidroformilació de les trans-N-1-propeniltartarimides sintetitzades s'ha dut a terme amb catalitzadors de rodi no quirals amb la intenció d'obtenir els aldehids de manera diastereoselectiva. Els resultats obtinguts indiquen que és la naturalesa del substrat la que controla la formació de l'alquil complex i que l'estructura del catalitzador no influeix, de forma determinant, en la selectivitat. Per altra banda, no s'han observat en cap cas excessos diastereoisomèrics superiors al 10%, fet que indica que els diferents substituents no tenen un efecte clar sobre l'estereoselectivitat de la reacció.
El tercer i darrer objectiu ha estat l'obtenció de l'N-acetil-2-pirrolina a partir de l'N-al·lilacetamida mitjançant la reacció d'hidroformilació. Aquest heterocicle nitrogenat pot usar-se com a buillding-block en la síntesi de diferents molècules amb activitat biològica, especialment alcaloides. La hidroformilació de l'N-al·lilacetamida s'ha portat a terme emprant catalitzadors de rodi i les difosfines Bisbi i Xantphos, i el difosfit tert-butil Biphephos com a co-catalitzadors. Amb el sistema Rh/Xantphos s'obtenen quimio- i regioselectivitats superiors al 90% en l'aldehid lineal o els seus derivats. La ciclació intramolecular del 2-acetamidobutanal, producte majoritari de la reacció d'hidroformilació, i la posterior deshidratació de l'alcohol resultant, permet obtenir l'N-acetil-2-pirrolina a partir de l'N?al·lilacetamida mitjançant un procés one pot amb una excel·lent economia atòmica. S'ha estudiat en profunditat la ciclació i posterior deshidratació. Així s'ha determinat que catalitzadors àcids de tipus Brönsted provoquen l'aparició de productes de doble condensació no desitjats i que el millor catalitzador per aquestes reaccions és el tamís molecular de 3 Å finament polvoritzat i assistit per una destil·lació en continu de l'azeòtrop toluè/aigua. Amb aquest mètode s'ha pogut obtenir el producte desitjat a partir de l'N?al·lilacetamida, CO, H2 i un 0.0002% de Rh amb un rendiment del 41%.
Three main goals were set at the beginning of this work, all of them related with the hydroformylation reaction and its application in the synthesis of fine chemicals.
The first goal is the synthesis of three chiral ditioacetate ligands coming from the L?(-)-ethyl lactate and bicyclic diols, that in some cases contain an atropoisomeric centre. These ligands could be used in the enantioselective hydroformylation of olefins catalysed by rhodium complexes or in other asymmetric reactions. The ditioacetates were prepared but not enantiomerically pure, because of the racemization of the "classical" estereogenic centre in the last of the five steps of the synthetic pathway designed. In this last step, the basicity of the tioacetate anion used in the nucleophilic substitution of the corresponding ditosilate intermediates was enough to abstract the a?carbonilic hydrogen. As far as we know, there is no precedent of such a reaction with this anion.
The second goal of this work is the diastereoselective hydroformylation of three homochiral trans-N-1-propenyltartarimides. The synthetic pathway consists, first of all, in the condensation of the N-allylamine and the L-(-)-tartaric acid to obtain the N?allyltartarimide. The esterification of the OH groups of this imide with the suitable anhydrides allows the synthesis of the corresponding N-allyltartarimides functionalised with the CH3COO-, (CH3)3COO- and PhCOO- groups. Finally, the isomerization of these imides leads to the trans-N-1-propenyltartarimides. The literature indicates that imide isomerization is a difficult reaction, usually it requires high levels of catalyst and heavy reaction conditions. In this work a number of rhodium and ruthenium complexes has been tested as catalysts. The best result were found using RuClH(CO)(PPh3)3 (1% molar). It is possible to reach yields up to 90% in two hours of reaction with a regioselectivity in the trans isomer up to 90%. As far as we know that results represent the best ones ever reported in such a reaction. The hydroformylation of the trans-N-1-propenyltartarimides has been done using non-chiral rhodium complexes as catalysts with the aim of obtaining the aldehydes in a diastereoselective way. The results obtained indicate that the nature of the substrate is controlling the alkyl complex formation during hydroformylation and that there is not any effect of the catalyst in the selectivity. Moreover, diastereomeric excess in the aldehydes formation does not exceed 10%, which indicates that there is not a clear effect of the substrate nature in the stereoselectivity of the reaction.
The third and last goal of this work is the synthesis of N-acetyl-2-pyrroline through the hydroformylation of N-allylacetamide. This heterocycle containing nitrogen can be used as building-block for the synthesis of a number of molecules with biological activity, specially alkaloids. The hydroformylation of N-allylacetamide was attempted using rhodium catalysts and diphosphines (Bisbi and Xantphos) or diphosphites (tert-butil Biphephos) as co-catalysts. With the catalytic system Rh/Xantphos, chimio- and regioselectivities exceeding 90% in the linear aldehyde or their derivatives are obtained. 2-acetamidobutanal is the major product of the hydroformylation reaction, it cycles in an intramolecular way to obtain the corresponding alcohol, the dehydration of which leads to the N-acetyl-2-pyrroline in a one-pot process with an excellent atomic economy. The cycle formation and the dehydration reaction of the alcohol has been deeply investigated. It has been found that Brönsted catalysts promote double condensation products formation which are undesirable. After a number of tests the best catalyst for the one-pot reaction referred above is 3 Å molecular sieves finely powdered and assisted by a continuous distillation of the toluene/water azeotrop. According to this method it is possible to obtain N-acetyl-2-pyrroline from N-allylacetamide, CO, H2 and a 0.0002% of rhodium with a global yield of 41%.

Els nous lligands 3,5-dimetil-4-(etilamino)metilpirazole (HL1) i 3,5-dimetil-4-(isopropilamino)metilpirazole (HL2), són capaços de coordinar a Rh(I) de forma exodidentada, i formar espècies "zwitterióniques" pirazolat-amoni. Les estructures cristal·lines dels complexos dinuclears [Rh(HL1)(COD)]2Cl2 i [Rh(HL2)(COD)]2Cl2 confirmen que els metalls presenten una geometria pla-quadrada, coordinant-se al lligand COD i a dues molècules de lligand pirazolat pont. Per reacció de complexació dels lligands prèviament desprotonats (L1 i L2) amb Rh(I) s'obtenen els complexos neutres [Rh(L1)(COD)]2 i [Rh(L2)(COD)]2. Tant els complexos iònics com els neutres, reaccionen amb monòxid de carboni per donar els complexos [Rh(HL1)(CO)2]2Cl2, [Rh(HL2)(CO)2]2Cl2, [Rh(L1)(CO)2]2 i [Rh(L2)(CO)2]2. Tots els complexos presenten una solubilitat notable en dissolvents polars i, fins i tot en aigua, mentre que són insolubles en hidrocarburs saturats.1, 2
Tant els lligands 1-aminoalquilpirazole potencialment didentats (NN') com els potencialment tridentats (NN'N), reaccionen amb el dímer [RhCl(COD)]2 per donar lloc a les espècies [Rh2Cl2(L)(COD)2] (L=NN' o NN'N). Les dades de RMN junt amb les de conductivitat són coherents amb l'existència d'un equilibri en solució entre la forma iònica [Rh(L)(COD)]+ [RhCl2(COD)]- i una forma neutra [Rh(COD)Cl][m-(L)][Rh(COD)Cl]. Els espectres de masses d'electroesprai confirmen la presència de les espècies iòniques [Rh(L)(COD)]+[RhCl2(COD)]- en solució.3
Per reacció del lligand bis[(3,5-dimetil-1-pirazolil)metil]etilamina (1) amb [Rh(COD)(THF)2][BF4] s'obté el complex [Rh(COD)(1)][BF4], que per posterior tractament amb CO, es transforma en els complexos [Rh(CO)2(1)][BF4] i [Rh(CO)(1)][BF4]. Tant les dades estructurals obtingudes per difracció de Raigs X, com les de RMN de tots aquests compostos, donen evidència de la flexibilitat del lligand (1) que adapta la seva forma de coordinació k2 o k3 i la seva configuració fac o mer a la situació electrònica i estèrica al voltant de l'àtom de Rh(I).4
La reacció del lligand 1-[(P-difenil)-2-fosfinoetil]-3,5-dimetilpirazole (2) i del lligand anàleg N-N' 1-[(N-etil)-2-aminoetil]-3,5-dimetilpirazole (1) amb [Rh(COD)(THF)2][BF4], dóna lloc als complexos [Rh(COD)(2)][BF4] (4) i [Rh(COD)(1)][BF4] (3). La substitució del lligand COD en els complexos 3 i 4, per CO dóna lloc als complexos [Rh(CO)2(1)][BF4] (5) i [Rh(CO)2(2)][BF4] (6). La reacció del complex [Rh(COD)(THF)2][BF4] en proporció M/L 1/2 amb el lligand 2 N-P dóna lloc al complex [Rh(2)2][BF4] (7) que presenta les dues molècules del lligand en disposició cis en una geometria pla-quadrada entorn del Rh(I). Bombollejant CO en una solució del complex (7), s'obté el complex [Rh(CO)(2)2][BF4] (8) que consisteix en un àtom de Rh(I) amb un entorn pla-quadrat amb els dos àtoms de fòsfor en disposició trans, on un dels lligands 2 està coordinat de forma didentada, mentre que l'altre ho està de forma monodentada.5
El lligand 1-[(P-difenil)-2-fosfinoetil]-3,5-dimetilpirazole (1), desplaça la trifenilfosfina del complex [RuCl2(PPh3)3] per formar els complexos [RuCl2(PPh3)(1)] (2) o [RuCl2(1)2] (3), depenent de si es treballa en proporció M/L 1/1 o 1/2 respectivament. Quan es porta a terme la reacció del complex 2 de 16e- amb acetilens, aquest descomposa. Mentre que quan es porta a terme la mateixa reacció però amb el complex 3 de 18e-, s'obtenen els metal·locumulens [RuCl(1)2(C=C=CPhCH3)][BF4] (4), [RuCl(1)2(C=C=CPh2)][BF4] (5) i [RuCl(1)2(C=CHPh)][PF6] (6). De la resolució de l'estructura cristal·lina per difracció de Raigs X del complex 5, s'obté una cel·la unitat que conté dos enantiòmers.6

1. Esquius, G.; Pons, J.; Yáñez, R.; Ros, J.; Solans, X.; Font-Bardía, M. J. Organomet. Chem. 2000, 605, 226.
2. Esquius, G.; Pons, J.; Yáñez, R.; Ros, J.; Solans, X.; Font-Bardia, M. Acta Cryst. 2002, C58, m133.
3. Esquius, G.; Pons, J.; Yáñez, R.; Ros, J. J. Organomet. Chem. 2001, 619, 14.
4. Mathieu, R.; Esquius, G.; Lugan, N.; Pons, J.; Ros, J. Eur. J. Inorg. Chem. 2001, 2683.
5. Esquius, G.; Pons, J.; Yáñez, R.; Ros, J.; Mathieu, R.; Donnadieu, B.; Lugan, N. Eur. J. Inorg. Chem. 2002, a la impremta.
6. Esquius, G.; Pons, J.; Yáñez, R.; Ros, J.; Mathieu, R.; Donnadieu, B.; Lugan, N. J. Chem. Soc., Dalton Trans. En preparació.
The new ligands 3,5-dimethyl-4-(ethylamino)methylpyrazole (HL1) and 3,5-dimetil-4-(isopropylamino)methylpyrazole (HL2), are able to coordinate to Rh(I) in a exodidentate mode, and to form "zwitterionic" species pyrazolate-ammonium. The crystal structures of dinuclear complexes [Rh(HL1)(COD)]2Cl2 and [Rh(HL2)(COD)]2Cl2 confirm the square-planar geometry of Rh(I) atoms, which are coordinated to a chelated COD ligand and to two pyrazolate ligands. The reaction of the ligands previously deprotonated (L1 and L2) with Rh(I) results in neutral complexes [Rh(L1)(COD)]2 and [Rh(L2)(COD)]2. The ionic complexes as well as the neutral ones, react with carbon monoxide to give the complexes [Rh(HL1)(CO)2]2Cl2, [Rh(HL2)(CO)2]2Cl2, [Rh(L1)(CO)2]2 and [Rh(L2)(CO)2]2. All the complexes synthesized are soluble in polar solvents such as water but insoluble in saturate hidrocarbons.1, 2
New didentate (NN') and tridentate (NN'N) 1-aminoalkylpyrazoles react with [RhCl(COD)]2 to give [Rh2Cl2(L)(COD)2] (L=NN' or NN'N) complexes. The NMR spectra and molar conductances of these complexes suggested the presence of an equilibrium in solution between 1:1 electrolyte species [Rh(L)(COD)]+ [RhCl2(COD)]- and a neutral molecular form [Rh(COD)Cl][m-(L)][Rh(COD)Cl]. Electrospray mass spectrometry study confirmed the presence of ionic species [Rh(L)(COD)]+[RhCl2(COD)]-.3
The reaction of bis[(3,5-dimethyl-1-pyrazolyl)methyl]ethylamine (1) ligand with [Rh(COD)(THF)2][BF4] results in [Rh(COD)(1)][BF4] complex, which was treated with CO to obtain [Rh(CO)2(1)][BF4] and [Rh(CO)(1)][BF4] complexes. The NMR spectra and the structures of these complexes reveal that 1 is a very flexible ligand which adapts its bonding mode (k2 or k3) and its configuration (fac or mer) to various electronic and steric situations around Rh(I).4
The reaction of 1-[(P-diphenyl)-2-phosphinoethyl]-3,5-dimethylpyrazole (2) and the related N-N' didentade ligand 1-[(N-ethyl)-2-aminoethyl]-3,5-dimethylpyrazole (1) with [Rh(COD)(THF)2][BF4], leads to the complexes [Rh(COD)(2)][BF4] (4) and [Rh(COD)(1)][BF4] (3). The 1,5-COD ligand in complexes 3 and 4 can easily be displaced by carbon monoxide leading to the complexes [Rh(CO)2(1)][BF4] (5) and [Rh(CO)2(2)][BF4] (6). The reaction of two equivalents of 2 with complex [Rh(COD)(THF)2][BF4] leads to [Rh(2)2][BF4] (7) in which the two molecules of 2 ligand are in cis position. Complex (7) reacts with CO to give complex [Rh(CO)(2)2][BF4] (8) which presents a square-planar structure with the two phosphorus atoms in trans position and only one of the two ligands 2 is k2 coordinated, the second one being k1 coordinated by the phosphorus atom to rhodium.5
The didentate ligand 1-[(P-diphenyl)-2-phosphinoethyl]-3,5-dimethylpyrazole (1) forms, depending on the stoichiometry of reactants, the [RuCl2(PPh3)(1)] (2) or [RuCl2(1)2] (3) complexes by reaction with [RuCl2(PPh3)3]. Complex 2 decomposes by reaction with acetylene derivates. Reaction of complex 3 with terminal alkynes leads to the formation of new cationic metallacumulenes: [RuCl(1)2(C=C=CPhCH3)][BF4] (4), [RuCl(1)2(C=C=CPh2)][BF4] (5) and [RuCl(1)2(C=CHPh)][PF6] (6). The crystal structure of complex 5 consists of two independent ion pairs per unit cell, whose cation corresponds to two enantiomers.6

1. Esquius, G.; Pons, J.; Yáñez, R.; Ros, J.; Solans, X.; Font-Bardía, M. J. Organomet. Chem. 2000, 605, 226.
2. Esquius, G.; Pons, J.; Yáñez, R.; Ros, J.; Solans, X.; Font-Bardia, M. Acta Cryst. 2002, C58, m133.
3. Esquius, G.; Pons, J.; Yáñez, R.; Ros, J. J. Organomet. Chem. 2001, 619, 14.
4. Mathieu, R.; Esquius, G.; Lugan, N.; Pons, J.; Ros, J. Eur. J. Inorg. Chem. 2001, 2683.
5. Esquius, G.; Pons, J.; Yáñez, R.; Ros, J.; Mathieu, R.; Donnadieu, B.; Lugan, N. Eur. J. Inorg. Chem. 2002, in press.
6. Esquius, G.; Pons, J.; Yáñez, R.; Ros, J.; Mathieu, R.; Donnadieu, B.; Lugan, N. J. Chem. Soc., Dalton Trans. In preparation.

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

Orientador: Regina Buffon
Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica
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Mestrado

La present tesi doctoral està adreçada al desenvolupament de catalitzadors que permetin dur a terme processos sintètics de manera més eficient i sostenible. Es presenten dues noves famílies de catalitzadors suportats, ambdues pertanyents al grup de complexos organometàl·lics moleculars immobilitzats sobre un suport sòlid. La primera família inclou complexos de Pd amb lligands carbè N-heterocíclic monodentats de gran impediment estèric, immobilitzats sobre òxids inorgànics, com ara sílicas, alúmina o òxid de titani. Aquesta família de catalitzadors es va aplicar en dos tipus de reaccions: i) reaccions d'acoblament C-C i ii) semireducción d'alquins. Entre les reaccions d'acoblament esmentades, els complexos de [Pd (NHC)] immobilitzats es van aplicar a les reaccions de Suzuki, Heck i Sonogashira, i es van avaluar en base a la seva activitat, selectivitat i reciclabilitat. A més, en el cas de les reaccions de Suzuki i Sonogashira, aquests catalitzadors també es van aplicar en condicions de flux continu. L'aplicació d'aquesta família de catalitzadors en la semireducció selectiva d'alquins es va dur a terme utilitzant dues metodologies diferents: utilitzant hidrogen molecular, o bé utilitzant el sistema trietilamina / àcid fòrmic com donador de H (condicions de transferència d'hidrogen). La segona família de catalitzadors suportats contempla complexos de Rh (I) estabilitzats amb lligands bidentats de tipus carbé N-heterocíclic, amb quiralitat axial, i funcionalitzats amb un grup piré. La immobilització d'aquests complexos de Rh sobre la superfície de nanotubs de carboni "multi-walled" va tenir lloc mitjançant interaccions de tipus "pi-pi stacking" entre la superfície dels nanotubs i el grup piré present en el lligand. Finalment, es presenten els resultats obtinguts en l'aplicació d'aquests complexos de Rh en diversos processos catalítics.
La presente tesis doctoral se centra en el desarrollo de catalizadores que permitan llevar a cabo procesos sintéticos de manera más eficiente y sostenible. Se presentan dos nuevas familias de catalizadores soportados, ambas pertenecientes al grupo de complejos organometálicos moleculares inmovilizados sobre un soporte sólido. La primera familia incluye complejos de Pd con ligandos carbeno N-heterocíclico monodentados de gran impedimento estérico, inmovilizados sobre óxidos inorgánicos, como sílicas, alúmina u òxido de titanio. Esta familia de catalizadores se aplicó en dos tipos de reacciones: i) reacciones de acoplamiento C-C y ii) semireducción de alquinos. Entre las reacciones de acoplamiento mencionadas, los complejos de [Pd(NHC)] inmovilizados se aplicaron en las reacciones de Suzuki, Heck y Sonogashira, y se evaluaron en base a su actividad, selectividad y reciclabilidad. Además, en el caso de las reacciones de Suzuki y Sonogashira, estos catalizadores también se aplicaron en condiciones de flujo continuo. La aplicación de esta familia de catalizadores en la semireducción selectiva de alquinos se llevó a cabo utilizando dos metodologías diferentes: utilizando hidrógeno molecular, o bien utilizando el sistema trietilamina/ácido fórmico como dador de H (condiciones de transferencia de hidrógeno). La segunda familia de catalizadores soportados contempla complejos de Rh(I) estabilizados con ligandos bidentados de tipo carbeno N-heterocíclico, con quiralidad axial, y funcionalizados con un grupo pireno. La inmovilización de estos complejos de Rh sobre la superficie de nanotubos de carbono "multi-walled" tuvo lugar mediante interacciones de tipo "pi-pi stacking" entre la superficie de los nanotubos y el grupo pireno presente en el ligando. Finalmente, se presentan los resultados obtenidos en la aplicación de estos complejos de Rh en varios procesos catalíticos.
The present PhD thesis aims at contributing to the development of more efficient and sustainable synthetic processes through catalysis. In this regard, two families of new solid-supported catalysts are presented. Both families belong to the group of molecularly defined organometallic complexes immobilized onto a solid support. The first family includes Pd complexes of sterically hindered monodentate N-Heterocylic Carbene ligands supported onto inorganic oxide materials, namely silicas, alumina and titania. This family of catalysts was applied in two types of reactions: i) C-C cross-couplings and ii) semireduction of alkynes. Among cross-coupling reactions, the supported [Pd(NHC)] complexes could be applied in Suzuki, Heck and Sonogashira couplings and their performance was assessed in terms of activity, selectivity and reusability. For the Suzuki and Sonogashira couplings, the catalysts were also appied under continuous flow conditions. The application of this family of catalysts in the selective reduction of alkynes was carried out following two different methodologies: using hydrogen gas, or using triethylamine/formic acid as the H-donor system (transfer hydrogenation conditions). The second family of solid-supported catalysts features Rh(I) complexes bearing axially chiral bidentate N-Heterocyclic carbene ligands functionalized with a pyrene moiety. Immobilization of these Rh complexes onto the surface of multi-walled carbon nanotubes was achieved by means of "pi-pi stacking interactions" between the surface of the nanotubes and the pyrene moiety present in the ligand. Results obtained from the application of these complexes as catalysts in various reactions are presented.

Os catalisadores imobilizados foram preparados misturando-se o ligante Cp’, [C5Me4(n-propyl-Si(OEt)3)], com RhCl3.xH2O e, em seguida, por reação com sílica Aerosil 200 (sistema A) ou por copolimerização com TEOS (sistema B). Ambos os sistemas foram aplicados na hidrogenação de olefinas e mostraram-se altamente ativos e robustos, permitindo um grande número de reciclagens (NR = 1,0 ×105, sistema A e 2,0 ×104, sistema B). As técnicas de caracterização (IV-DRIFTS, 13C-CPMAS, e MET) indicaram que as espécies ativas eram de natureza molecular. Os experimentos de deuteração mostraram a presença de complexos tetra-hapto-Cp’-Rh na superfície da sílica durante os testes catalíticos. O sistema Cp’/ Rh+3 em fase homogênea também se mostrou ativo na hidrogenação de olefinas, permitindo 25 recargas de substrato (NR = 1,2 ×104). Entretanto, os espectros de RMN (1H and 13C) em fase líquida revelaram-se complexos, em desacordo com o que seria esperado para o dímero [Rh(η5-Cp(Me)4(n-propyl)- Si(OR)3)Cl(μ-Cl)]2. Os espectros no IV em estado sólido mostraram bandas que indicaram a formação de ligações siloxano. Essas informações, adicionadas à observação de sólidos de cor marrom, tanto na etapa de síntese quanto após as reações de catálise, indicaram que os grupos alcoxila do ligante sofreram condensações, que podem ter sido promovidas tanto por ácidos de Lewis (Rh+3) quanto por ácido de Arrhenius (HCl proveniente do RhCl3.xH2O).
Immobilized catalysts were prepared by mixing the ligand Cp’, [C5Me4(n-propyl- Si(OEt)3)], with RhCl3.xH2O for subsequent reaction with silica Aerosil 200 (system A) or by copolymerization with TEOS (system B). Both systems were applied on olefin hydrogenation, showing high activity and robustness, allowing for many recycles (TON = 1.0 ×105 for system A and 2.0 ×104 for system B). The characterization techniques (IRDRIFTS, 13C-CPMAS, and TEM) suggest a molecular nature for catalytic species. According to the deuteration experiment, a tetra-hapto-Cp’-Rh would be formed on the surface during the catalytic runs. Homogeneously, the Cp’/ Rh+3 system proved also to be active on 1-hexene and 1,7-octadiene hydrogenation, allowing for 25 recharges of substrate (TON = 1.2 x 104). However, NMR techniques (1H and 13C) in liquid state (DMSO-d6) showed complex spectra in discordance of a simple molecular structure anticipated for the dimer [Rh(η5- Cp(Me)4(n-propyl)-Si(OR)3)Cl(μ-Cl)]2. Infrared spectroscopy in solid state reveals bands that would be ascribed to siloxanes bonds formation. This information, together with the observation of brown solids either during the syntheses or after catalysis reaction, indicated that the ligand has polymerized, which may occured by the assistance of acids (Lewis acid, Rh+3 and Arrhenius acid, HCl evolved from RhCl3.xH2O).

La síntesi i caracterització estructural d'un nou tipus de macrocicles nitrogenats de 15, 20 i 25 membres, els quals contenen triples i dobles enllaços i diferents unitats aríliques a la seva estructura, ha estat estudiada. S'han preparat els complexos de pal·ladi(0) dels corresponents macrocicles poliinsaturats de 15 membres, els quals són estables a l'aire i a la humitat i en alguns casos presenten quiralitat. La seva caracterització completa s'ha portat a terme mitjançant RMN i difracció de raigs-X. S'ha estudiat també la reacció de cicloisomerització d'aquests macrocicles emprant diferents catalitzadors basats en metalls de transició, observant-se que el catalitzador de Wilkinson, de rodi(I), és el que ha donat més bons resultats. Finalment, s'ha realitzat una introducció a l'estudi del mecanisme d'aquest tipus de reaccions mitjançant ESI-MS, així com també un estudi inicial de la reacció de cicloisomerització enantioselectiva.
The synthesis and structural analysis of a new type of 15-, 20- and 25-membered nitrogen-containing polyunsaturated macrocycles has been carried out. Palladium(0) complexes of 15-membered polyunsaturated azamacrocycles, which are air and moisture stable and in some cases present chirality, has been prepared and fully caracterized by means of NMR spectroscopy and X-ray diffraction. The cycloisomerization reaction of these macrocycles using different catalysts based in different transition metals has been studied. It was observed that Wilkinson's catalyst (rhodium(I) catalyst) gave the best results. A brief look at the mechanism of cyclotrimerization reaction by means of ESI-MS has been carried out. Finally, an introduction in the study of the enantioselective cycloisomerization reaction of these macrocycles has been done.

En la presente memoria se describe el estudio sobre la preparación y reactividad de derivados carbocíclicos de litio, y la preparación y reactividad de derivados de carbenos N-heterocíclicos de paladio y de rodio. En el primer capítulo se estudia la reacción de litiación del clorometilciclopropano y del bromometilciclobutano empleando litio metálico y una cantidad subestequiométrica de un areno, y la posterior reacción de los intermedios de litio generados con distintos compuestos carbonílicos. El uso de DTBB (4,4’-di-terc-butilbifenilo) en THF a –78 oC y en presencia del electrófilo (condiciones de reacción tipo Barbier) dio lugar, tras hidrólisis, a los correspondientes cicloalquilmetilalcanoles. Por el contrario, llevando a cabo el proceso de litiación con naftaleno en dietil éter a 0 ó 25 oC, el intermedio de litio sufre reordenamiento hacia el derivado homoalil-litio o bishomoalil-litio. La posterior reacción con compuestos carbonílicos permite la preparación de alcoholes insaturados. En el segundo capítulo se estudia en primer lugar la preparación de sales de imidazolio funcionalizadas con un grupo hidroxilo, por apertura de epóxidos con imidazol y posterior reacción con haluros de alquilo. A continuación, estas sales se han empleado en la preparación de complejos metálicos de paladio y rodio con un ligando carbeno N-heterocíclico. Los complejos, bien definidos, biscarbénico de paladio [(NHC)2PdCl2] y monocarbénico de rodio [(NHC)Rh(COD)Cl] han sido preparados por metalación directa empleando precursores básicos tanto de paladio como de rodio. Finalmente, se ha estudiado la actividad catalítica de estos complejos en diferentes procesos. El complejo de paladio se ha empleado en la reacción de acoplamiento de Hiyama, en ausencia de fluoruros y por irradicación en microondas, de diferentes (trialcoxi)arilsilanos con bromuros y cloruros de arilo. También se estudio la reacción de acoplamiento de Heck-Matsuda, catalizada por NHC-Pd, de diferentes tetrafluoroboratos de bencenodiazonio con acrilatos, acrilamida, estireno y ciclohexeno. Por otra parte, el complejo de NHC-Rh se ha mostrado activo en la reacción de adición conjugada de ácidos arilborónicos a cetonas α,β-insaturadas.

la primera parte de la memoria consiste en la preparacion
de los ligandos quirales diosr2 la segunda y tercera
parte tratan sobre la preparacion y caracterizacion de
nuevos complejos de rodio (i) con los ligandos ditiolato
y ditioeter asi como el estudio de su reactividad frente
a monoxido de carbono y ligandos fosforados. en la cuarta
parte se estudia la hidroformilacion asimetrica de
estireno utilizando los complejos de rodio (i)
preparados. el complejo (rh2(dios)(cod)2) es un precursor
activo, si bien los excesos enantiomericos obtenidos son
bajos. la utilizacion del par (-)-dios/ (+)-bdpp da lugar
a un 34% de exceso enantiomerico. se han utilizado otros
complejos como precursores. los mejores resultados se
obtienen con (rh(ome)(cod))2/4 (+)-bdpp con el que se
alcanza un 52% de exceso enantiomerico. la ultima parte
trata sobre la hidroformilacion asimetrica de otros vinil
arenos utilizando el sistems precursor que mejores
resultados habia dado en la hidroformilacion de estireno.

con este sistema se alcanzan regioselectividades en el
aldehido ramificado de 95-97% y excesos enantiomericos de
hasta el 65%.

La hidrogenación catalítica asimétrica es uno de los métodos más importantes en síntesis orgánica. Este proceso permite acceder a importantes productos quirales a escala multigramo utilizando hidrógeno (que es barato) y pequeñas cantidades de catalizador. Dichas hidrogenaciones requieren el empleo de complejos metálicos que contienen ligandos quirales y se presentan como un método muy atractivo desde el punto de vista de la economía atómica. Hasta el momento, se han descrito una amplia variedad de ligandos quirales empleados en la hidrogenación enantioselectiva. En nuestro grupo de investigación, existe una larga trayectoria de trabajo en este campo y recientemente se han diseñado y sintetizado ligandos con quiralidad en el átomo de fósforo, siendo la aminodifosfina MaxPHOS uno de los ejemplos. El complejo Rh-MaxPHOS ha ofrecido excelentes excesos enantioméricos en la hidrogenación asimétrica de a y ß dehidro aminoácidos. Estos buenos resultados abrían la puerta a una exploración más detallada sobre la capacidad de hidrogenación de este complejo ante diversos tipos de sustratos. Así, el primer objetivo de la presente tesis doctoral consistió en ampliar el alcance de este catalizador en una galería de N-acil-enamidas (ß-cetoenamidas. enamidas cíclicas tri-sustituidas y a-heteroarilenamidas) que posteriormente dieran lugar a aminas quirales con interés farmacológico. Por otro lado, el complejo Rh-MaxPHOS fue aplicado por primera vez a la reacción de Pauson-Khand intramolecular de una forma satisfactoria obteniendo moderados rendimientos (30-70%) y elevadas purezas ópticas (hasta un 86%) para diversos 1,6-eninos. Por consiguiente, se pensó en preparar otros compuestos metálicos con la misma aminodifosfina. Concretamente, se consideró en coordinar la difosfina MaxPHOS con iridio como metal y aplicar el compuesto en catálisis asimétrica. Específicamente, se aplicó en la hidrogenación asimétrica de enlaces C=C (olefinas trisustituidas con grupo polar adyacente) y C=N (iminas), donde la hidrogenación con rodio no permite reducir u obtener los productos finales deseados con elevada pureza óptica. En el marco del estudio de la hidrogenación asimétrica con nuestro catalizador quiral Rh-MaxPHOS, se decidió extender esta metodología a otro tipo de compuestos que, a su vez, también dieran lugar a productos de interés farmacológico. El grupo de la profesora Escubedo estaba interesada en el estudio de los efectos biológicos de cada enantiómero del MDMA, más conocido como éxtasis (3,4-metilenedioximetanfetamina), para analizar su interacción en los receptores nicotínicos acetilcolina. Teniendo en cuenta los buenos resultados obtenidos con el complejo Rh-MaxPHOS en la hidrogenación de varios tipos de sustratos, se planteó una colaboración en la que propusimos una síntesis asimétrica mediante la hidrogenación enantioselectiva de ß-aril-enamidas catalizada por el complejo de rodio (I) Rh-7. Desafortunadamente, esta ruta sintética no ofreció buenos resultados y se buscó una vía alternativa. Con este propósito, visualizamos una nueva y eficiente síntesis de ambos enantiómeros del MDMA basada en una reducción diastereomerica de iminas derivadas de la terc-butilsulfinamida ópticamente pura, que proporciona un simple y práctico método de obtener ambos enantiómeros del MDMA. Otra aplicación en catálisis asimétrica con el complejo Rh-7, se basó en llevar a cabo una nueva síntesis del ácido 2-aminosubérico, teniendo como etapa clave la hidrogenación enantioselectiva. El ácido 2-aminosubérico se ha utilizado en la síntesis de análogos de péptidos bioactivos como la oxitocina, vasopresina, somatostatina o calcitonina como cadena metilénica metabólicamente estable en la sustitución del puente disulfuro entre cisteínas. En este sentido, una de las líneas abiertas en nuestro grupo de investigación es la síntesis de derivados de somatostatina. Así, nos planteamos el diseño y efectuamos una síntesis de péptidos análogos de somatostatina mediante la introducción del ácido 2-aminosubérico en sustitución del puente disulfuro en la cadena peptídica, manteniendo otros aminoácidos no naturales en la secuencia que habían ofrecido una elevada actividad biológica. También, quisimos estudiar la importancia de la longitud de la cadena metilénica en este péptido cíclico. Así, sintetizamos otro análogo peptídico mediante la introducción de un aminoácido natural comercialmente disponible (Fmoc-D-Glutámico) en lugar del ácido 2-aminosubérico y de este modo, comparamos sus estructuras por RMN.
Asymmetric catalytic hydrogenation is one of the most important methodologies in organic synthesis. This process allows significant access to multi-gram scale chiral products using inexpensive hydrogen and low catalyst loadings. Such hydrogenations require the use of metal complexes containing chiral ligands, which are attractive in terms of atomic economy. So far a variety of chiral ligands have been described and used in enantioselective hydrogenations. In our research group, there is a long history of work in this field and we have recently designed and synthesized ligands with chirality at the phosphorus atom; aminodiphosphine MaxPHOS being one example. The Rh-complex with MaxPHOS ligand (Rh-7) has offered excellent enantiomeric excesses (ee) in the asymmetric hydrogenation of a and ß dehydroaminoacids. These promising results opened the door to a more detailed hydrogenation study of this complex with various types of substrates. The first objective of this thesis was to expand the scope of this catalyst to different N-acyl enamides (ß-ketoenamides, cyclic tri-substituted enamides and a-heteroarylenamides) which subsequently give rise to chiral amines of pharmacological interest. Furthermore, the Rh-MaxPHOS complex was for first time applied to the intramolecular Pauson-Khand reaction satisfactorily obtaining moderate yields (30-70%) and high optical purity (up to 86%) for various 1,6 -enines. Therefore, other metal compounds with the same aminodiphosphine were prepared. Specifically, it coordinated to iridium and applied in asymmetric catalysis. It was then applied in the asymmetric hydrogenation of C = C (tri-substituted olefins with adjacent polar group) and C = N (imines), where the hydrogenation with rhodium fails to reduce the desired final products with high optical purity. Under the study of the asymmetric hydrogenation with our chiral catalyst Rh-MaxPHOS (Rh-7), it was decided to extend this approach to other types of compounds which, in turn, also gave rise to products of pharmacological interest. The group of the professor Elena Escubedo was interested in the study of the biological effects of each enantiomer of MDMA, known as ecstasy (3,4-methylenedioxymethamphetamine), to analyze their interaction in the nicotinic acetylcholine receptors. Taking into account the promising results obtained with the Rh-7 complex in the hydrogenation of various types of substrates, a partnership in which we proposed an asymmetric synthesis by enantioselective hydrogenation of ß-aryl-enamides catalyzed by rhodium complex was proposed employing Rh-7. Unfortunately, this synthetic route did not offer good results and an alternative route was sought. For this purpose, we envisioned a new and efficient synthesis of both enantiomers of MDMA based optically pure diastereomeric reduction of imines derived from tert-butylsulfinamide, which provides a simple and practical method of obtaining both enantiomers of MDMA. Another application in asymmetric catalysis with Rh-7 complex was based on performing a new synthesis of 2-aminosuberic acid, with the key enantioselective hydrogenation stage. 2-aminosuberic acid has been used in the synthesis of analogues of bioactive peptides such as oxytocin, vasopressin, somatostatin, or calcitonin as a metabolically stable methylene chain in the replacement of the disulfide bridge between cysteines. In this sense, one of the open lines in our research group is the synthesis of analogues of somatostatin. Thus, we designed and synthesized analogues of somatostatin peptides with 2-aminosuberic acid replacing the disulfide bridge in the peptide chain, keeping other unnatural amino acids in the sequence that had previously displayed a high biological activity. Also, we wanted to study the importance of the methylene chain length of this cyclic peptide. Thus, another peptide analog was synthesized by introducing a commercially available natural amino acid (Fmoc-D-Glutamic acid) instead of 2-aminosuberic acid and we compared their structures by NMR.

Ce mémoire présente une analyse de la réponse tribologique d’un contact cylindre/plan soumis à des sollicitations de fretting sous chargement complexe, à savoir une sollicitation normale de force sinusoïdale et une sollicitation tangentielle de déplacement sinusoïdal, toutes deux possiblement sujettes à des fluctuations d'amplitude, de fréquence et de déphasage entre sollicitations. On s'intéresse plus particulièrement à l’usure des guides de grappe en 304L par les crayons en 316L nitrurés, induite par les vibrations de l’écoulement du fluide primaire dans les réacteurs nucléaires.L’étude expérimentale menée dans un environnement non représentatif mais très simple, à savoir un milieu sec et à l'ambiante, montre une usure non négligeable des deux contre-corps ce qui révèle les propriétés fragiles du tube nitruré dans cet environnement. Une très forte dépendance des faciès d’usure avec l’amplitude de glissement est notée. Seule la cinétique d’usure du tube nitruré est influencée par l'évolution de la charge normale. Aussi, une description analytique de l’énergie de frottement est développée, en prenant compte de l’ensemble des paramètres de chargement.En solution aqueuse lithium-bore, choix de milieu un peu plus représentatif mais en restant néanmoins à l'ambiante, seul le plan en acier 304L s’use, le cylindre en acier 316L nitruré n’étant pas sujet à de l'usure détectable. Un couplage avec des phénomènes corrosifs est proposé. En fretting simple, le confinement du contact augmente localement la valeur du pH et l’analyse de l’influence de la fréquence de fretting suggère que seule la couche passive est usée entre chaque glissement. Sous chargement complexe, la fluctuation de la charge normale permet une meilleure accessibilité de la solution dans l’interface frottée, augmentant localement les effets tribocorrosifs. Une loi d’usure multiplicative prenant en compte les différents effets de fluctuation des sollicitations est introduite et sa stabilité est vérifiée.Un modèle de calculs par éléments finis permet de simuler les profils d’usure en fretting simple et aussi en présence de force normale variable. En fretting simple, les résultats de simulation d'essais où seul le plan 304L s'use sont satisfaisants. En revanche, la non-superposition des profils expérimentaux et numériques lorsque la force normale fluctue confirme la présence de phénomènes physiques dans l'interface non encore représentés dans l'outil numérique
This PhD thesis presents an analysis of the fretting wear of a cylinder/plane contact subject to complex loading conditions, namely a normal sinusoidal force solicitation and a tangential sinusoidal displacement, both possibly subject to fluctuations in amplitude, frequency and phase shift between signals. The purpose of this work is to study the wear of 304L cluster guides by nitrided 316L rods due to flow-induced vibrations of primary fluid in nuclear reactors.Firstly, the experimental study conducted in a dry and ambient temperature - a non-representative but very simple environment - shows significant wear of both counter-bodies, which reveals the fragile properties of the nitrided tube in this environment. A very strong dependence of the fretting scar morphology with the sliding amplitude is noted. Only the wear kinetics of the nitrided tube is influenced by the evolution of the normal load. Also, an analytical description of friction energy is developed, taking into account all loading parameters.In a second hand, in aqueous lithium-boron solution, a slightly more representative choice of medium but still remaining in the ambient, only the 304L steel plane wears out, the 316L nitrided steel cylinder is not subject to detectable wear. A coupling with corrosive phenomena is proposed. In simple fretting, contact confinement locally increases the pH value. Moreover, the analysis of the influence of the fretting frequency suggests that only the passive layer is worn between each slip. Under complex loading, the fluctuation of the normal load allows a better accessibility of the solution in the rubbed interface, increasing locally the tribocorrosive effects. A multiplicative wear law taking into account the various effects of normal force fluctuation is introduced and its stability is checked.Finally a finite element calculation model is used to simulate wear profiles in simple fretting and also in the presence of variable normal force. Only cases where the plan wears out (lithium-boron environment) have been simulated. In simple fretting, test simulation results are satisfactory. On the other hand, the non-superposition of the experimental and numerical profiles when the normal force fluctuates, confirms the presence of physical phenomena in the interface which are not yet represented in the numerical tool

La memoria de tesis titulada “Inmovilización de complejos organometálicos en soportes sólidos para aplicación en catálisis” presenta una serie de trabajos encaminados a la obtención de catalizadores híbridos, que sean estables, activos, selectivos y reutilizables en reacciones de hidrogenación e hidroformilación de olefinas. Para ello, se han estudiado diversos métodos para inmovilizar complejos metálicos en materiales carbonosos y sólidos inorgánicos: adsorción física, anclaje por formación de un enlace covalente e intercambio iónico. Estos catalizadores se han usado en las reacciones mencionadas, analizando sus propiedades catalíticas (actividad y selectividad), así como la robustez de los mismos y las posibilidades de reutilización.

This dissertation comprises three parts and is presented in two chapters. Chapter 1 concerns Arthrobacter, a bacterium with an intriguing growth cycle. Whereas most bacteria exist as either a rod or coccus, this bacterium shares the rod/coccus lifestyle. It therefore seemed important to examine the growth regulatory pathways from the rod and coccus. The committed step, that catalyzed by aspartate transcarbamoylase (ATCase), in the pyrimidine biosynthetic pathway was chosen. The ATCase in Arthrobacter is like the well known Pseudomonas enzyme except that it has an active dihydroorotase (DHOase) associated. Included in Chapter 1 is the description of a microorganism, Burkholderia cepacia, whose ATCase has characteristics that are at once reminiscent of bacteria, mammals, and fungi. It differs in size or aggregation based on environmental conditions. In addition, it has an active DHOase associated with the ATCase, like Arthrobacter. B. cepacia is important both medically and for bioremediation. Since B. cepacia is resistant to most antibiotics, its unique ATCase is a prime target for inhibition. Whereas the first chapter deals with the de novo pathway to making pyrimidines, which is found mainly in the lag and log phase, Chapter 2 addresses the salvage pathway, which comes more into play during the stationary phase. This section focuses on the isolation, identification, and grouping of a number of natural soil bacteria from various soil locations. These organisms are important agriculturally, medically, and industrially. Addition of these soil isolates to poor soils has been found to improve the soil. In a previous study by D.A. Beck, the salvage schemes for a number of laboratory strains of microorganisms were determined. Nine separate classes of salvage were designated by determining the salvage enzymes present. In this study emphasis has been placed on soil bacteria, which had not previously been analyzed. A number of species of soil bacteria were identified using the MIDI. The salvage enzymes were then determined for these organisms and a comparison of these isolates to the previous study was performed in order to group the new organisms into 19 salvage schemes, that is 10 more than in the previous study.

La tête de bielle n'est pas un solide mono-corps mais un solide multi-corps. Le serrage non-adapté des vis d'assemblage et les discontinuités des solides peuvent produire des phénomènes indésirables comme le glissement du coussinet dans son logement. Malgré des logiciels de calculs performants permettant de prédire le comportement des paliers il existe encore de nombreuses avaries notamment liées aux contacts entre le coussinet et son logement. La difficulté de la modélisation du contact coussinet/logement réside principalement dans l'interaction entre les différents solides et les conditions de fonctionnement. Cette étude propose une solution pour analyser ce problème par couplage entre un logiciel de calcul élatohydrodynamique (ACCEL) et un logiciel permettant le calcul du contact avec frottement entre les coussinets et le corps de bielle (ABAQUS). Après une étude bibliographique des études antérieures dédiées à la modélisation numérique et expérimentale des paliers de tête de bielle, la première partie est dédiée à une description des modèles numériques utilisés pour prédire le comportement élastohydrodynamique de paliers lubrifiés ainsi que les techniques employées pour étudier le contact sec avec frottement en mécanique. La deuxième partie présente la solution adoptée pour réaliser le couplage entre le logiciel ACCEL et le logiciel ABAQUS. Le modèle a été premièrement validée dans le cas d'un palier soumis une charge tournante. Par la suite, plusieurs calculs paramétriques, réalisés sur un cas type de palier de tête de bielle, nous ont permis de montrer l'influence des conditions de fonctionnement (diagramme de charge, vitesse de rotation, etc.) ainsi que d'autres caractéristiques de la bielle (coefficient de frottement, épaisseur du coussinet, etc) sur le comportement du palier et plus précisément sur le glissement relatif entre les coussinets et le corps de bielle
The connecting rod is not a single body but a multi-body solid. A non-appropriate screw tightening, coupled with the solid discontinuities, can lead to undesirable phenomena such as the rotation of the shell in its housing. Despite modern numerical tools, capable to predict the bearing EHD behaviour, there are still many damages related to cumulative microslip between the bearing shell and the conrod body. The difficulty of modelling the shell/conrod contact is mainly due to the interaction between the solids and the operating conditions. This study presents a solution to analyse this problem, by coupling an elastohydrodynamic (EHD) software (ACCEL) with a commercial software (ABAQUS) able to predict the frictional contact between the shell and the conrod. After a literature review of previous studies dedicated to the numerical and experimental modelling of connecting rod bearings, the first part is dedicated to a description of the numerical models used to predict the EHD behaviour of lubricated bearings. Follows the presentation of the techniques used to study the dry frictional contact mechanics. The next part presents the adopted solution used to couple the two software. The model was first validated in the case of a bearing submitted to a rotating load. Subsequently, several parametric calculations are presented. We were able to show the influence of the operating conditions (load diagram, velocity,...) as well as other characteristics of the conrod (friction coefficient, thickness of the shell, etc.) on the performances of the bearing and more exactly on the microslip between the shells and the conrod body

Today, the main research field for the automotive industry is to find solutions for active safety. In order to perceive the surrounding environment, tracking nearby traffic objects plays an important role. Validation of the tracking performance is often done in staged traffic scenarios, where additional sensors, mounted on the vehicles, are used to obtain their true positions and velocities. The difficulty of evaluating the tracking performance complicates its development. An alternative approach studied in this thesis, is to record sequences and use non-causal algorithms, such as smoothing, instead of filtering to estimate the true target states. With this method, validation data for online, causal, target tracking algorithms can be obtained for all traffic scenarios without the need of extra sensors. We investigate how non-causal algorithms affects the target tracking performance using multiple sensors and dynamic models of different complexity. This is done to evaluate real-time methods against estimates obtained from non-causal filtering. Two different measurement units, a monocular camera and a LIDAR sensor, and two dynamic models are evaluated and compared using both causal and non-causal methods. The system is tested in two single object scenarios where ground truth is available and in three multi object scenarios without ground truth. Results from the two single object scenarios shows that tracking using only a monocular camera performs poorly since it is unable to measure the distance to objects. Here, a complementary LIDAR sensor improves the tracking performance significantly. The dynamic models are shown to have a small impact on the tracking performance, while the non-causal application gives a distinct improvement when tracking objects at large distances. Since the sequence can be reversed, the non-causal estimates are propagated from more certain states when the target is closer to the ego vehicle. For multiple object tracking, we find that correct associations between measurements and tracks are crucial for improving the tracking performance with non-causal algorithms.

碩士
國立臺灣大學
化學工程學研究所
97
I studied the supramolecular rod-comb block copolymers formed by complexa- -tion of an amphiphilic surfactant , dodecylbenzenesulfonic acid (DBSA) , with the poly(2-vinylpyridine) (P2VP) blocks in a rod-coil block copolymer , poly(phenylene vinylene)-b-poly(2-vinyl pyridine)(PPV-b-P2VP). The rod-coil copolymer complexes exhibited structure-within-structure morphology. On the larger block copolymer lenth scale , the PPV blocks are microphase-separated from the P2VP(DBSA)x blocks and the smaller-scale lamellar mesophase organized by the P2VP(DBSA) comb blocks. This thesis is dedicated to resolving the hierarchical structures of the rod-comb PPV-b-P2VP(DBSA)x supramolecular system. Small angle X-ray scattering (SAXS), wide angle X-ray scattering (WAXS) , transmission electron microscopy (TEM) and polarized optical microscopy (POM) have been used for the structure characterization. In particular, temperature-dependent SAXS and WAXS have been utilized to probe the thermally-induced phase transition processes such as order-order transition (OOT) and order-disorder transition (ODT). The effects of copolymer composition with volume fraction,f , of P2VP blocks of 0.27 and 0.52) and the complex compositon have been systematically investigated. In f=27-PPV/2VP(DBSA)x systems. For x=0.5 and x=1.0, the rod-comb diblocks copolymer both exhibited a lamellar-within-lamellar morphology. But when x=1.0, the block copolymer exhibits a lamellar structure with two length scales . The larger one consists of fully-stretched P2VP chain in a P2VP(DBSA) bilayer and the other one consists of fully-stretched P2VP chain in a P2VP(DBSA) single layer which was assumed to be alleviating system’s free energy. In f=52-PPV/2VP(DBSA)x systems. For x=0.143,0.4 and 0.6, the system’s morphology changes from a lamellar structure with only one length scale to lamellar-within-lamellar hierarchical structures. For x=0.8, a phase transformation reaction occurs and the resulting morphology can not be reaily defined. For x=1.0, the rod-comb diblocks copolymer exhibtd a cylinder-within-lamellar morphology, where the PPV cylindrical domain of ca. 8.2nm in diameter embedded in the matrix consisting of the lamellar mesophase with the interlamellar distance of ca. 2.9nm organized by the P2VP(DBSA) comb block.

The original aim of my diploma thesis was examination of fixed samples of cladocerans from the Daphnia longispina species complex from reservoirs Vír and Vranov for the presence of 4 groups of microparasites: microsporidia, oomycetes, the protozoan Caullerya mesnili, and the yeast Metschnikowia bicuspidata. The next aim was to determine the effect of parasites on Daphnia fecundity, and determination of their spatial and temporal distribution within reservoirs. From the total number 4452 of examined Daphnia females, however, only 56 individuals were infected. This number was not sufficient for the planned analyses. As I recorded for all examined individuals the clutch size, I thus dealt to a large extent with an alternative issue: the temporal and spatial variation of, and the influence of environmental factors on Daphnia fecundity. Both studied reservoirs are characteristic by canyon-shaped profile that allows formation of environmental gradients on the horizontal as well as vertical axis. The results confirm that reservoir identity, season, and location within the reservoir (or gradient of food supply) have all significant effects on fecundity. During my work I have encountered difficulties associated with determining microparazites from fixed zooplankton samples. The appendix section of my thesis...

Complex rehabilitative care for pre-school children undergoing c urative stays is the care of which the main task is to promote the health of a child as a whole or, if impaired, to bring it back to normal. A child sanatorium is a health care facility providing long-term preventive care for child patients through its complex therapeutic and rehabilitative methods during the child{\crq}s entire curative stay. It strives for reaching the optimum health condition of a child and for the elimination of possible fallouts. Curative stays are recommended by pediatricians. Generally, curative stays are designed for children between 3 and 15 years of age. They are covered by all health insurance companies. The aim of the thesis was to find out the current possibilities of the use of curative stay offers in the Czech Republic and how the offer of such stays is used, specifically in the mountainous climatic conditions. Also, the work aimed at the factors leading to the fact that some children use the curative stays repeatedly. In order to gather the necessary data to define the aim of the thesis, the method of questionnaire was used and the technique of written questionnaire was used to collect the data. The research used parents and other relatives of the pre-school children who at least once participated in the curative stay together with their child or children. The research was conducted at the Child Sanatorium of Javorník in Šumava during the months of January and February 2007. The hypothesis based on the presumption that the opportunity to use the offer of curative stays for pre-school children is influenced mostly by socio-economic factors was not confirmed. It has been detected that the physicians play an important role in this field. The second hypothesis concerning the repetitive use of the curative stays offer as not being directly linked to the curative effect of the previous stays was also not confirmed because the reasons leading the guardian escort to the decision to send the child or children for a repetitive curative stay are directly linked to the fact that the recently undergone stay has helped the health condition of their child or children.

It is well known that communication systems employing multiple transmit and multiple receive antennas provide high data rates along with increased reliability. Some of the design criteria of the space-time block codes (STBCs) for multiple input multiple output (MIMO)communication system are that these codes should attain large transmit diversity, high data-rate, low decoding-complexity, low decoding –delay and low peak-to-average power ratio (PAPR). STBCs based on real orthogonal designs (RODs) and complex orthogonal designs (CODs) achieve full transmit diversity and in addition, these codes are single-symbol maximum-likelihood (ML) decodable. It has been observed that the data-rate (in number of information symbols per channel use) of the square CODs falls exponentially with increase in number of antennas and it has led to the construction of rectangular CODs with high rate. We have constructed a class of maximal-rate CODs for n transmit antennas with rate if n is even and if n is odd. The novelty of the above construction is that they 2n+1 are constructed from square CODs. Though these codes have a high rate, this is achieved at the expense of large decoding delay especially when the number of antennas is 5or more. Moreover the rate also converges to half as the number of transmit antennas increases. We give a construction of rate-1/2 CODs with a substantial reduction in decoding delay when compared with the maximal- rate codes. Though there is a significant improvement in the rate of the codes mentioned above when compared with square CODs for the same number of antennas, the decoding delay of these codes is still considerably high. For certain applications, it is desirable to construct codes which are balanced with respect to both rate and decoding delay. To this end, we have constructed high rate and low decoding-delay RODs and CODs from Cayley-Dickson Algebra. Apart from the rate and decoding delay of orthogonal designs, peak-to-average power ratio (PAPR) of STBC is very important from implementation point of view. The standard constructions of square complex orthogonal designs contain a large number of zeros in the matrix result in gin high PAPR. We have given a construction for square complex orthogonal designs with lesser number of zero entries than the known constructions. When a + 1 is a power of 2, we get codes with no zero entries. Further more, we get complex orthogonal designs with no zero entry for any power of 2 antennas by introducing co- ordinate interleaved variables in the design matrix. These codes have significant advantage over the existing codes in term of PAPR. The only sacrifice that is made in the construction of these codes is that the signaling complexity (of these codes) is marginally greater than the existing codes (with zero entries) for some of the entries in the matrix consist of co-ordinate interleaved variables. Also a class of maximal-rate CODs (For mathematical equations pl see the pdf file)