Dissertations / Theses on the topic 'Rh(I) chemistry]'
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King, A. P. "Structural and reactive studies of Rh(110) and Rh(111) surfaces." Thesis, University of Cambridge, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377227.
Full textWang, Yaquan. "New routes to Rh (and CeOâ†2-promoted) Rh/SiOâ†2 catalysts for alcohol synthesis." Thesis, Brunel University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359923.
Full textEmslie, David James Hannington. "The redox chemistry of Rh(I) pyrzolylborate and related complexes." Thesis, University of Bristol, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302160.
Full textAlshehri, Feras. "The hydrogenation of substituted benzenes over Rh/silica." Thesis, University of Glasgow, 2017. http://theses.gla.ac.uk/8342/.
Full textSmith, Joshua J. "Stereoselective Rh- and Cu-catalysed additions to imines and aldehydes." Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/39370/.
Full textKorkis, Stamatis E. "New reactive sites enabled via an allyl-to-allyl 1,4-Rh(III) migration." Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/48787/.
Full textTelep, David A. "Investigation into optimal Rh(III) dopant placement in silver bromide emulsions /." Online version of thesis, 1993. http://hdl.handle.net/1850/11745.
Full textThammajak, Nirawat. "Synthesis and characterisation of metal oxides isostructural with La₁₈Li₈Rh₅O₃₉." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:5a97db26-edb3-45e0-972d-e516da0384d3.
Full textSchreiber, Tara N. "SYNTHESIS AND COMPLEXATION OF RHODIUM TRICHLORIDE BY 1-AZA-4,7-DITHIACYCLONONANE AND DERIVATIVES." University of Akron / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=akron1153756558.
Full textMedvetz, Douglas Allen. "The Synthesis, Characterization, and Antitumor Properties of Ag(I), Cu(II), and Rh(III) Metal Complexes." University of Akron / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=akron1216840371.
Full textAardaneh, Khosro. "Separation of 103Pd from Ag and Rh targets for production of '103 Pd seeds' for prostate cancer brachytherapy." Thesis, Stellenbosch : Stellenbosch University, 2002. http://hdl.handle.net/10019.1/53050.
Full textENGLISH ABSTRACT: Radiochemical separation of 103Pd from natAg, usmg a 66 MeV proton-induced reaction at iThemba LABS, was studied and a radiochemical method was developed for the separation. For the separation, which comprises the separation of Pd from a large amount of target material (16 g Ag), as well as Rh radioisotopes produced from decay of their Pd parents (mainly 101Rhand IOORh),three ion exchange resins were tested: a Chelex 100 chelating resin, the AG 1-X8 anion exchange resin and a AG MP-I anion exchange resin. For the optimum elution ofPd from the latter two resins, two elution curves using water and 5% ammonia solution, were obtained. With an average recovery of 97.4% and sharper elution curve from the macroporous AG MP-I, this resin was finally chosen for routine production. To achieve the separation, a simple, easily operated radiochemical processing system was designed and installed in a hot cell. Radiochemical separation of 103Pd from a Rh target was also studied and several cation and anion exchange resins were tested. A carrier-free separation of 103Pd was developed, using an AG 1-X8 anion exchange resin. Bombarded tablets of RhCh.3H20, as the targets, were used for these separations. The procedure, originally designed for the separation of Pd from Cu and Rh, was modified using H202 for the oxidation of Ru prior to the sorption on the resin and successfully used for the separation of isotopes of Rh from the isotopes of Pd, Ru, Tc, Nb, Mo, Zr and Y, which were produced by 400 MeV 160_ and 12C-induced RhCb.3H20 targets. To elute the Pd from the resin, 5% ammonia solution was used; the recovery was about 92%. To prepare the Rh target for routine production, an electroplating method of Rh on a Cu substrate was developed. Rh(CI04)3, in 0.5 M perchloric acid, was used as the electrolyte bath. The electroplated Rh was then dissolved by an alternating current technique, using 6 M HCI and a current density of 2 Alcm2. For production of the seeds, I03Pd was sorbed on the weakly basic anion exchange resin Amberlite IRA-93 (600-700 Il), by recycling a 0.5 M Hel solution of Pd through a 0.5 cm x 1 cm column for 2 hours. The distribution of I03Pd on the resin beads was measured and RSD of5.7% was obtained. A funnel was designed to transfer the I03Pd-loaded resin beads into the Ti tubes to prepare the seeds (0.7 mm LD., 0.8 mm D.D., and 4.5 mm length). To enclose the tubes as capsules, the end caps were made from 0.02 mm Ti sheet and several pieces were designed and machined for the welding of the caps to the tubes. A spotwelding machine was used for the welding, after small, but vital modifications.
AFRIKAANSE OPSOMMING: Palladium-l03 kan volgens twee produksieroetes by iThemba LABS vervaardig word, naamlik deur die volgende protongeïnduseerde reaksies: natAg(p,xn)lo3Cd (ty,=7.3 m) ~ 103Ag (ty,=1.1 h) ~ 103Pden I03Rh(p,n) ~ 103Pd. 'n Radiochemiese metode om 103Pd van die Ag-skyfmateriaal te skei, is ontwikkel. Hierdie metode, wat gebaseer is op anioonuitruilerchromatografie met die makroporeuse hars AG MP-I, behels die skeiding van I03Pd van 'n groot hoeveelheid skyfmateriaal (16g Ag), sowel as van Rh-radionukliede (hoofsaaklik looRh en IOlRh), wat geproduseer word deur die verval van hulle Pd-moederisotope. As die Pd met 5% ammonia oplossing geëlueer word, is 'n 97.4% herwinning moontlik. 'n Radiochemiese paneel is ontwerp, gebou en in 'n warmsel geïnstalleer vir roetine produksie. 'n Metode om Rh op 'n kopersubstraat te elektroplateer is ook ontwikkel om 'n Rh-skyf te verkry vir die protonbombardement. 'n Oplossing van 0.5 M HCI04 - Rh(HCI04)3 is as die elektrolietbad gebruik. Die geëlektroplateerde Rh is opgelos in 6 M HCI deur gebruik te maak van 'n wisselstroomtegniek, met 'n stroomdigtheid van 2A1cm2. 'n Metode om "draervrye" I03Pd vanaf die Rh-skyfmateriaal te skei, is ook ontwikkel. Gebombardeerde pille van RhCh.3H20 is as skywe gebruik in die onaktiewe studies. AGI-X8 anioonuitruilerhars is vir hierdie skeidings gebruik en daar is gebruik gemaak van 'n metode wat oorspronklik ontwerp is vir die skeiding van Pd van Cu en Rh. Hierdie prosedure is net effens aangepas deur H202 te gebruik vir die oksidasie van Ru, alvorens dit op die hars gesorbeer is. Hierdie metode is ook suksesvol gebruik vir die isolering van Rh van radionukliede van Pd, Ru, Tc, Nb, Mo, Zr, ens, wat geproduseer is deur 400 MeV 160_ en 12C-geïnduseerde reaksies met Rh in RhCi).3H20 skywe. 5% ammoniakoplossing is gebruik om die Pd uit die hars te elueer, met 'n herwinning van 92%. Om die saadjies vir implantering te maak, is 103Pd op 'n matige basiese anioonuitruilerhars Amberlite IRA-93 gesorbeer deur 'n 103pd-oplossing, in 0.5 M Hel, deur 'n 0.5 ' lcm kolom te hersirkuleer vir 2 uur. 'n Tregter is ontwerp om die I03Pd-gelaaide harskorrels oor te dra na die titaanbuisies (0.7 mm binnedeursnit, 0.8 mm buitedeursnit en 4.5 mm lank). Om die buisies te verseël, is dekseltjies uit 'n 0.02 mm titaanplaat gesny. Verskeie dekseltjies is gemasjieneer om op die buisies vas te sweis. 'n Punt-sweismasjien is gebruik vir die sweiswerk nadat geringe, maar belangrike, aanpassings aan die masjien gedoen is.
Degtyareva, Natalya N. "Platinum, Rhodium, and Ruthenium Complexes as potential PDT agents." The Ohio State University, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=osu1124238450.
Full textAkhimie, Regina Nicole. "Investigation of Rh2(II,II) complexes for applications in photochemotherapy and mismatch detection." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1511892689942643.
Full textSvetlanova, Anna. "Thermodynamics and Kinetics of Small Molecule Binding to [Cyclopentadienyl-Ru-NO] and [Rh-CO] Electrophilic Centers." DigitalCommons@USU, 1996. https://digitalcommons.usu.edu/etd/7188.
Full textNegrón, Ana Cecilia Valderrama. "Síntese, caracterização e investigação da potencialidade biológica de carboxilatos dinucleares de Ru, Rh e Cu com nitroimidazóis." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/46/46134/tde-03092014-165321/.
Full textThe interaction of dinuclear metal moieties [M2(µ-O2CCH3)4] (M = Ru, Rh or Cu) with 5-nitroimidazolic Iigands (L = metronidazole, nimorazole, secnidazole, tinidazole) were investigated. New compounds were synthesized and characterized by elemental analysis, spectroscopic (UV-VIS-NIR, FTIR, Raman, EPR) methods, magnetic measurements and thermogravimetry. Diruthenium complexes of general formula [Ru2(µ-O2CCH3)4(L)2]PF6 show absorption bands at ca, 310 nm (IL), 420 nm (π(RuO,Ru2) → π*(Ru2)) and 1000 nm (δ(Ru2) → δ*(Ru2)). These bands are typical of Ru2(II,III) tetracarboxylates where the metal centers are bonded by a metal-metal multiple bond of order 2.5. Values of µeff (3.80 - 4.40 MB) indicate an electronic configuration σ2 π4 δ2 π*2 δ*1, where three electrons are unpaired on each Ru2 unit. The differences Δv(CO2) = vas - vs (~ 50 cm-1), where vas(CO2) = 1443 - 1450 cm-1 and vs(CO2) = 1397 - 1409 cm-1, confirm the coordination through bridging carboxylates. The shifting of v(C=N) bands to higher energies compared to the free nitroimidazoles is an evidence of the coordination of these ligands through the N3 ring atoms. Bands that may be attributed to v (Ru-O) [IR, ~405 cm-1 (Veu) and ~345 cm-1 (Va2u)], v (Ru-N) [IR, 465 - 478 cm-1] and v(Ru-Ru) [Raman, ~ 326 - 334 cm-1] stretchings give evidence of the formation of bonds involving the ruthenium ions. The compounds are thermically stable up to ~200°C; above this temperature they start to decompose with loss of axial ligands followed by disruption of the dinuclear core. All complexes exhibit behavior of 1:1 electrolytes in solution, confirming the presence of the PF6- counter- ion. The values of half-wave potentials (E1/2, ~0,25 V) are similar for all the nitroimidazole derivatives but somewhat lower than that for the aqua-complex [Ru2(µ-O2CCH3)4(H2O)2]PF6 (0,31 V). Partition assays in n-octanol/water system show the high hydrophylicity of the compounds. The rhodium complexes [Rh2(µ-O2CCH3)4(L)2] exhibit a typical π(Rh2) → σ*(Rh2) transition at ~555 nm (solution) and ~525 nm (solid). The zero-values of µeff confirm that the species are diamagnetic. In this case the metal centers are linked by a single bond. The differences Δv (~ 110 cm-1), [Vas(CO2), ~1590 cm-1; vs(CO2), 1423 - 1436 cm-1], confirm the coordination through bridging carboxylates. Axial ligand coordination through the N3 nitroimidazole atom is also confirmed by the shifting of v (C=N) frequencies. Bands that may be attributed to v(Rh-O) [IR, ~385 cm-1 (Veu) and ~340 cm-1 (Va2u)], v(Rh-N) [IR, 475 - 490 cm-1] and v(Rh-Rh) [Raman, ~ 170 and 230 - 240 cm-1] stretchings agree with the formation of bonds involving the rhodium ions. These compounds also undergo decomposition above 200°C, but in this case the loss of nitroimidazole ligands occurs along with the disruption of the dimetal core. The copper complexes [Cu2(µ-O2CCH3)4(L)2] display the so-called Band I at ~700 nm, which is attributed to the dxz,yz → dx2-y2 transition. The characteristic dimmer band (Band II) was observed at ~370 nm for the metronidazole derivative in the solid state. The values of µeff (1.40 - 1.55 MB) and of EPR parameters (g//= 2.160 - 2.180; g = 2.010 - 2.050; D = 0.287 - 0.296) are in agreement with a carboxylate-bridged dinuclear structure and with antiferromagnetic coupling that indicates the presence of some type of interaction between the metal centers. The differences Δv (ca. 180 cm-1), [Vas(CO2), 1619 - 1629 cm-1; Vs(CO2), 1425 - 1433 cm-1], confirm the coordination through bridging carboxylates Axial ligand coordination through the N3 nitroimidazole atom is also confirmed by the shifting of v(C=N) frequencies. The band v(Cu-O) is observed at ~350 cm-1. These compounds also start to decompose above 200°C, initially with the loss of one of the nitroimidazole ligands, followed by loss of the second and disruption of the dimetal core, simultaneously. The compounds are hydrophilic. Therefore, all the studied complexes of general formula [M2(µ-O2CCH3)4(L)2] (M = Ru, Rh, Cu; L = 5-nitroimidazole) exhibit structures with dimeric units. Two metal centers are bonded by four equatorial bridging carboxylate ligands through oxygen atoms in a cage-like motif. Nitroimidazole molecules occupy the axial positions coordinating the metal through the N3 imidazole ring atom. Since dimeric tetracarboxylates are potential metal drugs and 5-nitromidazoles belong to an important class of broad clinicai spectrum, in vitro assays were performed to assess the antitumoral, radiosensitizer and antimicrobial (bactericide and fungicide) activities of the new ruthenium and copper complexes. The Ru2 (II,III) complexes are more active against tumor (HeLa) than normal (NCTC clone L929) cells, while the Cu2 (II,II) analogous promote tumor cell death at lower concentrations. Copper complexes also displayed the best radiosensitizer activity at low radiation doses and 80% of cell survival. The compounds are inactive against aerobic bacteria, but are active against the anaerobic, being the copper-metronidazole complex the most efficient. This is the first report of the antifungal activity of Ru2(II,III) complexes. They exhibit activity at concentrations somewhat higher than current used drugs. The rhodium complexes were not submitted to biological assays due to their low aqueous solubility.
Joyce, Lauren Elizabeth. "Ru(II), Os(II), and Rh2(II,II) Complexes as Potential Photodynamic Therapy Agents." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1291176129.
Full textMasetti, Andrea. "Synthesis and characterization of high-nuclearity Rh-Au clusters stabilized by carbonyl ligands." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/24411/.
Full textWieczysty, Martin David. "C-H functionalisation of 2-aryl cyclic 1,3-dicarbonyl compounds ; Enantioselective Rh(I)-catalysed cyclisation of arylboron compounds onto ketones." Thesis, University of Edinburgh, 2015. http://hdl.handle.net/1842/18741.
Full textGIOFRE', SABRINA. "SYNTHESIS OF NITROGEN-CONTAINING HETEROCYCLIC SYSTEMS OF BIOLOGICAL INTEREST THROUGH DOMINO STRATEGIES." Doctoral thesis, Università degli Studi di Milano, 2020. http://hdl.handle.net/2434/701960.
Full textParry, Imogen Sophie. "Collisional and photoexcitation of transition metal clusters." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:b1f2fc37-97ff-4500-ab34-ceb7e515b9d2.
Full textPrigent, Jocelyn. "Étude des composés substitués LaNi5-xMx (M=Ru, Rh, Pd, Ag, Re, Os, Ir, Au) et de leurs propriétés d'hydrogénation." Phd thesis, Université Paris Sud - Paris XI, 2008. http://tel.archives-ouvertes.fr/tel-00442613.
Full textNegrón, Ana Cecilia Valderrama. "Síntese e caracterização de carboxilatos de Rh(II) e seus adutos com metronidazol: ensaios biológicos com vistas à vtividade radiossensibilizadora de tumores." Universidade de São Paulo, 2000. http://www.teses.usp.br/teses/disponiveis/46/46134/tde-01092014-164032/.
Full textRadiosensitizers are chemical agents that enhance the radiation sensitivity of hipoxic tumor cells aiming to better radiotherapy efficacy in the treatment of cancer. Some Rhodium (II) carboxylates and its adducts with nitroimidazole derivatives, have been tested as radiosensitizers in high doses of radiation, being obtained significant results. In this work, several Rhodium carboxylates and one Rhodium amidate previously described were synthesized: propionate, trifluoroacetate, citrate and , trifluoroacetamidate, as well as their respective adducts with nitroimidazole of general formula [Rh2(RCOO)4metro2] for the carboxylates and [Rh2(CF3CONH)4metro2] for the trifluoroacetamidate adduct. The compositions where characterized by elementary analysis, electronic and infrared spectroscopy and proton nuclear magnetic resonance. The results of that characterization allowed us to establish the synthesis routes and confirm the bridge type structure of the Rodhium compounds, beyond the presence of the metronidazole at the axial positions in the proportions of 1:2. The radiosensitizing effects of these Rh (II) complexes were tested in vitro by irradiation of Chinese hamster (CHO k1) cells under hipoxic atmosphere in the presence of the complexes, using gamma rays from a 60Co source and doses of 2,7 and 4,3 Gy. A cytotoxicity test has been performed to determinate the non-toxic concentrations of these compounds, in order to rule out the possibility of cellular death induced by the complexe´s cytotoxicity. A 2,7 Gy dose showed no interesting effects but under a 4,3 Gy dose, the complex Rh2(CH3 COO)4 showed a higher radiosensitizing effect than the order compounds and close to previously reported effects which required high radiation doses. As there was not a significant change in the radiosensitizing effect between the carboxylate and the amidate and their respective metronidazole adducts it was performed the measurement of the formation constant of that adducts. The results of that measurements gave evidence of adduct decomposition when in dilute aqueous solution.
Mirambet, François. "Proprietés structurales et physiques de nouveaux stannures ternaires a base d' uranium et d'element de transition (Fe, Co, Ni, Ru, Rh, Pd, Ir, Pt)." Phd thesis, Université Sciences et Technologies - Bordeaux I, 1993. http://tel.archives-ouvertes.fr/tel-00139024.
Full textWang, Bo. "An atomistic approach to graphene and carbon clusters grown on a transition metal surface." Thesis, University of St Andrews, 2011. http://hdl.handle.net/10023/2069.
Full textLi, Xin. "Development and Application of Chemical and Structural Biology Approaches to Probe Protein Function." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1306439016.
Full textPommer, Linda. "Oxidation of terpenes in indoor environments : A study of influencing factors." Doctoral thesis, Umeå University, Ecology and Environmental Science, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-29.
Full textIn this thesis the oxidation of monoterpenes by O3 and NO2 and factors that influenced the oxidation were studied. In the environment both ozone (O3) and nitrogen dioxide (NO2) are present as oxidising gases, which causes sampling artefacts when using Tenax TA as an adsorbent to sample organic compounds in the air. A scrubber was developed to remove O3 and NO2 prior to the sampling tube, and artefacts during sampling were minimised when using the scrubber. The main organic compounds sampled in this thesis were two monoterpenes, alfa-pinene and delta-3-carene, due to their presence in both indoor and outdoor air. The recovery of the monoterpenes through the scrubber varied between 75-97% at relative humidities of 15-75%.
The reactions of alfa-pinene and delta-3-carene with O 3, NO2 and nitric oxide (NO) at different relative humidities (RHs) and reaction times were studied in a dark reaction chamber. The experiments were planned and performed according to an experimental design were the factors influencing the reaction (O3, NO2, NO, RH and reaction times) were varied between high and low levels. In the experiments up to 13% of the monoterpenes reacted when O3, NO2, and reaction time were at high levels, and NO, and RH were at low levels. In the evaluation eight and seven factors (including both single and interaction factors) were found to influence the amount of alfa-pinene and delta-3-carene reacted, respectively. The three most influencing factors for both of the monoterpenes were the O 3 level, the reaction time, and the RH. Increased O3 level and reaction time increased the amount of monoterpene reacted, and increased RH decreased the amount reacted.
A theoretical model of the reactions occurring in the reaction chamber was created. The amount of monoterpene reacted at different initial settings of O3, NO2, and NO were calculated, as well as the influence of different reaction pathways, and the concentrations of O3 and NO2, and NO at specific reaction times. The results of the theoretical model were that the reactivity of the gas mixture towards alfa-pinene and delta-3-carene was underestimated. But, the calculated concentrations of O3, NO2, and NO in the theoretical model were found to correspond to a high degree with experimental results performed under similar conditions. The possible associations between organic compounds in indoor air, building variables and the presence of sick building syndrome were studied using principal component analysis. The most complex model was able to separate 71% of the “sick” buildings from the “healthy” buildings. The most important variables that separated the “sick” buildings from the “healthy” buildings were a more frequent occurrence or a higher concentration of compounds with shorter retention times in the “sick” buildings.
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Lee, Sumin. "Rh(III)-Catalyzed Alkene Difunctionalization for the Synthesis of Nitrogen-Containing Compounds." Thesis, 2021. https://doi.org/10.7916/d8-45vd-yy03.
Full textZorzitto, Alexander. "Enantioselective Rh(I)-Catalyzed Conjugate Alkynylation of 5-Benzylidene Meldrum’s Acid with TMS-acetylene." Thesis, 2009. http://hdl.handle.net/10012/4629.
Full textCamp, Greville Lionel. "Phosphine and phosphonite complexes of Mn(III), Co(III) and Rh(III) porphyrins." Thesis, 2003. http://hdl.handle.net/10413/3982.
Full textThesis (M.Sc.)-University of Natal, Pietermaritzburg, 2003
Kong, Jongrock 1972. "Rh-catalyzed reductive coupling under hydrogenation conditions and nucleophilic catalysis via phosphine conjugate addition." Thesis, 2007. http://hdl.handle.net/2152/3301.
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Bartholoméüs, Johan. "Réactions d’amination de liens C-H : synthèse d’amines propargyliques à partir de N-mésyloxycarbamates et études mécanistiques." Thèse, 2016. http://hdl.handle.net/1866/18430.
Full textThe nitrogen containing compounds represent a large portion of the active substances in medicinal chemistry. The work reported in this manuscript describe the efforts devoted to the development of a new method of amination of propargylic C-H bonds. Our research group has developed recently a new metal nitrene precursor, N-mesyloxycarbamates, to perform amination reactions on various C-H bonds. During the development of our methodology, the synthesis of N-mesyloxycarbamate has undergone many improvements, including improved global scale synthesis and effectiveness. Similarly, efforts were devoted to reduce the number of steps required for the synthesis of the reagent by developing the synthesis of an intermediate enantioselectively. Finally, the synthesis of this reagent was also considered using continuous flow chemistry. During development of the method of synthesis of propargylic amines, we have found that acetic acid plays a key role in the conservation of good selectivity and reactivity of the reaction. These observations allowed to develop an efficient diastereoselective process in order to obtain propargylic amines with moderate to good yields and with excellent diastereoselectivities. Following the study of the scope of our process, we tried to determine the reaction mechanisms governing the reactivity and selectivity. We have shown that the reactive species of the catalyst system was indeed a metal nitrene, and that the rate-determining step was the insertion. Experiments made by oxidizing the rhodium catalytic species suggested that several oxidation states of this species may be present and active in the catalytic system.
Lindsay, Vincent. "Synthèse stéréosélective de dérivés cyclopropaniques di-accepteurs par catalyse avec des complexes de rhodium(II)." Thèse, 2012. http://hdl.handle.net/1866/8976.
Full textDi-acceptor cyclopropane derivatives are valuable synthetic intermediates in the preparation of complex molecular structures, with applications in several fields of chemistry. During this work, we investigated the synthesis of these units in enantioenriched form via the Rh(II)-catalyzed cyclopropanation of alkenes using di-acceptor diazo compounds as substrates. Following the initial development of a method for the catalytic asymmetric cyclopropanation of alkenes using nitro diazoketones, many experimental studies on the mechanism of stereoinduction in this reaction were performed. We were able to identify the p-methoxyphenylketone group of the substrate and catalyst Rh2(S-TCPTTL)4 as a key combination for the obtention of high diastereoselectivities and enantiomeric excesses. This led to the development of two distinct stereoselective cyclopropanation methods, using either an cyano diazoketone or a keto diazoester. We demonstrated the utility of the enantioenriched cyclopropane derivatives obtained by these three methods in a variety of synthetic manipulations, including the nucleophilic addition of amines and cuprates, the formal cycloaddition with an aldehyde, and the synthesis of biologically relevant cyclopropane derivatives. A thorough structural study of chiral Rh(II) complexes allowed us to determine the factors responsible for their enantioinduction ability in our reaction system, which has enormous implications in other metal-carbene reactions using these catalysts. The unveiling of an unexpected conformation called 'All-up', and the presence of stabilizing interactions controlling the rigidity of this arrangement have been crucial in our understanding of the mechanism. As part of this investigation, we developed a general method for the synthesis of heteroleptic Rh(II) complexes, thus multiplying the number of catalysts available in the development of new stereoselective reactions, and allowing us to conduct a more detailed structural study. Moreover, we have developed a particularly efficient method for the synthesis of another type of di-acceptor cyclopropane derivative via Rh(II) catalysis, cyanocyclopropylphosphonates. The highly enantioenriched products obtained in this transformation are interesting substrates for tandem reactions of nucleophilic addition / olefination of carbonyl compounds, and are precursors of useful molecules in medicinal chemistry, such as aminocyclopropylphosphonic acids.
Piras, Henri. "Synthèse de sulfilimines et de sulfoximines catalysée par les métaux de transition." Thèse, 2016. http://hdl.handle.net/1866/16005.
Full textSulfilimines and sulfoximines are interesting building blocks that have found many applications both in medicinal chemistry and agrochemistry. During our work, we have developed new efficient methods for the synthesis of these moieties. A catalytic amount of metal complex is used to enhance the reactivity of an electrophilic nitrogen source towards thioethers and sulfoxides. Our group has developed an expertise in the development of stereoselective C-H bond amination and aziridination reactions using chiral N-mesyloxycarbamate as electrophilic amination reagents. The large scale synthesis of the chiral reagent was first investigated. It was then tested in a diastereoselective dirhodium(II)-catalyzed amination of thioethers and sulfoxides, to produce respectively chiral sulfilimines and sulfoximines in excellent yields and selectivities. During the optimization process, we have found that some additives proved instrumental to enhance both the reactivity and the selectivity of the reaction. Mechanistic studies has been carried out to elucidate the exact role of the additives. We have observed that Lewis bases, namely 4-dimethylaminopyridine (DMAP), can coordinate to a rhodium(II) dimer catalyst, modifying its structural and redox properties. These studies suggest that a mixed-valent dirhodium Rh(II)/Rh(III) complex is the catalytically active species in the thioether amination process. Moreover, we have discovered that the use of bispyridinium salts is crucial to enhance the selectivity of the amination reaction. Diastereoselectivities were also influenced by the nature of the leaving group of the N-sulfonyloxycarbamate. Based on the results, we hypothetized a rhodium nitrenoïd species as key intermediate in the amination process. Continuous flow techniques were employed in the development of a very efficient amination process of thioethers and sulfoxides, using azides as electrophilic amination reagents. Based on the photochemical decomposition of azide derivatives with a simple and commercially available iron(III) complex, we were able to produce sulfilimines and sulfoximines in excellent yields. We investigated the design of a new type of capillary photoreactor to further reduce the residence time of the amination process. The technical improvements were pivotal to enhance the efficiency and productivity of the reaction process.