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Synthesis Characterization And Reactivity Of Rheniumi Trisacetylene And Oxo Bisacetylene Complexes Oxygen Atom Transfer Reactions Of Rhenium Triazacyclononane Compounds
Download Synthesis Characterization And Reactivity Of Rheniumi Trisacetylene And Oxo Bisacetylene Complexes Oxygen Atom Transfer Reactions Of Rhenium Triazacyclononane Compounds full books in PDF, epub, and Kindle. Read online Synthesis Characterization And Reactivity Of Rheniumi Trisacetylene And Oxo Bisacetylene Complexes Oxygen Atom Transfer Reactions Of Rhenium Triazacyclononane Compounds ebook anywhere anytime directly on your device. Fast Download speed and no annoying ads. We cannot guarantee that every ebooks is available!
Book Synopsis Synthesis, Characterization and Reactivity of Rhenium(I) Tris(acetylene) and Oxo Bis(acetylene) Complexes; Oxygen Atom Transfer Reactions of Rhenium Triazacyclononane Compounds by : Rebecca Renae Conry
Download or read book Synthesis, Characterization and Reactivity of Rhenium(I) Tris(acetylene) and Oxo Bis(acetylene) Complexes; Oxygen Atom Transfer Reactions of Rhenium Triazacyclononane Compounds written by Rebecca Renae Conry and published by . This book was released on 1991 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis American Doctoral Dissertations by :
Download or read book American Doctoral Dissertations written by and published by . This book was released on 1990 with total page 768 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Dissertation Abstracts International by :
Download or read book Dissertation Abstracts International written by and published by . This book was released on 1991 with total page 660 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Rhenium-catalyzed Oxygen-atom Transfer Reactions by : Eric C. Brown
Download or read book Rhenium-catalyzed Oxygen-atom Transfer Reactions written by Eric C. Brown and published by . This book was released on 2002 with total page 406 pages. Available in PDF, EPUB and Kindle. Book excerpt: In situ reduction of hydrido-tris-(3,5-dimethylpyrazolyl)borato(trioxo) rhenium(V) with triphenylphosphine or triethylphosphite leads to a reactive rhenium(V) species that catalytically deoxygenates epoxides at 75-105°C. The reaction is stereospecific, except for trans- and cis-butene oxide which formed minor amounts of the opposite isomer. A variety of different functional groups were tolerated and even epoxides that reacted slowly could be pushed to greater than 95% conversion given extended time and/or higher temperature. The absence of clustering processes shows how the choice of ligand can have a major influence on the design of the catalytic cycle. The rhenium(V) species formed from reduction of Tp'ReO3 was identified as Tp'Re(O)(OH)2. Tp'Re(O)(OH)2 reacted with ethanol and HCl to form ethoxide and hydroxo chloride complexes, respectively. In addition, Tp'Re(O)(OH)2 was an excellent catalytic and stoichiometric reagent for the deoxygenation of epoxides and sulfoxides. Loss of water from Tp'Re(O)(OH)2 to form the catalytically active species Tp'Re02 was shown to be a necessary preequilibrium process. The kinetic behavior of the catalytic system is complex. First-order behavior in [Re][subscript T], zero-order dependence in [PPh3] and saturation behavior for epoxide were observed. The reversible formation of a coordinated epoxide complex was proposed to explain the saturation behavior. The epoxide complex was shown experimentally and computationally to engage in two separate reactions: ring expansion to form a syn-diolate complex, and direct fragmentation to alkene and trioxide. A steady-state concentration of diolate is eventually reached explaining a "burst" of alkene production prior to generation of a pseudo-zero-order catalytic system. The diolate formed is the syn-isomer, which is the kinetically formed product. Direct epoxide fragmentation is the primary source of alkene. This process was determined to be four times faster than ring expansion for cis-stilbene oxide. The synthesis and characterization of a tethered-epoxide Cp* rhenium trioxide complex has been achieved. Reduction of this complex leads to an unsaturated rhenium(V) species that is immediately complexed by the tethered epoxide. Experimental data and molecular mechanics modeling support intramolecular coordination of the epoxide to the rhenium center. These results confirm that the coordinate epoxide is a viable intermediate in rhenium-catalyzed epoxide deoxygenations.
Book Synopsis Synthesis, Characterization and Reactivity of Rhenium(III) Complexes for Catalytic, Stoichiometric and Insertion Reactions by : Damaris Esther Pérez
Download or read book Synthesis, Characterization and Reactivity of Rhenium(III) Complexes for Catalytic, Stoichiometric and Insertion Reactions written by Damaris Esther Pérez and published by . This book was released on 2018 with total page 123 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Catalytic Applications of Rhenium Compounds and Hydrogen Atom Transfer Reactions of Substituted Phthalimide N-oxyl Radicals by : Yang Cai
Download or read book Catalytic Applications of Rhenium Compounds and Hydrogen Atom Transfer Reactions of Substituted Phthalimide N-oxyl Radicals written by Yang Cai and published by . This book was released on 2004 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this work, methyltrioxorhenium (MTO) was found to be an active catalyst for two reactions: one is the reduction of hydronium ions by Eu[Subscript aq]2 to evolve H2; the other is reduction of perchlorate ions to chloride ions by Eu[Subscript aq]2+ or Cr[Subscript aq]2+ in acidic solution. Kinetic studies were carried out and reaction mechanisms were proposed to agree with all the experimental data. In the hydrogen evolution reaction, a rhenium(V) hydride complex was postulated in the scheme to generate H2 by a proton-hydride reaction. Under similar conditions, Cr2+ ions do not evolve H2, despite E0[Subscript Cr][Difference]E0[Subscript Eu]. In addition, no H2 formation was observed in the presence of perchlorate ions because the reaction between methyldioxorhenium (MDO) and perchlorate ions has a much faster rate than that of hydrogen evolution. A six-coordinate rhenium(V) compound MeReO(edt)(bpym) was prepared, characterized, and investigated for oxygen atom transfer reactions between picoline N-oxide and triarylphosphines. We found it is a good catalyst for the reaction, even though it is less active than those five-coordinate rhenium(V) dithiolato compounds. The kinetics showed that the reaction has a first-order dependence on both rhenium and picoline N-oxide. Triarylphosphines were found to inhibit the reaction, and those phosphines with more electron-donating groups in para positions had slower reaction rates. This study proves a hypothesis: there should be a steric requirement for the potential catalyst in the oxygen transfer reactions, which is the necessary existence of an open coordination site on rhenium center. In the last chapter, we studied three different types of reactions of phthalimide N-oxyl radicals (PINO·) and N-hydroxylphthalimide (NHPI) derivatives. First, the self-decomposition of PINO· follows second-order kinetics. However, when excess of 4-Me-NHPI are used in the system, it was found that H-atom abstraction competes with the self-decomposition of 4-Me-PINO·. Second, the hydrogen atom self-exchange reactions between PINO· and substituted NHPI were found to follow H-atom transfer rather than the stepwise electron-proton transfer pathway. Last, the investigations of hydrogen abstraction from para-xylene and toluene by PINO· show large kinetic isotope effects, with the reaction becoming slower when the ring substituent on PINO· is more electron donating.
Book Synopsis Reactions and Mechanisms of Rhenium Catalyzed Oxygen Atom Transfer by : Joachin Jude Arias
Download or read book Reactions and Mechanisms of Rhenium Catalyzed Oxygen Atom Transfer written by Joachin Jude Arias and published by . This book was released on 2001 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis The Synthesis, Characterization and Reactivity of High Oxidation State Rhenium Imido and Oxo Complexes by : Tiow-Gan Ong
Download or read book The Synthesis, Characterization and Reactivity of High Oxidation State Rhenium Imido and Oxo Complexes written by Tiow-Gan Ong and published by . This book was released on 2000 with total page 466 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Synthesis, Characterization, and Reactivity of Low-valent Rhenium Oxo-alkoxide and Hydride Complexes by : Torsten K. G. Erikson
Download or read book Synthesis, Characterization, and Reactivity of Low-valent Rhenium Oxo-alkoxide and Hydride Complexes written by Torsten K. G. Erikson and published by . This book was released on 1988 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Synthesis and Reactivity of Organometallic Rhenium(V) Oxo Compounds by : June-Ho Jung
Download or read book Synthesis and Reactivity of Organometallic Rhenium(V) Oxo Compounds written by June-Ho Jung and published by . This book was released on 1999 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Synthesis, Characterization, and Reactivity of Rhenium Dithiodiolate and Monothiodiolate Complexes by : Pitak Chuawong
Download or read book Synthesis, Characterization, and Reactivity of Rhenium Dithiodiolate and Monothiodiolate Complexes written by Pitak Chuawong and published by . This book was released on 2001 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt: The rhenium dithiodiolate, Hydrido-tris-(3,5-dimethyl- 1 -pyrazol yl) borato(ethane- 1,2-dithiodiolato)(oxo)rheni um(V), and Hydrido-tris-(3,5-dimethyl- 1 -pyrazolyl)borato(phenylethanedithiodiolato)(oxo)rhenium(V), were synthesized by reductive cyclocondensation of alkane-1,2-dithiols with Tp'Re03 in a one pot fashion. The rhemium monothiodiolate, Hydrido-tris-(3,5-dimethyl- 1 -pyrazolyl) borato(ethane- 1,2-monothiodiolato)(oxo)rhenium(V), and Hydrido-tris-(3,5- dimethyl- 1 -pyrazolyl)borato(propanemonothiodiolato)(oxo)rhenium(V), were also synthesized by using the same procedure. The syn and anti isomers of rhenium phenylethanedithiodiolate and rhenium propanemonothiodiolate were characterized by using COSY, nOe, and HSQC experiments. An X-ray crystal structure of the rhenium ethanedithiodiolate was obtained, and an unusually small dihedral angle (S-C-C-S) of about 12° was observed. The solution conformation of these compounds was investigated by using a Karplus relationship between vicinal coupling constants and dihedral angle. The dihedral angle for the ethanedithiodiolate appeared to be 38° indicating a staggered geometry for the ring. All of these complexes failed to cyclorevert to any detectable extent at 120°C after 7 days. This observation reflects the thermal stability of rhenium dithiodiolate and monothiodiolate complexes. Energetics of ethylene addition to tetrathioperrhenate anion (ReS4−) and addition of hydrogen sulfide to the alkene adduct were calculated by DFT calculation using LACVP** basis set with B3LYP functionals. The heat of reaction of ethylene addition to ReS4− was 15.4 kcal/mol, and 111.1 kcal/mol for addition of hydrogen sulfide to the alkene adduct. These results are consistent with the stability of the dithiodiolate complex toward cycloreversion reaction. Reaction of Tp'Re03 and ethylene sulfide led to the rhenium ethanedithiolate complex both with and without acid catalysis. This observation led to a proposed multi step mechanism.
