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Chemical Kinetics in Support of Syngas Turbine Combustion

Description: This document is the final report on an overall program formulated to extend our prior work in developing and validating kinetic models for the CO/hydrogen/oxygen reaction by carefully analyzing the individual and interactive behavior of specific elementary and subsets of elementary reactions at conditions of interest to syngas combustion in gas turbines. A summary of the tasks performed under this work are: 1. Determine experimentally the third body efficiencies in H+O{sub 2}+M = HO{sub 2}+M (R1) for CO{sub 2} and H{sub 2}O. 2. Using published literature data and the results in this program, further develop the present H{sub 2}/O{sub 2}/diluent and CO/H{sub 2}/O{sub 2}/diluent mechanisms for dilution with CO{sub 2}, H{sub 2}O and N{sub 2} through comparisons with new experimental validation targets for H{sub 2}-CO-O{sub 2}-N{sub 2} reaction kinetics in the presence of significant diluent fractions of CO{sub 2} and/or H{sub 2}O, at high pressures. (task amplified to especially address ignition delay issues, see below). 3. Analyze and demonstrate issues related to NOx interactions with syngas combustion chemistry (task amplified to include interactions of iron pentacarbonyl with syngas combustion chemistry, see below). 4. Publish results, including updated syngas kinetic model. Results are summarized in this document and its appendices. Three archival papers which contain a majority of the research results have appeared. Those results not published elsewhere are highlighted here, and will appear as part of future publications. Portions of the work appearing in the above publications were also supported in part by the Department of Energy under Grant No. DE-FG02-86ER-13503. As a result of and during the research under the present contract, we became aware of other reported results that revealed substantial differences between experimental characterizations of ignition delays for syngas mixtures and ignition delay predictions based upon homogenous kinetic modeling. We adjusted emphasis of Task 2 to understand ...
Date: July 31, 2007
Creator: Dryer, Frederick
Partner: UNT Libraries Government Documents Department

The generation of efficient supported (Heterogeneous) olefin metathesis catalysts

Description: Over the past decade, a new family of homogeneous metathesis catalysts has been developed that will tolerate most organic functionalities as well as water and air. These homogeneous catalysts are finding numerous applications in the pharmaceutical industry as well as in the production of functional polymers. In addition the catalysts are being used to convert seed oils into products that can substitute for those that are now made from petroleum products. Seed oils are unsaturated, contain double bonds, and are a ready source of linear hydrocarbon fragments that are specifically functionalized. To increase the number of applications in the area of biomaterial conversion to petrol chemicals, the activity and efficiency of the catalysts need to be as high as possible. The higher the efficiency of the catalysts, the lower the cost of the conversion and a larger number of practical applications become available. Active supported catalysts were prepared and tested in the conversion of seed oils and other important starting materials. The outcome of the work was successful and the technology has been transferred to a commercial operation to develop viable applications of the discovered systems. A biorefinery that converts seed oils is under construction in Indonesia. The catalysts developed in this study will be considered for the next generation of operations.
Date: April 5, 2013
Creator: Grubbs, Robert H.
Partner: UNT Libraries Government Documents Department

The Chemistry of HO{Sub 2}NO{Sub 2} and the Photochemistry of the HO{Sub X}-NO{Sub X}-CO{Sub X} System

Description: The objectives of this work were: (1) to investigate formation and destruction reactions of peroxynitric acid, HO{sub 2}NO{sub 2} and (2) to study the photochemistry and kinetics of the HO{sub x} - NO{sub x} - CO{sub x} system were also studied. Investigations were done using infrared spectroscopy to observe the behavior of species involved with the reactions of interest. Several techniques were used, including expansion of reactants into an evacuated cell, static cell decays under constant illumination, and periodic photolysis of flow systems, Infrared absorption cross sections were obtained for CO, CO{sub 2}, NO, NO{sub 2}, N{sub 2}O{sub 5}, HNO{sub 3}, H{sub 2}O{sub 2}, and H{sub 2}O. The spectroscopic measurements were used to derive kinetic information on the systems under study,
Date: August 1, 1980
Creator: Littlejohn, David
Partner: UNT Libraries Government Documents Department

Cluster Chemistry

Description: Metal cluster chemistry is one of the most rapidly developing areas of inorganic and organometallic chemistry. Prior to 1960 only a few metal clusters were well characterized. However, shortly after the early development of boron cluster chemistry, the field of metal cluster chemistry began to grow at a very rapid rate and a structural and a qualitative theoretical understanding of clusters came quickly. Analyzed here is the chemistry and the general significance of clusters with particular emphasis on the cluster research within my group. The importance of coordinately unsaturated, very reactive metal clusters is the major subject of discussion.
Date: May 1, 1980
Creator: Muetterties, Earl L.
Partner: UNT Libraries Government Documents Department

The Decomposition of Ammonia on the Flat (111) and Stepped (557) Platinum Crystal Surfaces

Description: Ammonia adsorption, desorption and decomposition to H{sub 2} and N{sub 2} has been studied on the flat (111) and stepped (557) single crystal faces of platinum using molecular beam surface scattering techniques. Both surfaces show significant adsorption with sticking coefficients on the order of unity. The stepped (557) surface is 16 times more reactive for decomposition of ammonia to N{sub 2} and H{sub 2} than the flat (111) surface. Kinetic parameters have been determined for the ammonia desorption process from the Pt(111) surface. The mechanism of ammonia decomposition on the (557) face of platinum has been investigated.
Date: February 1, 1980
Creator: Guthrie, W. L.; Sokol, J. D. & Somorjai, G. A.
Partner: UNT Libraries Government Documents Department

Carbon-13 Chemical Shifts in Solid Metal Sandwich Compounds

Description: C!wmical shielding parameters are reported for the metallocenes of Fe, Ru, Mg; biscyclopentadionyl complexes Cp{sub 2}TiCl{sub 2}, (CpMe{sub 5}){sub 2}CoCl, and (CpMe{sub 5}){sub 2}Fe and bisbenzene chromium. The shielding tensor anisotropy seems to reflect the character of bonding. Motion detected in many of these compounds and has been used in some cases to assign the shielding tensor principle directions.
Date: August 1, 1980
Creator: Wemmer, D. E. & Pines, A.
Partner: UNT Libraries Government Documents Department

Determination of the Reactive Spin State of 1,4-Dehydrobenzenes

Description: Two approaches have been used to determine the spin state(s) of 1 ,4- dehydrobenzenes produced in the solution reaction of diethynyl olefins. The first method relies on the "spin correlation effect" which postulates a relationship between the spin state of a caged radical pair and the ratio of cage and escape reactions (C/E) which may occur in the pair. When the 2,3-di-n-propyl-1,4-dehydrobenzene biradical (4) abstracts hydrogen from 1,4-cyclohexadiene, a radical pair is generated. If a mixture of 1,4-cyclohexadiene-d{sub 0} and -d{sub 4} is employed it is possible, by performing a VPC-MS analysis, to determine the ratio C/E leading from the radical pair to the reduced product, o-dipropylbenzene 10. Applying this method to the reaction of Z-4,5-diethynyl-4-octene (3), C/E was found to be 0.6, independent of the concentration of 1,4-cyclohexadiene (between 0.1 and 10 M) in the chlorobenzene reaction solution. This result suggests the presence of the singlet state of 4 in the reaction of 3. Independent support for this analysis came from the reaction of 3,4-dimethyl-1,5-diyn-3-ene (11) in hexachloroacetone solvent in an NMR probe. The major product, 1,4-dichloro-2,3-dimethylbenzene (12), obtained by chlorine abstraction from the solvent, showed CIDNP polarization (emission) in the aromatic protons. The interpretation of this result is straightforward and indicates solvent trapping of the singlet state of the intermediate 2,3-dimethyl-1,4~dehydrobenzene. Both of these experiments indicate that only the singlet state of 1,4-dehydrobenzenes is generated upon thermal reaction of diethynyl olefins. The failure to observe evidence for the triplet state of the 1,4-dehydrobenzenes under the reaction conditions requires that, if the triplet is the ground electronic state, the rate of intersystem crossing from the singlet must be <10{sup 9} sec {sup -1}.
Date: September 1, 1980
Creator: Lockhart, Thomas P. & Bergman, Robert G.
Partner: UNT Libraries Government Documents Department

The Coordination Chemistry of Metal Surfaces

Description: In coordinately unsaturated molecular metal complexes, carbon-hydrogen bonds of the peripheral ligands may, if the stereochemistry allows, closely approach a metal center so as to develop a three-center two-electron bond between the carbon, the hydrogen, and the metal atoms, C-H-M. In some instances, the interaction .is followed by a scission of the C-H bond whereby the metal is effectively oxidized and discrete M-H and M-C {sigma} bonds are forrned. This class of metal-hydrogen-carbon interactions and reactions is shown to be a common phenomenon in metal surface chemistry. Ultra high vacuum studies of nickel and platinum with simple organic molecules like olefins, and arenes are described. These surface chemistry studies were done as a function of surface crystallography and surface composition. The discussion is largely limited to the chemistry of methyl isocyanide, acetonitrile, benzene and toluene. Molecular orbital calculations are presented that support the experimental identification of the importance of C-H-M metal bonding for metal surfaces.
Date: October 1, 1980
Creator: Muetterties, Earl L.
Partner: UNT Libraries Government Documents Department

Crossed Molecular Beam Studies of Chemiluminescent Reactions: F{Sub 2} + I{Sub 2}, Br{Sub 2} and ICl

Description: The chemiluminescent bimolecular halogen-halogen reactions, F{sub 2} + I{sub 2}, Br{sub 2} and ICl, have been studied by the crossed molecular beam technique. Undispersed chemiluminescence was measured as a function of collision energy and, for I{sub 2} + F{sub 2}, as a function of the two beam pressures. Although no spectra were obtained to positively identify the emitters as IF*, ClF* and BrF*, arguments are given to support this identification. The observed reaction thresholds of 4.2 and 5.9 kcal/mole for I{sub 2} + F{sub 2} and ICl + F{sub 2} , respectively, are the same as the threshold energies for production of the stable trihalogens I{sub 2}F and ClF. This coincidence of threshold energies, as well as similar high collision energy behavior, implies that the chemiluminescent reaction proceeds via a stable trihalogen intermediate. This mechanism can explain our results and the results of other workers without resorting to a symmetry forbidden four center reaction mechanism. A threshold of 11.3 kcal/mole was found for Br{sub 2} + F{sub 2} , no threshold for Br{sub 2}F has been previously reported. Laser enhancement of the I{sub 2} + F{sub 2} reaction was attempted, but no enhancement was seen.
Date: May 1, 1980
Creator: Kahler, C. C. & Lee, Y. T.
Partner: UNT Libraries Government Documents Department

Flow Pyrolysis and Direct and SiF{Sub 4}-Sensitized Laser-Induced Decomposition of Tetralin. Identification of Retro-(2+4) Cleavage as the Primary Homogeneous Thermal Decomposition Channel

Description: In an effort to determine the products and mechanism of the truly homogeneous thermal decomposition of the aromatic hydrocarbon tetralin, we have examined the products formed from this compound upon energization by conventional flow pyrolysis, infrared multiphoton excitation, and SiF{sub 4}-sensitized infrared laser thermal activation. Six major products are formed in these reactions, but the product ratios depend upon the mode of energization. Flow pyrolysis gives a result analogous to those observed earlier; i.e. almost exclusive dehydrogenation, leading to dihydronaphthalene and naphthalene. Direct and sensitized IR laser-induced decomposition, however, leads to ethylene loss (presumably by an initial retro-[2+4] reaction) as the predominent decomposition mode, giving benzocyclobutene. We believe these results are due to the fact that direct thermal decomposition, both in our experiments as well as in previous studies, involves predominant surface-catalysis. In the laser-induced reactions, which are uncomplicated by problems due to surface-catalysis, the true homogeneous decomposition takes place, and this involves retro-[2+4] cleavage. Mechanistic details of these processes were studied by examining the isotope distribution in the products formed on SiF{sub 4}-sensitized laser photolysis of 1,1,4,4-tetradeuteriotetralin.
Date: May 1, 1980
Creator: Berman, Michael R.; Comita, Paul B.; Moore, C. Bradley & Bergman, Robert G.
Partner: UNT Libraries Government Documents Department

A Brief History of Industrial Catalysis

Description: This history covers: catalytic cracking and other acid catalysed reactions; zeolite catalysis; dual functional catalysis; hydrogenation catalysis and hydrogen production; catalytic hydrocarbon dehydrogenation; catalytic alkylation and dealkylation; catalytic coal liquefaction and gasification; heterogeneous oxidation, arnmoxidation, chlorination, and oxychlorination catalysis; olefin disproportionation catalysis; industrial homogeneous catalysis; catalytic polymerization; catalysis for motor vehicle emission control; fuel cell catalysis; and the profession of the catalytic chemist or engineer. The discussion is mostly limited to the rapid growth of industrial catalysis between the second World War and 1978.
Date: June 1, 1979
Creator: Heinemann, Heinz
Partner: UNT Libraries Government Documents Department

Electronic Solution Spectra for Uranium and Neptunium in Oxidation States (III) to (VI) in Anhydrous Hydrogen Fluoride

Description: Spectra have been recorded for solutions in anhydrous hydrogen fluoride (AHF) of uranium and neptunium in oxidation states (III) to (VI). The spectra for U(III), Np(III) and Np(IV) in AHF are very similar to those in acidified aqueous solution, but that for U(IV) suggests that the cationic species is UF{sub 2}{sup 2+}. The AHF spectra for the elements in oxidation states (V) and (VI) are not comparable with those of the formally analogous aqueous solutions, where the elements exist as well-defined dioxo-cations. However, the AHF spectra can be related to spectra in the gas phase, in the solid state or in non-aqueous solvents for each element in its appropriate oxidation state.
Date: October 1, 1980
Creator: Baluka, M.; Edelstein, N. & O'Donnell, T. A.
Partner: UNT Libraries Government Documents Department

Effects of Metal-Support Interactions on the Synthesis of Methanol Over Palladium

Description: The synthesis of methanol and other products from CO and H{sub 2} was studied over Pd catalysts prepared by adsorption of Pd({pi}-C{sub 3}H{sub 5}){sub 2} on MgO, ZnO, La{sub 2}O{sub 3}, {gamma}-Al{sub 2}O{sub 3} , SiO{sub 2}, TiO{sub 2}, and ZrO{sub 2} as well as over a SiO{sub 2}-supported Pd catalyst prepared from PdCl{sub 2} and Pd black. Both the activity and selectivity of Pd were affected strongly by the nature of the support and the composition of the Pd precursor. The specific activity for methanol synthesis decreased in the order Pd/La{sub 2}O{sub 3} >> Pd/SiO{sub 2} [derived from PdCl{sub 2}] > Pd/ZrO{sub 2} > Pd/ZnO ~ Pd/MgO > PdTiO{sub 2} > Pd/Al{sub 2}O{sub 3} ~ Pd/SiO{sub 2} [derived from Pd({pi}-C{sub 3}H{sub 5}){sub 2}] >> Pd black while the specific activity for hydrocarbon synthesis decreased in the order Pd/TiO{sub 2} > Pd/ZrO{sub 2} > Pd/La{sub 2}O{sub 3}> Pd/Al{sub 2}O{sub 3} ~ Pd/SiO{sub 2} [derived from PdCl{sub 2}] > Pd/SiO{sub 2} [derived from Pd({pi}-C{sub 3}H{sub 5}){sub 2}] ~ Pd black >> Pd/MgO > Pd/ZnO. Dimethyl ether production was observed over four of the catalysts and the activity for formation of this product decreased in the order Pd/Al{sub 2}O{sub 3} >> Pd/TiO{sub 2} >> Pd/MgO ~ Pd/ZrO{sub 2}. The effects of support composition on the catalytic properties of Pd are discussed in the light of current ideas concerning metal-support interactions and the acid-base properties of the support.
Date: April 1, 1980
Creator: Ryndin, Yu A.; Hicks, R. F.; Bell, A. T. & Yermakov, Yu I.
Partner: UNT Libraries Government Documents Department

A Study of Fundamental Reaction Pathways for Transition Metal Alkyl Complexes: [Parts 1 and 2]

Description: I. This study reports the rapid reaction under mild conditions of internal or terminal alkynes with methyl (acetyl~ acetonato) (triphenylphosphine) nickel (1) in either aromatic or ether solvents. In all cases vinylnickel products 2 are formed by insertion of the alkyne into the nickel=methyl bond. These complexes may be converted into a variety of organic products (e.g. alkenes, esters, vinyl halides) by treatment with appropriate reagents. Unsymmetrical alkynes give selectively the one regioisomer with the sterically largest substituent next to the nickel atom. In order to investigate the stereochemistry of the initial insertion, a x-ray diffraction study of the reaction of 1 with diphenylacetylene was carried out. This showed that the vinylnickel complex formed by overall trans insertion was the product of the reaction. Furthermore, subsequent slow isomerization of this complex, to a mixture of it and the corresponding cis isomer, demonstrated that this trans addition product is the kinetic product of the reaction. In studies with other alkynes, the product of trans addition was not always exclusively (or even predominantly) formed, but the ratio of the stereoisomers formed kinetically was substantially different from the thermodynamic ratio. Isotope labeling, added phosphine, and other experiments have allowed us to conclude that the mechanism of this reaction does involve initial cis addition. However, a coordinatively unsaturated vinylnickel complex is initially formed which can undergo rapid, phosphine-catalyzed cis-trans isomerization in competition with its conversion to the isolable phosphine-substituted kinetic reaction products. II. The reaction of CpMo(CO){sub 3}H (1a) with CpMo(CO){sub 3}R (2, R= CH{sub 3}, C{sub 2}H{sub 5}) at 50{degrees} C in THF gives the aldehyde RCHO and the dimers [CpMo(CO){sub 3}]{sub 2} (3a) and [CpMo(CO){sub 2}]{sub 2} (4a). Labeling one of the reactants with a methylcyclopentadienyl ligand it was possible to show that the mixed dimers MeCpMo(CO){sub 3}-(CO){sub 3}MoCp (3b) and MeCpMo(CO){sub ...
Date: June 1, 1980
Creator: Huggins, John Mitchell
Partner: UNT Libraries Government Documents Department

Synthesis and Structure of Two Crystalline Forms of Cyclooctatetraenethorium (IV) Dichloride Bistetrahdrofuran

Description: Th(C{sub 8}H{sub 8})Cl{sub 2}(OC{sub 4}H{sub 8}){sub 2} crystallizes in two modifications. The {alpha}-form, space group P2{sub 1}/n, has dimensions: a = 8.589(4) {Angstrom}, b = 27.222(10) {Angstrom}, c = 7.950(4) {Angstrom}, {beta} = 96.92(5){degrees}, Z = 4 and d{sub x} = 1.99 g/cm{sup 3}. The {beta}-form, space group P2{sub 1}/c, has dimensions: a = 13.036(6) {Angstrom}, b = 11.601 (6) {Angstrom}, c = 24.598(10) {Angstrom}, {beta} = 102.90(5) {degrees}, z = 8 and d{sub x} = 2.02 q/cm{sup 3}. The {alpha}-form has one molecule in the asymmetric unit whereas the {beta}-form has two which are chemically equivalent but crystallographically different. The study thus yields three independent determinations of the same molecular structure. Thorium is bonded to the cyclooctatetraene ring, to two chlorine atoms, and to two oxygen atoms from the tetrahydrofuran moieties. Significant distances (averaged) are: Th-Cl = 2.69 {Angstrom}, Th-O = 2.57 {Angstrom}, and Th to plane of C{sub 8}H{sub 8} = 2.02 {Angstrom}.
Date: March 1, 1980
Creator: Zalkin, Allan; Templeton, David H.; Vanda, Carole La & Streitwieser, Jr., Andrew
Partner: UNT Libraries Government Documents Department

SYNTHESIS, CHARACTERIZATION, AND STRUCTURE OF A URANYL COMPLEX WITH A DISULFIDE LIGAND, BIS(DI-n-PROPYLAMMONIUM) DISULFIDOBIS (DI-n-PROPYLMONOTHIOCARBAMATO) DIOXOURANATE(VI)

Description: Olive-green crystals of the title compound, [({underline n}-C{sub 3}H{sub 7}){sub 2}NH{sub 2}{sup +}]{sub 2} [UO(({underline n}-C{sub 3}H{sub 7}){sub 2}NCOS){sub 2}(S{sub 2}){sup -2}, are orthorhombic, space group Pcan, with {underline a}= 15.326(6) {Angstrom}, {underline b} = 17.474(6) {Angstrom}, {underline C} = 14.728(6) {Angstrom}, and Z = 4, (d{sub X} = 1.45 g/cm{sup 3}). For 1833 data, I >{sigma}, R = 0.052, and R{sub w} = 0.069. The structure was revealed by single-crystal x-ray diffraction studies to consist of [(n-C{sub 3}H{sub 7}){sub 2}NH{sub 2}]+ cations and [UO{sub 2}(({underline n|-C{sub 3}H{sub 7}){sub 2}NCOS){sub 2}(S{sub 2}){sup -2} anions with the uranium atom at the center of an irregular hexagonal bipyramid. The uranyl oxygen atoms occupy the axial positions. The equatorial coordination plane contains the disulfide (S{sub 2}{sup -2}) group bonded in a "side-on" fashion, and two oxygen and two sulfur donor atoms from the monothiocarbamate ligands. Interatomic distances are S-S = 2.05(1) {Angstrom}, U-S= 2.714(3) {Angstrom} (disulfide); U-S= 2.871(3) {Angstrom} and U-O = 2.46(1) {Angstrom} (thiocarbamate); U-O = 1.81(1) {Angstrom} (uranyl), The nitrogen atom in the dipropylammonium cation is hydrogen bonded to the uranyl oxgyen atoms,
Date: May 1, 1981
Creator: Perry, Dale L.; Zalkin, Allan; Ruben, Helena & Templeton, David H.
Partner: UNT Libraries Government Documents Department

Theoretical Challenge to the Experimentally Determined Geometrical Structure of Dimethylsilaethylene

Description: The equilibrium geometries of (CH{sub 3}){sub 2}Si=CH{sub 2} and H{sub 2}Si=CH{sub 2} have been determined at the self-consistent-field level of electronic structure theory using a double zeta basis set augmented with d functions on all heavy atoms. For the parent silaethylene, large scale configuration interaction (6920 configurations) demonstrates that electron correlation effects do not qualitatively alter the predicted structure. On this basis it is concluded that the experimental electron diffraction geometry of Mahaffy, Gutowsky, and Montgomery is likely to be seriously incorrect. Specifically the theoretical prediction for the dimethylsilaethylene Si=C distance is 1.692 {Angstrom}, while the range of experimental values presented was 1.815 - 1.835 {Angstrom}.
Date: September 1, 1980
Creator: Yoshioka, Yasunori; Goddard, John D. & Schaefer, III, Henry F.
Partner: UNT Libraries Government Documents Department

Theory of Transition Times: Catalysis at Rotating Disk Electrodes

Description: An exact solution to the problem of convective diffusion to a rotating disk electrode with a prescribed initial profile and current step conditions at the surface is presented. Based on this solution a current density-transition time relationship is established which in the limit reduces to a previously proposed expression that accounts for experimentally observed deviations from the Sand equation. Applications of this theory in connection with the determination of rate parameters for electroactive species undergoing a catalytic reaction at the electrode surface are discussed.
Date: March 1, 1980
Creator: Scherson, Daniel A. & Ross, Philip N.
Partner: UNT Libraries Government Documents Department

Vinylidene: A Shallow Minimum on the C{Sub 2}H{Sub 2} Potential Energy Surface. Static and Dynamical Considerations

Description: The potential energy surface for the singlet vinylidene {yields} acetylene rearrangement has been investigated using nonempirical molecular electronic structure theory. A double zeta plus polarization basis set was used in conjunction with configuration interaction (CI) including single and double excitations, a total of 13,861 configurations. Newly developed analytic CI gradient techniques were used to locate precisely the vinylidene and acetylene minima and the transition state connecting them. The classical barrier height is calculated to be 8.1 kcal, or 7.2 kcal after correction for the effects of higher excitations, and our best estimate of the true classical barrier is 6 kcal (± ~ 1 kcal). Harmonic vibrational analyses were carried out about each of the three stationary points, and zero point energy effects lower the effective barrier by 1.8 kcal. Even for ener,gies below this, however, tunneling through the barrier is found to be extremely rapid; for example, with no vibrational excitation energy (above its zero point energy) the lifetime of vinylidene with respect to rearrangement to acetylene is calculated to be only ~ 10{sup -9} sec, and with 2 kcal of excitation energy this decreases to ~ 10{sup -11} sec.
Date: September 1, 1980
Creator: Osamura, Yoshihiro; Schaefer, III, Henry F.; Gray, Stephen K. & Miller, William H.
Partner: UNT Libraries Government Documents Department

SPECTRUM AND ENERGY LEVELS OF Pr{sup 3+} IN ThBr{sub 4}

Description: The strong features in the absorption spectrum and the laser excited fluorescence spectrum have been interpreted as arising from levels of Pr{sup 3+} in the D{sub 2d} symmetry site of ThBr{sub 4} . 43 energy levels have been fitted to the parameters with an RMS deviation of 61 cm{sup -1}. The values of the crystal field parameters are. B{sub 0}{sup 2} = 260.0 cm {sup -1}, B{sub 0}{sup 4} = - 644.2 cm{sup -1}, B{sub 4}{sup 4} = 929.2 cm{sup -1}, B{sub 0}{sup 6} = 1089.0 cm{sup -1} and B{sub 4}{sup 6} = 240.6 cm{sup -1}. The presence of other crystal symmetry sites is observed.
Date: June 1, 1980
Creator: Conway, J. G.; Krupa, J. C.; Delamoye, P. & Genet, M.
Partner: UNT Libraries Government Documents Department

Separation of Diastereomers, Structural Isomers, and Homologs of n5 -Cyclopentadienyl Cobalt and Dinuclear Molybdenum Complexes by Reverse Phase High Performance Liquid Chromatography Using Deoxygenated Solvents

Description: High Performance Liquid Chromatography (HPLC) is being used as an analytical and preparative tool for the characterization and isolation of a series of air-sensitive organometallic compounds, Reverse phase chranatography with octadecylsilyl-modified silica (ODS) as a stationary phase and polar mobile phases saturated with argon are employed in the separation of products,
Date: November 1, 1980
Creator: Huggins, John M.; King, Joseph A., Jr.; Peter, K.; Vollhardt, C. & Winter, Mark J.
Partner: UNT Libraries Government Documents Department

REACTION PATH HAMILTONIAN: TUNNELING EFFECTS IN THE UNIMOLECULAR ISOMERIZATION HNC u> HCN

Description: The reaction path Hamiltonian model recently formulated by Miller, Handy, and Adams [J, Chern. Phys. 72, 99 (1980)] is applied to the unimolecular isomerization HNC {yields} HCN. The reaction path, and the energy and force constant matrix along it, are calculated at the SCF level with a large basis set ("double zeta plus polarization"), and the microcanonical rate constant k(E) is computed in the energy range near and below the classical threshold of the reaction, It is seen, for example, that rates as fast as 10{sup 5} sec{sup -1} can occur at energies ~ 8 kcal/mole below the classical threshold.
Date: May 1, 1980
Creator: Gray, S.K.; Miller, W.H.; Yamaguchi, Y. & Schaefer, III, H.F.
Partner: UNT Libraries Government Documents Department

REACTIONS OF {eta}{sup 5}-CYCLOPENTADIENYLCOBALT(III) ALKYLS WITH COBALT(I) PHOSPHINES AND IRON CARBONYLS. EVIDENCE FOR DIRECT {eta}{sup 5} -CYCLOPENTADIENYL AND TRIMETHYLPHOSPHINE GROUP TRANSFER BETWEEN METAL CENTERS

Description: We have found that {eta}{sup 5}-methylcyclopentadienyl- (triphenylphosphine)dimethylcobalt(III) (1) undergoes intermolecular cyclopentadienyl ligand exchange with {eta}{sup 5}-cyclopentadienylbistriphenylphosphinecobalt(I). The unsubstituted cyclopentadienyl(triphenylphosphine)dimethylco-balt(III) undergoes exchange of phosphine for carbon monoxide with both Fe(CO){sub 4} and Fe(CO){sub 5} by two different mechanisms. The first involves electrophilic displacement of coordinated phosphine by unsaturated Fe(CO){sub 4} and the second takes place by electrophilic displacement of CO from Fe(CO){sub 5} by the unsaturated CpCoMe{sub 2} fragment (generated by phosphine dissociation from the saturated starting material).
Date: August 1, 1980
Creator: Bryndza, H. E. & Bergman, R. G.
Partner: UNT Libraries Government Documents Department

The Application of High Resolution Electron Energy Loss Spectroscopy to the Study of Model Supported Metal Catalysts

Description: Model supported metal catalysts were fabricated by evaporating a small quantity of rhodium onto an oxidized aluminum substrate. High resolution electron energy loss spectroscopy (ELS) was successfully used to obtain the vibrational spectra of carbon monoxide chemisorbed on these model catalysts. The ELS spectra are compared with vibrational spectra obtained by infrared spectroscopy and inelastic electron tunneling spectroscopy for CO chemisorbed on similar model catalysts.
Date: March 1, 1980
Creator: Dubois, L. H.; Hansma, P. K. & Somorjai, G. A.
Partner: UNT Libraries Government Documents Department