Browsing by Subject "Organometallic compounds"
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Item Electrochemical Reactions and Mechanisms of Organic and Organometallic Compounds in Aprotic Solvents(Texas Tech University, 1980-08) Root, Duane KeithNot Available.Item Electrochemical synthesis of organometallic nickel compounds with chemical applications(Texas Tech University, 1982-12) Lyster, Thomas HNot availableItem Fundamental surface science investigations of systems designed to address technological issues(2003) Yan, Xiaoming; White, John M.Organometallic chemical vapor deposition of (MeCp)Ir(COD) onto Rh is simulated experimentally with and without co-reactant oxygen via isothermal reaction mass spectrometry. Auger electron spectroscopy (AES) is used to analyze the resulting film purity. Without oxygen, continuous film deposition occurs above 750 K. A large amount of carbon incorporates, and a final composition of C4Ir is inferred. At the steady state of film growth, acetylene is the only volatile product. Before reaching steady state, various hydrocarbon species are observed. With enough oxygen, the precursor combusts and pure Ir is deposited above 600 K. At steady state, the main by-products are CO and H2O. The thermal decomposition of tert-butoxy (TBO) with co-adsorbed O and NO is studied using temperature programmed desorption and AES on Rh foil and Cu(111). On Cu(111) with NO(a), some TBO decomposes below 240 K to form H2O, CO, CO2, C2H2, proposed imide and acetate, and others disproportionate to tert-butyl alcohol, isobutene and adsorbed oxygen at 610 K. On Rh with NO(a), two oxygen-containing fragments—TBO and a stabilized oxametallacycle—coexist. The proposed oxametallacycle decomposes at 350 K to acetone, while TBO, relatively stable in the presence of N and NO, decomposes to isobutene at 500 K. On Rh with O(a), TBO is stable only up to 380 K where, assisted by O, it decomposes to acetone and butene via a transient form of the oxametallacycle. Thermally evaporated Ag is deposited onto a thin solid water layer on clean hafnia, titania and functionized titiania surfaces. After thermal desorption of water, scanning tunneling microscopy (STM) and atomic force microscopy (AFM) reveals Ag particles on these surfaces. On HfO2, particles have lateral dimensions between 5 and 20 nm and, in many cases, with heights exceeding the thickness of the original water layer. More interesting, particles form 1D bead-like strings spontaneously on 18 L ice. However, on trimethyl acetic acid (TMAAH) pre-saturated TiO2(110), only a few huge particles form. The difference is attributed to the different surface hydrophilicities, which affect both the initial ice layer growth and the competition between dewetting and desorption of adsorbed water.Item Investigation of alkylindium-metal carbonyl reaction and synthesis of xenophilic compounds(Texas Tech University, 2002-12) Li, ZhengrongThe study of the salt elimination reactions of transition metal chlorides with tetracarbonylferrate, tetracarbonylcobaltate and pentacarbonylmanganesate to synthesize xenophilic complexes in which the Type A metal has neutral ligands was carried out. The reduction-oxidation reactions in which electrons were transferred from the pentacarbonyl-manganesate and tetracarbonylferrate anions to the transition metal cations hindered the formation of the metal-metal bond between transition metals. In the reactions of transition metal chlorides with tetracarbonylcobaltate anion no reaction occurred unless tetracarbonylcobaltate anion yielded anionic carbonyl cobalt clusters when the less polar solvents replaced THF (THF = tetrahydrofuran). The exception was that the Group 4 metal chlorides reacted with tetracarbonylcobaltate anion to yield the hydrotetracarbonylcobalt. The introduction of pyrroUdine reduced the oxidation potentials of Group 7, 8 metal cations so that the synthesis of xenophilic complexes was possible. In the reaction of an equal molar mixtvire of trimethyl and triethyl indium with octacarbonylcobalt that generates ketone, the statistical distribution of ketone products was obtained. The pathways for such reaction are proposed. The compound Mn2(CO)8(C4H9N)2 (C4H9N = pyrrolidine) has been synthesized by placing Mn2(CO)10 into hexanes containing pyrrolidine. A single crystal X-ray structure determination shows the pyrrolidine molecules attach to the manganese atoms in the equatorial position. The bond length between manganese atoms is 2.9415(7) A, longer than that in Mn2(CO)10 and in diaxial substibuted Mn2(CO)10. This is the first disubstituted Mn2(CO)10 by monodentate nitrogen ligand that has trans-equatorial geometry.Item Ireland-Claisen rearrangement of cyclopentanecarboxylates and studies directed toward the total synthesis of subergorgic acid(2002-12) Yin, Jiandong; Gilbert, John C.The purpose of this project is to explore the Ireland-Claisen rearrangement of five-membered ring ester substrates, and its application to the total synthesis of subergorgic acid. Previous investigations by the Gilbert group showed that alkenyl 2-methylcyclopentanecarboxylates and alkenyl 2- methoxycyclopentanecarboxylates undergo the rearrangement with complete refacial selectivity for the former, whereas the facial selectivity was mostly lost for the latter. The current studies confirmed these results and additionally demonstrated excellent diastereoselectivity in the rearrangement of the substituted alkenyl 2-methylcyclopentanecarboxylates. The high stereoselectivity is attributed to high diastereoselectivity in the formation of kinetic enolates from substrate esters, followed by [3,3]-sigmatropic rearrangement preferentially through a chair-like transition state. The high diastereoselectivity of this type of Ireland-Claisen rearrangement served as the fundamental basis of our approach to the synthesis of subergorgic acid, and in practice effected the stereochemical control for four out of the total of five asymmetric centers present in the molecule. The subsequent construction of rings A and C of subergorgic acid was attempted through several strategies, but each met with obstacles. Although most of these were overcome, it was not possible to accomplish the desired goal largely because of steric factors. Although our intended approach did not provide a short, viable route to the total synthesis of subergorgic acid, it did afford valuable insights regarding the IrelandClaisen rearrangement in five-membered ring systems. The formation of spirocompounds from both sterically and stereoelectronically demanding systems as seen in this work has the potential to serve as a general strategy for synthesis of such sub-units in both natural and unnatural products.Item Low valent and mixed valent cyclopentadienyl complexes of the group 13 elements(2001-12) Gorden, John David, 1972-; Cowley, Alan H.A variety of low-coordinate bonding environments that feature group 13 elements have been explored. The highlights in this area include the isolation and structural characterization of the decamethylborocenium cation, the most tightly squeezed metallocene and the first compound to adopt a s/p geometry in the solid state, the synthesis of the first gallocenium cation, the first examples of main group constrained geometry compounds, and the first examples of multidecker p-block cations. The reactivities of monovalent group 13 pentamethylcyclopentadienide compounds with conjugated systems and electron-deficient tris(perfluorophenyl) compounds has also been explored. It has been found that [(C5Me5)M]n (M = Al, Ga) fragments will undergo oxidative addition to diazabutadienes, resulting in the formation of monomeric five-membered ring systems. Furthermore, it has been shown that the reactions of [(C5Me5)M]n clusters (M = Al, Ga) with (C6F5)3M (M = B, Al, Ga, In) yield the first examples of group 13 M(I)-M(III) donor-acceptor complexes, the first valence isomer of a dialane, and a unique inverse sandwich complex featuring p-bonding to perfluorophenyl ligands. It has further been found that the reactions of (C5Me5)2AlMe and (C5Me5)3Ga with tetramethylimidazol-2-ylidene yield unprecedented (C5Me5)2MH carbene complexes and tetramethylfulvene.Item Organometallic precursors for novel material design(2007) Agapiou, Kyriacos, 1978-; Jones, Richard A., 1954-As part of a broad program directed toward the discovery of inorganic and inorganic-organic hybrid materials that exhibit interesting and/or useful properties (e.g. electronic, photonic, magnetic, etc.), several distinct projects dealing with the identification and synthesis of novel organometallic complexes have arisen. The unveiling of such metal-complexes or new applications for existing complexes adds to the repertoire of candidates that may be incorporated into or used to generate new materials. The research conducted addresses (1) the design of precursors for the chemical vapor deposition (CVD) growth of amorphous metallic alloys, (2) the design, synthesis, and study of a novel class of polymerizable organometallic precursors for heterocomposite photovoltaic materials and (3) the preparation of triazolato ruthenium complexes vis-à-vis "click" cycloaddition chemistry.Item Solution chemistry of some group Va organometallics(Texas Tech University, 1976-05) Kuykendall, Gregory LewisNot availableItem The synthesis of perfluorinated compounds by direct fluorination: organometallic compounds and carboranes(2001-12) Callahan, Ryan Patrick; Lagow, Richard J.Item Synthetic approaches to problems in materials science: development of novel organometallic compounds for specific applications(2002) Pietryga, Jeffrey Michael; Cowley, Alan H.The chemical vapor deposition of thin, epitaxial layers of titanium nitride for use in electronic devices is a subject of continuing research. The development of novel titanium hydrazides as single-source precursors for titanium nitride has been outlined. The molecular structures of a series of titanium hydrazides utilizing 1,1-dimethylhydrazide(-1), 1,2-diphenylhydrazide(-1), 1,2- diphenylhydrazide(-2), trimethylhydrazide and N,N’-bis(trimethylsilyl)- benzamidinate ligands are presented. By examination of the variation in structure and hydrazide ligand bonding modes from one ligand system to the next, the effects of small changes in the hydrazide substitution on overall titanium hydrazide geometry have been elucidated. In an effort to create novel olefin polymerization catalysts, the first structurally authenticated examples of p-block element complexes utilizing the “constrained geometry” ligand, [(C5Me4)(t-BuN)SiMe2] -2 (CGC), have been prepared. P-block element constrained geometry complexes show dramatic structural differences from the known d- and f-block metal complexes. Group 13 complexes (CGC)EMe·(THF) (E = Al, Ga) exhibit unprecedented η1 σ-type interactions between the group 13 element and the C5Me4 ring. The dinuclear complexes [Mg2Cl3(THF)6][GaCl3(CGC)GaCl2] and [Mg2Cl3(THF)6][InBr3(CGC)InBr2] feature an equally unprecedented bridging bonding mode for the constrained geometry ligand, and are the first unequivocal examples of η2 π-donation to a gallium(III) or indium(III) metal center, respectively. Group 15 complexes (CGC)ECl and the corresponding tetrachloroaluminate salts [(CGC)E][AlCl4] (E = P, As, Sb) undergo rearrangement of the constrained geometry ligand itself to produce entirely unpredicted complexes. The crystallographically observed molecular structures have been compared to those predicted by DFT calculations. Ethylene polymerization studies employing several of these p-block complexes have been performed.