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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Synthesis, structural characterization and reactivity of metallacarboranes of lanthanides and early transition metals. / CUHK electronic theses & dissertations collection

January 2005 (has links)
Alkane elimination reaction of Hf(CH2SiMe3) 4 with a zwitterionic salt 1-Me2NHCH2CH2 -1,3-C2B10H12 has resulted in the isolation and structurally characterization of the first example of half-sandwich group 4 metallacarborane alkyls of the C2B10 system. This is also a new route to high-valent group 4 metallacarboranes. / Alkane or amine elimination reactions are also effective methods for the preparation of half-sandwich group 4 metal] acarboranes of the C 2B9 system. The Lewis base functionalized sidearm can effectively stabilize half-sandwich group 4 metallacarborane alkyls through intramolecular coordination. These novel metallacarborane alkyls undergo insertion reaction with alkyne and intramolecular hydrogen atom abstraction reactions. / High-valent group 4 half-sandwich metallacarboranes incorporating an eta 7-carboranyl ligand have been prepared and structurally characterized. The heteroatom-containing pendant sidearms on the carborane cage are both electronically and entropically necessary for the formation of such complexes. / Reaction of [(Me2NCH2CH2)C2B 10H11]Na2 with YCl3 gives eta 1:eta6-[(Me2NCH2CH2)C 2B10H11]YCl(THF)3 containing an exopolyhedral Y-Cl bond, which offers an important intermediate for the preparation of lanthanacarboranes bearing the Ln-C or Ln-X (X = heteroatoms) bonds. On the other hand, it implies that Lewis base functionalized carboranes can stabilize half-sandwich metallacarboranes via the coordination of heteroatom from the sidearm. Silylamine elimination reactions of the neutral ligand 7-Me2NHCH2CH2-7,8-C 2B9H11 with Ln[N(SiHMe2)2] 3(THF)2 are effective method for the preparation of half-sandwich lanthanacarboranes. / Reactions of alkali metal salt of these carboranes with LnCl3 in the presence of excess alkali metal afford a novel class of 13-vertex closo-metallacarboranes incorporating eta7-carboranyl ligands [{eta1:eta1:eta7-[(DCH 2CH2)RC2B10H10]Ln}{Na(solvent) x}]n. Structural studies show that the Lewis base functionalized sidearms have some effects on the coordination environments of the central metal atom, but do not change the gross structures of the 13-vertex closo-metallacarboranes. The reactivity patterns of these 13-vertex closo-metallacarboranes have been studied for the first time. / Several mono- and bisfunctional carboranes (DCH2CH2)RC 2B10H10 (R = H, DCH2CH2, D = MeO, Me2N) have been designed and successfully synthesized. They can be conveniently converted into the monoanions, the dianions and the tetraanions by treatment with suitable reagents. Their applications in organolanthanide and group 4 organometallic chemistry have been studied. / Cheung Mak-shuen. / "June 2005." / Adviser: Kevin W. P. Leung. / Source: Dissertation Abstracts International, Volume: 67-01, Section: B, page: 0258. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (p. 169-181). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract in English and Chinese. / School code: 1307.
42

Soil bioavailability of rare earth elements and their effects on tree growth.

January 2007 (has links)
Wong, Man Wing. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 173-188). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgements --- p.v / Table of Contents --- p.vii / List of Tables --- p.xi / List of Figures --- p.xiii / List of Plates --- p.xv / Chapter Chapter 1 --- Introduction / Chapter 1.1 --- Definition of Rare earth elements --- p.1 / Chapter 1.2 --- Discovery of REEs --- p.5 / Chapter 1.3 --- Physical and chemical properties of REEs --- p.6 / Chapter 1.4 --- Abundance of REEs on earth --- p.10 / Chapter 1.4.1 --- Bastnasite --- p.11 / Chapter 1.4.2 --- Monazite --- p.14 / Chapter 1.4.3 --- Xenotime --- p.16 / Chapter 1.5 --- Reserves and resources --- p.16 / Chapter 1.5.1 --- World reserves --- p.16 / Chapter 1.5.2 --- REE resources in China --- p.18 / Chapter 1.6 --- Production and demand of REEs --- p.20 / Chapter 1.6.1 --- Production and demand in US --- p.21 / Chapter 1.6.2 --- Production and export in China --- p.23 / Chapter 1.6.3 --- Production in other countries --- p.24 / Chapter 1.7 --- Separation of REEs --- p.24 / Chapter 1.7.1 --- Classical methods --- p.24 / Chapter 1.7.2 --- Modern methods --- p.25 / Chapter 1.7.2.1 --- Ion exchange separation --- p.25 / Chapter 1.7.2.2 --- Solvent extraction --- p.25 / Chapter 1.8 --- Applications --- p.26 / Chapter 1.8.1 --- Alloys --- p.26 / Chapter 1.8.2 --- Permanent magnets --- p.28 / Chapter 1.8.3 --- Catalysts --- p.29 / Chapter 1.8.4 --- Glass additives --- p.30 / Chapter 1.8.5 --- Phosphors in television screens and similar fluorescent surfaces --- p.31 / Chapter 1.8.6 --- Fertilizers and feed additives --- p.32 / Chapter 1.9 --- REEs in the environment --- p.33 / Chapter 1.9.1 --- REEs in soil --- p.33 / Chapter 1.9.2 --- REEs in plants --- p.35 / Chapter 1.10 --- Overview of toxicological studies of REEs --- p.36 / Chapter 1.11 --- Current study --- p.38 / Chapter 1.11.1 --- Thesis outline --- p.3 8 / Chapter 1.11.2 --- Objectives --- p.38 / Chapter 1.11.3 --- Significance --- p.39 / Chapter Chapter 2 --- Phytotoxicity of rare earth elements / Chapter 2.1 --- Introduction --- p.41 / Chapter 2.1.1 --- Ecotoxicity of REEs --- p.41 / Chapter 2.1.2 --- Toxicity tests using higher plants --- p.43 / Chapter 2.1.3 --- Advantages of seed germination and root elongation test --- p.44 / Chapter 2.1.4 --- Selection of species --- p.46 / Chapter 2.1.5 --- Endpoint of test --- p.47 / Chapter 2.1.6 --- Median effect estimates --- p.50 / Chapter 2.1.7 --- Objective --- p.50 / Chapter 2.2 --- Materials and methods --- p.50 / Chapter 2.2.1 --- Test species --- p.51 / Chapter 2.2.2 --- Test chemicals --- p.51 / Chapter 2.2.3 --- Range finding test --- p.51 / Chapter 2.2.4 --- Definitive test --- p.52 / Chapter 2.2.5 --- Statistical analyses --- p.52 / Chapter 2.3 --- Results --- p.53 / Chapter 2.3.1 --- Range finding test --- p.53 / Chapter 2.3.2 --- Definitive test --- p.53 / Chapter 2.3.2.1 --- Germination rate --- p.53 / Chapter 2.3.2.2 --- Root length --- p.55 / Chapter 2.3.2.3 --- Germination index --- p.58 / Chapter 2.3.3 --- The median effective concentration --- p.61 / Chapter 2.4 --- Discussion --- p.62 / Chapter 2.4.1 --- Dose-response curves of REEs --- p.62 / Chapter 2.4.2 --- Relative toxicity of the four REEs --- p.63 / Chapter 2.4.3 --- Mechanism of effect of REEs on seed growth --- p.67 / Chapter 2.4.4 --- Comparison between different endpoints --- p.68 / Chapter 2.4.5 --- Comparison between different species --- p.70 / Chapter 2.4.6 --- Limitations and improvement --- p.71 / Chapter 2.4.7 --- Methods of measuring root length --- p.72 / Chapter 2.5 --- Conclusions --- p.73 / Chapter Chapter 3 --- Growth of tree seedlings in soil treated with rare earth elements / Chapter 3.1 --- Introduction --- p.75 / Chapter 3.2 --- Materials and methods --- p.77 / Chapter 3.2.1 --- Soil --- p.77 / Chapter 3.2.2 --- Tree seedlings --- p.77 / Chapter 3.2.3 --- REEs --- p.78 / Chapter 3.2.4 --- Greenhouse experiment --- p.78 / Chapter 3.2.5 --- Soil analysis --- p.80 / Chapter 3.2.5.1 --- Initial properties --- p.80 / Chapter 3.2.5.2 --- Post harvest analysis --- p.81 / Chapter 3.2.6 --- Plant analysis --- p.83 / Chapter 3.2.7 --- Statistical analysis --- p.83 / Chapter 3.3 --- Results --- p.84 / Chapter 3.3.1 --- Growth --- p.84 / Chapter 3.3.1.1 --- Height --- p.84 / Chapter 3.3.1.2 --- Basal diameter --- p.87 / Chapter 3.3.1.3 --- Biomass --- p.89 / Chapter 3.3.1.4 --- Standing leaf number --- p.92 / Chapter 3.3.1.5 --- Chlorophyll fluorescence --- p.95 / Chapter 3.3.2 --- Tissue contents --- p.97 / Chapter 3.3.2.1 --- REEs concentrations --- p.97 / Chapter 3.3.2.2 --- Nitrogen concentrations --- p.99 / Chapter 3.3.2.3 --- Phosphorus concentration --- p.101 / Chapter 3.3.2.4 --- Mineral concentrations --- p.102 / Chapter 3.3.3 --- Soil --- p.104 / Chapter 3.3.3.1 --- Initial properties --- p.104 / Chapter 3.3.3.2 --- REEs concentrations --- p.106 / Chapter 3.3.3.3 --- Nitrogen and phosphorus concentrations --- p.107 / Chapter 3.3.3.4 --- Mineral concentrations --- p.109 / Chapter 3.4 --- Discussion --- p.110 / Chapter 3.4.1 --- Effects of REEs on growth --- p.110 / Chapter 3.4.2 --- Mechanisms of the effect of REEs --- p.112 / Chapter 3.4.3 --- Nutrient uptake --- p.114 / Chapter 3.4.4 --- Soil nutrient contents --- p.116 / Chapter 3.4.5 --- Comparison between REEs --- p.118 / Chapter 3.4.6 --- Comparison between species --- p.121 / Chapter 3.5 --- Conclusions --- p.123 / Chapter Chapter 4 --- Bioavailability and accumulation of rare earth elements / Chapter 4.1 --- Introduction --- p.124 / Chapter 4.2 --- Materials and Methods --- p.126 / Chapter 4.2.1 --- Soil --- p.126 / Chapter 4.2.2 --- Tree seedlings --- p.126 / Chapter 4.2.3 --- Pot experiment --- p.127 / Chapter 4.2.4 --- Chemical speciation of soil --- p.129 / Chapter 4.2.5 --- Statistical analysis --- p.130 / Chapter 4.3 --- Results --- p.130 / Chapter 4.3.1 --- Plant performance --- p.130 / Chapter 4.3.2 --- Tissue contents of La --- p.144 / Chapter 4.3.3 --- Soil --- p.144 / Chapter 4.3.3.1 --- Soil final pH --- p.146 / Chapter 4.3.3.2 --- Soil La contents --- p.146 / Chapter 4.3.4 --- "Association between pH, organic matter and La contents in soil and plant" --- p.149 / Chapter 4.4 --- Discussion --- p.151 / Chapter 4.4.1 --- Growth performance of tree seedling on different soil conditions --- p.151 / Chapter 4.4.2 --- Comparison between growth parameters --- p.152 / Chapter 4.4.3 --- Speciation in soils --- p.154 / Chapter 4.4.4 --- Bioavailability of REEs in soil --- p.155 / Chapter 4.4.5 --- Factors affecting bioavailability of REEs --- p.158 / Chapter 4.4.6 --- Distribution of REEs in plants --- p.162 / Chapter 4.5 --- Conclusions --- p.165 / Chapter Chapter 5 --- General conclusions --- p.167 / Chapter 5.1 --- Summary of major findings --- p.167 / Chapter 5.2 --- Suggestions for further investigation --- p.171 / References --- p.173
43

Rare earth elements distributions and strontium isotope data from the Gem Park igneous complex, Colorado

Roden, Mary Kathleen January 2011 (has links)
Typescript. / Digitized by Kansas Correctional Industries
44

Chemical exchange processes in lanthanide (III), dioxouranium (VI) and sodium (I) complexes

White, Alex, 1962- January 1987 (has links) (PDF)
Bibliography: leaves 132-147.
45

Synthesis and structural determination of alkali and alkaline earth metal containing bismuth vanadates /

Bliesner, Rebecca J. January 2001 (has links)
Thesis (Ph. D.)--Oregon State University, 2002. / Typescript (photocopy). Includes bibliographical references. Also available via the World Wide Web.
46

Surface structurally controlled sectoral zoning in fluorite implications to understanding heterogeneous reactivity at the mineral-water interface /

Bosze, Stephanie Lynn. January 2001 (has links)
Thesis (M.S.)--Miami University, Dept. of Geology, 2001. / Title from first page of PDF document. Document formatted into pages; contains viii, 150 p. : ill. Includes bibliographical references.
47

The spectroscopy of trivalent lanthanoid ions in organic hosts /

Flanagan, Bernadine Mary. January 2002 (has links) (PDF)
Thesis (Ph. D.)--University of Queensland, 2002. / Includes bibliographical references.
48

An investigation of novel reactivity and bonding in rare earth metal complexes

Johnson, Kevin Ross David January 2012 (has links)
The synthesis, structure and reactivity of organolanthanide complexes supported by a family of novel bis(phosphinimine)carbazole and bis(phosphinimine)pyrrole pincer ligands is presented. Through the systematic development of the ligand frameworks, rare earth metal species with unique structure and reactivity were encountered. A variety of complexes that exhibited unusual bonding modes were prepared and characterized by single-crystal X-ray diffraction and multinuclear NMR spectroscopy. Modulation of the ligand frameworks allowed for rational manipulation of the steric and electronic environment imparted to the metal. Incorporation of a variety of N-aryl rings (mesityl, phenyl, para-isopropylphenyl and 2-pyrimidine) and PR2 moieties (PPh2, PO2C2H4 and PMe2) into the ligand design led to rare earth complexes that revealed diverse reaction behaviour. In particular, C–H bond activation, sigmatropic alkyl migration and ring opening insertion reactivity were observed. Kinetic and deuterium labeling studies are discussed with respect to the unique reaction mechanisms encountered during the study of these highly reactive organometallic rare earth complexes. / xxvi, 247 leaves : ill. (some col.) ; 29 cm + 1 CD-ROM
49

Chemical exchange processes in lanthanide (III), dioxouranium (VI) and sodium (I) complexes /

White, Alex, January 1987 (has links) (PDF)
Thesis (Ph. D.)--University of Adelaide, 1987. / Includes bibliographical references (leaves 132-147).
50

Structural systematics of complexes of lanthanoid picrates with unidentate O-donor ligands and other related arrays /

Chan, Eric J. January 2006 (has links)
Thesis (Ph.D.)--University of Western Australia, 2006.

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