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This dissertation, "Group 4 Complexes Bearing Tridentate Aryloxide-based Ancillary Ligands: Synthesis, Characterization and Application as Olefin Polymerization Catalysts" by Ka-ho, Tam, 譚家豪, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled GROUP 4 COMPLEXES BEARING TRIDENTATE ARYLOXIDE- BASED ANCILLARY LIGANDS: SYNTHESIS, CHARACTERIZATION AND APPLICATION AS OLEFIN POLYMERIZATION CATALYSTS Submitted by Tam Ka Ho for the degree of Doctor of Philosophy at The University of Hong Kong in 2006 The preparation, characterization, crystal structures and olefin polymerization behavior of a class of Group 4 complexes, and in particular the Zr(IV) derivatives 1 1 [Zr(L )Cl (D)] [H L = 2,6-di(3-tert-butyl-5-methylphen-2-ol)pyridine; D = ethers, 2 2 ketones and Cl(HPR )], have been undertaken. These [O, N, O] catalysts exhibit excellent activities with MAO for ethylene polymerization. Studies to assess the impact of the donor group during catalysis suggest that the same active species is generated and the donor does not play an active role. Superior activities were observed with the Bu Al/Ph CB(C F ) cocatalyst in ethylene polymerization and - 3 3 6 5 4 -1 -1 propylene copolymerization (36,590 and 15,700 g mmol h respectively). Insight into the behavior of the catalytic system with MAO has been derived from gel permeation chromatography and NMR analyses of the polymers prepared under 1 13 different reaction conditions. H and C NMR end-group analyses reveal resonances for saturated methyl chain-end groups only, and undetectable levels of unsaturated vinyl chain ends. This indicates that for the polymerization chain-transfer mechanism, the conventional β-H transfer reactions are insignificant and the unusual chain transfer to Al pathway is vastly dominant. Group 4 complexes supported by unsymmetric tridentate [O, N, O] ligands bearing different substituents on the two aryloxide rings have been prepared, in order to develop new catalytic systems capable of stereospecific α-olefin polymerization. Their activities for ethylene polymerization with MAO are significantly lower than the symmetric [O, N, O] analogues. A number of group 4 bis(benzyl) complexes supported by tridentate pyridine-2- phenolate-6-aryl [O, N, C] ligands, with alkyl and halogen substituents at the R position ortho to the metal, have been prepared. This enabled direct comparison with the CF -substituted [O, N, C] analogues, which were recently reported to exhibit novel C-H---F-C contacts in solution with potential applications for attractive ligand---polymer interactions. The molecular structure of the Zr derivative bearing an ortho-Cl group was determined, revealing the benzyl moieties in an unusual 'anti, anti' configuration. Saliently, this polyethylene catalyst in conjunction with Bu Al/Ph CB(C F ) displayed the best activity thus far observed for [O, N, C] 3 3 6 5 4 -1 -1 catalysts (8630 g mmol h ). A series of group 4 bis(benzyl) complexes supported by newly designed [O, C, N] ligands bearing R substituents ortho to the metal has been prepared, such that the σ- aryl moiety resides trans to the alkyl/polymer chain, and catalyst decomposition pathways such as olefin insertion into the M-C(sp ) bond are impeded. The crystal structure of the CF -substituted hafnium(IV) complex features weak intramolecular 31 C-H---F-C (CF ---methylene) interactions. The H NMR spectra of [M(O, C, N- CF )(CH Ph) ] analogues revealed coupling (assigned to J [via M---F] for Hf and
An approach to the investigation of the thermodynamic and kinetic stability of variable-valence metal complexes has been developed. Concepts of the generalised inverse problems of quantitative instrumental analysis and the complex formation equilibria are introduced. The procedure for this investigation is regarded as a sequential procedure for solving these two inverse problems. The classical methods for investigating the complex formations in solution are analysed in terms of these in-verse problems. Their generalisations are given to determine together with the formation constants also redox-decomposition rate constants of variable-valence metal complexes and the rate law of numerous redox processes, for which the rate-determining step is the decay of an intermediate complex, are presented. Classification is discussed and their implementation on the examples of the study of the complexation and in-tramolecular redox decomposition of cerium(IV) hydroxo complexes with some dicarboxylic, oxycarboxylic acids and aliphatic polyatomic alcohols in dependence on acidity (pH 0.73.4) of a sulphate medium at the ionic strength I=2 and temperatures of 10.043.0℃C by UV-Vis spectroscopy and pH measurements. The region of existence, composition, ligand speciation, stability constants of the complexes [CeOH(H-xR)n]3-nx, rate constants, and activation energies of the intramolecular redox decomposition were determined for these complexes on the sulphate background. The rate law of the redox process occurring in the studied systems on the basis of the calculated constants and set of all the chemical and algebraic equations describing the equilibria in systems is derived, and the quantitative model of this process is created. The existence of positive correlation between thermodynamic and kinetic stability of the complexes [CeOHH-xR]3-x with x > 2 and its absence for x > 2 was found on the sulphate background. Discussed also are the computational aspects of solving the regarded generalised problems. This book is well-suited for researchers in the chemistry of co-ordination compounds, physical chemistry, and biochemistry, as well as faculty and advanced students.
In this study, by applying a salt metathesis approach between Ce(OtBu3)2(NO3)2(THF)2 and the potassium salts of mono- and ditrimethylsilyl substituted cyclopentadienes, we were able to isolate two new Ce(IV) metallocenes, including to the best of our knowledge, the first structurally characterized bis-cyclopentadiene Ce(IV) compound.
Alkoxo and Aryloxo Derivatives of Metals gives a comprehensive account of the chemistry of metal alkoxides and metal aryloxides, including their industrial applications such as microelectronics, ceramics, nonlinear optical materials, high-temperature superconductors, specialized glasses, and other advanced novel materials. It is an invaluable reference source book. The book is an updated edition of Metal Alkoxides, published by Academic Press in 1978, with additional coverage of metal aryloxides. It reflects the enormous growth in interest in this field in recent years. Alkoxo and aryloxo derivatives are organic compounds with metals for useful industrial purposes. Alkoxo and Aryloxo Derivatives of Metals will appeal to a wide-ranging audience, including university researchers and chemistry graduate students in industrial laboratories concerned with microelectronics, ceramics, glasses and other advanced novel materials; any laboratories doing research on nonlinear optical materials, high-temperature superconductors, ceramic materials, and specialized glasses. It can also serve as a supplementary text for final year courses in advanced inorganic chemistry, e.g., metallo-organic chemistry.