Thesis (Ph. D.)--University of Chicago Graduate School of Business, August 1999. / Includes bibliographical references. Also available on the Internet.

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This dissertation concerns the use of bicyclic guanidinate ligands to prepare new dimetal paddlewheel compounds. Specifically, Ru_2^6+, Re_2^6+, Re_2^7+, and Os_2^7+ compounds will be examined to observe any changes brought about by using bicyclic guanidinate ligands with varying ring sizes. In the Ru_2^6+ compounds, different ligand ring sizes cause a change in the electronic configuration and magnetic properties. Bicyclic guanidinate ligands allow the preparation of Re_2^7+ compounds from Re_2^6+ compounds, both of which are examined structurally and electrochemically. [Os2(hpp)4]^+ is examined to improve upon earlier studies, yielding a model of the g-tensor components with respect to the compound structure. An additional project included in the dissertation involves the study of an asymmetric trinickel extended metal atom chain. The structural effects of the asymmetry are examined to help elucidate the magnetic behavior that differs significantly from symmetric trinickel extended metal atom chains.

The purpose of the study is to use the data of the companies that are listed (including OTC) in Taiwan Stock Exchange to examine whether companies engage in earnings management in the years convertible bonds are issued and de-listed. We also want to know if there is any difference of earnings management whether convertible bonds are issued domestically or abroad. Discretionary current accruals are adopted as proxies for earnings management and the regression models are used to control the related variables. The empirical results indicate that companies conduct earnings management in the years convertible bonds are issued and there is no significant difference of earnings management whether convertible bonds are issued in Taiwan or abroad. However, the data after 2001 indicate that companies that issued convertible bonds abroad have less earnings management than those that issued convertible bonds domestically. The results also show no significant difference in the years convertible bonds are de-listed. The reasons may be due to the relatively small sample size or companies may not use discretionary accruals to conduct earnings management.

A goal of the modern protein chemist is the design of novel proteins with specific activities or functions. One hurdle to overcome is the ability to accurately predict the pKas of ionizable groups upon their burial in the interior of a protein, where they are typically perturbed from their intrinsic pKas. Most discussion of intrinsic pKas is based on model compound data collected prior to the 1960's. We present here a new set of intrinsic pKas based on model peptides, which we think are more applicable than the model compound values. We observe some differences with the model compound values, and discuss these by critically examining the compounds originally used for the dataset. One interaction affecting the pKas of ionizable groups in proteins that is not well understood is the effect of hydrogen bonds. The side chain carboxyl of Asp33 in RNase Sa is buried, forms 3 intramolecular hydrogen bonds, and has a pKa of 2.4 in the folded protein. One of these hydrogen bonds is to the side chain hydroxyl of Thr56. We mutated Thr56 to alanine and valine and observed that the mutations relieves the perturbation on the carboxyl group and elevates its pKa by 1.5 and 2 units, respectively. The side chain carboxyl of Asp76 in RNase T1 is completely buried, forms 3 intramolecular hydrogen bonds to other side chain groups, and has a pKa of 0.5 in the folded protein. Mutating any of the hydrogen bonding groups to the carboxyl affects its pKa differently, depending on the group mutated. Mutating all of the hydrogen bonding groups, creating a triple mutant of RNase T1, reverses the perturbation on the pKa and elevates it to about 6.4, very near the observed pKa of other carboxyl groups buried in hydrophobic environments. We compared these experimental results with predicted results from theoretical models based on the Solvent Accessibility Corrected Tanford- Kirkwood Equation and the finite difference solution to the linearized Poisson- Boltzmann Equation. The comparisons revealed that these models, most often used by theoreticians, are flawed when typically applied, and some possible improvements are proposed.

Thesis (Honors)--College of William and Mary, 2009. / Includes bibliographical references (leaf 60). Also available via the World Wide Web.

Thesis (M. Sc.)--University of Hong Kong, 1966. / Typewritten.

Thesis (Ph. D.)--Hong Kong University of Science and Technology, 2003. / Includes bibliographical references. Also available in electronic version. Access restricted to campus users.

The electron density function of molecular systems supplies a package of information. Quantum mechanical methods of producing and analyzing this function have been significantly improved during the past few years. The advent of accurate pseudopotentials and corresponding basis sets for Kohn-Sham density functional and for post-Hartree-Fock electron-correlated approaches have enabled the inclusion of scalar relativistic and spin-orbit coupling effects as well as electron correlation effects into the electron density function. The unpacking of the information embedded in such a function via the quantum theory of atoms in molecules (QTAIM) became possible by utilizing the very new subshell fitting method of reconstructing the density distribution of core electrons that had been replaced by the pseudopotentials. These theoretical advances were applied in this thesis to characterize and explore the topological features of metal-metal bonding as one of the fundamental types of bonds formed between two elements. Group 11 and 12 transition metals which include gold and mercury as the most relativistic elements were the main focus of this work. Mono and poly-nuclear compounds (with up to 4 metal atoms) in both pure metal clusters and chloro-complexes were studied by ab initio MØller-Plesset perturbation calculations followed by QTAIM analysis on the relaxed density. Some of these chloro-complexes of copper, gold, zinc and cadmium metals were identified in the gas phase by mass spectrometric experiments. The general formulas of the set of molecules studied in group 11 were : M2, MCl, MCl+, MCl2, MCl2+, M2Cl+, M2Cl2^(s+), M2Cl3+, M3Cl2+, M3Cl3+, M3Cl5+, M4Cl5+ and M4Cl7+ and in group 12 were : M2, MCl, MCl+, MCl2, M2Cl3+, M3Cl5+, M4Cl7+ and M2^(s+). The topological features of metal-metal bonding were calculated along with atomic properties for each individual local minimum isomer found. The comparison of the metal-metal bonding within the complexes and with the dimers revealed new features of metal-metal bonding in 3d, 4d and 5d transition metal elements of groups 11 and 12. With the aid of strong correlation between bond dissociation energy and electron density at the location of the bond critical points found in the case of dimers, the strength of the metal-metal bonding in the complexes was estimated. The electron density’s basin properties calculated accurately for all the clusters and their isomers in this thesis provided more insight also into the nature of M-Cl bondings in the group 11 and 12 chloride clusters. Ultimately the bonding information was used to predict the viability of these clusters in the gas phase. / published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

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