published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

Reevaluation of organosulfur heats of formation resulted in the conclusion that the sulfur-sulfur bond of aliphatic disulfides is nearly 15 Kcal/mole stronger than the disulfide carbon-sulfur bond energy. Semi-empirical calculations using AM1, MNDO and MINDO/3 from the AMPAC program package confirmed these results and clarified their relative impact on organosulfide and disulfide properties. / Existing organoselenium bond energy data were also reevaluated and erroneous assumptions discovered. New bond energy estimates were made via a new procedure. It was concluded that the selenium-selenium bond is also stronger than the selenium-carbon of aliphatic diselenides. / The above results led to the conclusion that loss of molecular dichalcogen from molecules such as disulfides or diselenides is favored over the stepwise loss of a single chalcogen by about 40 Kcal/mol. Loss of molecular diselenium from dibenzyl diselenide is reported. The average carbon-selenium bond energy of the latter is calculated to be only 27 Kcal/mol. / The preparation of 2-thiatriselenides (RSeSSeR) and 2,3-dithiatetraselenides (RSeSSSeR) has been achieved from selenosilanes. The products were characterized by $ sp{77}$Se NMR and the trends of chemical shifts were analyzed. / The preparation of the first selenium transfer reagents, including the first unsymmetrical chalcogen transfer reagent, is reported. Their use to effect the synthesis of 2-selenatrisulfides (RSSeSR) is also reported. Low temperature $ sp{77}$Se NMR was used to elucidate the reaction mechanism and characterize several intermediates such as selenuranes, selenonium ions and azole selenides. In addition, 2,3-diselenatetrasulfides (RSSeSeSR) were characterized by $ sp{77}$Se NMR.

[Formulae and special characters can only be approximated here. Please see the pdf version of the abstract for an accurate reproduction.] Group 15 Lewis base adducts of Group 11 coinage metal salts of the form MX : L (1:n), where M=Cu(I),Ag(I),Au(I); X=(pseudo-)halide (Cl,Br,I,SCN,CN) and oxyanion; L-uni- or bi-dentate pnicogen ligand and n=1-4, may adopt monomeric, dimeric, oligomeric or polymeric structural forms. For the purpose of this study, the pnicogen bases are divided into two groups: the 'harder' nitrogen base ligands and 'softer' phosphine/arsine/stibine ligands. A sizeable body of structural data exits for adducts of silver(I) salts. Those with uni-dentate nitrogen base ligands are usually restricted to readily accessible liquid bases such as pyridine and its derivatives. The extension of such series to encompass ligands with more varied base characteristics may assist in the access of new bonding modes and stereochemistry, leading to control of these and of stoichiometry. Herein a number of complexes of copper(I) salts with uni-dentate nitrogen and bi-dentate phosphine/arsine/stibine adducts with differing degrees of complexity have been characterized, extending the known range of structural forms. Systematic variations in stoichiometry, halide, ligand and solvent of crystallization have provided a range of complexes whose structures have been determined by single crystal X-ray diffraction techniques. The structural relationship between these and other known adducts, often including their silver analogues, are considered, permitting comparisons of various common features and differences. The first section of this thesis (Chapter 3 and Chapter 4) reports a number of complexes of the form CuX : L (1:n) (CuX)Ln, L=uni-dentate nitrogen base ligand with n=1-3, the second section (Chapter 5 through Chapter 10) reports adducts with bi-dentate bis(diphenylpnicogeno)alkane ligands, Ph2E(CH2)xEPh2 (whereE=P,AS,Sb and x=1-6). The structural types and copper(I) coordination environments are influenced by CuX (salt) : ligand stoichiometry, the stereochemistry and basicity of the ligand, the type and size of the counter-ion (where applicable) and crystallization solvent. The structural types found for copper(I) (pseudo-)halide and oxyanion species are similar to those found for their silver(I) analogues, although the transitions between structural types may occur with different pnicogen and halide atoms, consequent on the smaller size of the copper(I) ion and differences in stereochemical preferences.

The contents of Section 2.2 and Chapter 4 first appeared in proceedings of the 12th International Conference on Web Information Systems and Technologies, 2016 (www.webist.org). The contents of Section 2.3 and Chapter 5 first appeared in DBSJ Journal, vol. 14, article no. 2, March 2016. The contents of Section 2.5 and Chapter 7 first appeared in proceedings of the 11th Asia Information Retrieval Societies Conference, Lecture Notes in Computer Science, vol. 9460, pp. 188-200, 2015 (The final publication is available at link.springer.com). / 京都大学 / 0048 / 新制・課程博士 / 博士(情報学) / 甲第19854号 / 情博第605号 / 新制||情||105(附属図書館) / 32890 / 京都大学大学院情報学研究科社会情報学専攻 / (主査)教授 田島 敬史, 教授 田中 克己, 教授 吉川 正俊 / 学位規則第4条第1項該当 / Doctor of Informatics / Kyoto University / DFAM

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The details of the electronic structure and bonding in ferrocenes and early transition metal bent metallocenes are probed by photoelectron spectroscopy. The fundamental electronic interaction of the methyl group substituted for a hydrogen on a metal-coordinated cyclopentadienyl ring is shown by a combined core and valence pe spectroscopic study of a series of methyl-substituted ferrocenes. Shifts of core and valence ionization energies upon methyl substitution are equivalent and additive for the iron atom. Knowledge of the core ionization energy shifts for both carbon and iron allow the relative changes in atomic charges upon methyl substitution to be found. In these molecules, the methyl group is found not to be an inductive electron donor as is commonly assumed. The primary electronic effect of methyl substitution is on the valence orbitals of the cyclopentadienyl ring. Methylation of the cyclopentadienyl rings of ferrocene causes a dramatic redistribution of valence electron density and greatly increases the covalent nature of metal-ring bonding. An understanding of the electronic effect of methylation of metal-coordinated cyclopentadienyl rings is used to establish the relative locations of ring π and Cl ionizations in the pe spectra of group IV and V early transition metal bent metallocene dichlorides with both unsubstituted cyclopentadienyl and pentamethylcyclopentadienyl ligands. The differences in chloride and methyl ligand bonding to an early transition metal center are reflected in the photoelectron data of the dichlorides and related dimethyls. The relative differences in metal-chlorine and metal-carbon bond strengths are also shown in the pe data. The relationship between bond strengths and ionization energies is detailed for early transition metal bent metallocenes of niobium and tantalum with a variety of ligands. The relative bond strength/ionization energy information for metal-hydrogen and metal-carbon bonds is shown to help in understanding the stability of niobocene and tantalocene ethylene-hydride complexes and their resistance to intramolecular olefin insertion. Evidence from the pe data concerning the electron distribution as well as the relative bond strengths in these ethylene-hydride complexes is found supporting the consideration of these complexes more properly as metallacyclopropane-hydrides.

The 1,3 dipolar cycloaddition between carbonyl ylids (generated from cyclobutene epoxides flanked by esters) and norbornyl alkenes – the ACE reaction – offers a facile method for the construction of polynorbornyl molecular frameworks. This reaction has, as described in this dissertation, underpinned the construction of molecular frameworks that have peptides and amino acids attached. Such highly rigid peptide-frameworks are of use in the field of peptidomimetics; the template molecule governs the final positioning of any attached groups such that a precise arrangement of amino acids can be achieved without the need to construct entire proteins. In the course of any ACE reaction the ester flanked cyclobutene epoxide is transformed to a 1,3 dipole, the esters serve to stablise this reactive intermediate and are as a consequence incorporated in the reaction product. Modification of these esters provides pseudo-equatorial points for peptide attachment. These methyl esters were replaced with tert-butyl esters to provide pseudo-axial attachment points that could be selectively addressed. The optimal strategy for peptide-framework construction involved direct condensation of carboxyl protected amino acids to bicyclo[2.2.1]hept-5-ene-2-endo-carboxylic acid as well as condensation of amino acids to cyclobutene epoxides derived from this acid. The ACE reaction of (±) bicycloheptene-2-endo-carboxylic acid derivatives with cyclobutene epoxides synthesised from such racemic acid derivatives provided a mixture of enantiomers and meso compounds. In order to control the position of the attachment points – and hence the final location of the attached peptides – the ACE reaction required chiral starting materials. Accordingly, all peptidoframeworks were derived from the chiral (2S)-(-)-bicycloheptene carboxylic acid. The ACE reaction of this (S)-norbornene with the (S)-epoxide provided a peptide framework in which the attached amino acids were positioned pseudo-axially. Deprotection of the amino acid allowed peptide chain building in the pseudo-axial direction. Using this strategy a framework with an alanine residue and a triglycine peptide was synthesised. By combining this strategy with the ter-butyl ester variant a framework with pseudo-axial alanine and pseudo-equatorial glycine residues was manufactured.

In this paper we review the current state of research on the issue of discourse structure (DS)/information structure (IS) interface. This field has received a lot of attention from discourse semanticists and pragmatists, and has made substantial progress in recent years. In this paper we summarize the relevant studies. In addition, we look at the issue of DS/ISinteraction at a different level - that of phonetics. It is known that both information structure and discourse structure can be realized prosodically, but the issue of phonetic interaction between the prosodic devices they employ has hardly ever been discussed in this context. We think that a proper consideration of this aspect of DS/IS-interaction would enrich our understanding of the phenomenon, and hence we formulate some related research-programmatic positions.

Sequence alignment is a basic but powerful technique in molecular biology. Macromolecular sequences (DNA, RNA and protein sequences) can be aligned based on some criteria. The goal of sequence alignment is to find the similarity and the difference of input sequences. With various purposes, there are different algorithms In this thesis, we present a new algorithm which aligns sequences with consideration of secondary structures. Traditionally, a sequence alignment algorithm considers only the primary structure, which is the amino acid chain. When we make use of the information of protein secondary structure such as alpha helix, beta sheet etc, the sensitivity of pairwise alignment can be improved.

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