Molecules with unusual steric crowding are always interesting in chemistry. They give the opportunity to explore the limits of stable molecular structures and the synthesis of unnatural products. They also provide points of calibration for modern computational methods. This dissertation describes the design, synthesis and characterization of two types of crowded complex aromatic compounds. The goal of the first project was to synthesize in-keto cyclophanes, that is, molecules with ketone oxygens pressed toward the centers of benzene rings. Several likely precursors were synthesized and fully characterized, but attempts to make the in-keto cyclophanes themselves were unsuccessful. The nonbonded interaction between the ketone oxygen and basal benzene ring may be so close in the target structures as to prevent the formation of an in-keto cyclophane. The second project describes the design, synthesis and characterization of several macrobicyclic, bis(triarylelement)-containing cyclophanes with various bridgehead heteroatoms. Computational studies accurately predicted that when the bridgehead substituents are small (lone pairs or protons), an in,in bridgehead stereochemistry is strongly favored, but larger bridgehead substituents favor the formation of in,out stereoisomers. The NMR spectra of several of these compounds show unusual through-space spin-spin coupling between atoms along the central axis. Most importantly, one of these compounds, an in,in-bis(hydrosilane), possesses a hydrogen-hydrogen nonbonded contact distance of approximately 1.56 Å, a new “world record” for such a contact in any crystallographically characterized compound. / 1 / Jie Zong

A series of conformationally constrained 2,6-bisferrocenylphenyl thioethers were synthesized via Suzuki-Miyaura cross coupling reactions. Structural information was obtained using X-ray crystallography and dynamic ¹H NMR spectroscopic studies, showing highly constrained m-terphenyl systems. Interaction of the ferrocene moieties through space mediated by the sulfur were studied by ultra-violet photoelectron spectroscopy (UPS), cyclic voltammetry, differential pulse voltammetry, UV-Vis-NIR spectroscopy and DFT computations. Electrochemical results show two, fully reversible 1e⁻ redox processes for the ferrocenes where the separation of peaks is affected by both solvent and supporting electrolyte, suggesting significant electrostatic interaction which is further confirmed in the gas phase by UPS studies. To determine if these interactions could be observed at greater distances, extended m-terphenyl complexes were shown in which 2-sulfur and 3-aromatic moieties were synthesized using a developed selective Suzuki-Miyaura monocoupling procedure in good yields. In these systems, interaction was not observed by electrochemistry or UPS. This suggests the distance between redox centers (~16 Å) is too great for electrostatic interaction, even though there is enhanced interactions observed in the truncated systems. Two new bisferrocenylphenylsulfoxides were also synthesized and studied to determine the effect of the polar sulfoxide bond on through space interaction between the ferrocene moieties. The electronic and redox properties of these compounds were studied by ultra-violet photoelectron spectroscopy, cyclic voltammetry, differential pulse voltammetry, and DFT computations. Electrochemical results for 2,6-bis(ferrocenyl) thioanisole S-oxide show two, fully reversible one electron redox processes. The initial oxidation shows a 62 mV negative shift compared to the sulfide analog 2,6-bis(ferrocenyl)thioanisole, and an increased peak separation for the oxidations of 160 mV. No peak separation is observed in the extended sulfoxide system. No intervalence charge transfer band was observed in the truncated sulfoxide complex by monitoring the UV-Vis/NIR spectroscopy of the mixed valence complex, ruling out electronic communication. Thus, the through space electrostatic interactions of the sulfoxide causes the non-equivalent ferrocenes in the truncated system to have different oxidation potentials. Synthesis was developed towards the synthesis of 1,8-bisferrocenyl-9-(alkylthio) anthracene complexes. It was observed that due to steric congestion at the C9 position of the anthracene scaffold, standard thionation reactions did not proceed as expected. Instead, the reaction of 1,8-dibromo-9-anthrone with Lawesson reagent afforded the intramolecular nucleophilic aromatic substitution cyclization product in quantitative yields. The reaction of the same anthrone under studied dithioketal formation conditions led to sulfur-rearrangement, giving the undesired 1,8-bisferrocenyl-10-(ethylthio)anthracene derivative, as confirmed by X-ray crystallography. Attempted Newman-Kwart rearrangement of 1, 8-dibromoanthracen-9-yl) dimethylcarbamothioate afforded no significant observed product formation, and decomposition of starting materials when heated for extended times. 1,8-bisferrocenyl-9-(methoxy)anthracene was synthesized and structurally characterized by dynamic X-ray crystallography to confirm connectivity. Electrochemical experiments show 2 reversible redox processes separated by 115 mV. Chemical oxidation experiments show unexpected, strong electronic coupling in the mixed valence complex. This coupling was characterized by near-IR absorption at 941 nm, indicating intervalence charge transfer (IVCT). Single electron reduction of 1,8-bisferrocenyl-9-(methoxy)anthracene, followed by quenching with various electrophiles afforded an inseparable mixture of products, one of which was identified by mass spectrometry as the desired 1,8-bisferrocenyl-9-(methylthio)anthracene product. However, this complex was not separable from the mixture and further characterization was not possible. All other routes attempted to incorporate sulfur into the system afforded no conversion of starting materials or decomposition of the reaction mixture.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第18293号 / 工博第3885号 / 新制||工||1596(附属図書館) / 31151 / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 中條 善樹, 教授 秋吉 一成, 教授 赤木 和夫 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

The family of polycyclic aromatic hydrocarbons naphthalene, acenaphthene and acenaphthylene, containing rigid organic backbones, allow the study of non-bonded intramolecular interactions. Due to the rigid framework, heteroatoms that are substituted at the peri-positions (positions 1- and 8- of the naphthalene ring and positions 5- and 6- of the acenaphthene and acenaphthylene rings) are forced to occupy space that is closer than the sum of their van der Waals radii, resulting in severe steric strain and unique interactions. In spite of this, a vast amount of peri-substituted naphthalenes have been prepared, however acenaphthene and acenaphthylene compounds have received much less attention. Preparation of these sterically crowded systems is possible because of the backbones ability to relieve strain as a result of both attractive and repulsive interactions. Attractive interactions relax the backbone via formation of weak or strong bonds between the substituents. Alternatively, repulsive interactions can result in the deformation of the backbone away from its natural geometry by buckling the ring system and causing the peri-bonds to distort in-plane and out-of-plane. Peri-substituted systems can also ease strain by forming compounds with bridging atoms or through bidentate coordination to form metal complexes with, for example, metal bis(phosphine) or bis(thiolate) moieties. The competition between attractive and repulsive forces, the method by which peri-substituted compounds relieve steric strain, is investigated in this thesis using a variety of different peri-moieties and the aforementioned organic backbones. Chapter 2 initially focuses on the formation of a series of platinum bis(phosphine) complexes, constructed from corresponding peri-substituted naphthalenes, 1,8-naphthosultone and 1,8-naphthosultam, the chemistry of which is outlined in Chapter 1. A corresponding study of platinum bis(phosphine) complexes, constructed from analogous 5,6-dihydroacenaphtho[5,6-cd]-1,2-dithiole and 5,6-dihydroacenaphtho[5,6-cd]-1,2-diselenole bidentate ligands is provided in Chapter 6. The chemistry of peri-substituted naphthalenes is well documented and a number of reviews have been written on this subject. Chapter 3, meanwhile, reviews the chemistry of related acenaphthene and acenaphthylenes which have seen increasing use in the literature over the last few years. Chapter 4 investigates the relationship between repulsive and attractive interactions that occur between the peri-substituents in a series of bis-chalcogen, mixed chalcogen-chalcogen and mixed halogen-chalcogen acenaphthylenes. By comparison with their known naphthalene and acenaphthene counterparts, the effect the rigid aromatic ring system has on the molecular geometry is examined. Finally, Chapter 5 looks at a series of acenaphthene and acenaphthylene compounds containing ArTe peri-substituents and explores how repulsive and attractive interactions affect molecular conformation and Te•••Te spin-spin coupling constants.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第19006号 / 工博第4048号 / 新制||工||1623(附属図書館) / 31957 / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 中條 善樹, 教授 赤木 和夫, 教授 秋吉 一成 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

Di-n-propyl dicyanofumarate (DnPrDCF) and di-isopropyl dicyanofumarate (DiPrDCF) have been used as one-electron acceptors in the synthesis of charge-transfer salt magnets with decamethylmetallocenes, MCp*2 (M = Mn, Cr). Salts of each acceptor with each metallocene have been characterized and the structures of the chromium analogues have been solved. The two acceptors are structurally similar to dimethyl dicyanofumarate (DMeDCF) and diethyl dicyanofumarate (DEtDCF), which have been previously studied and found to form charge-transfer salt magnets with the aforementioned decamethylmetallocenes. A typical structural motif is present in these types of charge-transfer salts which allows for the comparison of magnetic properties based on the length or size of the alkyl group of the dialkyl dicyanofumarate. Some trends were established based on the magnetic properties of the homologous series including ordering temperature/bulkiness of the alkyl group and intrastack distances/theta values. Correlation of magnetic and structural properties may give some insight into "through-space" magnetic coupling, of which little is understood. / Master of Science

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第19406号 / 工博第4122号 / 新制||工||1635(附属図書館) / 32431 / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 中條 善樹, 教授 澤本 光男, 教授 赤木 和夫 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

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