bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photoreactivities of Contact Charge-Transfer Complexes between 1,1-Diarylethenes and Oxygen Molecules. Dimerization and Oxygenation Accelerated in Medium Polar Solvent
Authors: Kojima Masanobu , Ishida Akito , Takamuku Setsuo 
Published: June 2006

Abstract
The selective excitation of contact charge-transfer (CCT) bands of 1,1-diarylethenes [Ar = 4-MeOC6H4 (1a); 4-MeC6H4 (1b); Ph (1c)] with molecular oxygen in CH2Cl2 and MeCN resulted in the formation of the corresponding 3,3,6,6-tetraaryl-1,2-dioxanes (2) as a primary product, together with diaryl ketones (3). The reaction mechanism and intermediates for the production of 2 and 3 were studied in terms of the effects of the solvent polarity, additives, substituents on the aromatic rings, and the excitation wavelength on the product distribution, as well as in terms of the result of the photolysis of 2. On the basis of these results, it was shown that 2 was produced through dimer cation radicals of 1, whereas 3 was formed through the photolysis of 2 and the autoxidation of 1 initiated by neutral radical species, which must have been generated by the reaction of monomer cation radicals of 1 (1•+) with a superoxide anion radical. In particular, the formation of 2 depended to a large degree on the solvent polarity; namely, 2 was produced more efficiently in CH2Cl2 with moderate polarity rather than in MeCN with high polarity. Moreover, the reactivities of monomer and dimer cation radicals of 1 were investigated by γ-radiolyis and pulse radiolysis. For 1a and 1b, the transient-absorption spectra of their dimer cation radicals trapped by oxygen molecules were directly observed at 365 ns after pulse irradiation. The reactivities of 1•+ are also discussed based on the optimum structure, charge density, and spin density, obtained by semi-empirical molecular orbital calculations (PM3 method).
Regioselective Arylation Reactions of Biphenyl-2-ols, Naphthols, and Benzylic Compounds with Aryl Halides under Palladium Catalysis
Authors: Satoh Tetsuya , Inoh Jun-ichi , Kawamura Yoshiki , Kawamura Yuichiro , Miura Masahiro , Nomura Masakatsu 
Published: June 2006

Abstract
Biphenyl-2-ols undergo regioselective mono- and diarylation upon a treatment with aryl iodides in the presence of a palladium catalyst in DMF using Cs2CO3 as a base to produce 1,1′ : 2′,1″-terphenyl-2-ol and 2′,6′-diphenylbiphenyl-2-ol and their derivatives. The reaction of 1-naphthol selectively occurs at its 8-position to give 8-aryl-1-naphthols. In the reaction of 2-naphthol with aryl bromides, diarylated compounds, 1-(2-arylphenyl)-2-naphthols, are formed as the single major products. Under similar conditions, benzyl ketones, phenylacetonitrile, and methyl phenylacetate are arylated at their benzylic position.
Magnetic Properties of 8H-Type Hexagonal Ba(Na1/4Ru3/4)O3
Authors: Kim In-Seon , Nakamura Tetsuro , Itoh Mitsuru 
Published: June 2006

Abstract
The magnetic properties of 8H-type hexagonal-type Ba(Na1/4Ru3/4)O3 having a 2D geometry of Ru5+(t2g3) ions were studied by magnetic-susceptibility measurements in the temperature range 5 K &lt; T &lt; 700 K. In this structure, the face-shared RuO6 octahedra form (Ru2O9)8− clusters with a 2D array, which are sandwiched by 2D layers of the NaO6 and the RuO6 corner-shared octahedra. The magnetic data show an antiferromagnetism-like behavior, and could be well fitted to a Curie-Weiss law above 520 K with μeff = 3.74 μB and θ = −1330 K. At a lower temperature range of 262 K &lt; T &lt; 520 K, it showed a reduced magnetic moment of μeff = 2.32 μB and θ = −221 K by a new Curie–Weiss law fit. The χ(T) behavior showed a strong external field dependence below 262 K, and magnetic anomaly peaks could be observed in low-field FC data at 30, 110, and 180 K, respectively. The magnetic properties of Ba(Na1/4Ru3/4)O3 are discussed concerning both a long-range 3D antiferromagnetic order and a spin-glass-like behavior.
Lithium Diffusion in LixCoO2 Electrode Materials
Authors: Nuspl Gerhard , Nagaoka Masataka , Yoshizawa Kazunari , Mohri Fumihito , Yamabe Tokio 
Published: June 2006

Abstract
The minimum energy migration path and the minimum barrier height of lithium diffusion are discussed for the layer compound LixCoO2. The Universal Force Field (UFF) is adapted for use in solid state compounds. Molecular dynamics simulations with additional impulse dynamics method, performed at a microcanonical ensemble, point out that the lithium migration between the Co–O octahedron layers takes place by ion hopping from one octahedral to another octahedral site via an interstitial tetrahedral site. The barrier height of lithium migration is estimated to be 28.7 kJ mol−1 (0.30 eV) for an original layer distance of 2.54 Å; a potential energy profile is developed from molecular mechanics calculations. The observation that the repulsive van der Waals interaction between Li+ and neighboring O2− ions is the most important contribution to the barrier height is consistent with the fact that the activation energy of lithium diffusion is very sensitive to the layer distance, within the experimentally observed values.
Charge Effects in Photoinduced Electron-Transfer Reactions between [Ru(bpy)3]2+ and Viologen Derivatives
Authors: Hamada Taisuke , Tsukamoto Masaya , Ohtsuka Hiroshi , Sakaki Shigeyoshi 
Published: June 2006

Abstract
Photoexcited *[Ru(bpy)3]2+ is oxidatively quenched by methylviologen (MV2+) and 1,1′-bis(2-carboxyethyl)-4,4′-bipyridinium (BCEBP2+) with a similar rate constant at pH 2.2; kqobs = 1.48 × 109 and 1.58 × 109 mol−1 dm3 s−1 (30 °C) for MV2+ and BCEBP2+, respectively. However, *[Ru(bpy)3]2+ is much more slowly quenched by MV2+ than by BCEBP0 at pH 5.0, where the superscript “0” represents that BCEBP is neutral; kqobs = 1.01 × 109 and 1.74 × 109 mol−1 dm3 s−1 for MV2+ and BCEBP0, respectively. The reverse electron-transfer reaction between [Ru(bpy)3]3+ and one-electron-reduced ·BCEBP+ (krevobs = 3.33 × 109 mol−1 dm3 s−1) proceeds slightly more rapidly than the reaction between [Ru(bpy)3]3+ and ·MV+ (krevobs = 2.80 × 109 mol−1 dm3 s−1) at pH 2.2 (30 °C), while the former reaction (krevobs = 5.85 × 109 mol−1 dm3 s−1) proceeds 2-times as rapidly as the latter reaction (krevobs = 2.74 × 109 mol−1 dm3 s−1) at pH 5.0. These differences at pH 5.0 between MV2+ and BCEBP0 are interpreted in terms of charge effects on the diffusion and diffusional dissociation of an exciplex and an encounter complex. The electron-transfer reactions in the exciplex and the encounter complex have been analyzed according to Marcus theory. The difference in an electronic coupling matrix element (Hrp) between MV2+ and BCEBP2+ or 0 is discussed in terms of the charge effects and steric effects.
Rotational Effects on the Channel Three Decay in Benzene: in Support of the Preisomerization Mechanism
Authors: Kanamaru Nobuaki 
Published: June 2006

Abstract
The “Channel 3” phenomena in benzene were investigated concerning a model scheme as an extension of that applied for a typical intermediate case molecule, pyrazine. Using a multiple doorway-states formalism, the difficulties in interpreting such as insufficient density of states for the intermediate dark levels were eliminated based on a preisomerization diagram involving a benzene isomer, most probably benzvalene. By a detailed examination of information about the title subject in the literature concerning both experiments and theory, several questions were raised and answered while making proposals for further study.
Inherent Automorphism and Q-Conjugacy Character Tables of Finite Groups. An Application to Combinatorial Enumeration of Isomers
Authors: Fujita Shinsaku 
Published: June 2006

Abstract
Q-Conjugacy character tables are proposed for finite groups and applied to combinatorial enumeration. Thus, the maturity of an irreducible representation is related to the maturity of a finite group by means of the relationship between the inherent automorphism of the group and its inner portion. As a result, a character table is transformed into a more concise form called a Q-conjugacy character table. Matured characters are defined as dominant-class functions on the basis of such a Q-conjugacy character table. Thereby, a matured character is represented by a linear combination of Q-conjugacy characters. By starting from Q-conjugacy character tables, characteristic monomial tables for finite groups are obtained. They are applied to combinatorial enumeration of isomers.
Structure and Electrochemical Properties of Directly Bound Dinuclear Cobaltadithiolene Complexes. Substituent Effect on Reduction Potentials and Mixed-Valence States
Authors: Akiyama Takeo , Amino Masaki , Saitou Tsutomu , Utsunomiya Koutoku , Seki Ken-ichi , Ikoma Yoshiharu , Kajitani Masatsugu , Sugiyama Toru , Shimizu Kunio , Sugimori Akira 
Published: June 2006

Abstract
The X-ray structures and electrochemical properties of the dinuclear cobaltadithiolene complexes, μ-(1,4-disubstituted 1,3-butadiene-1,2,3,4-tetrathiolato)-bis[(η5-cyclopentadienyl)cobalt(III)], have been investigated. In the diphenyl derivative, two benzene rings in the same molecule are located face to face with the distance of 3.5 Å, while in the dimethyl derivative, two methyl groups are in remote positions. However, in the electrically neutral dinuclear complexes, there is no evidence for the intramolecular interaction between two aryl groups in solutions. Electrochemical and spectrochemical investigations revealed that in electrically neutral state, the interaction between two cobaltadithiolene moieties is small, while in monoanioic state it becomes greater. The Hammett’s plot for ΔEr1/2 (ΔEr1/2 = Er1/2(red.1) − Er1/2(red.2)) shows that the electron-attracting substituents can stabilize the mixed-valence state, [Co(II)–Co(III)]−. The smaller ΔEr1/2 values for the complexes having aryl substituents are due to the smaller interactions between the anioic and neutral moieties, because of the steric hindrance of aryl groups which inhibit the conjugation of the two cobaltadithiolene rings.
Potential Sweep Voltammetry of Ion-Transfer at Liquid/Liquid Interface with Preceding Chemical Reaction. Determination of the Rate and Equilibrium Constants from Voltammetric Curves
Authors: Katano Hajime , Senda Mitsugi 
Published: June 2006

Abstract
The behavior of potential sweep voltammograms for the ion-transfer across the liquid/liquid interface with preceding chemical reactions is discussed. The theoretical results are expressed in the form of the working curves for the peak current, peak potential, and half-peak potential as a function of the kinetic-current parameter, which contains the rate and equilibrium constants of the preceding chemical reaction and the rate of the potential sweep. The working curves are applied to analyze the voltammograms for the transfer of Pb2+ ion to nitrobenzene facilitated by 1,4,7,10,13,16-hexathiacyclooctadecane present in nitrobenzene from aqueous medium containing citrate3− ion. The dissociation and association rate constants and the formation constant of Pb2+–citrate3− complex in W-phase are 4.5 × 104 s−1 and 8.0 × 1010 M−1 s−1and 106.3 M, respectively.
Spectro-Diffractometry for Chemical-State Analysis Based on In-Advance Simulations
Authors: Xiao Yanan , Hayakawa Shinjiro , Gohshi Yohichi , Oshima Masaharu , Okudera Hiroki , Toraya Hideo , Ohsumi Kazumasa 
Published: June 2006

Abstract
We performed an in-advance simulation and experiments involving resonant X-ray powder diffraction with the incident X-ray energy being near to the absorption edge of a particular element in order to distinguish two chemical states of that element based on the principle of spectro-diffractometry. According to the simulation, we found reflections that are relatively sensitive to the exchange of the two anomalous scattering factors (f′) of the specified element at two crystallographic sites. The simulation and experiment results demonstrated that it is possible to obtain f′ curves for the two chemical states by measuring only a few peaks that are sensitive to f′ without greatly increasing the refinement errors, and that the way of selecting the peaks greatly influence the results. In other words, in-advance simulations are very important in this method. This method may make it possible to obtain nearly the same result in one-tenth machine time, and, moreover, to obtain site-selective XANES for powder samples using limited machine time.
Syntheses and Properties of a New Type of Lewis Acids Incorporating Linked Bisphenoxide Moiety
Authors: Ohba Yoshihiro , Ito Kazuaki , Maeda Hiroyuki , Ebara Hiroaki , Takaki Shin , Nagasawa Tomomi 
Published: June 2006

Abstract
Several ligands for a new type of Lewis acid, which incorporates two linked phenols, were synthesized and the reaction of these ligands with trimethylaluminum quantitatively gave Lewis acids. These Lewis acids were found to be an efficient promoter for the rearrangement of epoxides to carbonyl compounds as well as a useful protector of acetophenone against hydride-reduction. The VT-NMR spectrum and NOESY spectrum of a 1 : 1 complex of Lewis acid 2a (methyl[2,2′-(m-xylene-α,α′-diyl)bis(4,6-di-t-butylphenoxido)aluminum and acetophenone provided data on the structure of a complex of acetophenone and 2a.
The Regioselective 1,4-Addition Reaction of Alkenylboronic Acids to α,β,α′,β′-Unsaturated Ketones
Authors: Hara Shoji , Shudoh Hisashi , Ishimura Shigeyuki , Suzuki Akira 
Published: June 2006

Abstract
The effect of substituents on the double bond of α,β-unsaturated ketones for the 1,4-addition reaction rate of alkenylboronic acids induced by cyanuric fluoride was studied in detail. When the steric hindrance around the β-carbon of the unsaturated ketones increased, the 1,4-addition reaction rate significantly decreased. An alkyl substituent on the α-carbon was also found to significantly affect the 1,4-addition reaction. From these results, unsymmetric α,β,α′,β′-unsaturated ketones (10a—f) were designed for the regioselective 1,4-addition reaction with alkenylboronic acids (4a—j). Since they have substituents to disturb the 1,4-addition reaction on only one double bond, the alkenylboronic acids reacted with them from only one side to selectively provide γ,δ,α′,β′-unsaturated ketones (11a—q). Further transformations of the resulting γ,δ,α′,β′-unsaturated ketones were also performed.
Photoacid and Photobase Generators: Prospects and Their Use in the Development of Polymeric Photosensitive Systems
Authors: Shirai Masamitsu , Tsunooka Masahiro 
Published: June 2006

Abstract
This article describes the recent progress in the preparation of a set of compounds which can generate acids or bases upon irradiation of light. These compounds are called photoacid generators and photobase generators, respectively. Photoacid generators can be divided into two groups according to their characteristics; i.e., ionic- and non-ionic compounds. Photobase generators are fewer than photoacid generators. These compounds are widely used in the field of polymeric photosensitive systems such as photoinitiated polymerization, photoinduced crosslinking of polymers and oligomers, photoinduced degradation of polymers, and photoinduced transformation of functional groups in polymer chains. In particular, this article focuses on the applications of photoacid and photobase generators to promote the development of photoresist and UV curing materials.
Solid State Photoisomerization of But-3-en-1-yl Group in Cobalt Complexes
Authors: Yamada Taro , Ohashi Yuji 
Published: June 2006

Abstract
The but-3-en-1-yl group bonded to the cobalt atom in some cobaloxime complexes is isomerized to the but-2-en-1-yl group in the solid state on exposure to a xenon lamp. In order to make clear the relationship between the reaction rate and the crystal structure, six complexes with different axial base ligands were prepared; piperidine, 1, 1-vinylimidazole, 2, pyrrolidine, 3, 1-methylimidazole, 4, 4-t-butylpyridine, 5, and triphenylphosphine, 6. The crystal structures were determined by X-ray analyses and the reaction rates were estimated from the change of the 1H NMR spectra observed in several intermediate stages. One of the photo products, which has 1-vinylimidazole as an axial base ligand, 7, was prepared separately and its crystal structure was also analyzed. A pair of the but-3-en-1-yl groups are in contact with each other around an inversion center in the crystal structures of 2, 5, and 6, whereas the but- 3-en-1-yl groups in 1, 3, and 4 are isolated from the other but-3-en-1-yl groups of the neighboring molecules in their crystal structures. The reaction rates of the former complexes are significantly greater than those of the latter complexes, except 2. This suggests that the cooperative motion of the but-3-en-1-yl groups plays an important role in the process of the isomerization. A pair of the but-3-en-1-yl groups around an inversion center in 2 are too closely packed for the isomerization to occur even if the cooperative motion is taken into account.
Ion Fragment Imaging of the Photodissociation of Methyl Iodide Small Clusters at 266 nm
Authors: Tanaka Yoshiki , Kawasaki Masahiro , Matsumi Yutaka 
Published: June 2006

Abstract
Photofragment iodine atoms and methyl radicals from the photodissociation of small clusters of methyl iodide at 266 nm were detected, using ion photofragment imaging spectroscopy. Three different components of the I+ image were observed with average laboratory translational energies of the I fragments, &lt;E(I)&gt; = 2, 16, and 25 kcal mol−1 and anisotropy parameters, β = 0, 2.0 ± 0.6, and 2.1 ± 0.5, respectively. Similarly, for CH3+three different components in the CH3+ image correspond to average laboratory translational energies, &lt;E(CH3)&gt; = 5, 25, and 38 kcal mol−1 and β = 0, 2.0 ± 0.2, and 2.2 ± 0.6, respectively. These results suggest the following reaction mechanisms; a) a CH3I chromophore in small clusters is excited to the A band (n,σ*) system of free CH3I, survives intact within the clusters and dissociates, b) dissociation of the CH3I moiety in the small clusters that have two adjacent iodine atoms results in the formation of slow photofragment iodine atoms and fast methyl radicals, and c) dissociation of other types of small clusters results in the formation of fast iodine atoms and slow methyl radicals.
EPR Spectra and Structure of the Radical Cations of Fluorinated Ethylenes and Propenes
Authors: Itagaki Yoshiteru , Shiotani Masaru , Hasegawa Akinori , Kawazoe Hisao 
Published: June 2006

Abstract
EPR spectra for the radical cations of a series of fluorinated ethylenes and propenes, generated by irradiation with γ-rays in halocarbon solid matrices, have been observed at low temperature. The spectra consist of a hyperfine structure with a nearly axial symmetry mainly due to fluorine nuclei. For the trifluoro olefin cations, CF2=CFX+ (X = H, CH3, or CF3), the experimental spectra were successfully analyzed in terms of the three 19F nuclei with coaxial parallel components. This may strongly suggest a planar structure for the radical cations, similarly to the case of the CF2=CF2+ cation already reported. On the other hand, for mono- and di-fluoro olefin radical cations, it is difficult to conclude the planar structure unequivocally from the experimental 19F and 1H hf splittings. Thus, the optimized geometry of the radical cations was calculated by an ab initio MO method. In contrast with the ethylene cation and the propene cation, having nonplanar twisted structures, the fluorinated ethylene and propene cations are concluded to have planar structures. Calculations at the INDO levels including the evaluation of interatomic dipole-dipole interactions were done for the geometries of the radical cations optimized by the ab initio method. The calculated results strongly support the EPR spectra observed and assigned to the radical cations.
Thermochromic Crystals of the CT Complex between N-Salicylidene-2-aminopyridine and 1,3,5-Trinitrobenzene
Authors: Tanaka Masashi , Imai Takayuki , Goto Takehiko , Taka Jun-ichiro , Akamatsu Mitsuhiro , Kashino Setsuo , Mogi Kouichi 
Published: June 2006

Abstract
N-Salicylidene-2-aminopyridine (NSAP) and 1,3,5-trinitrobenzene (TNB) form two kind of crystalline (1/2) complexes, forms I and II. The thermochromism was observed in a charge transfer complex form I, but not in form II. The thermochromism of these crystals was studied based on the temperature dependence of the X-ray analysis and the IR and visible absorption spectra together with the theoretical analysis.
Enhanced Emission of Nd3+ in Liquid Systems: Formation of Symmetrical Rigid Shells of Tightly Solvated DMSO Molecules and Weakly Coordinated Low-Vibrational β-Diketonato Ligands
Authors: Hasegawa Yasuchika , Iwamuro Mitsunori , Murakoshi Kei , Wada Yuji , Arakawa Ryuichi , Yamanaka Tatsuhiko , Nakashima Nobuaki , Yanagida Shozo 
Published: June 2006

Abstract
Coordination structures of neodymium(III) complexes with some β-diketones were investigated in terms of their correlations with emission efficiency in deuterated dimethylsulfoxide (DMSO-d6). The analysis of UV-vis spectra, 13C NMR, electrospray mass spectrometry (ES-MS) spectra, XANES and EXAFS analysis of tris(hexafluoroacetylacetonato)neodymium(III) complex, [Nd(hfa-H)3(H2O)2], and tris[bis(perfluorooctanoyl)methanato]neodymium(III), [Nd(pom-H)3], in DMSO indicated that the deuterated tris(hexafluoroacetylacetonato)neodymium(III), Nd(hfa-D)3, and deuterated tris[bis(perfluorooctanoyl)methanato]neodymium(III), Nd(pom-D)3, in DMSO-d6 should have a symmetrical, rigid and bulky shell composed of six inner-coordinating DMSO molecules and three weakly coordinating hfa-D and pom-D molecules. The improvement in the emission efficiency of the neodymium complexes with the low vibrational and weakly coordinating β-diketonates in DMSO-d6 was ascribed to their symmetrical rigid coordination structures, which should suppress radiationless transition via vibrational excitation and energy migration in the fluid system.
Bis(1-benzyl-4-aza-1-azoniabicyclo[2.2.2]octane) Peroxodisulfate: A Mild and Efficient Oxidant for Cleavage of Nitrogen Double Bonds and Oxidation of Alcohols under Anhydrous Conditions
Authors: Hajipour Abdol Reza , -Baltork Iraj Mohammadpoor , Kianfar Godaraz 
Published: June 2006

Abstract
Bis(1-benzyl-4-aza-1-azoniabicyclo[2.2.2]octane) peroxodisulfate (1), is readily prepared as an orange solid from commercially available 1,4-diazabicyclo[2.2.2]octane and potassium peroxodisulfate. This reagent easily converts hydrazones, semicarbazones, oximes, and alcohols to the corresponding carbonyl compounds with excellent yields.
Zinc Metal-Promoted Stereoselective Olefination of Aldehydes and Ketones with gem-Dichloro Compounds in the Presence of Chlorotrimethylsilane
Authors: Ishino Yoshio , Mihara Masatoshi , Nishihama Shintaro , Nishiguchi Ikuzou 
Published: June 2006

Abstract
A combination of zinc metal and a catalytic amount of chlorotrimethylsilane has been found to promote the transformation of various aldehydes and ketones with gem-dichloro compounds, such as benzylidene dichloride (1a) and methyl dichloroacetate (1b), to the corresponding cross-coupling products, such as substituted styrene 3 and methyl acrylates 4 derivatives, under mild reaction conditions in THF. The E-isomer of the corresponding alkenes was obtained stereoselectively in good-to-excellent yields. The reaction serves as a very convenient one-pot procedure.
Synthesis and Structure of Sulfur-Bridged [1·n](2,5)Thiophenophanes (n = 4—6)
Authors: Katano Naoki , Sugihara Yoshiaki , Ishii Akihiko , Nakayama Juzo 
Published: June 2006

Abstract
Sulfur-bridged [1·n](2,5)thiophenophanes (n = 4—6) were prepared by cyclization of dibromo derivatives of the corresponding linear oligo(thio-2,5-thienylenes) (1) on reactions with Na2S. The best results were obtained by heating 1 and Na2S in the presence of Cs2CO3 in NMP (24% yield for n = 4, 16% for n = 5, and 10% for n = 6). The reactions gave less satisfactory results either in the presence of CuI (Cu2O) or in the absence of these additives. The results of the X-ray structural analyses of these three compounds are also reported.