Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Volume 66 , Issue 11
Showing 1-50 articles out of 59 articles from the selected issue
  • Toshikatsu Koga, Yousuke Seki, Ajit J. Thakkar
    1993 Volume 66 Issue 11 Pages 3135-3141
    Published: 1993
    Released: August 16, 2006
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    The conventional double-zeta (DZ) approximation uses two Slater-type functions χnlm’s with different exponents for the description of each occupied atomic orbital φnlm, where the two principal quantum numbers n’s are assumed to be the same. We show that the removal of this implicit restriction improves the DZ functions nontrivially for the ground-state atoms Li through Xe. The largest improvement 0.0267 a.u. in the atomic energy is found for Pd. The valence orbital energies are generally improved, particularly for the 4d-orbital of the fourth-row atoms. It is also found that the conventional DZ functions given in the literature can be further improved by reoptimization of the exponents.
  • Nozomu Uchida, Tomoo Shiomi, Kiyokazu Imai, Hiroshi Tatewaki
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 11 Pages 3142-3152
    Published: 1993
    Released: August 16, 2006
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    In the polymerization of vinyl benzoate, the tacticity of the obtained polymer is changed toward less isotactic by UV irradiation. To explain this phenomenon, it was assumed that the growing terminal of the polymer was excited by UV irradiation and that the coplanarity of the vinyl benzoates was broken. It was thus naturally concluded that the existence of a twisted radical reduced the isotacticity. To examine the above assumption, the electronic structures of the ground and excited states of 1-(benzoyloxy)ethyl radical () were studied as a model of the growing terminal of the polymer by ab initio SCF and CI calculations. The present calculation, however, showed that the planer structure was stable in both the ground and excited states.
  • Alberto Gobbi, Gernot Frenking
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 11 Pages 3153-3165
    Published: 1993
    Released: August 16, 2006
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    The equilibrium geometries, energy differences, and vibrational frequencies for the energetically lowest lying 1A1 and 3B1 states of NH2+, NHX+, and NX2+ (X = F, Cl, Br, I) are theoretically predicted using ab initio quantum mechanical methods at the MP4/6-311G(2df)//MP2/6-31G(d) level of theory. Effective core potentials are employed for bromine and iodine. The isoelectronic carbenes CH2, CHX, and CX2 are also calculated. The electronic structure of the molecules is investigated using the topological analysis of the electronic wave function.
  • Yousuke Inagaki, Yutaka Matsumi, Masahiro Kawasaki
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 11 Pages 3166-3170
    Published: 1993
    Released: August 16, 2006
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    Doppler profiles of H atoms from the photodissociation of H2O2 at 193 nm were measured by a laser-induced fluorescence method at 121.6 nm. On the average, 149 kJ mol−1 of energy is released as translational energy, which corresponds to about to 60% of the available energy. Doppler width anisotropy data show that the anisotropy parameter, β, for the photofragment angular distribution is −0.26 ± 0.11. This result implies that the H2O2 Ã1A state is responsible for H atom formation.
  • Masashi Tanaka
    1993 Volume 66 Issue 11 Pages 3171-3174
    Published: 1993
    Released: August 16, 2006
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    The reflection spectra of the crystal of chloranil-hexamethyl benzene and fluoranil-perylene charge-transfer complexes were measured, and the charge-transfer degrees in these complexes were estimated. Furthermore, the polarized IR absorption spectra of these crystals were measured and compared with those of the powders of the complexes and the component compounds in the KBr disks. The thermochromism of these CT complex crystals was studied by differential scanning calorimetry and the IR spectra.
  • Katsuhisa Ohta, Ryousei Kawa-ai
    1993 Volume 66 Issue 11 Pages 3175-3184
    Published: 1993
    Released: August 16, 2006
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    Classical spin alignment in radical reactions is studied by the GSF-HF wave function in H3 model system. The GSF-HF wave function introduces a simple classical picture of electronic spins directly and leads to the classical Heisenberg model. The instability of various spin alignments is studied on the GSF-HF electronic energy surface. In compensation for the classical spin freedom, the GSF-HF method does not satisfy quantum mechanical spin-symmetry. The GSF-HF wave function is analyzed with a projection operator constructed by a full-CI wave function.
  • Sun Chia-chung, Xiao Xing-cai, Huang Xu-ri, Li Ze-sheng
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 11 Pages 3185-3188
    Published: 1993
    Released: August 16, 2006
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    By means of polymer chemical kinetics and statistics, the combinatorial coefficient of the Aa1, Aa2–BbCc type distribution is factorized to approach the explicit expression of the mean square radius of gyration. Furthermore, a recursion formula for the evaluation of the kth radius of gyration is obtained.
  • Kazuo Takatsuka
    1993 Volume 66 Issue 11 Pages 3189-3202
    Published: 1993
    Released: August 16, 2006
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    Is proposed quasi-action variable as a means to analyze the onset of classical chaos in molecular vibrational systems. The basic idea rests on a symplectic area generated by a classical trajectory in phase space, from which the geometrical information of a torus and its breakdown in extracted. The Fourier spectrum of the time derivative of this symplectic area centers on the following definition and findings: (1) in an integrable system, the action variables can be simply calculated in terms of the above Fourier amplitudes, (2) the quasi-action variable is also defined in a similar way and is a good approximation to the corresponding action variable, but (3) the construction of the quasi-action variable does not depend on the integrability and hence it it defined as well even for a chaotic system, and (4) the characteristics of chaos can be analyzed in the continuous spectrum of the quasi-action variable. Some numerical examples of the quasi-action variable are presented for a system of what we call phase-space large amplitude motion. As a byproduct, a simple method has been devised to calculate very accurate frequencies and amplitudes from the so-called Fast-Fourier-Transform (FFT) spectra without resorting to the so-called window technique.
  • Hajime Katô
    1993 Volume 66 Issue 11 Pages 3203-3234
    Published: 1993
    Released: August 16, 2006
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    Calculation of rotational level energies and line intensities of diatomic molecules and its application to alkali metal diatomic molecules are reported. The effects of spin–orbit interaction, rotational interaction, spin–rotation interaction, spin–spin interaction, hyperfine interaction, and Zeeman interaction are considered.
  • Hiroshi Nakatsuji, Takuji Higashioji, Manabu Sugimoto
    1993 Volume 66 Issue 11 Pages 3235-3240
    Published: 1993
    Released: August 16, 2006
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    The 77Se chemical shifts of nine selenium compounds, SeRR′ (R, R′ = H, Me, Et, Ph, SiH3, GeH3), are theoretically investigated by ab initio Hartree–Fock/finite perturbation method. The calculated values agree well with the experimental values. The Se chemical shift is dominated by the Se valence 4p AO contribution to the paramagnetic term, and shows a parallelism with the 4p-hole population and the net charge of the central Se atom. The Se chemical shift moves downfield as an increase of the hole in the 4p orbitals, and therefore, as an increase in the electron-withdrawing ability of the ligands attached to the selenium atom.
  • Kazunaka Endo, Chiaki Inoue, Naoya Kobayashi, Takuji Higashioji, Hiros ...
    1993 Volume 66 Issue 11 Pages 3241-3244
    Published: 1993
    Released: August 16, 2006
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    The X-ray photoelectron spectra of polyvinyl alcohol (PVA) were analyzed by an ab initio MO method using the 1,3,5-hexanetriol (HTO) molecule. The theoretical spectral patterns derived from the Gelius–Siegbahn model showed good agreement with the spectra observed between 0—30 eV. The present results suggest several new assignments for the XPS spectra. The core-level C1s peaks at 285.0 and 286.5 eV correspond to the C1s electron levels arising from the CH2 and CH(OH) groups, respectively.
  • Hidekazu Watanabe, Masaharu Aoki, Suehiro Iwata
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 11 Pages 3245-3252
    Published: 1993
    Released: August 16, 2006
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    With the ab initio molecular orbital calculations, the structures of the neutral clusters Al(H2O)n were optimized, and the vertical ionization energy was evaluated. Two types of the stable clusters are found; the one has a structure [Al(H2O)](H2O)n−1 and the other has [Al(H2O)2](H2O)n−2. The former type of the clusters, in which only one water molecule is directly bonded, is more stable than the latter. The calculated ionization energy with the multi-reference configuration interaction is in very good agreement with the experimental energy determined recently by Fuke’s group, only for the series of the former type of clusters. The structures of the [Al(H2O)n]+ were determined, and the incremental stability energy was evaluated. A very stable ring structure is found in [Al(H2O)4]+. The ring structure persists in [Al(H2O)5]+, but only substantial deformation. The extremely stable structure of [Al(H2O)4]+ explains the observed product distribution of the photo-dissociation recently reported by Fuke’s group.
  • Michihiko Sugawara, Miwa Kato, Yuichi Fujimura
    1993 Volume 66 Issue 11 Pages 3253-3258
    Published: 1993
    Released: August 16, 2006
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    The mechanism of above-threshold dissociation (ATD) of both hydrogen and deuterium molecular ions has theoretically been investigated. A quantum-mechanical, time-dependent nuclear wave-packet theory has been applied to evaluation of the kinetic energy distributions of H2+ and D2+ photodissociations. The time-dependent shift of the kinetic energy distribution to the low energy side, which is common to both H2+ and D2+ ATD, is interpreted in terms of dynamic Stark shift. The different behavior in the intensity ratio of the kinetic energy distribution between H2+ and D2+ ATD is qualitatively explained by applying the Landau–Zener model to radiative coupling between the ATD channels involved.
  • Alexander M. Mebel, Djamaladdin G. Musaev, Nobuaki Koga, Keiji Morokum ...
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 11 Pages 3259-3270
    Published: 1993
    Released: August 16, 2006
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    Ab initio MO study of structure, stability and rearrangements of nido-metallaboranes with Ir, Co, and Fe transition metals has been performed at HF and correlated MP2 levels. Reasonable agreement with experiment has been found for RHF optimized geometry of [(IrB5H8)(CO)(PH3)2] iridaborane, and the MP2 optimization improves the agreement to the maximum error of 0.035 Å. Two geometric isomers, 2- with basal Ir and 1- with apical Ir are close in energy for [(IrB5H8)(CO)(PH3)2]. NMR 11B and 1H chemical shifts calculated by the IGLO method qualitatively reproduce experimental spectra. Methods more sophisticated than MP2 would be necessary for accurate calculations of metallaboranes with first row transition metals.
  • Shigeki Obata, Kimihiko Hirao
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 11 Pages 3271-3282
    Published: 1993
    Released: August 16, 2006
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    The stability and vibrational frequencies of protonated ethane, C2H7+, have been studied by ab initio molecular orbital theory. The IR spectra for C2H7+ recorded by Y. T. Lee’s group were interpreted from a theoretical point of view. Ab initio computations predict the existence of two isomers, a bridged structure, and a tight and loose open form. The loose open form is represented as an H2 molecule attached loosely to a classical open C2H5+ ion. The different behavior observed in the IR spectra can be attributed to the changing ratio of the bridged C2H7+ to the open C2H5+ isomers. The final interpretation of these data is that the spectrum at 150 Torr (1 Torr = 133.322 Pa) arises from the bridged structure which is the most stable form of C2H7+. The additional band in the spectrum observed at 60 Torr originates form the weakly bound complex which dissociates upon absorbing a single IR photon.
  • Shinichi Yamabe, Tsutomu Minato
    1993 Volume 66 Issue 11 Pages 3283-3288
    Published: 1993
    Released: August 16, 2006
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    Ketene dimerizations to diketene and to 1,3-cyclobutanedione are studies theoretically. Their transition state (TS) structures are determined, for the first time, with correlated wavefunctions. The present calculation demonstrates that the two reactions proceed concertedly. The intrinsic reaction coordinates (IRCs) starting from the TSs are traced so as to seek the origin of the selectivity of the two reactions. At their initial stages, a one-center type charge transfer (donative orbital interaction) takes place, enhanced by polarization interactions in the charge-acceptor ketene. The back-donative orbital interactions are found to control the selectivity.
  • Shigeyoshi Sakaki, Kazuya Mine, Daisaku Taguchi, Toru Arai
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 11 Pages 3289-3299
    Published: 1993
    Released: August 16, 2006
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    An ab initio MO/SD-CI study was carried out on the formation reaction of oxanickelacyclopentene, 1, from Ni(PH3), CO2, C2H2. Because C2H2 coordinates to Ni(PH3) more strongly than does CO2 by ca. 11 kcal mol−1 at the SD-CI level, coordination of C2H2 to Ni(PH3) takes place first. The resultant Ni(PH3)(C2H2) reacts with CO2 to yield 1 with no activation barrier and a significant exo-thermicity of 68 kcal mol−1 at the HF level, but a moderate barrier of 30 kcal mol −1 and exo-thermicity of 17 kcal mol−1 at the SD-CI level. 1 takes a three-coordinate T-shaped structure, due to the low-spin d8 electron configuration of Ni(II). Ni(PH3) stabilizes the transition state through a charge-transfer interaction from the occupied d orbital of Ni to the unoccupied π* orbitals of CO2 and C2H2. The electron re-distribution during the reaction is discussed, based on orbital mixing among the d orbital of Ni and the π and π* orbitals of C2H2 and CO2.
  • Shigeru Obara, Kimihiko Hirao
    1993 Volume 66 Issue 11 Pages 3300-3308
    Published: 1993
    Released: August 16, 2006
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    An equation has been derived for a correlated electronic wave function satisfying the two-particle correlation cusp condition. Molecular integrals of spatial operators in the equation have been formulated based on the recursive formulations of general molecular integrals given by Honda, Sato, and Obara. An efficient scheme of computing them is proposed by taking advantage of the recursive and translational relations of the integrals.
  • Akira Naito, Satoru Tuzi, Hazime Saitô
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 11 Pages 3309-3313
    Published: 1993
    Released: August 16, 2006
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    The N–H bond lengths of simple petides were determined under the condition of high-resolution spectroscopy by analyzing the dipolar side-band patterns obtained from samples of natural abundance, as recorded by 15N two-dimensional (2D) separated local dipolar field (SLDF) NMR spectroscopy combined with cross-polarization and magic-angle spinning (CP-MAS) techniques. It was found that the dipolar side-band pattern obtained from the one-dimensional (1D) cross section taken from the 2D spectrum can be conveniently used to distinguish the 15N signal of the N–H group from that of the N–C group, whose peak positions are very close to each other. Further, spectral simulations of the 15N dipolar patterns of the peptides were performed in order to determine the N–H bond lengths of the amino acid residues of natural abundance at the C-terminus. These values were determined to be 1.07, 1.12, and 1.09 Å for Ala–Gly, Gly–Pro–Ala, and Ala–Pro–Gly, respectively, with an accuracy of 0.01—0.02 Å. The obvious difference in the bond lengths between the last two compounds suggests that the degree of interchain packing, as estimated from the N–H bond lengths, significantly differs between Gly–Pro–Ala and Ala–Pro–Gly. This finding is consistent with the previous data regarding the presence or absence of ring-puckering motion at the Pro residue, as examined by the 13C spin-lattice relaxation times in the laboratory frame.
  • Jun-ichi Adachi, Nobuhiro Kosugi
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 11 Pages 3314-3318
    Published: 1993
    Released: August 16, 2006
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    NaCl clusters with a Cl ion vacancy, Na66+, Na6Cl126−, Na14Cl122+, and Na14Cl184−, are calculated by ab initio molecular orbital calculations to investigate electronic states of F centers in alkali halides. The model clusters are embedded in a point charge field. Description of “1s” ground and “2s” and “2p” excited states of an electron trapped by the vacancy is discussed concerning to basis set and cluster size. The 1s and 2p wave functions of the F-center electron are efficiently described by one s Gaussian-type function placed on the vacancy center and one p Gaussian-type functions placed on the nearest neighbor Na ions when Na 3s is of double ζ quality. The 1s–2p excitation energy is in good agreement with the experimental data. As regards the electron binding energies and the orbital size the 1s wave function almost converges in the cluster Na6Cl126− but the 2p wave function does not converge even in the largest cluster Na14Cl184−.
  • Akitomo Tachibana
    1993 Volume 66 Issue 11 Pages 3319-3325
    Published: 1993
    Released: August 16, 2006
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    Wannier phenomenon is examined for a stability analysis of a time-reversal electron pair scattering. Imagine a pair of electrons interacting one another. It is found that the nature of the interelectron interaction is to stabilize the time-reversal scattering state. This nature survives even under the influence of a scattering center. To conclude, we shall prove the following results: 1) inside the reaction zone of the scattering center, one of the electrons is trapped, pressing the other electron to the barrier of the reaction zone, or letting the other electron go away over the barrier of the reaction zone, namely, a time-reversal scattering state of the electron pair is unstable, while 2) outside the reaction zone, if the critical radius rc is reached, then the time-reversal scattering state of the electron pair is stabilized. The critical radius rc has an intrinsic importance as a measure of the coherence length ξ of the Cooper pair that exhibits the time-reversal symmetry.
  • Shogo Sakai
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 11 Pages 3326-3333
    Published: 1993
    Released: August 16, 2006
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    The reaction mechanisms of Mg (1S and 3P) atom and XH molecules (X = F, OH, NH2, Cl, SH, and PH2) were studied by ab initio molecular orbital methods. A localized molecular orbital centroid analysis along the reaction coordinate shows that the Mg(1S) atom insertion into the X–H bonds occurs through the pull–push mechanism. The activation barriers for the Mg(1S) atom insertion are approximately the same values for each groups (X = F and Cl, OH and SH, and NH2 and PH2).
    For the Mg(3P) atom reactions with above six compounds, the hydrogen abstraction (produces MgH and H) and/or the exchange reaction (produces MgX and H) were studied. Both reactions of Mg(3P) atom are the same one with two-step mechanism. The first step is an electron transfer from a Mg atom into the X–H bonds, which corresponds the transition state. The activation barrier height of the reaction is explained by adiabatic electron affinity of the X–H bonds. The second step is the formation of the products (Mg–X+H or Mg–H+X), which is clarified by the difference of Mg–X and Mg–H bond energies.
  • Kaoru Kobayashi, Shigeru Nagase
    1993 Volume 66 Issue 11 Pages 3334-3338
    Published: 1993
    Released: August 16, 2006
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    In order to provide theoretical insight into the structures of silicon clusters of current interest, several representative structural models proposed up to now for the medium size clusters are investigated by means of semi-empirical and ab initio molecular orbital calculations. Unlike general expectation based on the hitherto proposed structural models, it is suggested that silicon clusters also prefer spherical cage (fullerene-like) frameworks with the increase in the size, as do carbon clusters.
  • Shinichi Yamabe, Tsutomu Minato
    1993 Volume 66 Issue 11 Pages 3339-3344
    Published: 1993
    Released: August 16, 2006
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    Geometries of two title intermediates brought about by bromination and oxymercuration are studied with PM3 and ab initio molecular orbital calculations. For thirteen Br+ intermediates, the regular Markovnikov type structures are obtained and they depend upon the electronic donating strength. On the other hand, geometries of thirteen Hg(OCOCH3)2 intermediates are found to be almost the same and of the isosceles-triangle forms. Steric repulsion occurs not between two acetate groups but between one acetate and the substituents attached to olefins.
  • Yoko Sonoda, Suehiro Iwata, Yoshihiro Osamura
    1993 Volume 66 Issue 11 Pages 3345-3351
    Published: 1993
    Released: August 16, 2006
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    The reaction mechanisms involving the formation of hydrocarbons in interstellar space were examined in terms of an ab initio molecular orbital calculation. The reaction energies and potential energy surfaces producing CH and C2H were evaluated based on the scheme for ion-molecule reactions proposed by the late H. Suzuki. According to the very attractive potentials of positive ions with the hydrogen molecule, most of the reactions proceed via energy-rich intermediates, such as CH4+, C2H+, C2H2+, C2H3+, and C3H+. Consequently, the model proposed by Suzuki has been confirmed concerning the result that the reactions are exothermic and without an energy barrier up to C3+ formation.
  • Kenichi Yoshikawa, Nobuyuki Magome
    1993 Volume 66 Issue 11 Pages 3352-3357
    Published: 1993
    Released: August 16, 2006
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    Self-movement of an oil–water system induced by chemically-driven Marangoni instability was studied. Depending on the shape of the vessel and the amount of oil and water solutions, various modes of movement were generated, such as random, rotational, and ameba-like. The most significant finding is the realization of a spatially directed mechanical movement. The mechanism of such chemomechanical transduction is discussed in relation to an imbalance of the interfacial tension due to a nonlinear oscillation at the interface.
  • Hiroshi Kato, Koichi Yamashita, Keiji Morokuma
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 11 Pages 3358-3361
    Published: 1993
    Released: August 16, 2006
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    The geometries, electronic structures, and energies of the neutral and cationic B12 and B13 clusters were investigated by the ab initio molecular orbital method. Several planar and non-planar stationary structures were optimized for neutrals and cations of each cluster size. A characteristic C2v cyclic form with one atom in the middle was found to be stable for each cluster. While the D5d icosahedral B12+ was found to be the most stable, the triplet D5d icosahedral B12 was stable but energetically unfavorable than the C2v cyclic B12. All the three-dimensional structures considered for B13 and B13+ clusters were unstable.
  • Masaki Sasai
    1993 Volume 66 Issue 11 Pages 3362-3371
    Published: 1993
    Released: August 16, 2006
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    A new lattice model of liquid water is developed. The hydrogen bond network is represented by the Ising variables with the method similar to the one used in combinatorial problems in random graph. Thermodynamic properties of the model are studies with the mean-field approximation. Phase diagram, density maximum, and anomalies of supercooled water are discussed. Dynamical properties are also investigated by using the coupled-map-dynamics method. Energy fluctuation is shown to have 1/f like long time correlation. The network structural rearrangement takes place collectively in localized regions.
  • San-Chung Lin, Yung-Yun Wang, Chi-Chao Wan, J. -Cheng Chang
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 11 Pages 3372-3376
    Published: 1993
    Released: August 16, 2006
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    Investigating the electrochemical reduction behavior of MnO4, we determined the consecutive reduction/oxidation potentials of MnO4 by the cyclic voltammetric method. We have also confirmed that MnO42− is reduced into MnO43−. We then investigated the cause of the generation of MnO2 on the electrode surface with the rotating ring-disk electrode method. The reversibility of the reduction of MnO4 depends on the concentration of KMnO4 and KOH. Reversibility increases when the concentration of KOH increases, but the reversibility decreases when the concentration of KMnO4 increases. The reaction rate of MnO4/MnO42− follows the law:
  • Akio Yuchi, Atsushi Tanaka, Manabu Hirai, Takashi Yasui, Hiroko Wada, ...
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 11 Pages 3377-3381
    Published: 1993
    Released: August 16, 2006
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    The complexation equilibria of divalent and lanthanoid metal ions with 1,2-bis(o-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid (BAPTA) and 2-[(2-amino-5-methylphenoxy)methyl]-6-methoxy-8-aminoquinoline-N,N,N′,N′-tetraacetic acid (quin2) were studied by pH titration. In lanthanoids, BAPTA shows a maximum stability for Pr3+, whereas quin2 has higher affinities for heavier ones. These trends are discussed in terms of the rigidity and donor atoms of these ligands. Intense fluorescence was observed for quin2 complexes of Group-2 and -3 elements. Among the lanthanoids, only Sc, Y, La, Gd, and Lu enhance the fluorescence at around 380 nm.
  • Akira Toki, Hiroaki Yonemura, Taku Matsuo
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 11 Pages 3382-3386
    Published: 1993
    Released: August 16, 2006
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    On the addition of α-cyclodextrin (CD), an intramolecular charge-transfer absorption band of an anthracene-viologen linked compound rapidly disappeared with elapsed time. The reason was ascribed to formation of a through-ring CD complex, which hinders direct interaction between the donor- and acceptor moieties. Thermodynamic parameters, including the energy of activation for complexation of α-CD, were evaluated by the use of the charge-transfer absorption band in D2O- and H2O solutions. Solvent deuterium isotope effects were observed with the free energy change on complexation, but not with the energy of activation for formation of the through-ring CD complex. An open, extended conformer of the linked compound was proposed as the model of the activated state for forming the through-ring CD complex.
  • Susumu Kitagawa, Satoshi Kawata, Mitsuru Kondo, Youichi Nozaka, Megumu ...
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 11 Pages 3387-3392
    Published: 1993
    Released: August 16, 2006
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    The new copper(I) coordination polymers, {[Cu2(2,6-Me2pz)3](ClO4)2(C3H6O)2} (1) and {[Cu2(2-Clpz)4.5](ClO4)2} (2) (2,6–Me2pz = 2,6-dimethylpyrazine; 2–Clpz = 2-chloropyrazine) have been synthesized and their structures have been X-ray crystallographically characterized. 1 crystallizes in the monoclinic, space group P21/a with a = 15.520(5), b = 19.315(2), c = 12.493(2) Å, β = 110.82(2)°, U = 3322(2) Å3, and Z = 4. 2 is orthorhombic, space group Pbca with a = 28.567(6), b = 17.560(9), c = 11.512(9) Å, U = 5774(8) Å3, and Z = 8. These complexes show an infinite sheet structure of macrocations with uninteracting ClO4 anion. 1 shows planar sheets composed of Cu6 hexagons, in which copper atoms are three-coordinate and linked by 2,6-Me2pz molecules. Acetone molecules sit over the cavities of the Cu6 hexagons, resulting in an intercalated layer between the copper sheets. 2 provides the unique polymers having an unprecedented four coordination geometry in binary copper–pyrazine systems. There are terminal and bridging types of 2-Clpz molecules, which produce Cu6 and Cu4 motifs for infinite pleated sheets. The factors governing the mode of polymerization are found by examination of the crystal structures for a series of copper(I) polymers of pyrazine derivatives.
  • Satoshi Hayakawa, Toshinobu Yoko, Sumio Sakka
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 11 Pages 3393-3400
    Published: 1993
    Released: August 16, 2006
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    51V static and magic-angle spinning (MAS) NMR spectra of crystalline divalent metal vanadates, M3(VO4)2 (M = Mg, Sr, Ba, Zn, Pb) and Mg2M′(VO4)2 (M′ = Sr, Ba, Pb) and divanadates, M2V2O7 (M = Mg, Ca, Sr, Ba, Zn, Pb) have been measured. In vanadates and dichromate-type divanadates, the 51V isotropic chemical shifts decrease linearly with decreasing electronegativity of divalent metal atom adjacent to the VO4-tetrahedron. This was interpreted by considering that the electron density and the symmetry of VO4-tetrahedron increases with decreasing electronegativity of divalent metal atom. This effect was more significant in vanadates than in divanadates. In divanadates the isotropic chemical shifts of the thortveitite-type configuration appeared at lower frequencies than that of the dichromate-type configuration. This was explained by assuming that the degree of s-hybridization of the oxygen orbitals in the V–O–V bonds is higher in the thortveitite-type than in the dichromate-type.
  • Hiroyuki Sakai, Terufumi Fujiwara, Takahiro Kumamaru
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 11 Pages 3401-3406
    Published: 1993
    Released: August 16, 2006
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    An increased chemiluminescence (CL) emission was produced upon mixing an acidified solution of silicate with a basic solution of luminol and hydrogen peroxide. The new CL reaction was used to develop a simple and rapid post-column detection system for selective determination of silicate after separation by ion-exclusion chromatography (ICE). Separation of silicate from other anions like phosphate, nitrite, sulfide or carbonate ion was achieved using a low-capacity cation-exchange column and a dilute perchloric acid solution as an eluent. Also, the present method has an advantage of eliminating interferences from ionic metal species. The detection limit of 50 ng cm−3 and a linear calibration graph with a dynamic range from 100 ng cm−3 to 30 μg cm−3 was obtained for silicon(IV). The proposed ICE-CL method was applied to the determination of silicate in tap and river water samples.
  • Yumiko Ishihara, Katsuhiko Saido, Tadashi Ikemura, Tomoyuki Takesue
    1993 Volume 66 Issue 11 Pages 3407-3413
    Published: 1993
    Released: August 16, 2006
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    Polymer degradation was investigated by examining reactions with alternate daylight exposure and immersion in aqueous environments. Crosslinked polymers were produced by the carbonium ion reaction of carbonyl groups in benzenesulfonic acid aqueous solution.
  • Kenichi Sakai, Yukihiko Hashimoto, Kazushi Kinbara, Kazuhiko Saigo, Hi ...
    1993 Volume 66 Issue 11 Pages 3414-3418
    Published: 1993
    Released: August 16, 2006
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    Enantiomerically pure 1-(3-methoxyphenyl)ethylamine (1), which is a key intermediate of new phenyl carbamate drugs, was obtained by a diastereomeric method with high resolution efficiency (E) by using enantiomerically pure mandelic acid (2) as a resolving agent. The first crystallization of the mixture of diastereomeric salts from methanol gave a less-soluble diastereomeric salt in 70% yield with 99% diastereomeric excess. Recrystallization of the salt from 2-propanol gave (R)-1·(R)-2 in 97% yield with 100% diastereomeric excess (total E = 68%). The crystal structure of the less-soluble diastereomeric salt, (R)-1·(R)-2, was determined by X-ray crystallography. The crystal data are: Monoclinic, space group P21, a = 12.642(4), b = 5.890(2), c = 10.855(4) Å, β = 103.68(3)°, V = 785.4(5) Å3, Z = 2, R = 0.058 for 1450 unique reflections. The X-ray crystallography revealed that the high resolution efficiency was due to a layer-like arrangement of the enantiomerically pure acids, of which two layers sandwiched a layer of the amines by hydrogen bonds, as well as the helical column formed by hydrogen bonds between the acids and the amines, as observed for the less-soluble diastereomeric salt of 1-phenylethylamine with mandelic acid.
  • Takehito Tsukinoki, Keiko Ishimoto, Hirohisa Tsuzuki, Shuntaro Mataka, ...
    1993 Volume 66 Issue 11 Pages 3419-3422
    Published: 1993
    Released: August 16, 2006
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    The reduction of benzaldehyde (1a) with Raney alloys in a 10% aq NaOH solution afforded benzyl alcohol (2a) in various yields (17—81%). In this reaction benzoic acid was also obtained as a by-product at the same time. This suggests that a Cannizzaro reaction competes with the reduction. In a 10% aq Na2CO3 solution the reduction of 1a with Raney alloys proceeded under ultrasonic irradiation to give almost exclusively 2a. In addition, we almost could not observe a Cannizzaro reaction in these experiments based on a comparison with a reduction in a 10% aq NaOH solution. A crossed Cannizzaro reaction between formaldehyde and benzaldehyde did not occur in a 10% aq NaOH solution/THF/MeOH, but afforded the reductive coupling compound hydrobenzoin.
  • Misako Aida
    1993 Volume 66 Issue 11 Pages 3423-3429
    Published: 1993
    Released: August 16, 2006
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    The hydrogen bonding interaction energies between peptide units were calculated using the ab initio MO method with the STO-3G, 7,3/2,1 and 6-31G basis sets and a correction of the basis set superposition errors (BSSE). The same systems were also investigated using an ab initio potential which has recently been developed and the AMBER potential, which is widely used. The energy profiles calculated using the ab initio potential are similar to those calculated using the 6-31G basis set. The distance and angle dependencies of the hydrogen bonding interactions are well represented by the ab initio potential. In contrast, they are not reproduced by the AMBER potential.
  • Masaru Ishida, Takamichi Aoyama, Yasufumi Beniya, Shinichi Yamabe, Shi ...
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 11 Pages 3430-3439
    Published: 1993
    Released: August 16, 2006
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    Theoretical and experimental studies are presented about π-facial selectivities in Diels–Alder reactions of 5-substituted cyclopentadienes (1). The HOMO and the NHOMO of 1 were readily predicted from the orbital mixing rule to be distorted to favor the syn- and anti-attack, respectively. The frontier orbital is dependent on the n-orbital energy (εn) of the substituent relative to the π-HOMO energy (επ) of the diene. For επ > εn, the syn π-facial selectivity is predicted since the HOMO contains the diene π-HOMO as the main component. For επ < εn, the anti π-facial selectivity is predicted since the π-HOMO most contributes to the NHOMO. For ε π εn, the loss of π-facial selectivity is predicted since the HOMO and the NHOMO both contribute to the reaction. The qualitative theory was examined by ab initio molecular orbital calculation on 1 (X = NH2, PH2, AsH2, OH, SH, SeH, F, Cl, and Br) and PM3 calculation of the activation energies on Diels-Alder reactions of 1 (X = NH2, PH2, AsH2, SbH2, OH, SH, SeH, TeH, F, Cl, Br, and I) with maleic anhydride. The observed selectivities of chalcogen-substituted cyclopentadienes (X = SPh and SePh) were in agreement with the theoretical prediction.
  • Masaaki Yoshifuji, Kazunori Kamijo, Kozo Toyota
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 11 Pages 3440-3443
    Published: 1993
    Released: August 16, 2006
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    A sterically hindered bromobenzene, 2-bromo-1,5-di-t-butyl-3-(methoxymethyl)benzene, was prepared and converted to the corresponding phosphonous dichloride. The dichloride was then utilized to stabilize a low-coordinate phosphorus compound such as 1-[2,4-di-t-butyl-6-(methoxymethyl)phenyl]-2-(2,4,6-tri-t-butylphenyl)diphosphene. Furthermore, the dichloride gave a cyclization product 1-chloro-2,1-oxaphosphaindan with elimination of chloromethane on standing at room temperature.
  • Kazuo Akagi, Kazue Mochizuki, Yoshifumi Aoki, Hideki Shirakawa
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 11 Pages 3444-3450
    Published: 1993
    Released: August 16, 2006
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    Novel homogeneous catalyst system of composed tetraethoxytitanium–trimethylaluminum, Ti(OEt)4–AlMe3, is employed for synthesis of polyacetylene film. It is confirmed that the present system has a high catalytic activity for acetylene polymerization, and its activity is comparable to that of the representative Ti(O-n-Bu)4–AlEt3 catalyst system. Experimental conditions, especially for preparation and aging of the catalyst, are optimized in view of properties of polyacetylene film such as cis content, mechanical stretchability, and electrical conductivity. The homogeneity of the present catalyst aged at room temperature enables us to synthesize highly conductive non-stretched and stretched films whose electrical conductivities after iodine doping are 2.0 × 103 and 1.2 × 104 S cm−1, respectively. Discussion has also been made in terms of the effect of high-temperature aging for the catalyst, the role of co-catalyst as a reductant, and the dependence of electrical conductivity on film thickness.
  • Hitoshi Takeshita, Bing Zhu Yin, Kanji Kubo, Akira Mori
    1993 Volume 66 Issue 11 Pages 3451-3455
    Published: 1993
    Released: August 16, 2006
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    Condensation of 2,7-dibromotropone and 7-bromo-4-isopropyl-2-(4-tolysulfonyloxy)tropone with oligoethylene glycol bis(2-mercaptoethyl) ethers gave sulfur-containing crown ether derivatives. Among these mercurophilic derivatives, triethylene glycol bis(2-mercaptoethyl) derivatives transport and extract mercury ion excellently.
  • Koichi Narasaka, Yasushi Kohno
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 11 Pages 3456-3463
    Published: 1993
    Released: August 16, 2006
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    Oxidation of N-1-(tributylstannyl)alkyl carboxamides and carbamates with ammonium hexanitratocerate(IV) or ferrocenium hexafluorophosphate generates their N-acyliminium ions by the elimination of tributylstannyl radical under mild reaction conditions. The iminium ions thus formed react with various carbon nucleophiles to give the corresponding addition products.
  • Masaya Nakata, Junji Ohashi, Kunihiko Ohsawa, Toru Nishimura, Mitsuhir ...
    1993 Volume 66 Issue 11 Pages 3464-3474
    Published: 1993
    Released: August 16, 2006
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    The C1–C14 segment of venturicidins, (2R,6R)-3,6-dihydro-6-[(E)-7-(dimethoxyphosphinyl)-1-methyl-6-oxo-1-heptenyl]-2-methoxy-5-methyl-2H-pyran-2-acetic acid (1), has been synthesized. The C8–C13 segment of venturicidins, (E)-2-bromo-7-(4,4′-dimethoxytriphenylmethoxy)-2-heptene (2), was lithiated with t-butyllithium and the resulting vinyllithium compound was coupled with the C1–C7 segment, (2Z,7S)-7-(t-butyldimethylsilyloxy)-8-(t-butyldiphenylsilyloxy)-2-methyl-5,5-(trimethylenedithio)-2-octenal (4), to afford the alcohol. A subsequent seven-step conversion of this alcohol furnished the synthesis of the C1–C13 segment, (2R,6R)-3,6-dihydro-6-[(E)-6-hydroxy-1-methyl-1-hexenyl]-2-methoxy-5-methyl-2H-pyran-2-acetate (9). Finally, the known four-step transformation led 9 to the target compound 1.
  • Akikazu Kakehi, Suketaka Ito, Jun-ichi Hakui
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 11 Pages 3475-3482
    Published: 1993
    Released: August 16, 2006
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    Various 1-pyridinio(thiocarbonyl)methylides and 2-isoquinolinio(thiocarbonyl)methylides react smoothly with dimethyl acetylenedicarboxylate at room temperature or at the reflux temperature in chloroform to give new heterocycles, dimethyl 10aH-pyrido[1,2-d][1,4]thiazepine-1,2-dicarboxylate derivatives, in moderate yields. Similarly, the reactions of some 3-(1-pyridinio)thiophene-2-thiolates with the same reagent afforded the corresponding dimethyl 6aH-pyrido[1,2-d]thieno[2′,3′-b][1,4]thiazepine-5,6-dicarboxylates. The structures of these 1,4-thiazepine derivatives were mainly assigned based on physical and spectral inspections, and were finally confirmed by X-ray analyses of three compounds.
  • Kazuaki Ishihara, Tohru Maruyama, Makoto Mouri, Qingzhi Gao, Kyoji Fur ...
    1993 Volume 66 Issue 11 Pages 3483-3491
    Published: 1993
    Released: August 16, 2006
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    In the presence of 20 mol% of a chiral (acyloxy)borane (CAB) complex prepared from BH3·THF and a chiral mono-O-acylated tartaric acid, achiral silyl enol ethers or ketene silyl acetals react with achiral aldehydes to afford the corresponding aldol-type adducts in good yields with high enantio- and diastereoselectivities. Furthermore, the reactivity of aldol-type reactions can be improved without reducing the enantioselectivity by use of 10—20 mol% of the CAB complex prepared from 3,5-bis(trifluoromethyl)phenylboronic acid and chiral tartaric acid derivative. The enantioselectivity can also be improved without reducing the chemical yield by use of 20 mol% of the CAB complex prepared from o-phenoxyphenylboronic acid and chiral tartaric acid derivative. The observed erythro selectivities and re-face attack of nucleophiles on carbonyl carbon of aldehydes imply that the extended transition state model is applicable.
  • Hiroyuki Yasuda, Taihei Nitadori, Noritaka Mizuno, Makoto Misono
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 11 Pages 3492-3502
    Published: 1993
    Released: August 16, 2006
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    The direct decomposition of nitrogen monoxide (NO) to N2 and O2 was carried out over valency-controlled La2−xA′xCu1−yB′yO4 (A′ = Sr, Ba, Ca, Ce; B′ = Zr, Al) mixed oxide catalysts with a K2NiF4-type structure. The catalysts were characterized by XRD, XPS, redox titration, and oxygen TPD. It was confirmed by XPS that the surface and bulk compositions generally agreed and by redox titration that the average oxidation number (AON) of copper varied widely from 1.60 to 2.30. XPS showed that the valency of surface copper agreed with AON for AON ≤ 2, while it was in the Cu2+ state for AON > 2.0. The amounts of oxygen desorbed in TPD and the oxygen nonstoichiometry of La2−xSrxCuO4 increased with x in parallel. The catalytic activity for NO decomposition showed a maximum at x = 0.4—0.5, and a good correlation was found between the catalytic activity and AON for all of the catalysts tested. The decomposition of dinitrogen oxide (N2O) was also carried out for La2−xSrxCuO4 for a comparison. Based on the much slower rate of decomposition for NO than that for N2O and the significantly high rate of oxygen TPD, it was concluded that the oxygen desorption was not the rate-determining step in the steady state. The relative activities of the catalysts studied are all well explained by a mechanism in which the active sites for NO decomposition over these catalysts are coordinatively unsaturated Cu 2+ ions on the surface that can be easily oxidized to Cu3+ upon NO adsorption.
  • Kazuo Takahashi, Tadaaki Inomata, Hiroshi Jinno
    1993 Volume 66 Issue 11 Pages 3503-3505
    Published: 1993
    Released: August 16, 2006
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    Ignition delay times were measured in a CH4–O2–HBr–Ar mixture behind reflected shock waves. Hydrogen bromide retarded methane ignition, though methyl bromide accelerated it. Model calculations showed that two different chain cycles, promotion and inhibition cycles, were formed for bromine-containing species. The inhibition cycle was predominant in the HBr addition.
  • Teiichiro Ogawa, Youichi Jinbou, Nobuaki Yonekura, Kenji Furuya, Keiji ...
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 11 Pages 3506-3507
    Published: 1993
    Released: August 16, 2006
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    Excitation functions of the fast group of H*(n = 3,4) show two thresholds at 22—23 and about 27 eV. Their comparison indicates that the dissociation process through the 1Σu+(2pσu)(nlσg) states are relatively more important for H*(n = 4).
  • Keiji Miyazaki, Takako Kimura
    Type: Accounts
    Subject area: AI
    1993 Volume 66 Issue 11 Pages 3508-3510
    Published: 1993
    Released: August 16, 2006
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    Trace moisture and other potential impurities (CO2, CH4, C2H6, and alkyl halides) in HCl and in HBr gases were analyzed by gas-phase FTIR spectroscopic technique. The detection limit was estimated to be 100 ppb with 2 cm−1 spectral resolution for 5-min measurement time at 1.2 kg cm−2 pressure, using an MCT detector and an 8-m-pathlength gas cell with BaF2 windows.
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