Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Volume 71 , Issue 12
Showing 1-28 articles out of 28 articles from the selected issue
  • Takeaki Iwamoto, Hideki Sakurai, Mitsuo Kira
    1998 Volume 71 Issue 12 Pages 2741-2747
    Published: 1998
    Released: June 05, 2006
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    Versatile reaction modes of tetrasilyldisilenes with various reagents have been disclosed. Typically, tetrakis(t-butyldimethylsilyl)disilene 1b reacts with 1-alkenes and a 1-alkyne having allylic hydrogens to afford the corresponding ene-addition products, while a reaction of 1b with styrene gives the [2+2] cycloaddition product. In contrast to tetra-t-butyldisilene and tetramesityldisilene, a reaction of 1b with a 1,3-butadiene gives quantitatively the [4+2] cycloaddition product. In accord with the biradical nature of disilene as predicted theoretically, tetrasilyldisilene 1b reacts with haloalkanes to provide the corresponding 2,3-dichlorotetrasilane or 2-alkyl-3-chlorotetrasilane probably via radical mechanisms. Facile nucleophilic additions of water, methanol, and methyllithium to 1b are indicative of the high electrophilicity of 1b.
  • Ryo Tamaki, Takuya Horiguchi, Yoshiki Chujo
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 12 Pages 2749-2756
    Published: 1998
    Released: June 05, 2006
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    Two different types of polymer hybrids having an interpenetrating polymer network (IPN) of the organic gel and silica gel were prepared by the in-situ polymerization method. One type is the IPN polymer hybrids of poly(N,N′-dimethylacrylamide) gel and silica gel that were prepared by simultaneous polymerization of N,N′-dimethylacrylamide and N,N′-methylenebisacrylamide in a methanol solution of tetramethoxysilane (TMOS). The other type is IPN polymer hybrids of polystyrene gel and silica gel that were prepared by the polymerization of styrene monomer in the presence of divinylbenzene and TMOS. Radical polymerization of these organic monomers proceeded effectively in the sol-gel reaction mixture of TMOS, resulting in homogeneous glassy materials. The formation of IPN structure was confirmed by the solvent extraction. The loss of organic elements could be prevented in both cases by the incorporation of cross-linking points in the organic network. The homogeneity of these IPN polymer hybrids were supported by nitrogen porosimetry measurements. The results demonstrated that the porous silicas obtained from the polymer hybrids had high surface areas and large pore volumes and exhibited a sharp distribution of pore size below 2 nm in both types of IPN polymer hybrids. These results indicate a molecular-level integration of the organic gel and silica gel in the IPN polymer hybrids.
  • Mohammad Mehdi Papari, Ali Boushehri
    1998 Volume 71 Issue 12 Pages 2757-2767
    Published: 1998
    Released: June 05, 2006
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    Viscosities, diffusion coefficients, and thermal-diffusion factors for eight equimolar binary gas mixtures (Ne+O2, Ne+CO2, Ne+N2O, Ne+SF6, Ar+O2, Ar+CO2, Ar+N2O, and Ar+SF6) were determined based on the principle of the corresponding states of viscosity using the inversion technique. The Lennard-Jones 12-6 potential energy function was used as the initial model potential required by the technique. Typically, the interaction potential of Ar+SF6 has been compared with those obtained from thermal-diffusion measurements. Our inverted potentials are in excellent agreement with it. The interaction potential energies from the inversion procedure reproduce the viscosities to within 1%, the diffusion coefficients to within 5%, and the thermal-diffusion factors to within 25%.
  • Yasuo Kameda, Kentaro Sugawara, Takeshi Usuki, Osamu Uemura
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 12 Pages 2769-2776
    Published: 1998
    Released: June 05, 2006
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    X-Ray diffraction and Raman spectroscopic measurements have been carried out for aqueous 10 mol% NaX (X = Cl, Br, ClO4, and NO3) solutions in order to determine the hydration structure of Na+ in concentrated aqueous solutions. Isotropic Raman spectra for NaX–H2O solutions exhibit a polarized peak centered at 183—187 cm−1. The corresponding peak in the isotropic spectra for NaX–D2O solutions is shifted to the lower frequency side by ca. 10 cm−1, indicating that the peak can be assigned to the totally symmetric vibrational mode of hydrated Na+, Na+(H2O)n. The least-squares fitting analysis was applied to the X-ray interference term observed for these solutions in order to discuss the hydration number of Na+ in concentrated aqueous solutions.
  • Jun Kawamata, Kuon Inoue, Tamotsu Inabe
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 12 Pages 2777-2786
    Published: 1998
    Released: June 05, 2006
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    X-Ray crystallographic analyses have been performed for the crystals of α,α′-dibenzylidenecycloalkanone (DBCA) derivatives which preferentially crystallize in non-centrosymmetric space groups and become second-order nonlinear optical crystals. We examined the obtained structures while paying attention to the intermolecular short contacts common to their structure. As a result, relatively short C–H···O contacts between the cycloalkanone rings were found for 8 out of 10 DBCA derivatives. The C–H···O distances for all cyclopentanone derivatives are almost the same as the sum of the van der Waals radius of carbon and that of oxygen; also, the geometrical characteristics found from the C–H···O contacts are consistent with the C–H···O hydrogen bond. The derivatives form a non-centrosymmetric one-dimensional chain with this contact. Their non-centrosymmetric crystal structures are led not only by their molecular shape, but also by this C–H···O interaction.
  • Kouichi Fukui, Hiroaki Ohya-Nishiguchi, Hitoshi Kamada, Masamoto Iwaiz ...
    1998 Volume 71 Issue 12 Pages 2787-2796
    Published: 1998
    Released: June 05, 2006
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    Electron spin-echo envelope modulation (ESEEM) measurements were made for three substituted oxovanadium(IV) phthalocyanines ([VO(tcpc)], [VO(tbpc)], and [VO(tapc)]), where the phthalocyanine rings are modified with four carboxyl, t-butyl, and amino groups, respectively. The 14N hyperfine coupling (HFC) and nuclear quadrupole coupling (NQC) tensors of the phthalocyanine isoindole nitrogens were determined by computer simulations of orientationally selected ESEEM spectra. The HFC tensors of these three complexes were found to be almost identical, and no appreciable effects from the substituents were detected. The isotropic HFC constants, as determined by the simulations, are |Aiso| = 7.08, 7.08, and 7.05 MHz for [VO(tcpc)], [VO(tbpc)], and [VO(tapc)], respectively. The NQC constants were also found to be very similar to one another: e2qQ/h = 2.2, 2.1, and 2.0 MHz for [VO(tcpc)], [VO(tbpc)], and [VO(tapc)], respectively. However, the simulations revealed a difference in the orientation of the NQC unique axis, where the unique axis is parallel to the V–N bond in [VO(tcpc)] and [VO(tbpc)], whereas this axis is perpendicular to the V–N bond within the phthalocyanine plane in [VO(tapc)]. An analysis of the NQC parameters based on the Townes-Dailey model indicates an increase in the electron population of the nitrogen π orbital in [VO(tapc)], which is consistent with the expected effects of the amino group.
  • Toshie Harazono, Etsuzo Yokota, Hiroshi Uchida, Tokuko Watanabe
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 12 Pages 2797-2805
    Published: 1998
    Released: June 05, 2006
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    Luminous properties of a green phosphor, Tb-doped Y3Al5O12, have been studied by 89Y (nuclear spin 1/2)-static and -magic angle spinning (MAS) NMR and 27Al (nuclear spin 5/2)-MAS NMR. In pure Y3Al5O12, a sharp signal at 239 ppm was observed in 89Y-MAS NMR spectrum, which was expected from a powder pattern due to 8O-coordinated Y in D2 symmetry in 89Y-static NMR spectrum. In the 27Al-MAS NMR spectrum of Y3Al5O12, two typical signals were observed, i.e., a sharp signal at 0 ppm due to 6O-coordinated Al in the octahedral site and a characteristic signal due to 4O-coordinated Al in the tetrahedral site. These 89Y and 27Al signals became broader in Tb-Y3Al5O12 with increasing in content of the doped Tb. In addition to the main peak at 239 ppm, furthermore, extra peaks appeared in the bottom of the main peak in 89Y-MAS NMR; these were assigned to the second nearest to the fifth nearest neighboring Y (Y2 to Y5) atoms to Tb atom substituted in the site of Y atom. Shifts of these Y atoms were reasonably explained by a pseudocontact shift via a paramagnetic Tb3+ ion. Incorporation of Tb3+ ions caused a large reduction in 89Y nuclear spin-lattice relaxation time from 4000s (pure Y3Al5O12) to several hundred seconds (3% Tb-Y3Al5O12) as well.
    The line-broadening of the signals was mainly dominated by the dipole–dipole interaction mechanism between the Al or Y resonating nucleus and a Tb3+ ion. The signals of Y atoms in the sites where either one of the nearest neighboring Y1 atoms was replaced by Tb atom were not detected because of the large line-broadening.
    The stronger brightness was obtained in the specimens which showed the much broader linewidth in 27Al-MAS signals and in 89Y-static NMR signals under the same Tb content. So we concluded that the homogeneous distribution of Tb3+ ions in Tb-Y3Al5O12 plays a key role for the higher brightness in the green phosphor as in the red phosphor.
  • Takahiro Seki, Takashi Fukuchi, Kunihiro Ichimura
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 12 Pages 2807-2816
    Published: 1998
    Released: June 05, 2006
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    An azobenzene (Az) containing amphiphile having a urea head group [N-(10-{4-[(4-hexylphenyl)azo]phenoxy})decylurea (6Az10-Urea)] was synthesized for the first time, and the spreading behavior, morphology, absorption spectral features, and photoreactivity of this amphiphile at the air–water interface was examined. The features of this monolayer were argued in comparison with those of a carboxylic acid derivative of the homologous structure. Polymer-like stable stable monolayers were formed form 6Az10-Urea both in the trans and cis forms of the Az unit, possibly indicating the formation of intermolecular bifurcated NH···O=C hydrogen bonds of urea heads. Unlike monolayers of simple long alkylureas, the present monolayer did not show a thermal phase transition within the temperature region examined (10—35 °C). In the trans-6Az10-Urea monolayer, the Az unit formed tilted aggregates. In this aggregation state, the trans-to-cis photoisomerization in the 6Az10-Urea monolayer was completely hindered despite the fact that the monolayer was more expanded than that of a corresponding carboxylic acid derivative in which the photoisomerization proceeded.
  • Yasuo Toyoshi, Teruyuki Nakato, Toshio Okuhara
    1998 Volume 71 Issue 12 Pages 2817-2824
    Published: 1998
    Released: June 05, 2006
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    Solid-state pinacol rearrangement of 1,1,2-triphenyl-1,2-ethanediol was performed over various solid acids at room temperature. The reaction was initiated by grinding a mixture of the solid reactant and catalyst for 5 min at room temperature. Heteropoly compounds (Cs2.5H0.5PW12O40 and H3PW12O40) and polymer resins (Amberlyst®-15 and Nafion®/SiO2), all which possess strong acidities, were active, whereas H-ZSM-5, SiO2–Al2O3, and p-toluenesulfonic acid were inactive. Cs2.5H0.5PW12O40 showed the highest activity (per unit catalyst weight). The turnover number, which is defined as the number of molecules reacted divided by the number of protons on the surface, exceeded 20 for 9 h, indicating that the solid–solid reaction proceeded catalytically. This activity of Cs2.5H0.5PW12O40 was higher than that for the solid–liquid reaction carried out in chloroform at room temperature, demonstrating the superiority of the solid–solid catalysis. Powder X-ray diffraction measurements indicated that the reactant crystals became nearly amorphous by grinding with Cs2.5H0.5PW12O40, while the crystallinity of Cs2.5H0.5PW12O40 was unchanged. The microstructure built up from fine particles of Cs2.5H0.5PW12O40 would be favorable to intimate contact of the reactant with the catalyst.
  • Setsuko Yajima, Yuko Hasegawa
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 12 Pages 2825-2829
    Published: 1998
    Released: June 05, 2006
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    The enthalpy change in the adduct formation of tris[1-(2-thienyl)-4,4,4-trifluoro-1,3-butanedionato]lanthanoids (LnA3) with 1,10-phenanthroline (phen) as well as the formation constant of the adduct has been determined in chloroform across the lanthanoid series at 298 K by calorimetric titration and solvent-extraction techniques. The enthalpy change in the first adduct formation changes remarkably from light lanthanoids (endothermic) to heavy ones (exothermic), while the entropy change decreases largely from the middle to the heavy lanthanoids along with a small change from light to the middle of the series. Such a trend has been explained on the basis of the difference in the dehydration from lanthanoid(III) chelates and in the strength of the new bonding of chelates formed between tris(β-diketonato) lanthanoid(III) and phen across the lanthanoid series.
  • Kazuhiko Tsukagoshi, Masahiko Hashimoto, Miwa Otsuka, Riichiro Nakajim ...
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 12 Pages 2831-2836
    Published: 1998
    Released: June 05, 2006
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    Phenylboronic acid sites were introduced onto the inner wall of a fused-silica capillary through the polymerization of 3-acrylamidophenylboronic acid after activating the wall by a silane coupling reagent. The phenylboronic acid-modified capillary was examined from various viewpoints of separation chemistry. Nucleosides having cis-diol groups were mainly used as model samples. The phenylboronic acid-modified capillary successfully separated a mixture of nucleosides, for example, an adenosine and deoxyadenosine mixture, in capillary electrophoresis. The separation was based on an interaction between the cis-diol groups and the phenylboronic acid sites on the capillary wall. The cooperation of borate migration buffer with the modified capillary could improve the resolution. The separation of a D- and L-glucoses mixture was also indicated with the coexistence of β-cyclodextrin in electrophoresis using a modified capillary. Furthermore, mixtures of nucleosides were separated with satisfactory results by chromatography utilizing a solute-wall interaction in the modified capillary, where the eluate was delivered through the capillary by a gravity method without any electrophoresis. The separation of biological constituents in this study, which took advantage of the interaction between the solutes and the inner wall of the capillary, is interesting as a new separation technique in not only capillary electrophoresis, but also capillary chromatography.
  • Yonezo Maeda, Masaki Suzuki, Shigeyuki Hirose, Shinya Hayami, Takayuki ...
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 12 Pages 2837-2843
    Published: 1998
    Released: June 05, 2006
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    New spin-crossover iron(III) complexes [FeM(salten)L]X with an alkali ion in a macrocycle have been prepared, and the magnetic properties of the complexes in the solid and in acetonitrile solution have been examined, where M is Li+, Na+, K+, or Rb+, H2salten is 4-aza-heptamethylene-1,7-bis(salicylideneiminate) and L is N-(4-picolyl)-aza-15-crown-5-ether. The spin-crossover behaviors of the iron(III) complexes dependent on temperature in the solid are observed on the Mössbauer spectra and magnetic susceptibilities, and those in acetonitrile on the electronic spectra. The magnetic properties of the complexes in the solid are changed with the species of alkali metal ions included in a macrocycle. Li-complexes show the magnetic moment of 4.00 B.M. at 300 K and 2.19 B.M. at 80 K, and Na-complexes 5.03 B.M. at 300 K and 4.21 B.M. at 80 K. The Mössbauer spectra of Li-complexes show that the interexchange rates of the spin-state transition between high-spin and low-spin states are as fast as the reciprocal of the lifetime of the excited state of 57Fe(10−7s) above 110 K. The magnetic behaviors of all of the complexes in acetonitrile are similar.
  • Masashi Nishida, Miwako Sonoda, Daido Ishii, Isao Yoshida
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 12 Pages 2845-2851
    Published: 1998
    Released: June 05, 2006
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    Water-soluble hydroxycalix[n]arene-p-sulfonates, 1nn (n = 4, 6, and 8), were quantitatively extracted from an aqueous solution into chloroform with trioctylmethylammonium ion (TMA+) over a wide pH range. The extraction reaction of 1nn with TMA+Cl and the extraction constants were determined from slope analyses of linearized extraction data and by the mole-ratio method. It was demonstrated that 1nn, having n moles of sulfonato groups in an aqueous solution, could be extracted as 1n (TMA+)n by associating with n moles of TMA+ at a pH lower than that at which protonic dissociation of hydroxyl groups takes place, and that 1n (TMA+)(n+j) was extracted at a pH higher than that for j moles of hydroxyl groups dissociate to form 1n(n+j)−. The extractability of 1nn increased in the order of n (4 < 6 < 8); also, the pH range where complete extraction took place became wider in the same order. As a possible application of the present extraction system, metal extraction with 144− was also shown for the purpose of selective separation of some metal ions.
  • Kohtaro Osakada, Kouji Hataya, Takakazu Yamamoto
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 12 Pages 2853-2858
    Published: 1998
    Released: June 05, 2006
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    Heating of a benzene or toluene solution of mer-[RhH(SAr)(SiHAr′2)(PMe3)3] (Ar = C6H5, C6H4Me-p, C6H4OMe-p; Ar′ = C6H5, C6H4Me-p, C6H4F-p, C6H4CF3-p) at 30—50 °C gives fac-[RhH2{SiAr′2(SAr)}(PMe3)3] quantitatively through thiolato group transfer from Rh to Si. X-Ray structural analysis of fac-[RhH2{SiPh2(SPh)}(PMe3)3] reveals octahedral coordination with three PMe3 ligands at facial coordination sites, while the 1H NMR spectra show the presence of two equivalent hydrido ligands. The other Rh complexes are isolated or characterized in situ by means of NMR spectroscopy. The reaction of mer-[RhH(SC6H4Me-p)(SiHPh2)(PMe3)3] to form the Rh complex obeys first-order kinetics with the kinetic parameters: ΔG = 98.6 kJ mol−1, ΔH = 94.9 kJ mol−1, and ΔS = −12 J mol−1 deg−1 at 298 K. The rate constants of the reaction of mer-[RhH(SC6H4X-p)(SiHPh2)(PMe3)3] (X = H, Me, OMe) increase with increasing Hammett constant σp of substituent X. The substituent of the diarylsilyl ligand of mer-[RhH(SC6H4X-p){SiH(C6H4Y-p)2}(PMe3)3] (X = Me or OMe; Y = H, Me, F, CF3) also influences the reaction rate constant, while the degree of enhancement is not directly related to the electron donating or withdrawing ability of substituent Y. Possible reaction mechanisms are discussed based on these results.
  • Toshiyuki Oshiki, Kazushi Mashima, Tsuneaki Yamagata, Kazuhide Tani
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 12 Pages 2859-2864
    Published: 1998
    Released: June 05, 2006
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    A hypervalent compound 1,5-bis(trifluoromethylsulfonyloxy)-1λ4,5λ4-dithiabicyclo[3.3.0]octane (1) oxidatively reacted with Pd2(dba)3 (dba = dibenzylidene acetone) in acetonitrile to give a dicationic complex [Pd(dtco)(CH3CN)2](OTf)2 (2) (DTCO = 1,5-dithiacyclooctane), in which the DTCO ligand coordinated in cis-chelation to the palladium metal. Acetonitrile in 2 was labile enough to be readily replaced by phosphine ligands to give dicationic DTCO-phosphine palladium complexes of the formula [Pd(dtco)(L)2](OTf)2 (3: L = PMe2Ph; 4: L = PPh3; 5: L2 = 1,2-bis(diphenylphosphino)ethane; 6: L2 = (R)-2,2′-bis(diphenylphosphino)-1,1′-binaphthyl). Molecular structures of 5 and 6 have been characterized by X-ray analysis, indicating that each of these two complexes consists of a discrete dicationic palladium(II) species [Pd(dtco)L2]2+ and two trifluoromethanesulfonate ions without any cation–anion bonding interaction, and revealing that the DTCO is coordinated to the palladium center as a bidentate ligand and that two phosphorus atoms ultimately coordinated to the metal in cis-fashion.
  • Lung-Shiang Luh, Yuh-Sheng Wen, Hiromi Tobita, Hiroshi Ogino
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 12 Pages 2865-2871
    Published: 1998
    Released: June 05, 2006
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    Photolysis of a 2 : 1 mixture of [Cp*Fe(CO)2Me] and Ph2CHSiH3 produces mainly the mononuclear silyl complex [Cp*Fe(CO)2{Si(H)2CHPh2}] (1) together with two silanediyl-bridged diiron complexes: cis- and trans-[Cp*2(CO)2Fe2(μ-CO){μ-Si(H)CHPh2}] (2), and [{Cp*Fe(CO)2}2]. The trans-2 complex isomerizes to cis-2 photochemically, but no cistrans isomerization occurs thermally below 100 °C. Photolysis of [CpFe(CO)2SiMe3] or [CpW(CO)3Me] in the presence of 1 produces novel silanediyl-bridged complexes [Cp*Fe(CO)(μ-CO){μ-Si(H)CHPh2}(CO)nMCp] (3: M = Fe, n = 1; 4: M = W, n = 2) in moderate yields. Complexes 3 and 4 have been characterized by X-ray diffraction analysis. To the best of our knowledge, complex 4 is the first example of a silanediyl-bridged Fe–W complex. The Cp and Cp* rings are mutually cis with the dihedral angle of 78.7(2)° in complex 3, but they are trans with the dihedral angle of 13.1(6)° in complex 4.
  • Masakazu Hirotsu, Masaaki Kojima, Wasuke Mori, Yuzo Yoshikawa
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 12 Pages 2873-2884
    Published: 1998
    Released: June 05, 2006
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    Tripodal tetradentate ligands (H2L1: N,N-bis(2-hydroxybenzyl)-N′,N′-dimethylethylenediamine, H2L2: N-(3,5-di-t-butyl-2-hydroxybenzyl)-N-(2-hydroxybenzyl)-N′,N′-dimethylethylenediamine, H2L3: N,N-bis(3,5-di-t-butyl-2-hydroxybenzyl)-N′,N′-dimethylethylenediamine, H2L4: N,N-bis(2-hydroxy-3-methoxybenzyl)-N′,N′-dimethylethylenediamine, H2L5: N-(3,5-di-t-butyl-2-hydroxybenzyl)-N-(2-hydroxy-3-methoxybenzyl)-N′,N′-dimethylethylenediamine) made it possible to prepare sterically controlled polynuclear manganese complexes. In the presence of carboxylate ligands, in contrast to the L3 ligand which gave mononuclear MnIII complexes, the other ligands afforded mixed-valence trinuclear complexes with an MnIII–MnII–MnIII arrangement. In methanol, the general formula of the products is [Mn3(L)2(carboxylato)2(OCH3)2]. While preparations in acetonitrile generated [Mn3(L1)2(ba)4] (ba = benzoate(1−)) and [Mn3(L2)2(ba)2(OH)2]. The structure of [Mn3(L1)2(ba)4] was determined by X-ray analysis. The three manganese cores are arranged linearly, and the central and terminal ions are bridged by a phenolate and two carboxylate groups. In the case of the L5 ligand, dinuclear and tetranuclear complexes were also obtained and structurally characterized. In the dinuclear complex, [Mn(L5)(CH3OH)(OCH3)MnCl2], a distorted octahedral MnIII and a five-coordinated MnII site are bridged by a phenolate and an alkoxo oxygen donor. The tetranuclear complex, [Mn4(L5)2(ba)6], including an MnIII–MnII–MnII–MnIII arrangement, is regarded as a carboxylato bridged dimer of a dinuclear unit, [Mn(L5)(ba)2Mn]+. Because the bulkiness of the L5 ligand lies between the L2 and L3 ligands, the dinuclear unit is favorable. Variable-temperature magnetic susceptibility measurements showed the ferromagnetic spin-exchange coupling for [Mn(L5)(CH3OH)(OCH3)MnCl2] and the antiferromagnetic one for [Mn3(L1)2(ba)4]. The phenolato and alkoxo bridges give rise to the ferromagnetic exchange interactions between MnIIIand MnII ions. On the other hand, the antiferromagnetic interactions stem from carboxylato bridges.
  • Takahiko Kojima, Kaoru Saeki, Kazuhiro Ono, Yoshihisa Matsuda
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 12 Pages 2885-2892
    Published: 1998
    Released: June 05, 2006
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    A series of novel square-planar palladium(II)-phosphole complexes was synthesized in good yields by a ligand-substitution reaction of [Pd(CH3CN)4](BF4)2 with 3,4-dimethyl-1-phenylphosphole (dmpp) and/or 3,3′4,4′-tetramethyl-1,1′-diphenyl-2,2′-biphosphole (bidmpp) in CH2Cl2; [Pd(dmpp)4](BF4)2 (1), [Pd(bidmpp)(dmpp)2](BF4)2 (2), and [Pd(bidmpp)2](BF4)2 (3). Those complexes were characterized by 1H and 31P NMR spectroscopies and X-ray crystallography for 3. The crystal structure of 3 revealed that the configurations of the phosphorus atoms were (R, R, S, S), indicating that the structure was a meso form with an intramolecular π–π interaction between the phenyl groups. 1H NMR spectroscopy suggested the structures of 1 and 2: Complex 1 has a water wheel-like C4h structure and complex 2 is C2 symmetric. In the 31P NMR spectra of those complexes, each resonance showed a smaller downfield shift than that observed for [Pd(dppe)2]Cl2 (dppe = 1,2-bis(diphenylphosphino)ethane), indicating that the palladium-phosphole interaction is governed by mainly a σ-donation, and that there is a small contribution from a π-back bonding interaction.
  • Motoko Hirooka, Shinkiti Koto
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 12 Pages 2893-2902
    Published: 1998
    Released: June 05, 2006
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    Dehydrative glycosylation using 2,3,4,6-tetra-O-benzyl-D-glucopyranose was carried out by the use of a condensing reagent system composed of diethylaminosulfur trifluoride (DAST), tin(II) triflate, tetrabutylammonium perchlorate, and triethylamine. Using this system, two tetrasaccharides, O-α-D-glucopyranosyl-(1→4)-O-α-D-glucopyranosyl-(1→3)-O-α-D-glucopyranosyl-(1→4)-D-glucopyranose and O-α-D-glucopyranosyl-(1→3)-O-α-D-glucopyranosyl-(1→4)-O-α-D-glucopyranosyl-(1→4)-D-glucopyranose, were synthesized.
  • Masaki Shimizu, Nobuko Yamada, Yoko Takebe, Takeshi Hata, Manabu Kurob ...
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 12 Pages 2903-2921
    Published: 1998
    Released: June 05, 2006
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    The treatment of tribromofluoromethane with BuLi in THF–Et2O (2 : 1) at −130 °C generated dibromofluoromethyllithium, which was allowed to react smoothly with a coexisting aldehyde or ketone (RR′C=O) to give fluorinated alcohol RR′C(OH)CFBr2 (3) in good yield. Alcohol 3 was converted stereoselectively to (E)-1-bromo-1,2-difluoro olefin 5 via fluorination with Et2NSF3, followed by dehydrobromination with lithium 2,2,6,6-tetramethylpiperidide, while (E)-1-bromo-1-fluoro olefin was obtained with high selectivity by acetylation of 3, followed by reductive elimination using EtMgBr/(i-Pr)2NH. Difluoro olefin 5 underwent a cross-coupling reaction with an aryl, alkenyl, or alkynylmetal reagent to afford the corresponding fluoro olefin with retention of configuration. On the other hand, the treatment of RCH[OCH2O(CH2)2OCH3]CFBr2 with BuLi at −130 °C in the presence of 4-heptanone gave the corresponding adduct diastereoselectively. The stereochemical outcome is explained in terms of chelation between lithium and oxygen atoms of the (2-methoxyethoxy)methyl group. Starting with 2-phenylpropanal, a product is obtained highly selectively containing three contiguous stereocenters including a –CFBr– moiety.
  • Yukio Hoshino, Hiroto Tanaka, Noboru Takeno
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 12 Pages 2923-2928
    Published: 1998
    Released: June 05, 2006
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    (E)-3-Benzylidene-4-chromanones were regioselectively reduced to 3-benzyl-4-chromanones through the 1,4-addition of dialkylboranes, especially 9-borabicyclo[3.3.1]nonane, in excellent yields. The reaction was efficiently promoted by some palladium catalysts. Among them, dichloro[1,1′-bis(diphenylphosphino)ferrocene]palladium(II) was most effective, followed by palladium(II) chloride. Furthermore, the reaction was characteristic of the structurally rigid exo-cyclic α,β-unsaturated ketones, such as (E)-3-benzylidene-4-chromanone, while no reaction occurred in the case of 3-benzyl-4H-chromen-4-one, which is an endo-cyclic one. 2-Benzylidene-3,4-dihydro-1(2H)-naphthalenone and 2-benzylideneindanone were similarly reduced at an olefin moiety only as the result of a 1,4-reduction.
  • Takayuki Doi, Masaru Takasaki, Sadahiro Nakanishi, Arata Yanagisawa, K ...
    1998 Volume 71 Issue 12 Pages 2929-2935
    Published: 1998
    Released: June 05, 2006
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    The Pd(0)-catalyzed domino cyclization-carbonylation of 5,8-dimethyl-5-(1,2-propadienyl)-2,8-nonadienyl acetate (7) was achieved at a rather higher temperature. The tricyclic and tetracyclic products, 15 and 16, were produced in 77% combined yield via five and six consecutive carbon–carbon bond formations, each step proceeding in > 94% yield.
  • Kiyoe Hamachi, Kenji Matsuda, Tetsuji Itoh, Hiizu Iwamura
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 12 Pages 2937-2943
    Published: 1998
    Released: June 05, 2006
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    3,4′-Bis(4,5-dihydro-4,4,5,5-tetramethyl-3-oxido-1-oxyl-3-imidazolio-2-yl)azobenzene (1) was synthesized starting from 3,4′-dimethylazobenzene via the diformyl derivative. Biradical 1 crystallized as dark blue-green needles; its crystal structure was determined by the X-ray crystallography. X-band ESR spectra of biradical 1 in the degassed toluene solution were measured in the temperature range 10—300 K. At 300 K the ESR spectrum showed nine lines centered at g = 2.006 (aN = 3.7 G). At 10 K the ESR spectrum showed a fine structure with zero-field splitting (zfs) parameters |D/hc| = 0.0026 cm−1and |E/hc| = 0.00014 cm−1. Magnetic susceptibility measurements revealed that the two radical centers coupled in a ferromagnetic way and the through-bond exchange interaction was determined to be 2J/kB = 8.36 ± 0.26 K with a Weiss constant θ = −0.39 ± 0.01 K. Photochromic reaction was monitored by ESR and UV-vis spectroscopy.
  • Katsuya Uchiyama, Ayako Ono, Yujiro Hayashi, Koichi Narasaka
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 12 Pages 2945-2955
    Published: 1998
    Released: June 05, 2006
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    Cyclization of 2-(3-hydroxyphenyl)ethyl ketone O-2,4-dinitrophenyloximes proceeds on the oxime nitrogen atom by the treatment with NaH and then with 2,3-dichloro-5,6-dicyano-p-benzoquinone and acetic acid to yield quinolin-8-ols regioselectively. The reaction in the presence of Na[BH3(CN)] affords 1,2,3,4-tetrahydroquinolin-8-ols. The present cyclization proceeds via alkylideneaminyl radical intermediates generated by the single electron transfer between 3-hydroxyphenyl and 2,4-dinitrophenyl moieties.
  • Nobuyuki Mase, Yoshihiko Watanabe, Takeshi Toru
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 12 Pages 2957-2965
    Published: 1998
    Released: June 05, 2006
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    The reactions of α-(arylsulfinyl) enones with alkyl radicals having a hydroxy or acetal group were examined under photo-irradiation in the presence of benzophenone. High diastereoselectivity was observed in the photo-induced radical reaction of 2-(arylsulfinyl)-2-cyclopentenones having a bulky aryl group, such as the 2,4,6-triisopropylphenyl or 2,4,6-trimethylphenyl group. The photo-induced reaction of 3-[(2,4,6-triisopropylphenyl)sulfinyl]-3-pentene-2-one in 1,3-dioxolane also gave a single diastereomer of the 1,3-dioxolan-2-yl adduct.
  • Takahiro Gunji, Akira Setogawa, Kazue Asakura, Yoshimoto Abe
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 12 Pages 2967-2972
    Published: 1998
    Released: June 05, 2006
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    Isocyanatooligosiloxanes and their alkoxy derivatives were synthesized. The hydrolysis of triisocyanato(methyl)silane followed by distillation provided 1,1,3,3-tetraisocyanato-1,3-dimethyldisiloxane in good yield. The reaction of 1,1,3,3-tetraisocyanato-1,3-dimethyldisiloxane with ethanol, isopropyl alcohol, and t-butyl alcohol proceeded selectively to afford partially alkoxy substituted isocyanatodimethyldisiloxanes, (RO)n(NCO)4−nMe2Si2O (R = Et, n = 1—4; R = Pri, n = 1—4; and R = But, n = 1—2). On the other hand, the hydrolysis of tetraisocyanatosilane provided a mixture of isocyanatooligosiloxanes. Hexaisocyanatodisiloxane was isolated by distillation from the reaction mixture with some impurities produced by the disproportionation of hexaisocyanatodisiloxane on heating. The reaction of hexaisocyanatodisiloxane with alcohols provided partially alkoxy-substituted isocyanatodisiloxanes, [(RO)n(NCO)3−nSi]2O (R = Et, n = 2—3; R = Pri, n = 1—3; and R = But, n = 1—2), selectively and in high yield.
  • Kazunori Matsuura, Akiko Tsuchida, Yoshio Okahata, Toshihiro Akaike, K ...
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 12 Pages 2973-2977
    Published: 1998
    Released: June 05, 2006
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    Adsorption behaviors of two different types of lactose-carrying polystyrenes, poly(p-vinylbenzamido-β-lactose) (PNLA, 1) and poly(N-p-vinylbenzyllactonamide) (PVLA, 2), onto cast films of polystyrene and self-assembled monolayers (SAMs) of 1-octadecanethiol and cystamine were investigated by applying a quartz-crystal microbalance (QCM). The amphiphilic artificial glycoconjugate polymers were strongly adsorbed on the hydrophobic surfaces, i.e. a polystyrene cast film and a SAM of 1-octadecanethiol, from their aqueous solution according to the Langmuir adsorption isotherm (the apparent association constant: Ka ≈ 107 M−1). On the other hand, they were adsorbed little on a hydrophilic SAM of cystamine. The saturated adsorption amounts of the polymers on the hydrophobic surfaces were 2—5 times larger than that calculated on the basis of an assumption of closed-packing monolayer adsorption, which suggests that the adsorbed polymers may take a loop-train-tail conformation. A SAM of 1-octadecanethiol adsorbed two times more of each polymer than a polystyrene cast film did. β-Galactoside-specific RCA120 and PNA lectins bound to the surfaces coated with the galactose-bearing polymers according to the Langmuir adsorption isotherm (Ka ≈ 106 M−1). The binding was stronger than that observed by the inhibition of hemagglutinating activity (about 104 M−1).
  • Tomonari Nakayama, Masayoshi Nomura, Kohji Haga, Mitsuru Ueda
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 12 Pages 2979-2984
    Published: 1998
    Released: June 05, 2006
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    Calix[4]resorcinarene (2,8,14,20-tetramethylcalix[4]arene-4,6,10,12,16,18,22,24-octol, abbrev. to C4-RA) derivative (4) having p-hydroxybenzyl groups on its exterior was prepared by the condensation of C4-RA and p-(allyloxy)benzyl bromide, followed by the cleavage of allyl groups with palladium catalyst and ammonium formate. Compound 4 having high transparency to UV-light above 300 nm was considered for a new resist matrix. A three-component photoresist consisting of 4, 2,6-bis(hydroxymethyl)-4-methylphenol (BHMP), and diphenyliodonium 9,10-dimethoxyanthracene-2-sulfonate (DIAS) showed a sensitivity of 19 mJ cm−2 (D1/2) and a contrast of 3.0 (γ1/2) when it was exposed to 365 nm light and post-exposure baked (PEB) at 110 °C for 5 min, followed by developing with a 0.2 wt% aqueous tetramethylammonium hydroxide (TMAH) solution. A fine negative image featuring 1 μm of minimum line and space patterns was observed on film of the photoresist exposed to 40 mJ cm−2 of UV-light at 365 nm with a scanning electron microscope.
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