Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Volume 46 , Issue 7
Showing 1-50 articles out of 95 articles from the selected issue
  • Motoo Shimada, Hiroshi Masuhara, Noboru Mataga
    1973 Volume 46 Issue 7 Pages 1903-1909
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    Ionic photodissociation of electron donor-acceptor (EDA) complexes of s-tetracyanobenzene (TCNB) and pyromellitic dianhydride (PMDA) with 2-methyltetrahydrofuran (MTHF) has been investigated by means of nsec flash photolysis and transient photocurrent measurements. The solvent-shared ion-pair of TCNB anion and MTHF cation is formed from the excited charge-transfer (CT) singlet state of a TCNB–MTHF complex, dissociating into solvated ions. TCNB complexes with aromatic hydrocarbons dissociate directly into ions from the lowest excited CT singlet state. Dissociation of PMDA complexes occurs in the CT triplet state in nonpolar solvents and mainly in the excited CT singlet state in polar solvents. The relative rate constant of radiationless process, which competes with ionic dissociation in the excited singlet state, can be deduced from the effect of solvent on ionic photodissociation. It has been confirmed for the first time that the ionic dissociation of a TCNB–benzene–1,2-dichloroethane (DCE) system occurs in the excited Franck-Condon (FC) state. It is pointed out that the latter dissociation mechanism is not inconsistent with all the results obtained for TCNB and PMDA complexes under various conditions.
  • Masamichi Akimoto, Etsuro Echigoya
    1973 Volume 46 Issue 7 Pages 1909-1913
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    Reactivity of Mo5+ formed on supported molybdena catalysts with oxygen or water was investigated by means of ESR spectroscopy. Mo5+ formed on the alumina carrier could not be oxidized with gaseous oxygen even at 450 °C and was poisoned by water at 200 °C losing its ESR signal. The Mo5+ formed on the titania carrier disappeared by reaction with either oxygen or water. The mechanism for the reactions was investigated and the different reactivities of Mo5+ with oxygen as regards carrier effect on the structure were discussed.
  • Norio Yui, Y\={o}ichi Kurokawa, Isozi Sakuraba
    1973 Volume 46 Issue 7 Pages 1914-1918
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    Equilibrium compositions of 1-butanol–water–MOH systems were studied at 25 °C, where MOH represents LiOH, NaOH, and KOH. Water and 1-butanol were determined by means of gas chromatography and the bases by titration. Apparent distribution ratio Kobs (molality of MOH in the aqueous phase/molality of MOH in the 1-butanol phase) was dependent on the concentration of base. A considerable amount of water was transferred from 1-butanol to the aqueous phase giving rise to an increase of base concentration. This suggests that the variation of Kobs depends principally on the variation of solvent composition. Kobs was expressed semi-empirically, considering the activity coefficients calculated by Miller’s equation and also the change in the standard free energy resulting from the variation in solvent composition. Decrease of 1-butanol in the aqueous phase with the base concentration obeyed the salting-out equation. The calculated salting-out coefficients were: LiOH 0.176, NaOH 0.192, and KOH 0.184. These values are correlated to Gurney’s unitary entropy. The results were compared with those previously obtained for alkali halides.
  • Oliver Johnson
    1973 Volume 46 Issue 7 Pages 1919-1923
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    The interstitial-electron model for metals supplements the concepts of band theory to give a detailed interpretation of the properties of metals. The instantaneous picture of vacant and electron-occupied interstices given by the model clarifies the complex gradations in electrical conductivity which are not explained by an electron per unit volume term. The consideration of polarization of the itinerant electron cloud by ion cores with high positive fields and of interpenetration of the more deformable ion cores by itinerant electrons is another new feature of the model. The interstitial-electron model leads to the expectation of parallel gradations for electronic heat capacity and magnetic susceptibility and an inverse relation of both of these properties with electrical conductivity. The presence of (\bare2) in the metal structure is associated with a positive Hall Coefficient for a metal, and a new correlation between positive Hall Coefficient and superconductivity for a metal is pointed out.
  • Oliver Johnson
    1973 Volume 46 Issue 7 Pages 1923-1928
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    The interstitial-electron model leads to localization of d-electrons on the metal ion cores starting with group 6 metals which would have all the tetrahedral and octahedral interstices occupied by itinerant electrons. In the model the itinerant electrons play the role of ligands and determine the degeneracy of the d-orbitals localized on the ion core. There are mutual accomodations as far as location of itinerant electrons in specific interstices and d-electrons in preferred orbitals. Consideration of metal properties, especially Hall Coefficients, leads to reasonable values for both localized and itinerant magnetic moments. The relatively large spatial extension of 3d-orbitals at low intermetallic distances accounts for the magnetic moments in Cr, Mn, Fe, Co, and Ni. A striking consequence of the application of the interstitial-electron model to Fe is that it reproduces in detail the regions of positive and negative magnetization (including the interlocking rings on edges and faces) observed in neutron diffraction studies by Shull and Mook.
  • Oliver Johnson
    1973 Volume 46 Issue 7 Pages 1929-1935
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    On the basis of the interstitial-electron model for metals the essential feature of the metallic state is the relatively free movement of electrons, (\bare), between interstices in a close-packed array of metal ions (positive cores). For a solid solution of one metal in another in which the metal ions have nearly the same size and core charge, the interstitial-electron structures which incorporate spatial and spin correlation of electrons are the same as for metals. Metallic properties can also result when the ratios of two less similar metals in an alloy are such as to give interstices with a constant ratio of the two metals surrounding them. Occupancy of such “homogeneous interstices” is the basis for intermetallic compounds and accounts for the Hume-Rothery rules. Intermetallic compounds such as γ phases (e.g. Cu5Zn8) are unique in that \bare and electron pairs must be assigned to two or more types of interstices which have different ratios of the two metal ions around them. This localization of \bare density explains the very poor conductivity, the hardness, the brittleness and the large diamagnetic susceptibility of γ phases. The structural framework of the interstitial-electron description accounts for the large composition range of the interstitial phases and can naturally include effects of ion core size and charge. Interpenetration of d10 ion cores by itinerant electrons which gives a balancing of the positive fields of the 2 ion cores accounts for the preponderance of d10 metals among intermetallic phases.
  • Oliver Johnson
    1973 Volume 46 Issue 7 Pages 1935-1940
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    A physical interpretation of the superconducting state based on the interstitial-electron model for metals is given within the framework of the BCS theory. The following conditions for itinerant electrons (\bare) and metal ion cores (Mn+) are postulated as necessary for superconductivity: (1) There must be a matching of \bare energies (velocity) and binding strength of Mn+ so \bare initiation of a lattice vibration is possible. (2) Movement of \bare and Mn+ must be synchronized so there is enhancement of \bare-phonon coupling. (3) There must be \bare of one spin available to enter such \bare-phonon “chains”. The model leads to \bare of opposite spin in phonon chains 500–5000 Å apart. It gives physical interpretations of the thermodynamic properties of superconductors and clearly shows that type of lattice influences superconductivity. It shows the basis for the new correlation observed between superconductivity and a positive Hall Coefficient. Since the model can incorporate the presence of anions as well as \bare, it provides a related explanation for superconductivity in non-metals.
  • Teruyo Yamashita, Hiroshi Shimizu
    1973 Volume 46 Issue 7 Pages 1940-1945
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    Dipolar correlation functions of non-interacting symmetric top molecules were obtained by quantum mechanical calculation. The effect of the rotation-vibration interaction on the correlation function is discussed, taking the constant ζ of the Coriolis coupling and the asymmetry Ix/Iz as parameters. It is shown that the decay of the correlation function for perpendicular vibrations very much depends on the sign and the magnitude of ζ. Some relationships between the shape of the correlation function and the value of the parameters are given.
  • Masaru Mitsuishi, Mieko Hashizume
    1973 Volume 46 Issue 7 Pages 1946-1948
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    The interaction between sodium alkyl sulfate and alkylpyridinium chloride or alkyltrimethylammonium bromide has been studied quantitatively by means of the conductometric method. The equilibrium constants of the reactions between them have been found to increase with an increase in the length of the alkyl chain. When the sum of the carbon atoms in an alkyl sulfate and of those of an alkylpyridinium chloride or of alkyltrimethylammonium bromide is less than twenty, no reaction has been found to take place. When it is larger than twentysix, precipitates of the complex have been found. The interaction has been found to depend greately on the length of the alkyl chain. The interaction decreases the heat content and increases the entropy.
  • Kenichi Okamoto, Shigekazu Kusabayashi, Hiroshi Mikawa
    1973 Volume 46 Issue 7 Pages 1948-1953
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    The photoconductivity of poly-N-vinylcarbazole in a surface-type cell was measured both in a high vacuum and in the air. Fresh films showed a large photocurrent in the lower π-π* absorption region and a small photocurrent in the visible region. The threshold of the photocurrent was found at about 600 mμ. By heat treatment or by pre-irradiation with UV-light or γ-ray, the photocurrent increased throughout the spectral region and its threshold shifted to a longer wavelength. Both the dark current and the photocurrent in the visible and the near IR regions must be due to the thermal or optical reexcitation of the trapped carriers. The activation energies of the dark current (0.4–1.3 eV) and the photocurrent (0.06–1.0 eV) differ according to the temperature range, the light wavelength, and the film history (whether fresh film or one of various pre-treated films). The activation energies are needed for carrier migration and can be explained by the “trapping conduction mechanism”.
  • Kenichi Okamoto, Shigekazu Kusabayashi, Hiroshi Mikawa
    1973 Volume 46 Issue 7 Pages 1953-1959
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    The dark conductivity in a sandwich-type cell of PVCz films was investigated in a high vacuum, taking the temperature, the applied voltage, and the film thickness as parameters. In low fields, the conductivity was proportional to the applied voltage. In high fields, however, it was proportional to the fourth power of the applied voltage. This nonohmic dark conductivity in high fields may be attributed to the Pool-Frenkel effect. A model of the energy-level diagram is presented which can explain the dark conductivity in both low and high fields.
  • Iwao Watanabe, Yu Yokoyama, Shigero Ikeda
    1973 Volume 46 Issue 7 Pages 1959-1963
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    Photoelectron spectra of some simple carboxylic acids and halogen substituted acetic acids were observed. Each spectrum contains a band which is associated with the ionization from an oxygen lone pair (n0) orbital of carboxyl group. The band associated with the n0 orbital is clearly separated from other bands, and its shape and width are quite similar among the various carboxylic acids. In the spectra of halogen substituted acetic acids, n0 band appears around the region of the lone pair bands of halogen atoms. The ionization potentials for oxygen lone pair orbital of carboxylic acids are measured and compared with the results of some semi-empirical SCF MO calculations. The agreements are quite satisfactory when ionization potentials are obtained from the difference of total energies of neutral molecule and its corresponding cation calculated using CNDO/2 or INDO method. MINDO/2 method also gives excellent values when Koopmans’ theorem is applied.
  • Kayoko Amita, Genzo Hashizume
    1973 Volume 46 Issue 7 Pages 1964-1968
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    The effect of eleven halides on the thermal decomposition of basic magnesium carbonate (4MgCO3·Mg(OH)2·4H2O) has been studied by means of thermogravimetry (TG), differential thermal analysis (DTA) and gas chromatography. The size of crystallite of magnesium oxide prepared by heating the carbonate containing halide was determined by X-ray diffractometry, the oxides being studied by transmission electron microscopy. The thermal decomposition of basic magnesium carbonate was influenced by the addition of beryllium chloride tetrahydrate, magnesium chloride hexahydrate, calcium chloride hexahydrate and magnesium bromide hexahydrate. The DTA curve was changed with the amount of additive, i.e., three endothermic peaks (at about 300, 430, and 530 °C) and an exothermic peak (at 490 °C) turned to only two endo-thermic peaks in the case where the molar ratio of an additive to the carbonate exceeded 0.005, the peak at higher temperature becoming sharp with shift toward lower temperature. The results of TG of basic magnesium carbonate corresponded to those of DTA. Gas chromatographic data showed that the composition of evolved gas varied with temperature. The activation energies of decarbonation and dehydration were obtained by gas chromatography by use of Freeman-Carroll’s technique. Increase in the amount of additive caused a decrease in the activation energy of decarbonation, but not in that of dehydration except for magnesium bromide hexahydrate. The size of crystallite of magnesium oxide prepared by calcination at 600 °C for 2 hr, increased with the increase in the amount of additive.
  • Arabinda Ray, D. N. Sathyanarayana
    1973 Volume 46 Issue 7 Pages 1969-1972
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    α-Cyanothioacetamide (CTAM) complexes of cuprous chloride CuCl–2CTAM and cuprous bromide CuBr–2CTAM have been prepared. The infrared spectra of CTAM and its complexes, and the laser Raman spectrum of CTAM have been recorded. Assignment of the frequencies of the ligand has been made on the basis of a normal coordinate analysis using the Urey-Bradley force field. The copper (I) complexes are inferred to have thiocarbonyl sulfur and amide nitrogen bonded CTAM as evidenced from infrared and electronic spectra.
  • Ram Gopal, D. K. Agarwal, Rajendra Kumar
    1973 Volume 46 Issue 7 Pages 1973-1976
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    A study of the apparent molal volume (φv) of some common salts and the tetraalkylammonium iodides in DMSO has been reported in this communication. All the salts studied here, including those containing the larger R4N+ ions, have a positive slope in the φv vs. \sqrtC curves, indicating a strong ionic interaction, apparently due to the medium dielectric constant of the solvent. This dielectric constant also promotes ion-association at higher concentrations and thus mutual penetration of the R4N+ ions is prevented. As a result, no negative slope in the φv vs. \sqrtC curves of the larger R4N-iodides is observed in this solvent. The effect of temperature on the limiting apparent molal volume, φ°, reveals that the ion-solvent interaction is comparatively stronger in the non-hydrogen bonded solvents like DMSO and DMF than that in strongly hydrogen-bonded solvents like NMA and NMP. Addition of a CH2-group to each of the four R-chains of the R4N+ ion increases its volume by about 70 ml per mole in DMSO, DMF, and NMA.
  • N. Sridhar, J. Rajaram, J. C. Kuriacose
    1973 Volume 46 Issue 7 Pages 1977-1979
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    Bromination of aromatic substrates like p-bromophenol, anisole, etc. by molecular bromine in acetic acid follows the rate expression, Rate=k[ArH][Br2]+k′[ArH][Br2]2. For the bromination of p-nitrophenol in acetic acid, variable orders in bromine and p-nitrophenol have been observed on varying the concentrations of reactants. A rate expression of the type, Rate=k[ArH][Br2]+k′[ArH][Br2]2+k″[ArH]2[Br2] has been proposed. The observations conform to a general mechanism for bromination provided a bromine molecule, a substrate molecule or solvent molecules can be the electrophile in the rate determining step, depending upon the conditions employed for the reaction.
  • Yukio Sato, Masahiro Hatano, Michio Yoneyama
    1973 Volume 46 Issue 7 Pages 1980-1983
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    The effect of potassium chloride on the absorption and optical rotatory properties of the poly-α,L-glutamic acid-acridine orange system in an aqueous solution was studied under various conditions. The stability of the helical conformation of poly-α,L-glutamic acid in this system was examined at different potassium chloride concentrations by estimating the helix fraction of the polymer. At pH 4.5, where poly-α,L-glutamic acid exists in the helix, it was found that the added potassium chloride raised the stability of the helical conformation of the polymer in this system. In this case, it was assumed that the added potassium chloride lowers the disturbance of helix formation by the bound acridine orange cation. However, when the solution’s pH was raised, the added potassium chloride lowered the extent of the helix fraction in this system. These phenomena were discussed on the basis of several experimental findings on the circular dichroism of the systems. Furthermore, from the change in the intensities of the circular dichroism with the variation in the potassium chloride concentration, it was presumed that the positive circular dichroism band at about 520 nm was due to the binding of dimeric acridine orange molecules to the polymer.
  • Masao Sakashita, Norio Sato
    1973 Volume 46 Issue 7 Pages 1983-1987
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    This paper examines the correlation between the structure and the reactivity of nickel hydroxide, using X-ray diffraction, DTA, IR spectroscopy, and gravimetry during dehydration. The degree of crystallization of β-nickel hydroxide depends on the preparation conditions of the hydroxide. Highly-crystallized β-nickel hydroxide has “free” hydroxyl groups, as is to be expected from its brucite structure. Poorly-crystallized β-hydroxide, however, has “hydrogen-bonded” hydroxyl groups, this finding is in disagreement with a previous result that “hydrogen-bonded” hydroxyl groups were found to exist only in α-form nickel hydroxide. The dehydration of the hydroxide is shown to take place in first-order kinetics with an activation energy which increases as the crystallization extends.
  • Michiko Konno, Hayao Kobayashi, Fumiyuki Marumo, Yoshihiko Saito
    1973 Volume 46 Issue 7 Pages 1987-1990
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    The crystal structures of K+(chloranil) have been studied by X-ray diffraction. Several polymorphs were recognized, two of which (α- and β-forms) grew into comparatively good crystals. The α-form is orthorhombic, space group P212121 with unit cell dimensions: a=13.49, b=17.02, c=4.03 Å. The β-form is orthorhombic, space group P2212 with unit cell dimensions: a=14.13, b=17.35, c=3.71 Å. The structure of the α-form was deduced from the Patterson synthesis and refined by the block-diagonal least-squares method. The final R value was 0.13 for 146 observed reflections. Chloranil anions are stacked with equal intervals in the crystal, forming columns parallel to the c axis, the interplanar spacing being 3.47 Å. The electrostatic energy calculated by Evjen’s method was about −148 kcal/mol, indicating that the structure is essentially ionic.
  • Osamu Takizawa, Jun Yamauchi, Hiroaki Ohya-Nishiguchi, Yasuo Deguchi
    1973 Volume 46 Issue 7 Pages 1991-1995
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    The radical pair system of a stable free radical, di-p-anisyl-nitric-oxide (DANO), has been observed in the magnetically-diluted crystal of 4,4-dimethoxy-benzophenone. The existence of the radical pair has been ascertained by the characteristic ESR absorptions, which give rise to the zero-field splitting and half-field resonance, of the powdered sample as well as by a comparison of the magnitude of the hyperfine coupling constant of the isolated radical with that of the pair system. The precise ESR measurements were performed using a single crystal containing 7.5% DANO radicals oriented well in the diamagnetic matrix. The fine structure parameters, |D| and |E|, have been determined to be 186 Gauss and 2 Gauss respectively, from which the distance between the two radical molecules in the pair system is estimated to be 5.4 Å. In order to deduce the structures of the radical pair, the g-value and the hyperfine coupling constant of the isolated radical have also been determined.
  • Yasukatsu Tamai, Yasuo Ohtsuka
    1973 Volume 46 Issue 7 Pages 1996-2000
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    The chlorination of C6H6 with a NaCl–FeCl3 (52: 48 in mol) melt was studied in a batch reactor at 250 °C and at a constant pressure. The main chlorinated products were monochlorobenzene (MCB) and dichlorobenzene (DGB). The isomers in DCB were ortho and para, and did not include the meta form. The rate of chlorination was nearly proportional to the benzene pressure in the range from 0.5 to 2.0 atm. When O2 was introduced into the reaction system, both the rate of chlorination and the selectivity of MCB increased with the increase in the partial pressure of O2. These facts suggest that chlorination proceeds by the electrophilic substitution on the melt surface. It was indicated by an X-ray diffraction examination of the powder of the salts used, which lost the activity for chlorination after a prolonged experiment in the presence of O2, that the source of Cl was FeCl3 and not NaCl in this reaction.
  • Tetsuo Morimoto, Hiromitu Naono
    1973 Volume 46 Issue 7 Pages 2000-2003
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    The surface water content has been determined on silica gel, magnesium oxide, zinc oxide, and titanium dioxide by means of active hydrogen analysis and by the successive-ignition-loss method. Except for magnesium oxide pretreated at 100 °C, it has been found that the water contents obtained from the two methods on every oxide tested are in good agreement with each other. The successive-ignition-loss method gives an extraordinarily high value of water content on magnesium oxide pretreated at 100 °C, probably because of the retention of inner hydroxyl groups. The present results indicate that the two methods are equally reliable for the quantitative determination of the water content on metal oxides. Moreover, the simultaneous application of both methods make it possible to estimate each amount of surface hydroxyl groups and physisorbed water molecules.
  • Masaki Kato, Yoshiyuki Saitake, Tetsuo Miyazaki, Zen-ichiro Kuri
    1973 Volume 46 Issue 7 Pages 2004-2007
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    When neopentane containing a small amount of cyclohexane is γ-irradiated at 77 K, the cyclohexyl radical is mainly formed by the energy transfer from neopentane to cyclohexane. The addition of CCl4, which is an electron scavenger and an excitation acceptor, to the mixture suppresses the formation of the cyclohexyl radical. This fact indicates that the energy transfer is not due to an ion-molecule reaction. When CO2, which can capture an electron in the neopentane matrix to form CO2, is added to the neopentane–cyclohexane mixture, scarcely any CO2 is formed by the irradiation. When ethyl chloride or nitrous oxide is added to the neopentane–cyclohexane mixture, the formation of the cyclohexyl radical is not suppressed, although these additives capture electrons effectively in the solid neopentane. The addition of tetramethylethylene (TME) to the neopentane–cyclohexane–carbon dioxide mixture does not affect the formation of the cyclohexyl radical, although an appreciable amount of TME+ is formed. These results show that the energy transfer is not due to the ionic process, but to a non-ionic process. The energy transfer is explained by two possible mechanisms, a selective abstraction reaction by the hydrogen atom and an excitation transfer via a highly-excited state.
  • Ryusaburo Furuichi, Herman A. Liebhafsky
    1973 Volume 46 Issue 7 Pages 2008-2010
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    Critical studies were made on the Dushman reaction, 6H++5I+IO3=3I2+3H2O. Rate measurements of radioactive iodine exchange away from chemical equilibrium gave results which made the rate law for the Dushman reaction doubtful. Measurements of d(H+)/dt confirmed the rate law. The contrary interpretation resulted because existing chemical information was not considered. This situation holds in many radioactive iodine exchange experiments done on the Dushman reaction.
  • Fusao Takusagawa, Akira Shimada
    1973 Volume 46 Issue 7 Pages 2011-2019
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    The crystal structure of orotic acid monohydrate (Vitamin B13) has been determined by the method of X-ray diffraction. The crystals are triclinic with the space group of P\bar1 and with cell dimensions of a=9.561, b=7.261, c=5.895 Å, α=117.6°, β=107.6°, and γ=90.4°. The structure was determined by an inspection of the sharpened Patterson map. The final R value was 5.75% for 1345 observed reflections. The uracil group of orotic acid resembles uracil itself in its molecular dimensions. The molecules are arranged in layers closely parallel to the (\bar2 1 1) plane. The orotic acid molecules are linked through two kinds of N–H···O hydrogen bonds in zig-zag chains extending in the [1 1 1] direction. Each chain is joined, by three kinds of O–H···O hydrogen bonds through the medium of a water molecule, with two neighboring chains, and each forms a sheet parallel to the (\bar2 1 1) plane. The hydrogen bond of the water molecule as an acceptor is of the F type, in which the bisector of lone pairs in the oxygen atom is directed toward a donor group.
  • Fusao Takusagawa, Ken Hirotsu, Akira Shimada
    1973 Volume 46 Issue 7 Pages 2020-2027
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    The crystal structure of the dipicolinic acid monohydrate has been determined by the method of X-ray diffraction. The crystal is orthorhombic, with a space group of P212121 and with cell dimensions of a=12.233, b=9.399, and c=6.817 Å. The crystal structure was solved by an inspection of the Patterson map. The final R value was 5.67% for 964 observed reflections. The pyridine ring has the C2v symmetry within the limits of experimental error. The protonation does not occur on the nitrogen atom of the pyridine ring, and two carboxyl groups consist of carbonyl and hydroxyl groups. There is a simple relation between the C–O bond length and the C–C–O bond angle. The molecules are arranged in layers closely parallel to the (0 0 1) plane. Each molecule on the same plane is hydrogen-bonded to form an endless chain along the b axis. These two chains on the planes at z=1⁄8 and 3/8 are linked together by the O–H···N hydrogen bond between the water and pyridine ring to form a double chain along the b axis. In this case, the angle between the N···H(7) vector of the hydrogen bond and the plane of the pyridine ring is 28°. This situation can be explained by the fact that two adjacent and bulky carboxyl groups wrap up the nitrogen atom as an acceptor of the hydrogen bond. The double chains are packed only by the van der Waals forces. The thermal diffuse scattering observed on Weissenberg photographs can be explained by this hydrogen-bond system.
  • Keikichi Nakamura
    1973 Volume 46 Issue 7 Pages 2028-2034
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    The deuteron and niobium magnetic resonance in the Nb–D system have been measured over a wide range of deuterium concentrations. It has been found that the order-disorder (β→α) phase transition temperature depends on the small amount of interstitial impurities as well as on the concentration of the deuterium. From the concentration dependency of deuterium (Nb) in the β phase, one can determine the amount of deuterium (Nb) in the β phase coexisting with that in the α phase. On the basis of this finding, a tentative Nb–D phase diagram has been proposed. It has been confirmed that the interstitial impurities decrease the deuterium concentration of the β phase which is in equilibrium with the α phase. The niobium signal intensity has been found to be greatly reduced by the interstitial oxygen and other impurities, while the line width is not affected. For the interpretation of these findings, a simple model has been proposed in which only the interstitial atoms, which are present within the spherical sphere of a critical radius, rc, from a niobium atom, eliminate the niobium resonance by means of the second-order quadrupole interaction.
  • Yuichi Fujimura, Masamune Onda, Takeshi Nakajima
    1973 Volume 46 Issue 7 Pages 2034-2039
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    The normal coordinates and the vibrational frequencies in the first excited singlet (1B2u), the second excited singlet (3B1u), and the first excited triplet (3B1u) states of naphthalene, whose geometries were calculated by a semiempirical method, are evaluated by assuming a simplified valence force field. The relation between the normal coordinates of two different electronic states is expressed on the basis of the Franck-Condon principle. The mixing among the excited-state normal coordinates, expressed in terms of the ground-state normal coordinates, is neglected in the present treatment. By using the simple relation between the normal coordinates of two different electronic states, the vibronic intensity distributions in the absorption spectra (1B2u1Ag, 1Lb, 1B1u1Ag, 3La, and 3B1u1Ag,3La) have been calculated. The vibronic intensity distribution of the 1B2u1Ag transition has been calculated, taking into consideration the intensity of the interpenetrating sets of the vibronic band groups on the basis of the Herzberg-Teller perturbation theory.
  • Yoshihito Takahashi
    1973 Volume 46 Issue 7 Pages 2039-2044
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    Data on the Kβ spectra for several compounds of silicon, aluminum, and sulfur are shown. The intensity of the Kβ′ line is affected not by the kinds of thrid-period atoms, but by their charges and by the kinds of ligand atoms. The degree of the contribution of each bonding group to the relative intensity of the Kβ′ line and to the chemical shift of the Kα1,2 lines are shown; they have additivity in the molecule. Therefore, the chemical shift of the Kα1,2 lines can be estimated from the molecular structural formula; the charge of the atom can also be estimated.
  • Michiro Hayashi, Keiichi Ohno, Hiromu Murata
    1973 Volume 46 Issue 7 Pages 2044-2052
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    The infrared spectra of ethylmethylsilane, CH3CH2SiH2CH3, its deuterated species, CH3CH2SiD2CH3, and a mixture of CH3CH2SiHDCH3, CH3CH2SiH2CH3, and CH3CH2SiD2CH3 have been measured in the gaseous, liquid, and crystalline states. The Raman spectrum of ethylmethylsilane has also been measured in the liquid state. Vibrational assignments have been made in relation to the rotational isomerism, on the basis of a modified Urey-Bradley force field, in which the force constants have been transferred from those for dimethylsilane and ethylsilane. The conclusion regarding the molecular forms of the rotational isomers, which has been obtained from the experimental evidence of the SiHD deformation vibrations for an asymmetrically-deuterated species, CH3CH2SiHDCH3, can be considered to be also supported by the present results of the normal vibration calculations.
  • Hitoshi Ohtaki, Masunobu Maeda
    1973 Volume 46 Issue 7 Pages 2052-2056
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    Dissociation constants of protonated 1,6-hexanediamine, 1,8-octanediamine, 1,10-decanediamine, 1,11-undecanediamine, and 1,12-dodecanediamine in aqueous mixtures of 0 to 90% (w/w) methanol were determined potentiometrically at 25°C, 0.1 M sodium chloride being used as an ionic medium. Values of pK2–pK1 of diamines were practically independent of the solvent composition in contrast to those of dicarboxylic acids, which increase monotonously with methanol concentration. Variations of pK1, pK2, and pK2–pK1 of diamines with solvent composition were discussed in comparison with those of dicarboxylic acids.
  • Yukio Suzuki, Yôichi Iida
    1973 Volume 46 Issue 7 Pages 2056-2060
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    The electron spin resonance (ESR) absorption and its variation with the temperature were measured with single crystals of the anion radical salts containing the mixed cations, [(C6H5)3PCH3]1−x+ [(C6H5)3AsCH3]x+(TCNQ)2\ ewdot, (0≤x≤1). The paramagnetic excited state of these salts is triplet in character, as was shown from the anisotropic zero-field splitting at low temperatures. The triplet state is not localized, but, rather, corresponds to the triplet exciton state. The exciton exchange frequency and its temperature dependence were determined by analyzing the line shapes of the ESR spectra. The exciton motion in the mixed crystal system was investigated in order to establish the character of the triplet excitons in ion radical salts.
  • Edward G. Janzen, Toshio Kasai, Keiji Kuwata
    1973 Volume 46 Issue 7 Pages 2061-2062
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    The simultaneous detection of gas phase atoms and free radicals produced in a 2450 MHz discharge is demonstrated by use of a previously described technique called spin trapping. The atoms or radicals are allowed to react with phenyl N-t-butyl nitrone to give relatively stable nitroxide radicals. The ESR spectra of these nitroxides provide the analytical data for identification of the atoms or radicals trapped.
  • Sakumitsu Sakagami, Akira Takase, Minoru Nakamizo, Hitoo Kakiyama
    1973 Volume 46 Issue 7 Pages 2062-2065
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    The molecular order in the liquid crystal states of p-n-octyloxybenzoic acid (OOBA) has been measured by means of a new method utilizing the polarization of the fluorescence. The polarized components of the fluorescence observed for the isotropic liquid state are independent of the rotation angle; this indicates that no molecular order exists in the liquid state. The polarized components of the fluorescence observed for the nematic state show that the molecular order of the aligned nematic state can be represented by a partially uniaxial orientation. The results observed for the nematic phase are also quantitatively discussed by the use of the uniaxial prolate ellipsoidal orientation pattern. On the other hand, the smectic state of OOBA is not affected by the surface action, and the observed patterns of the polarization of the fluorescence have very little angular dependence, in contrast with those for the nematic state. Furthermore, the molecular orientation for the crystal state of OOBA is briefly described.
  • Kiyoshi Okazaki, Rei Yugeta, Shin Sato
    1973 Volume 46 Issue 7 Pages 2066-2070
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    The gas-phase γ-radiolysis of a N2O-1-butene system has been reinvestigated. The other hydrocarbons used for the substrate are ethylene, propylene, 1,3-butadiene, cyclopropane, propane, and n-butane. The G-value of nitrogen from any system increased with an increase in the pressure of N2O and was saturated at about 4 mol% of N2O. The saturated value, G(N2)max, was much larger than the G-value of electrons estimated from the W-value of the hydrocarbon used and was rather strongly dependent upon the irradiation temperature, the dose rate, and the total dose. Some of the results were not consistent with those reported by the previous investigators. The reason for this discrepancy, and also the possible reaction mechanism to explain the large G(N2)max, have been discussed.
  • Takashi Shibahara, Shigetaka Koda, Masayasu Mori
    1973 Volume 46 Issue 7 Pages 2070-2074
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    The crystal and molecular structure of μ-peroxo-bis[nitrobis(ethylenediamine)cobalt(III)] dinitrate tetrahydrate, [NO2(en)2CoO2Co(en)2NO2](NO3)2·4H2O has been determined using visual intensity data of three dimensional Weissenberg photographs taken with Ni-Kα radiation. The brown-black salt is monoclinic with space group P21/n and cell dimensions a=10.755±0.011, b=12.941±0.008, c=9.709±0.006 Å, and β=100.4±0.1°. The least-squares refinement with anisotropic temperature factors gave an R index of 0.106. The coordinating ligands form nearly regular octahedra about the cobalt atoms, with Co–N(en), Co-N(NO2), and Co–O distances of about 1.95, 1.94, and 1.89 Å, respectively. Both NO2−,s are trans to the O–O bridge, and the geometry of Co-O-O-Co is trans planar with O–O distance of 1.53 Å and Co–O–O angle of 110°. The two Co–(en)2 moieties have δδ and λλ conformations.
  • Takeshi Imura, Seishi Takagi, Kazuo Kawabe
    1973 Volume 46 Issue 7 Pages 2075-2077
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    Photovoltaic behaviors are described of N,N,N′,N′-tetramethyl-p-phenylenediamine dissolved in various polar solvents. Positive photovoltage is observed on the illuminated electrode in highly polar solvents such as methanol and acetonitrile, and none in moderately polar ones such as ethanol and acetone. The influence of a few electrode metals on photovoltage has been examined. The electromotive force increases with the work function of metals from tantalum to platinum. Conditions for the appearance of photovoltage are discussed and the photo-ionization process of the aromatic diamine is considered.
  • Hiroshi Kataoka
    1973 Volume 46 Issue 7 Pages 2078-2086
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    Spin-forbidden absorption bands of K3[Co(CN)6] were reexamined employing conventional transmission spectroscopy, diffuse reflectance spectroscopy, and microspectrophotometry. A small but very distinct shoulder (ε≈0.3–0.4) obtained at a low temperature at 26000 cm−1 was assigned to the 3T1g1A1g transition. Another very small band (ε≈0.001) at 16300 cm−1 was probably due to an impurity. The emission spectra of K3[Co(CN)6] powder in the temperature range from room temperature to that of liquid hydrogen were observed by means of a modified Hitachi 203 fluorescence spectrophotometer. The broad emission band at room temperature showed some vibrational structures at low temperatures. The emission spectra of powders of [Cr(NH3)6](NO3)3 and [Cr(NH3)6][Co(CN)6] were also measured. The following results were obtained: i) Similar emission spectra, which seemed to originate from [Cr(NH3)6]3+, were observed with both complexes [Cr(NH3)6](NO3)3 and [Cr-(NH3)6][Co(CN)6] using mercury lines at 313, 365, and 435 nm for excitation, ii) With 254 nm excitation, such emission spectra as i) were not observed with [Cr(NH3)6](NO3)3, but the same emission spectra as in i) were observed with [Cr(NH3)6][Co(CN)6]. iii) The ratio of the emission intensities at 15000 cm−1 with 435 and 313 nm excitations was 1:0.25–0.30 for [Cr(NH3)6](NO3)3, but it was 1:1.5–1.7 for [Cr(NH3)6][Co(CN)6]. From these results, it was presumed that, in [Cr(NH3)6][Co(CN)6], there occurred an energy transfer from the complex anion to the complex cation. Furthermore, emission spectra were observed with [Cr(NH3)6](ClO4)3 and the equimolar mixture of complex salts [Cr(NH3)6](ClO4)3–K3[Co(CN)6] and [Cr(NH3)6](NO3)3–K3[Co(CN)6] for the purpose of confirming the energy transfer in [Cr(NH3)6][Co(CN)6]. The temperature dependence of the emission intensity was also discussed.
  • Hozumi Endo, Masataka Wakihara, Masao Taniguchi, Takashi Katsura
    1973 Volume 46 Issue 7 Pages 2087-2090
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    The phase equilibria in the V2O3–VO2 system were established at 1307 K by varying the oxygen partial pressures from 10−4 to 10−12 atm. Eight phases, V2O3, V3O5, V4O7, V5O9, V6O11, V7O13, V8O15, and VO2, were observed under these experimental conditions. Vanadium sesquioxide has an extensive range of solid solutions at 1307 K. Also, the phase diagram and isobaric lines of oxygen partial pressure in the V2O3 phase were determined from 1307 to 1700 K on the basis of our present and previous studies. Quenching and thermogravimetric methods were applied under a controlled oxygen atmosphere. The oxygen partial pressures were determined by means of a solid electrolyte cell composed of (ZrO2)0.85(CaO)0.15. The standard free energies of the oxidation of V2O3 to V3O5, of V3O5 to V4O7, of V4O7 to V5O9, of V5O9 to V6O11, of V6O11 to V7O13, of V7O13 to V8O15, and of V8O15 to VO2 were determined on the basis of the equilibrium oxygen partial pressure at 1307 K. The enthalpy and entropy data of the oxidations of V2O3 to V3O5 and of V3O5 to V4O7 were evaluated from the oxygen partial pressures on the basis of the present results and previous data.
  • Taitiro Fujinaga, Masatada Satake, Tatsuo Yonekubo
    1973 Volume 46 Issue 7 Pages 2090-2092
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    A method is described for the spectrophotometric determination of a minute quantity of cadmium. A cadmium complex stable at 90°C is easily extracted with melted naphthalene. The resulting mixture of cadmium complex and naphthalene is dissolved in dimethylformamide and absorbance of the solution is measured at 400 nm. Effects of pH, amounts of oxine, naphthalene and diverse salts are given.
  • Yoshimi Kurimura
    1973 Volume 46 Issue 7 Pages 2093-2096
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    Kinetic studies have been made of the reactions of FeEDTA2− with complex ions of the Co(NH3)5X2+ (X=F, Cl, Br, I, NO3, NCS, and N3) type. The pattern of reactivity suggests that FeEDTA2− reacts with Co(NH3)5X2+ mainly through an innersphere mechanism. The variation in the rate of the reactions of FeIIZm (Z=EDTA, CyDTA, EDTA-OH, and DTPA), in which the Z ligand is varied, with Co(NH3)5Cl2+ can be explained in terms of the steric effect, the charge effect, and the stabilization effect.
  • Tetsuhiko Yoshimura, Chie Miyake, Shosuke Imoto
    1973 Volume 46 Issue 7 Pages 2096-2101
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    The tetrakis β-diketonates of U(IV), Th(IV), and Ce(IV) with acetylacetone, trifluoroacetylacetone, hexafluoroacetylacetone, benzoylacetone, dibenzoylmethane, benzoyltrifluoroacetone, and thenoyltrifluoroacetone have been prepared and their infrared spectra measured in the range 4000–200 cm−1. In every chelate, a strong, broad and metal sensitive band related to the M–O stretching mode was found in the 200–250 cm−1 region.
  • Tetsuo Saji, Shigeru Aoyagui
    1973 Volume 46 Issue 7 Pages 2101-2105
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    The rate of the electron-exchange reaction between Cr(bipy)31+ and Cr(bipy)3 was measured in N,N-dimethylformamide by the ESR method, with the line-broadening procedure. The width of the partly-overlapped hyperfine lines was determined by comparing the observed spectrum with the computer-simulated one. The observed second-order rate constant was (1.5±0.4)×109 M−1 sec−1 at 25°C. When corrected for diffusion, this yielded the activation-controlled rate constant of 2.0×109 M−1 sec−1. It was pointed out that the rate constant obtained here was the largest of all those ever reported for the electron-exchange reactions in which the transition-metal complexes participated. The observed rate constant was in good agreement with the one calculated non-empirically according to the theory of R. A. Marcus. Although the value for the molecular radius must be chosen somewhat arbitrarily in applying this theory, the “good” radius was a reasonable one in view of the molecular geometry and dimensions of the reactants. The rate constant of the Heisenberg spin-exchange process was also determined to be 1.8×109 M−1 sec−1 at 25°C in the same solvent.
  • Yoshinori Kidani, Shinobu Naga, Hisashi Koike
    1973 Volume 46 Issue 7 Pages 2105-2107
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    With a view to applying mass spectrometry to the studies of metal chelates, we investigated the mass spectrometry of divalent metal oxinates (Mn, Co, Ni, Cu, Zn, Pb, and Pd). The molecular ion I, whose peaks correspond to the metal chelates in a 2: 1 ratio, were observed in every spectrum. A loss of 144 mass units from I, corresponding to one molecule of coordinated oxine, occurred to afford the fragment ions II of metal chelates in a 1: 1 ratio. The peaks of the fragment ions III which lost 28 mass units (CO) from II were observed for Mn, Co, Ni, Cu, and Pd chelates. In order to study the stability of metal chelates against electron impact, special attention was paid to the peaks of I and II, which are supposed to be affected strongly by the d-electron number, electronegativity, ionization potential, and the ionic radius of central metal atoms. The intensity ratios of peaks I to II were obtained in the order Zn>Ni>Pd≈Co>Mn>Cu>Pb. It has been shown that the intensity ratios are related to the charge-radius ratio (er) of central metal atoms and the stability constants (logk2) of oxine metal chelates.
  • Tokuji Ikeda, Mitsugi Senda
    1973 Volume 46 Issue 7 Pages 2107-2111
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    The polarographic behavior of monosaccharides in unbuffered neutral solution was investigated. The limiting current was ascertained to be an autocatalytic current which could be caused by the production of hydroxyl ion at the electrode surface. Equations for the characteristic limiting current and for the shape of current-potential curve were derived by use of the reaction layer concept. Experimental results for D-glucose, D-galactose, and D-xylose were fairly well expressed by these equations. The wave can also be applied to the determination of the mutarotation rate constants of monosaccharides, the values obtained (D-glucose: 0.53×10−3 s−1, D-galactose: 0.54×10−3 s−1, and D-xylose: 1.31×10−3 s-−1) being in fairly good agreement with those obtained by the polarimetric method (D-glucose: 0.4×10−3 s−1, D-galactose: 0.5×10−3 s−1, and D-xylose: 1.3×103 s−1).
  • Eiichi Sekido, Junichi Tanaka, Yoshitaka Masuda
    1973 Volume 46 Issue 7 Pages 2112-2118
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    Thermal and spectrophotometric studies of 8-mercaptoquinoline-5-sulfonic acid and its sodium salt synthesized by an improved method are reported. In order to determine the best formula for the weighing of organic reagent, the thermal stabilities of 8-mercaptoquinoline-5-sulfonic acid and its sodium salt and the amount of water of crystallization were examined with a thermal balance. It was found that the disodium dihydrate was of the best form. The ultraviolet and visible absorption spectra in aqueous-ethanol solution were measured, the tauto-meric constant Kt between neutral and zwitterion forms being estimated and acid dissociation constants obtained spectrophotometrically. The absorption spectra and the equilibrium constants of the reagents were compared with those of 8-mercaptoquinoline, 8-hydroxyquinoline and 8-hydroxyquinoline-5-sulfonic acid.
  • Osamu Yamauchi, Yasuo Nakao, Akitsugu Nakahara
    1973 Volume 46 Issue 7 Pages 2119-2124
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    On the basis of comparative studies of the equilibria involving copper(II) and triglycine (G·G·G), glycylglycyl-β-alanine (G·G·β-A), glycyl-β-alanylglycine (G·β-A·G), or β-alanylglycylglycine (β-A·G·G), the structures of the complexes formed at various pH values and the structure-stability relationship between the fusedring chelates have been discussed in reference to the equilibrium constants determined by potentiometric titration at 25°(μ=0.1 (KNO3)) and the properties of the copper(II) chelates isolated. For each tripeptide, the stability constant K1 for the 1: 1 complex and the constants for the deprotonation reactions Kc1 and Kc2 were calculated by the method of non-linear least-squares. For G·G·G, G·G·β–A, and G·β–A·G, the equilibrium indicating the formation of a protonated complex was detected at pH 3.5–4.5. The relatively small difference in the logK1 values (5.25–5.60) and the logKc1 values (5.23–5.36) and the larger difference in the −logKc2 values (5.54–6.73) have been interpreted in terms of the steric requirements around copper(II) in the fused-ring chelates. Relative stabilities of the fused-ring systems in the deprotonated chelates have been inferred from the K1Kc1Kc2 values to be in the order 5-6-5(G.β-A·G-Cu(II))\simeq6-5-5(β-A·G·G-Cu(II))>5-5-6(G·G·β-A-Cu(II))>5-5-5(G·G·G–Cu(II)).
  • Taku Nakano
    1973 Volume 46 Issue 7 Pages 2124-2128
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    Wide-line NMR studies of ammonia molecules in Hofmann-type clathrates with the general formula of M(NH3)2M′(CN)4·2C6D6 are reported. In the Hofmann-type clathrates, two ammonia molecules coordinate to the paramagnetic metal ions in trans positions and have only a slight interaction with each other. In powder samples, the proton NMR spectra of ammonia give fine structures with three components, which are caused by dipolar interaction between protons of the rotating triangular three-spin system. The signals shift to the higher-field side under the influence of the paramagnetic moments of the metal ions. The temperature dependence of the shifts and line shapes, where M is iron(II), cobalt(II), nickel(II), and copper(II), will be reported on. No rigid ammonia was found, even at the temperature of liquid nitrogen.
  • Teisuke Murayama, Motonobu Morioka
    1973 Volume 46 Issue 7 Pages 2129-2132
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    Polarographic behavior of o-hydroxyphenylmercury chloride was examined in aqueous nitric acid medium. An abnormal first wave and a peculiar angular-shaped second wave were observed. Equations of the current-potential curves of the first and second waves are derived on the following assumptions: the first wave is inhibited by a reduction product adsorbed on the surface of the dropping mercury electrode as solid particles, the adsorbed precipitate being reduced at the second wave. The equations agree well with the observed results.
  • Akira Ohyoshi, Tetsuo Shinohara, Yoshihiro Hosoyamada, Takato Yamada, ...
    1973 Volume 46 Issue 7 Pages 2133-2136
    Published: 1973
    Released: March 27, 2006
    JOURNALS FREE ACCESS
    The isotopic ligand-exchange reactions of cis-dibromotetraammineruthenium(III) were studied in aqueous and methanol-water solutions in order to distinguish them from those in the case of the monobromocomplex and in order to ascertain the role of the water molecule with respect to the reaction mechanism. In an aqueous solution, the reaction proceeds through the rate-determining aquation step with the SN2 mechanism: Ru(NH3)4Br2++H2O→Ru(NH3)4(H2O)Br2++Br, Ru(NH3)4(H2O)Br2++*Br→Ru(NH3)4Br*Br++H2O. This result is similar to that for the monobromocomplex. In the methanol solution (H2O∼1.5%), the exchange reaction proceeds through the SN1 mechanism: Ru(NH3)4Br2+→Ru(NH3)4Br2++Br, Ru(NH3)4Br2++*Br→Ru(NH3)4Br*Br+. When the concentration of water becomes very low, the number of solvated water molecules decreases; therefore, the coordinated bromide ion may easily be liberated. When the concentration of water is higher than 10%, the rate constant increases with the increase in the water concentration. Since the electronic spectra did not change during the exchange reaction, it would seem that the water molecule attacks a cis-position as a nucleophile. These results can be interpreted by postulating a hydrogen-bond between the proton of the water molecule and the coordinated bromide ion.
feedback
Top