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Masaru OHSAKU
1986 Volume 1986 Issue 11 Pages
1371-1376
Published: November 10, 1986
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Ab initio SCF MO calculations were carried out on methylsilanethiol, CH
3SiH
2SH, using STO-3 G, 3-21 G, 3-21 G*, STO-3 G*, and 3-21 G d (0.8 C + 0.6 S + 0.4 Si) as basis sets. The geometrical parameters obtained are compared with those observed and with those for structurally related compounds. The experimental parameters are reproduced very well by the 3-21 G +d set. The calculated total energies of the trans and gauche forms at the HF level are fairly close to each other. This explains the experimental small energy difference (40+30 cm
-1) between the rotamers. The potential energy curves of the rotation around the Si-S bond were calculated by using the STO-3 G and 3-21 G basis sets, and the results are compared with experiment and with those reported for other thiols. The calculated dipole moments of trans and gauche forms are in good agreement with observed dipole moments. A comparison of the dipole moments is also made between CH
3SiH
2SH and CH
3CH
2SH.
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Kenro HASHIMOTO, Yoshihiro OSAMURA, Suehiro IWATA
1986 Volume 1986 Issue 11 Pages
1377-1383
Published: November 10, 1986
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Ab initio closed-shell SCF method, combined with the energy gradient technique, was applied to study the molecular structures and the stability of (i) beryllium dihydride and its polymers (BeH
2)
n(n=1 to 5), and of (ii) monosubstituted beryllium hydrides HBeX (X=BH
2, CH
3, NH
2, OH, F and Cl). Basis set dependence on the geometries and the force constants of BeH
2 and (BeH
2)
2 was carefully examined. The minimal basis set gives us a qualitative picture for chemical bonding of beryllium, though at least the split-valence type basis set is needed to obtain quantitative results. The effect of the electron correlation on the dimerization energy of BeH
2 was studied with SDCI and MP 3 methods and was not so important as on the dimerization energy of Be atom. The dimer formation of BeH
2 results from the strong orbital interaction between a σ orbital (HOMO) of one of BeH
2 and a vacant 2p π orbital (LUMO) of the other. The energy gain from (BeH2)n (BeH
2)
n+1 was almost constant for n=-2, 3, and 4 (about 120 kJ/mol) and it is larger than that from BeH
2 to (BeH
2)
2 (about 80 kJ/mol). This result means that in the chemical bonding of Be atom the sp
3 hybridization is more favorable than the sp
2 hybridization, and the sp
2 is more than the sp hybridization.
With STO-3 G and 3-21 G basis sets the molecular structures of a series of monosubstituted beryllium hydrides and their dimers were determined, and the vibrational frequencies were evaluated for them. Bond lengths between a Be atom and a neighboring atom become shorter as the electronegativity of the neighboring atom increases. In particular, the bonding with oxygen is found to be very strong. These hydrides tends to dimerize, and the dimerization energy is about 60-400 kJ/mol, when the bridged atoms are hydrogen atoms, i rrespective of the terminal substituents.
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Yoshihiro OSAMURA
1986 Volume 1986 Issue 11 Pages
1384-1387
Published: November 10, 1986
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The molecular structure and vibrational frequencies are evaluated for the ground and the lowest excited singlet states of benzene by using ab initio MCSCF method. In the calculation, STO-3 G basis set is used, and all the electron configurations in six π orbitals are considered in the MCSCF procedure. The result shows that benzene in
1B
2u state has D
6h symmetry, and C-C and C-H bond lengths are calculated to be 1.4498Å and 1.0818Å, respectively. The O-O transition energy is determined to be 4.727 eV. The ordering of the vibrational frequencies agrees very well with experimental results. The normal vibrational vectors obtained from the present theoretical calculation would help to refine the empirical force field, especially on b
2u and e
1u modes.
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Shinichi YAMABE, Tooru TANAKA
1986 Volume 1986 Issue 11 Pages
1388-1394
Published: November 10, 1986
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An ab initio MO calculation is made for the substituent (X) effect on the phenonium ion, X-C
6H
4C
2H
4+ and C
6H
5C
2H
4-n(-Me)
n+ The electron-donating group X on para posit ion strengthens the bridge bond, while the electron-withdrawing group weakens it. The trend is interpretable in terms of the C
6H
4X
+→C
2H
4 back charge transfer. The methyl groups attached to the C
2H
4 site deform considerably the structure. They give the intermediate geometries in the “symmetric bridge-asymmetric open” spectrum.
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Keiko TAKANO, Haruo HOSOYA, Suehiro IWATA
1986 Volume 1986 Issue 11 Pages
1395-1403
Published: November 10, 1986
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To interprete the classical concept of the oxidation number accurate electron number analysis around the specified atom in molecules was performed with ab initio molecular orbital wave functions. The studied atomic species are H, C, N, O, F, P, S, and CI. The series of the tetrahedral ions, XO
n- (X=Si, P, S, Cl, Ar), were also studied. The atom difference spherically averaged electron density, Δ
ρo(R) =
ρo(R) _??_
ρoi (R), on a sphere with radius R centered at the atom concerned, was calculated with various quality of basis sets. There is no dramatic change in the electron number around a specified atom as the classical oxidation number predicts, but a subtle and stepwise change in the Δ
ρo(R) can be detected in parallel with the classical oxidation number. This is the case with not only the inorganic but also organic compounds. It was shown that for less ionic C-H, P-H, N-H, and N-Q bonds the classical assignment of the oxidation number should be a little modified as follows to get the consistency between this electron number analysis and the classical concept.
C-H
+1 → C-H
+0.5 ; P-H
+I → P-H
0N-H
+1 → N-H
0.5 ; N-O
-II → N-0
-1
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Kouji TASHIRO, Minako UNNO, Shigeru NAGASE, Hiroyuki TERAMAE
1986 Volume 1986 Issue 11 Pages
1404-1408
Published: November 10, 1986
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Force field parameters have been developed for molecules containing Si-Si bonds, by neans of ab initio molecular orbital calculations. These parameters have been used to calculate structures and relative conformational energies for acyclic and cyclic polysilanes. It is 'ound that polysilanes are conformationally very flexible compared with the carbon analogues. N. most interesting finding is that acyclic polysilanes prefer gauche conformations. This is n sharp contrast with the fact that the corresponding hydrocarbon polymers typically adopt znti conformations.
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Osamu KIKUCHI, Teruya KOZAKI, Kenji MORIHASHI
1986 Volume 1986 Issue 11 Pages
1409-1413
Published: November 10, 1986
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In the effective charge model of solvent effect, two structural factors were considered for each atom in a solute molecule; the solvent-shell volume and the surface area which is in contact with solvent. The CNDO/2 calculation of the conformation of acetylcholine in water indicated that the conformational energy map calculated without the structural factors was very similar to that in vacuum, while the stable conformations calculated with the solventshell volume factor were consistent with the conformation experimentally observed in water and those calculated by other theoretical models. The solvent-shell volume factor reflects the steric effect of nonbonded atoms appropriately and plays an important role in the conformational study of molecules in solution.
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Nozomu UCHIDA, Takashi MAEKAWA, Toshio YOKOKAWA
1986 Volume 1986 Issue 11 Pages
1414-1424
Published: November 10, 1986
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Structures and basicity of binary borate glass were studied by applying cluster approximation and MNDO semiempirical SCF-MO method. Optimized geometries of the characteristic structural unit in borate glass, pentaborate, triborate and diborate clusters showed good agreement with the experimentally determined ones. The bond length variations arising along with the formations of four fold coordinated boron (
4B) or non bridging oxygen (NBO) reflect the intramolecular charge rearrangement and conform well to the pred iction of Gutmann's bDnd length variation rule. Ten isomers of molecular formula [H
8B
12O
23]
2-, were constructed in order to represent the structures in various composition of binary borate glass. Delocalization energy resulting from molecular orbital interaction, sparkle affinity and proton affinity were estimated as the measures of the basicity in binary borate glass. On the basis of the hard and soft acid and base (HSAB) theory, BO
4- unit is classified rather into a hard base and NBO is classified rather into a soft one. A hard dopant cation is stabilized in the electrostatic field around BO
4- and a soft one coordinated by NBO and taken into the borate network. In the case where H
2O is the counter oxide, proton forms the OH terminal in the low H
2O content range and BO
4- appears in the medium H
2O content range. Thus, the proton behaves differently from the alkali metal cations.
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Youkoh KAIZU, Koji MIYAKAWA, Hiroshi KOBAYASHI
1986 Volume 1986 Issue 11 Pages
1425-1431
Published: November 10, 1986
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Hydrated cerium ions in aqueous media, are predominantly in a tricapped trigonal prism ([Ce(OH
2)
9]
3+). Upon 5 d←-4 f excitation, however, the excited hydrated ion dissoc iates one of the coordinated water molecules to form *[Ce(OH
2)
8]
3+. The destablization of coordination bonds in the excited complex is attributable to an increase in the antibonding character of 5 d orbitals compared with 4f orbitals. The angular-overlap model calculations were carried out on various geometries of octaaquacerium ions by taking into account the spin-orbit coupling. The theory predicts that the lowest 5 d ←-4 f excited Kramers doublet of [Ce(OH
2)
8]
3+ is energetically much lower than the lowest component state of [Ce(OH
2)
9]
3+, provided that the Ce-O distance is common for [Ce(OH
2)
8]
3+ and [Ce(OH
2)
9]
3+. A ligand-field stabilization is obtained at the expense of the bond dissociation. In the lowest substate of
2D(5d
1), the promoted electron occupies the d
z2 orbital which extends in the direction of the C
3 symmetry axis. The excitation results in a shift of the vertex water molecules to the equatorial and thus one of the equatorial water molecules is eliminated. The structure of the excited octacoordinate species in solution must be square antiprism, dodecahedron and/or cube. Due to their small energy differences, however, the structure must be fluxional.
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Masaoki OKU, Kichinosuke HIROKAWA
1986 Volume 1986 Issue 11 Pages
1432-1437
Published: November 10, 1986
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Auger electron (AES) and electron energy loss spectroscopies (EELS) have been used tostudy the chemical states at the intergranular fracture planes (IG) of Fe-2. 7 atom % P andFe-210 atom ppm S alloys, where the concentrations of phosphorus or sulfur atoms atIG are saturated. The discussion on the chemical states was carried out by comparingthe spectra of IG with those of the transgranular fracture planes (TG), iron phosphide, iron sulfide, and the ion sputtered surfaces of the compounds. The P L
2, 3VV Augerspectra from TG and IG of the Fe-P alloys have five peaks, but the spectrum from Fe
3P has six peaks. The loss energies of Fe 3p EELS of TG and IG coincide with each other, andthey are different from those of Fe
3P. The apparent loss energies due to the transitionsfrom the valence to conduction bands for IG change with the kinetic energy of the primaryelectron between 200 and 500 eV. These results indicate that the phosphorus atoms areatomically dispersed in the phosphorus segregated layer at IG. The S L
2, 3VV Auger spectrumof the Fe-S alloy indicates that the sulfur atoms are bound to the IG planes as if theywere adsorbed. The Fe M
2, 3VV spectrum of TG of the alloy in Fig. 5 exhibits peaks at43. 5 (a
1) and 45. 5 (a
2) eV. The latter peak due to the Fe M
2, 3-Fe 3 d( 1 )-Fe 3 d( 1 )transition was observed for IG of the Fe-S alloy, but not for IG of the Fe-P alloy . Theresults indicate that at IG planes the interaction between iron and phosphorus is strongerthan that between iron and sulfur. The ion sputtering to phosphide or sulfide gives themetallic iron peaks and the spectra of phosphorus or sulfur bound to iron . This impliesthat the mixed layer of the iron and phosphorus or sulfur atoms is prepared by the ionsputtering.
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Eizi HIROTA
1986 Volume 1986 Issue 11 Pages
1438-1445
Published: November 10, 1986
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In order to eliminate ambiguities in spectroscopically determined molecular stiucture caused by intramolecular vibrations, a method has been developed which analyzes ground-state rotational constants and 'vibration-rotation constants of a sufficient number of isotopes simultaneously by the least-squares method using equilibrium structure parameters and thirdorder anharmonicity constants as adjustable parameters. The method has been applied to HNO/DNO and HOCl/DOCl, for both of which not all vibration-rotation constants, have been determined, preventing the equilibrium structure from being determined through a conventional procedure of calculating equilibrium rotational constants. The equilibrium structures thus obtained are r
e (H-N) =1.0628 (25) Å, r
e(N-O) =1.2058 (27) Å, and θ
e (HNO) =109.09(24)° for HNO and r
e(H-O)=0.9654(35)Å, r
e(O-C1) =1.6891(29)Å, and θ
e(HOCl)= 103.2 1(60)°for HOCl, with three standard deviations in parentheses. The analysis has also yielded some of the third-order anharmonicity constants, which are indispensable in analyzing vibrational changes of molecular constants and also in discussing the dynamical behavior of molecules. The “diagonal” third-order constants which are determined are F
111= -25.31(22) aJ A
-3, F
222-77(12) aJÅ
-3. and F
333= 1.05(15) aJ rad
-3 for HNO and F
111= 42.5 (10.4) aJ A
-3, F
222=-21.8(8.4) aJ Å.
-3, and F
333= 0.42(1.14) aJ rad
-3 for HOCl, where the internal coorinates are numbered such that 1 for δr(H-X), 2 for δr(X-Y), and 3 for δθ(HXY), and the values in parentheses denote three standard deviations. It has also been shown that the method can be applied to molecules in an excited electronic state, using HNO in the A
1A
11 state as an example. The result is by no means satisfactory; the precision of the derived constants is not high. This is mainly ascribed to perturbations in the excited state, and the present analysis may provide us with chances of examining the interactions affecting the excited state. The method developed in the present paper will be applicable to a few other simple molecules such as bent XYZ-type molecules without involving any hydrogen/deuterium atoms and planar C
2v H
2XY-type, molecules.
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Munetaka NAKATA, Kozo KUCHITSU
1986 Volume 1986 Issue 11 Pages
1446
Published: November 10, 1986
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The equilibrium (r
e) structures of H
2O, NH
3, CH, , H
2S, PH
3, and SiH
4 have been estimated from isotopic differences in their zero-point average (r
z) structures by application of the r
e method, which has recently been developed in our laboratory. This method is a modification of Watson's mass-dependence method (r
m) for extending its applicability to molecules including hydrides; the second-order correction terms, which depend on isotopic masses, in Watson's expression of the moment of inertia are compensated for and only a limited number of the isotopic rotational constants for the ground vibrational state are needed. Its general form is
_??_
where δr
z(i) represents an isotopic difference for the r
z distance in question when i-th atom, m
i, is substituted by one of its isotopic species, m
e. The sum is taken over al l the constituent atoms. The r
e structures thus obtained are in good consistency with the reported re structures derived using rotational constants for excited vibrational states to within a 002Å and O.1°, except for the H-N-H angle in NH
3, where the influence of higher -order interactions is significant, as shown in Table 7.
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Shuzo SHIBATA, Kinya IIJIMA
1986 Volume 1986 Issue 11 Pages
1451-1457
Published: November 10, 1986
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The molecular structures of n-v type electron donor-acceptor complexes of boron trihalides with trimethylamine, trimethylphosphine, pyridine and dimethyl ether were determined in the gaseous phase by electron diffraction. From comparison with the results from X-ray diffraction and microwave spectroscopy, it appears that the results obtained from electron diffraction method are the most reliable to determine the structure and stability relation for these complexes. The systematic study yielded that the structural parameters of the cornplexed donor and acceptor changed significantly from those of the uncomplexed donor and acceptor and also changed continuously depending on the acceptor and donor without controversy reported so far. It was found that the acceptor and donor strengths were in the order of BF
3 <BCl
3 <BBr
3 <BI
3 and Me
20 <C
5H
5N <Me
3N <Me
3P, respectively.
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Hiroyuki KONDO, Hiroshi TAKEUCHI, Shigehiro KONAKA, Masao KIMURA
1986 Volume 1986 Issue 11 Pages
1458-1464
Published: November 10, 1986
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The molecular structure of diisopropyl sulfide has been investigated by gas-phase electron diffraction at 20°C. The most stable conformer has C
2 symmetry as shown in Fig.1 and Table 4. The important distances (r
g) and angles (∠
α) with the estimated limits of error are r(S-C) =1.830(3)A, r(C-C) =1.530(2)Å, ∠CSC = 103.5(12)°, ∠SCC
3 = 113.5 (4)°, ∠SCC
4=106.4(4)°, ∠CCC=111.3(8)°, and φ
1(CSCH) =57(8)°. Conformational analysis has been made on the basis of Models II and III (see Table 4). The relative abundance of the most stable conformer has been determined to be about 80±20% but no definite conclusion has been drawn on the concentrations of C
s and/or C
1 conformers.
The value of ∠SCC
3 is about 7° larger than that of ∠SCC
4. As found from Fig.1, this means that two isopropyl groups tilt away from each other as compared with the case of equal bond angles. The difference observed in the SCC angles of di-t-butyl sulfide is 10.5°, a value which is larger than the above difference in diisopropyl sulfide. The values of r
g(C-S) and
CSC in diisopropyl sulfide are about 0.02Å and 5° larger than those of dimethyl sulfide, respectively (see Table 6). The observed structures of the most stable conformers of diisopropyl ether, diisopropylamine and diisopropyl sulfide are compared with the results of molecular mechanics (MM 2) calculations in Table 7. The calculated values of ∠COC, ∠CNC and ∠CSC are about 3° smaller than the observed ones. The calculated dihedral angles are different from the observed ones by 3° to 13°.
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Yoshiyuki KAWASHIMA, Harutoshi TAKEO, Chi MATSUMURA
1986 Volume 1986 Issue 11 Pages
1465-1475
Published: November 10, 1986
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Various isotopic species of cis, trans-BH(OH)
2 and cis-BHF(OH) produced as reaction intermediates between diborane and water, and between BHF
2 and water, respectively, have been observed by microwave spectroscopy. The r
s and r
0 structures have been derived f rom the rotational constants obtained. Since the Kraitchman's equation gives imaginary va lues for some coordinates, the double substitution method is applied to the determination of these coordinates. The r
s structural parameters thus determined are in good agreement with the r
0 parameters determined by least squares fitting of all the observed rotational constants. The dipole moments and their directions have been obtained from the measurements of the Stark effect. These molecular parameters show good agreement with those predicted by ab initio MO calculations.
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Masao ONDA
1986 Volume 1986 Issue 11 Pages
1476-1478
Published: November 10, 1986
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The r
0 structures of chlorobenzene, 1, 3-dichlorobenzene, and 1, 2-dichlorobenzene have been determined by means of elaborate least-squares procedure. The distortion of the ring in t hese molecules was rather smaller than that in fluorobenzenes. The two C-Cl bonds of 1, 2 dichlorobenzene bend outwards each other by about one degree(/C(1)C(2)Cl=120.9), whereas the deflection in 1, 3-dichlorobenzene is little. The magnitude of distortion of C-Cl bonds agrees with the results of ab initio calculation. Similar distortion in 1, 2, 3-and 1, 2, 4trichlorobenzene was also predicted by similar calculation.
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Keiko NISHIKAWA, Kazumi NAGANO, Takao IIJIMA
1986 Volume 1986 Issue 11 Pages
1479-1483
Published: November 10, 1986
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The X-ray scattering intensities from liquid 1, 1, 1-trichloroethane (TCE) were measured at room temperature by the energy-dispersive method. Based on the local lattice structure model, structure simulation studies for TCE were carried out. A bcc model with random orientation of the methyl groups has well-reproduced the experimental data.
The number of molecules in the structure region, n, was determined by a trial and error method, and a least-squares refinement was carried out to determine the following four parameters; the lattice constant of the bcc cell a, the Prins parameter D, the radius up to the continuous region R
c and its damping factor I
c. The refined parameters with the standard deviations in parentheses are: a=6.78(0.11)Å, D=0.049(0.009)Å, Rc=12.70(0.48)A, and l
c=3.1(1.5)Å with n=51. These results indicate that TCE molecules are arranged in the head-tail head-tail packing (Fig.1) with the first nearest-neighbor distance of 5.87(0.09)Å in the liquid.
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Toshio YAMAGUCHI, Yoshirou TANAKA, Kazuhiko OZUTSUMI, Hitoshi OHTAKI, ...
1986 Volume 1986 Issue 11 Pages
1484-1491
Published: November 10, 1986
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As a part of the structural investigation of highly concentrated aqueous solutions of thallium( I ) carboxylates, the so called heavy liquids, X-ray scattering experiments wer e performed at 25°C on aqueous thallium( I ) malonate solutions with different thallium concentrations(0.6, 3.0, 6.0, and 9.0 mol·dm
-3). Raman spectra were also measur ed for both aqueous solutions and crystals of thallium( I ) malonate. The radial distribution functions (Figs.2, 3, and 5) and Raman spectra (Table 2) indicate that in the 9.0 mol·dm
-3 malonate solution thallium( I ) ions are bridged via malonate ion, forming polynuclear species (Fig.7). With increasing water content, the polynuclear species tend to decompose in aqueous solutions. The T1( I )-T1( I ) distances in the complex are estimated to be 404-460 pm, consistent with the values found in the crystal structures of Tl( I ) salts. The oxygen coordination around T1( I ) ion is characterized by their T1-0 distances of 262 pm ( × 2), 296 pm( × 2), and 366 pm ( × -2), indicating the existence of a stereochemically active lone pair of electrons of the Tl( I ) ion in the solution. The bond valences proposed by Brown are calculated for the obtained T1-0 distances, the result showing that the model in Fig.7 is appropriate.
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Akira ENDOH, Toshio YAMAGUCHI, Isao OKADA, Hitoshi OHTAKI
1986 Volume 1986 Issue 11 Pages
1492-1500
Published: November 10, 1986
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X-Ray diffraction was performed for a molten (Li-Na-K)Cl mixture of, the eutecticcomposition (53.5-8.6-37.9 mol%) at (625±3) K. In order to separate the obtained structurefunction s·i(s) and the radial distribution function G(r) to individual atomic interactions, molecular dynamics (MD) simulation was applied. By modifying the Tosi-Fumi pair potentials, the s·i(s) and G(r) functions derived from the MD simulation could well reproduce those obtained from the X-ray diffraction method. With the 3-dimensional structure obtained from the MD simulation, the pair correlation functions g(r), the running coordination numbers n(r), the distribution of coordination numbers of Cl
- ions and the angular correlati on functions of Cl
- ions around cations were calculated. Based on these results, the change of the structure on mixing each component melt is discussed. The nearest neighbor distances between like-ions change on mixing, whereas those between unlike-ions in the mixtu r e are almost the same as those in the pure melts. On the other hand, the peak positions in t h e angular correlation functions of Cl
- ions around Li
+ and K
+ ions in the mixture are differen t from those in the pure melts, whereas the shape of the angular correlation function around Na
+ ion is almost the same as that in the pure NaCl melt.
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Hiroshi MIYAMAE, Goro HIHARA, KOZO HAYASHI, Miharu NAGATA
1986 Volume 1986 Issue 11 Pages
1501-1508
Published: November 10, 1986
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Addition reaction products of lead(II) halides with Lewis bases have leen characterized according to their composition and structure. Many adducts form in composition (lead halide): (Lewis base) =1: 1 and 1: 2. However, the structure of 1: 1 adduct with a bidentate ligand apparently differs from that of 1: 1 adduct with an unidentate ligand. Futhermore, there are some different structures for 1: 2 adducts with unidentate ligands.
On the contrary, N, N'-dimethylthiourea forms 1: 1 and 1: 2 adducts, but the other thiourea derivative, tetramethylthiourea, only produces a 1: 1 adduct. In this paper we analyzed the crystal structure of 1: 1 adduct of lead(II) iodide with tetramethylthiourea 'to deduce why the base could not produce 1: 2 adduct. The structure is composed of linear array of Pb atoms bridged by two I and an S atoms. The bridges are alternately made by twøshort Pb-I (3.10-3.19Å) and a long Pb-S (3.50-3.57Å) bonds, and two long Pb-I (3.30-3; 34Å)and a short Pb-S (2.75-2.83Å) bonds along the chain. The three longer bonds locate behind the shorter bonds.
Electron density of the S atom of the thiourea molecule is increased in the presence of four methyl groups, and the 6 s
2 lone-pair electrons of Pb(II) atom avoid the short Pb-S bond. The Pb atom coordinated by such S atom could not accept another electron rich S atom. Thus, the 1: 2 adduct could not form in the system.
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Yasuo KAMEDA, Kazuhiko ICHIKAWA
1986 Volume 1986 Issue 11 Pages
1509-1516
Published: November 10, 1986
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The analysis of a time-of-flight neutron diffraction data for a liquid D
20 was carried out, for the first time, by applying the dynamical correction. The effect of the inelasticity on the data was expressed in terms of the logarithmic derivatives of the neutron-flux spectrum and the detector sensitivity with respect to the wave numbers of the incident and scattered neutrons, and the ratio of the flight distance of the scattered neutron to that of the incident neutron. The inelasticity correction in the self-scattering term reproduced the increase of the differential cross-section for neutron scattering with increasing Q above ca.10A-1 and with decreasing Q for Q≤10Å
-1, at 2θ=90° and 150°. The interference differential scattering cross-section, which gives all the structural information in molecular liquids, was divided into the intramolecular and iintermolecular terms. The initial stage in the analysis determined the molecular geometry through the intramolecularinterference term which involves the inelasticity contribution the internuclear distances in a D
20 molecule in liquid D
20, r
a(OD)and r
a(DD) are equal to 0.971±0.03Å and 1.55±0.02Å, respectively. Under the elastic approximation r
a(OD) and r
a(DD) were small by 1-3% and 5-10%, respectively. The second. stage in the analysis determined the intermolecular structure: the intermolecular pair distribution function goD(r) was obtained with sufficient accuracy with the aid of the other intermolecular pair distribution functions goD(r)and goo(r), the data of which were taken from the TOF neutron diffraction study due to Soper-Silver and the X-ray study due to NartenLevy, respectively. The form of intermolecular pair distribution function goD(r) indicates: (i) The first and second peaks locate at 1.92Å and ca.3 4Å (ii) The coordination number n(O…D) is equal to 2.3±0.3. (iii) The short range correlations between D and, O pairs in the nearest and second nearest water molecules are highly coordinated within the range of ca.4Å in the liquid D
20, since the Q dependence of goD(r) does not show any significant oscillation for Q>4Å.
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Keisuke UMAKOSHI, Isamu KINOSHITA, Keiji MATSUMOTO, Shun'ichiro OOI
1986 Volume 1986 Issue 11 Pages
1517-1520
Published: November 10, 1986
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The violet bis(2-aminoethyl 2-pyridyl sulfide)cppper(II) perchlorate [1] and blue bis(2-aminoethyl 2-pyridyl sulfoxide)copper(II) perchl3fate [2] were synthesized and have been characterized by means of X-ray crystallography. The Cu(II) atom in 'the cation o[1] is located at the center of symmetry and has a square-planar coordination by 4 N atoms. The S atom in Cu-NH
2CH
2CH
2S-C-N ring lies in the position near to the axial site. The Cu…S distance is 2.832(1) Å and the Cu→S vector intersects the coordination plane at 59.8°. The Cu atom in the centrosymmetric cation of [2] has an elongated octahedral coordination by 4 N (equatorial) and 2 O atoms (axial). The Cu-O distance is 2.301(7) Å.
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Hikaru ICHIDA, Hitomi FUKUSHIMA, Yukiyoshi SASAKI
1986 Volume 1986 Issue 11 Pages
1521-1523
Published: November 10, 1986
Released on J-STAGE: May 30, 2011
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2(NH
4)
2O·
2SeO
2.
5MoO
3·3H
2O was proved to be (NH
4)
4Se
2Mo
5O
21·3H
2O being isomorphous to (NH
4)
4S2Mo
5O
21·3H
2O. The structural difference between the two analogous heteropoly compounds is limited around the O atoms bonded to the heteroatoms. The distances of Se-Oranging from 1.67 to 1.73A are greater than those of S-0 of S
2Mo
5O
214- anion by 0.14. -0.20A. Mo-O bond lengths agree well with the corresponding ones found in the analogous structure, except for the shortened distances between Mo and O atoms bonded to the heteroatoms. There are short contacts which may be hydrogen bonds within 3.2A among NH
4+, H
2O and Se
2Mo
5O
214-. The hydrogen-bond acceptors in the anion are mainly terminal 0atoms. This intermolecular interaction is thought to act upon the deformation of the heteropolyanion molecule.
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Tokuhiko OKAMOTO, Toshihiko SUZUKI, Noboru MATSUI
1986 Volume 1986 Issue 11 Pages
1524-1530
Published: November 10, 1986
Released on J-STAGE: May 30, 2011
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Deterioration of humidity sensors has been investigated by EXAFS (Extended X-ray Absorption Fine Structure) and XANES (X-ray Absorption Near Edge Structure). The humidity sensors were composed of spinel structure materials, Zn
0.98Na
0.02Fe
2O
4 and Mg
0.98Na
0.02Fe
2O
4. The former was excellent in durability, but the latter was poor.
The experiment was carried out by a laboratory scale EXAFS equipment with a rotating anode type X-ray generator and a Si (220) Johansson type curved crystal. EXAFS and XANES spectra at the Fe K-absorption edge were measured in the transmisson mode. The spinel structure materials, ZnFe
2O
4, MgFe
2O
4 and related compounds were used as reference specimens. XANES spectra were derivated to enhance the difference between the specimens. Each spectrum from the two materials after a durability test was extremly diffe rent from each other. The spectrum obtained from Zn
0.98Na
0.02Fe
2O
4 was similar to that obtained from ZnFe
2O
4 in which Fe atoms occupy octahedral sites. In this specimen, no change was observed after the durability test. In the case of Mg
0.98Na
0.02Fe
2O
4, however, the spectrum varied from ZnFe
2O
4 type to MgFe
2O
4 type, in which Fe atoms exist in both octahedral and tetrahedral sites.
It was sug g ested that the deterioration of Mg
0.98Na
0.02Fe
2O
4 is attributable to the movement of Fe atoms. It was proved that the laboratory scale EXAFS equipment is extremely useful for studying not only the atomic radial distribution but the coordination geometry around the excited atoms.
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Yoshichika TAJIRI, Hisanobu WAKITA
1986 Volume 1986 Issue 11 Pages
1531-1538
Published: November 10, 1986
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The structures of bromocopper (II) complexes in methanolic (M 1, M 2, M 3, M 4), ethanolic (E), and aqueous (H) solutions were determined by the analyses of the Cu K- and Br K-edge EXAFS spectra using a curve-fitting method. The molar concentrations of Cu and Br in these solutions prepared by CuBr
2 and LiBr are 0.996 and 1.992 (M1), 1.015 and 5.381(M2), O.493 and 4.525 (M3), 0.260 and 4.073 (M4), 1.031 and 4.313 (E), and O.982 and 5.426 (H). In M 1 solution the interatomic distances for the Cu-O
eq, Br
eq-Cu, and Br
eq-O
eq(eq=equatorial) were 2.00A, 2.35Å, and 3.15Å respectively, and the Br
eq-Cu-O
eq, angle was estimated as about 92°. Therefore, trans-dibromo his (methanol) copper(II) complex with a slightly distorted planar structure was proposed to be dominant complex species in M 1solution. The interatomic distances in M 2, M 3, M 4 and E solutions were 2.37Å and 3.45A (average) for the Br
eq-Cu and Br
eq-Br
eq respectively. The Br
eq-Cu-Br
eqangle, paticularly in solutions M 2 and E, was estimated as about 95°. In these solutions, the tetrabromocopper (II) complex was proposed to exist with a distorted planar or a pseudo tetrahedral structure. The main copper(II) complex in solution H was not a tetrabromo complex but a mixedcoordinated bromoaquacopperan complex in which distances for the equatorial interactions for the Cu-O and Cu-Br were 1.99Åand 2.37Å respectively.
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Kiyotake ASAKURA, Yasuhiro IWASAWA, Haruo KURODA
1986 Volume 1986 Issue 11 Pages
1539-1546
Published: November 10, 1986
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The structures of the Ru catalysts derived from Ru
3(CO)
12 supported on the various oxides such as MgO, K-doped Al
2O
3, Al
2O
3, TiO
2, Sio
2, V
2O
5, and MnO
2 were studied by means of EXAFS (extended X-ray absorption fine structure). The surface Ru structures are illustrated in Fig.9. The structures obtained by supporting Ru
3(CO)
12 onto the oxides depended on the acidity and basicity of supports. [HRu
3(CO)
11]
- was formed on the basic supports like MgO and K-doped Al
2O
3, whereas [Ru
3(CO)
10 (H)(OA )] was created on the amphoteric support like Al
2O
3. On the more acidic supports like TiO
2, SiO
2 and V
2O
5, Ru
3(CO)
12 was physisorbed. The structures formed after the thermal treatments and H
2 reduction of the incipient surface Ru species can be explained in terms of the electronegativity of metal ions in the support oxides. On MgO and Al
2O
3 in which the electronegativities of the metal ions are relatively small, the chemical bonds between the surport oxygen and Ru atoms were formed after the thermal decomposition and H2 reduction. On TiO
2, SiO
2 and V
2O
5 in which the metal ions have large electronegativities, the Ru metal particles with no Ru-O bonding were observed. In the case of MnO
2, the oxidation of the Ru cluster by th e support was observed in addition to the metal-support interaction mentioned above.
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Yoshinori KITAJIMA, Nobuhiro KOSUGI, Haruo KURODA, Toshiaki OHTA
1986 Volume 1986 Issue 11 Pages
1547-1552
Published: November 10, 1986
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The local adsorption structure of S on a Ni(110) crystal surface is studied by the polarization-dependent surface EXAFS (extended X-ray absorption fine structure) method. The polarized S K-edge absorption spectra (2400-2900 eV) have been obtained by monitoring S K-LL Auger electron yield and by changing both polar and azimuthal angles of the incident synchrotron radiation. The results of the EXAFS data analysis show that the adsorbate S atom is on the hollow site of the Ni(110) surface and that the first and seco nd nearest neighbor Ni atoms are 2.19 and 2.31Å distant from the S atoms, respectively. This means that the first interlayer spacing in the Ni(110) surface is 10% larger than the spacing in the bulk.
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Kazuyuki TOHJI, Yasuo UDAGAWA, Mutsumi HARADA, Akifumi UENO
1986 Volume 1986 Issue 11 Pages
1553-1559
Published: November 10, 1986
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An attempt was made to improve an extended X-ray absorption fine structure (EXAFS)facility by the use of higher-order reflections from dispersing crystals. A resolution good enough to observe X-ray absorption near edge structure (XANES) has been obtained in the lower energy region (5-10 keV), and EXAFS measurements have been extended to cover up to about 26 keV, including K absorption edges of Ru, Rh, Pd, and Ag, which are important in catalysis. Some examples of the performances of this spectrometer are presented. By making use of the spectrometer, local structures around Cu and Rh atoms in Cu-Rh/SiO2catalysts have been studied by the EXAFS of Cu and Rh and also by the XANES of Cu. The catalysts prepared by two kinds of preparation procedures, the impregnation method and the alkoxide method, have been examined. In the catalysts prepared by both methods, Rh atoms are in the metallic environment and surrounded by other Rh atoms, but Cu atoms are not. It is concluded that Cu atoms have both Cu and Rh neighbors and are concentrated on the surface. The tendency is more pronounced in the catalyst prepared by the alkoxide method, indicating a difference in the metal particle size of the two catalysts prepared by the different methods.
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Nobuhiro Kosuci
1986 Volume 1986 Issue 11 Pages
1560-1565
Published: November 10, 1986
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We have to know, in advance of the EXAFS data analysis, both backscattering amplitude and total phase shift, fπ and φ, which appear in an approximate EXAFS function. These physical parameters are theoretically or experimentally derived but are strongly dependent on the analysis methods. The theoretical fπ and φ are heavily distorted, especially for heavy backscatterers, after the Fourier filtering. It is proposed that we should use the distorted theoretical parameters for the analysis and select a weighting function carefully in order to reduce truncation errors in the Fourier filtering.
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Hideaki FUJIWARA, Iwao YAMANAKA, Yoshio SASAKI
1986 Volume 1986 Issue 11 Pages
1566-1570
Published: November 10, 1986
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'H-NMR spectra of a tricyclic compound phenoxathiin have been analyzed in a nematic liquid crystal ZLI 1167 and the chemical structure and molecular orientation determined. A damping subroutine was incorporated into the modified LAOCN 3 program to improve the worse convergency encountered when corrections calculated for the variable parameters were large. The order and the structural parameters have been derived from the direct couplings and compared with those reported for the related tricyclic compounds. The dihedral angle between the two benzene rings was about 18° wider than that determined in a crystal state. This tendency resembles to the case of thianthrene. The order parameters supported that the long axis of phenoxathiin orients parallel to that of the liquid crystal. Comparison of the order parameters of some tricyclic compounds suggested that they are dependent on the molecular structure when measured in a same liquid crystal solvent.
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Tadao KONDO, Hirotoshi TAMURA, Shigehiro TAKASE, Toshio GOTO
1986 Volume 1986 Issue 11 Pages
1571-1578
Published: November 10, 1986
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Chemical degradation methods for structure determination of natural acylated anthocyanins lose many informations concerning the anomeric configuration and the attaching position of the sugar and the acyl moieties. We have succeeded in obtaining very fine
1H-NMR spectra of natural anthocyanins such as violanin[1], awobanin [3], and malonylawobanin [2] in their flavylium ion form, and in determining their complete stereostructures. It was found that [2], but not [3], was the real anthocyani n component of commelinin, the sky-blue pigment from Corn melina corn munis.
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Noboru OTAKE
1986 Volume 1986 Issue 11 Pages
1579-1586
Published: November 10, 1986
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Notonesomycin A is an antifungal antibiotic isolated from Streptomyces aminophilis subsp. notonesogenes 647-AV, and is effective against shealth blight disease of rice plant.
The structure of notonesomycin A has been elucidated on the basis of the NMR spectral data together with biosynthetic evidences using
13C-
13C double precursors.
Thus the unique structure of the antibiotic containing sulfate ester in the 32-membered lactone ring has been established.
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Osamu KIKUCHI, Misako ISHII, Kenji MORIHASHI, Mitsunobu NAKAYAMA
1986 Volume 1986 Issue 11 Pages
1587-1593
Published: November 10, 1986
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The method to determine the molecular structures of free radicals on the basis of the experimental ESR parameters and theoretical ones calculated by the INDO-UHF method was described. The functional, which involves the differences between experimental and theoretical values for the g-factors and the anisotropic and isotropic hyperfine coupling constants, was minimized to obtain the ESR parameter-optimized molecular structure. The method was applied to 12 free radicals, HCO, CF
3, NF
3+, CO
2-, NO
2, H
2NO, (CH
3)
2C0
+, CH
2CHCH
2, CH
2OCH
2+, C
2F
4, C
6H
5, and SiH
3Cl
-, and the calculated molecular structures were compared with the energy-optimized structures and the experimental ones. Better agreement with experiment was obtained in the ESR parameter-optimized structures. The proposed method shows efficiency and appropriateness to the elucidation of radical structures from the anisotropic informations on the g-factors and hyperfine coupling.
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Hiroshi YOKOI, Takemitsu KIKUCHI, Akira HANAKI
1986 Volume 1986 Issue 11 Pages
1594-1600
Published: November 10, 1986
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It has been revealed by ESR spectroscopy that the 1: 1 complexes of copper(II) with triglycine(glycylglycylglycine), tetraglycine, pentaglycine, hexaglycine, and octaglycine in aqueous solutions at pH 10 form dimers in equilibrium with monomers. The copper(II)complexes of glycinamide, glycylglycinamide, and biuret at pH 12 also form dimers. The equilibrium constant of 2 monomer ⇔ dimer for the tetraglycine complex has been determi ned to be 460 mol·dm
-3 at about 0°C by analyzing the concentration dependence of the intensity ratios of dimer and monomer ESR signals. Spin-exchange interaction energies for. the present dimers have been estimated to be of the order of -1 cm-
1 from the temperature dependence of intensity of ΔM=2 transitions. All the dimer ESR spectra observed were analyzed by computer simulation in order to estimate the structural parameters of r and ξ for parallel-planar dimers, where r is the Cu-Cu distance and ξ, the angle between the Cu-Cu direction and the normal to the molecular plane. The results indicate that the dimeric structures of the above complexes (r=4.0-4.3Å;ξ≤15°) are different from those in crystals, except for the triglycine complex (r=3.3A;≤=40°). It has been concluded that coordination of two or more deprotonated peptide nitrogens is required for the dimerization of the present kind of complexes. This may suggest that a so-called π-π interaction between two molecules with the π-electron system made up of the metal and coordinating deprotonated peptide(amide) groups is a possible driving force for the dimerization.
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Takashi IWASHITA
1986 Volume 1986 Issue 11 Pages
1601-1603
Published: November 10, 1986
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The specific line-broadening effects caused by the addition of a small amount of acid were noted for some 'H-NMR of stemotinine [1] and isostemotinine [2]. The molecular structure of [1] has recently been established by X-ray analysis, we could correlate the line-broadening effect with the stereochemistry of the spiro-lactone moieties of [1] and [2]. Since line-broadening was found to be induced by partial salt formation of the tertiary amino group, it may be widely observed with other alkaloids and may afford a versatile supplementary tool for the stereochemical study of alkaloids.
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Hideyuki HARUYAMA, Tomoko TAKAYAMA, Michio KONDO
1986 Volume 1986 Issue 11 Pages
1604-1606
Published: November 10, 1986
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The three-dimensional structure of rifamycin SV in solution was constructed by the combination of distance geometry and NMR spectroscopy. The dihedral angles derived from the analysis of the vicinal coupling constants and NOEs were used to restrict the possible conformations of the ansa chain moiety. The restricted spatial arrangements of the ansa chain and the naphthohydroquinone ring were demonstrated by the NOEs observed at H
3 on irradiating 20-CH
3, 24-CH
3 and 26-CH
3 group. Based on the above observation a set of the upper and the lower bounds of the interatomic distances was assigned and converted to the corresponding three-dimensional coordinates. Fig.3 shows the three-dimensional drawing of the resulting geometry, which is consistent with the observed NMR data as shown in Tables 1 and 2.
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Seiji TSUZUKI, Kazutoshi TANABE, Yoshinobu NAGAWA, Hiroshi NAKANISHI, ...
1986 Volume 1986 Issue 11 Pages
1607-1612
Published: November 10, 1986
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A molecular mechanics calculation program MM 2' was applied to biphenyl and naphthalene. Parameters for the central C-C bond of biphenyl and C-C bonds of naphthalene were adjusted to reproduce experimental structures and barrier heights of internal rotation. A stretching force constant for the central C-C bond of biphenyl, ks, was changed from 8.067to 5.0 (mdyn.A
-1), a bond distance constant, r
o, from 1.3923 to 1.48 (A), and a torsional constant, V
2, from 9.0 to 1.0 (kcal. mol
-1). The calculated central C-C bond length and torsional angle of the energy minimum conformer in biphenyl were 1.4909A and 45°, respectively. Maximum energies were reached when the torsional angle was 0° and 90°, and were 1.7 and O.9 kcal. mol
-1 higher than that of the energy minimum conformer, respectively. In the calculation of naphthalene, a bond distance constant, r
0, for C
1-C
2 bond was changed from 1.3923 to 1.37 and for other bonds from 1.3923 to 1.41 (A). Calculated bond distances of C
1-C
2, C
2-C
3, C
1-C
9, C
9-C
10 bonds were 1.3737, 1.4134, 1.4150, 1.4168 (A). Satisfactory agreement with available experimental data was obtained. In these calculations, bond order calculation to adjust parameters for conjugated bonds, as performed in MMPI, was not carried out. So these parameters used for the calculation of biphenyl and naphthalene may not be applied to highly strained derivatives, but to lower strained biphenyl and naphthalene derivatives. This method might generally be applicable to a series of conjugated molecules of similar structures.
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Shinji HASHIMOTO, Teizo KITAGAWA
1986 Volume 1986 Issue 11 Pages
1613-1621
Published: November 10, 1986
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Resonance Raman spectra of horseradish peroxidase (HRP) and yeast cytochrome c peroxidase (CcP) were observed and the structure in the heme vicinity characteristic of peroxidases, was discussed. The resonance Raman spectra of reaction intermediates were also observed and the Fe
4+=O stretching band was assigned on the basis of the isotope shifts. It became clear that the sixth ligand of the Fe
4+ heme of the intermediate was not the OH group but the 0 atom, and that the iron-bound oxygen atom was exchanged with that of solvent wh ile the measurements were carried out (3 min). This oxygen-exchange reaction took place only with the acidic form in which the proton involved in the heme-linked ionization was hydrogen-bonded to the iron-bound oxygen and the pH dependence of the exchange reaction appeared in parallel with the enzymic activity.
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Eri IGUCHI, Shin-ichi ITOH, Hiroaki TAKAHASHI
1986 Volume 1986 Issue 11 Pages
1622-1625
Published: November 10, 1986
Released on J-STAGE: May 30, 2011
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The photoactivated red species produced by UV irradiation of 2, 3-epoxy-2, 3-dihydro-2, 3-phenyl-1H-indenone (DPIO) has been studied by resonance Raman and IR spectroscopy. Taman bands at 1737 cm
-1 (IR band at 1730 cm
-1) and 1210 cm
-1 (IR band at 1210 cm
-1)f DPIO, which are assigned to the C=O stretch and epoxy ring-breathe, respectively, isappear upon irradiation with UV light, and instead, new bands at 1567 cm
-1 (IR bandt 1570 cm
-1) and 1256 cm
-1 (IR band at 1260 cm
-1) are observed. The spectral change is aterpreted in terms of valence tautomerisation as being due to heterolytic cleavage of the C-C bond of the epoxy ring to form zwitterionic 2, 3-diphenyl-2-benzopyrylium-4-olate (DBPO). the bands at 1567 and 1256 cm
-1 are attributed to the conjugated C-0- stretch and he pyrylium ring-breathe (main contribution from the conjugated C=O+-C symmertric tretch), respectively.
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Masao FUJIWARA, Mitsuo TASUMI
1986 Volume 1986 Issue 11 Pages
1626-1631
Published: November 10, 1986
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The effects of axial ligands (solvent molecules) on the vibrational spectra of chlorophyll a in solution were studied. When the Mg atom of chlorophyll a changes from the fivecoordinate state (one axial ligand) to the six-coordinate state (two axial ligands), four Raman bands (Figs.3-5) and two infrared bands (Fig.6) in the C=C stretching region shifted to lower frequencies by about.10 cm
-1, whereas a far-infrared band (Fig.7) showed an upshift of about 20 crn
-1. The latter band probably arises from a mode due to Mg-N stretching. These shifts were explained as a result of the elongation of C=C bonds and the shortening of Mg-N distances in a chlorin ring caused by the movement of the Mg atom from an out-of-plane position to the center of the ring.
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Seiichiro HIGUCHI, KOZO TANAKA, Shigeyuki TANAKA
1986 Volume 1986 Issue 11 Pages
1632-1636
Published: November 10, 1986
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The Raman optical activity (ROA) spectra were measured for aqueous solutions of Lproline, L-hydroxyproline and L-lysine. The ROA signals for the CH
2 scissoring mode are very strong in the case of L-proline and L-lysine, while in the case of L-hydroxyproline, the ROA signal for this band is not observed. This result suggests that the ROA is related to the presence of chained CH
2 groups in the molecule, and that a strong vibrational coupling due to such a CH
2 chain structure contributes to the intensities of the ROA signal for this vibrational mode. The ROA pattern at wavenumbers higher than 1300 cm
-1 is generally common among the three amino acids employed, reflecting the common L-type steric configuration around the a-asymmetric carbon.
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Seiichiro HIGUCHI, KOZO TANAKA, Shigeyuki TANAKA
1986 Volume 1986 Issue 11 Pages
1637-1642
Published: November 10, 1986
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The vibrational optical activity due to the chirality induced in biphenyl-type azo dyes by the interaction with bovine serum albumin (BSA) or human serum albumin (HSA) was measured with the Raman optical activity (ROA) method. The induced chirality was examined by use of the circular dichroism (CD) method. The induced chirality is found to vary remarkably among the dye-albumin combinations this is at variance with the reported experimental observation that the binding of azo dyes with albumins is in general nonspecific. The induced chirality is most intense for the BSA-trypan red (TR) system. The intensity of the induced CD for this system reaches a maximum for a BSA/TR molar ratio of 1. Raman and ROA measurements were then carried out for BSA-TR system (1/1), making use of the intensity enhancement due to the resonance Raman effect. The SO
3- stretching Raman band clearly changed upon complexation, suggesting that the SO
3- group plays an important role in the formation of the complex compound of BSA and TR. Reproducible ROA signals were obtained in the wavenumber region of Ph-N =stretching and SO
3- stretching vibrations, but no ROA signal was observed for azo group vibrations. These results indicate that the vibrational optical activity in this case originates from twisting in the biphenyl moiety of the dye molecule by the BSA-TR complex formation.
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Kaoru HANAYA, Kazuo OZAWA, Takashi MURAMATSU
1986 Volume 1986 Issue 11 Pages
1643-1649
Published: November 10, 1986
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The OH stretching absorptions of cis-2-substituted 5, 8-dimethyl-4--chromanols have been measured in dilute carbon tetrachloride solution. cis-2-Methyl[6] and cis-2-phenyl-5, 8dimethy1-4-chromanols [7]∼[10] take diequatorial conformation having 4-quasi-equatorial OH and 2-equatorial methyl or phenyl groups preferably. On the other hand, cis-2ethoxycarbony1-5, 8-dimethyl-4-chromanol [11] prefers the quasi-axial OH conformation. In order to confirm the conformational equilibrium, temperature dependence of the OH absorption intensities for[6]∼[10] and
1H-NMR of all the compounds were examined.
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Hideyuki KONISHI, Shinji KITAGAWA, Hisao NAKATA, Hiroshi SAKURAI, Akir ...
1986 Volume 1986 Issue 11 Pages
1650-1656
Published: November 10, 1986
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The value of kinetic energy released (KER) in the reaction [C
6H
5O] [C
5H
5]
+ CO for anisole and nitrobenzene is different from that for m- or p-substituted phenols. Collisionally activated dissociation (CAD) spectra of [C
2H
SO]
+ isomers are classified into two groups: Anisole and nitrobenzene again differ from others. Mass spectral studies predict the existence of at least two [C
6H
5O]+ isomers in the gas phase both for metastable (decomposing) and stable (nondecomposing) ions.
A comprehensive treatm ent including the MO calculations by MINDO/3 of structures of these [C
2H
2O] ions has been done to estimate structures and their heats of formation.
The oxocyclohexadienyl cation for both anisole and nitrobenzene, and [CH2=C=CHCH=CHC=O]
+ for substituted phenols are shown to be metastable ions. The cyc lopentadienecarbonyl cation is regarded as stable ions for anisole and nitrobenzene, but a mixture of structures such as [CH
2=C=CHCH, CHC=O]
+, [CH
2=CHCH=CCH=C=0]
+, etc. is assigned to the substituted phenols. Fragmentation pathways of these [C
6H
5O] isomers are also presented and discussed.
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Kimio ISA, Toshiaki KINOSHITA, Hiroki KIDO, Ryuji NAKATA, Keiko MIZUTA
1986 Volume 1986 Issue 11 Pages
1657-1664
Published: November 10, 1986
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Ni edta Complex was measured by FAB MS (Fast Atom Bombardment Mass Spectrometry). Quasi-molecular ions, (MA+H-1-H)+, (M+H)+, and (M+A)+ were obtained by this technique. The CAD spectra of these precursor ions, (MA-FH-FH)+ miz 371, (M+H)miz 393, and (M+A)+miz 415 obtained by tandem mass spectrometry are character istic of the ion structure. Almost all the cases indicate the main eliminations of COOH(-45) and 2COOH(-90). In the case of (MA-FH+H) precursor ion, the elimination of H
2O(-18) was observed, but in the case of (M+H) precursor ion the elimination of CO (-28) as well as H
2O was also observed. But in the case of (M+A)+ precursor ion, the elimination of CO(-28)increased extremely. In the c ase of (MAd-Hd-H) precursor ion, the CAD spectra of m/z 371, miz 165 were the largest ion without containing Ni metal and it was confirmed using the Ni isotope. Moreover, nonmetal, Li
2, Na
2, and K
2 edta were also measured by FAB M S/MS. In the case of CAD of (M+H)+ ion of Na2 edta, m/z 90 (CO
2Na
2+) as the main fragment peak was turned out to be 0 combined with two Na.
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Takeshi KINOSHITA, Takemichi NAKAMURA, Hidemi NAGAKI
1986 Volume 1986 Issue 11 Pages
1665-1670
Published: November 10, 1986
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Fast atom bombardment (FAB) mass spectrometry in conjunction with tandem mass spectrometry (MS/MS) provides the unambiguous molecular weight and structural information about many kinds of organic compounds. FAB often yields molecular ion species with little fragmentation, and therefore, gives molecular weight information but little structural information. Collisionally activated dissociation (CAD) spectra, obtained with an MS/MS instrument, of the selected ion species can provide fragmentation information which can be used for structural elucidation. Occasionally, metastable ion (MI) spectra, obtained with an MS/MS spectrometer, of the quasi-molecular ion (QM+) or the fragment ions give more useful and convenient information to determine the structure of the target compounds. Since the reproducibility of FAB MS/MS spectra is excellent, slight differences in relative daughter ion intensities of structural isomers afford an assignment, which is often not possible from the conventional mass spectrum alone. In this work, capabilities of FAB MS/MS for structural isomer differentiation and structure determination in the natural products field are demonstrated.
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Takekiyo MATSUO
1986 Volume 1986 Issue 11 Pages
1671-1682
Published: November 10, 1986
Released on J-STAGE: May 30, 2011
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Mass spectrometric approaches for the structural analysis of biopolimer, especially protein, have been studied. The recent progress of ion source (FD, FAB, SI MS) makes it possible to ionize and detect heavy peptides. For the sequence determination of unknown peptides, the combination of enzymic or chemical digestions, high performance liquid chromatgraphy, mass spectrometry, Edman degradation and computer analysis is the most effective method. For the characterization of protein variant, the mass spectrometric approach is very useful. Several techniques for determining unknown variants are explained by using the case of hemoglobin variant analysis.
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Yoko OHASHI, Yoshitaka NAGAI
1986 Volume 1986 Issue 11 Pages
1683-1689
Published: November 10, 1986
Released on J-STAGE: May 30, 2011
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Glycosphingolipids and phosphonosphingolipids were investigated with f ast atom bombardment mass spectrometry (FABMS) and/or secondary ion mass spectrometr y (SIMS). Application of B/E-constant and B
2/E-constant linked scannings in the positive mode made it possible to determine the mass number of long chain bases without ambiguity.
The sphingolipids generally show MH
+, (MH-H
2O)
+, (MH-saccharid e or MH-phosphonate)(Y-H
2O)
+, and +CH, C(NH
2) =CHR(Z
+), the last one being the k ey ion. Thus, the mass number of a long chain base is determined according to the Z
+ ion which is easily detectable as an even mass number ion in the region of m/z 200-400.
The method also provides information about the fatty acid m oiety in the ceramide independently through the reverse search of the ceramide by B/E-constant linked scanning of the daughter ion Z. Further linked scanning in the same mode from Y+ may lead to an assignment of the specific MH+ among other MH+s. Confirmation of the assignment is successfully made by sequential B/E-constant linked scannings from MH+→ Y
+ Z
+.
Provided that a neutral matrix is used, the method is applicable not only to the sphin genine or sphinganine homologs but also to the phytosphingosines which have an additional hydroxyl group in the long chain base.
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Yousuke SEYAMA
1986 Volume 1986 Issue 11 Pages
1690-1699
Published: November 10, 1986
Released on J-STAGE: May 30, 2011
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Mass spectrometry has been developed to characterize the chemical structure of organic compounds. Gas chromatography mass spectrometry (GC/MS) is suitable for the characterization of biological materials in a very small amount. Mass fragmentography is a sensitive and specific method for quantitative determination of such materials. The present paper describes applications of these techniques to the analysis of fatty acid metabolism in the Harderian gland of guinea pig. More than 90% of total lipids was identified as 1-0-alkyl2, 3-di-O-acylglycerol. The alkyl and acyl moieties consisted of saturated aliphatic chains ranging from 14 to 21 carbon atoms and 15 to 26 carbon atoms, respectively. About 60 mole %of them had methyl branches, which were located at the even-numbered carbon atoms. Fatty acid synthetase was isolated from this gland and analyzed by a new assay method for fatty acid synthetase using mass fragmentography. This enzyme produced many oddnumbered and methyl-branched fatty acids in the presence of methylmalonyl-CoA. These fatty acids are characteristic components of the lipid secreted from this gland. Substrate level regulation was demonstrated. The availability of methylmalonyl-CoA regulates the composition of fatty acids produced by the fatty acid synthetase from this gland. In the presence of acetyl-CoA, propionyl-CoA, malonyl-CoA, and methylmalonyl-CoA in appropriate concentrations the enzyme can produce the proper fatty acids needed for the synthesis of the 1-0-alkyl-2, 3-di-O-acylglycerol, especially for the acyl chain at the 2-position. Same procedures are also applicable to the diagnosis of congenital lipid metabolism, cerebrotendinous xanthomatosis, by quantitating cholestanol and bile acids in serum.
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Shigeko SUGIMOTO, Masaaki ARIME, Shozo KAWABATA, Yukio ONO
1986 Volume 1986 Issue 11 Pages
1700-1702
Published: November 10, 1986
Released on J-STAGE: May 30, 2011
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In-beam electron impact ionization, isobutane chemical ionization and field desorption mass spectrometry were applied for the characterization of organic tin compounds.
In these compounds, primary cleavages of the Sn-C, Sn-X, S n-O and Sn-S bonds took place prior to other reactions so that the analysis of their mass spectra was relatively simple. The ten isotopes of the tin atom gave the information whether a fragment ion con tained tin or not.
Moreo ver, the kind and the distribution of alkyl or carboxyl group attached directly to the tin atom were easily determined from their mass spectral cracking pattern.
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