Takehiko Simanouti

The Normal Vibrations of Polyatomic Molecules as Calculated by Urey‐Bradley Field. III. A Table of Force Constants

Assuming the Urey‐Bradley field for various chemical structures, stretching, bending and repulsive force constants were determined so as to give the best fit with the observed vibration frequencies. The magnitude of these force constants, especially of repulsive constants, was discussed.

The Normal Vibrations of Polyatomic Molecules as Calculated by Urey‐Bradley Field. II. Vibrations of Polythene, Ethane, and Their Deuterium Compounds

Assuming the Urey‐Bradley field as the type of intramolecular potential equations to calculate five optically active frequencies of polythene molecule were derived. If we assume as force constants KCH=4.2, HHCH=0.15, FHH=0.1, FHC=0.4, FHH′=0 and FHC′=−0.05 (105 dynes/cm), the observed frequencies of (CH2)n and (CD2)n as well as those of CH4, CD4, C2H6, C2D6, etc., were explained satisfactorily.

The Constant Frequency Raman Lines of N‐Paraffins

Assuming the Urey‐Bradley field for the intramolecular potential, we have calculated the normal frequencies of long chain molecules in the extended form. Especially the vibration type of the frequencies remaining almost constant throughout the homologous series has been discussed. The result has been applied to the assignment of Raman lines of N‐paraffins and of the infra‐red absorption lines of polyethylene.

Raman Effect, Infra‐Red Absorption, Dielectric Constant, and Electron Diffraction in Relation to Internal Rotation

The relative intensities of Raman lines of 1,2‐dichloroethane were determined in the gaseous state as well as in the liquid state. The result combined with that of the dipole measurement in the gaseous state enabled us to determine the equilibrium isomeric ratio of the trans‐ and the gauche molecules, which was in good agreement with that obtained from the absorption measurement of infra‐red spectra. This ratio could also explain satisfactorily the result of an electron diffraction experiment made by us for the vapor of 1,2‐dichloroethane. The statistical entropy of dihalogenoethanes was calculated from the molecular data and was compared with the third law entropy obtained from the thermal measurement. The frequencies of torsional oscillation about the C–C bond as axis were determined by the difference method and were found to be in agreement with the lowest frequencies of the observed Raman spectra.

The Raman Spectrum of Hexachlorodisilane

The Raman spectrum of hexachlorodisilane was observed in the liquid state and the normal vibrations of this molecule were calculated by use of the Urey‐Bradley field. The seven observed Raman frequencies could be assigned to the fundamental vibrations and the molecule was found to belong to the D3h′ symmetry. This means that the molecule exerts internal free rotation around the Si–Si bond as axis. This is in conformity with the experimental result of the electron diffraction investigation.

Molecular Theoretical Investigations on Hydrocarbons and their Substitution Products. IX

炭素單結合のまわりの分子内部廻轉に關する我々の結論に基いて,一般の鎖状飽和炭化水素の廻轉異性體の分子形態を決定した.而してその結果を三種の表現法によつて表した.尚正セタンの液體のラマン・スペクトルの實測値に基いて之等の廻轉異性體のうち何れが實現されてゐるかを定めた.