Masaaki Sakakibara

Vibrational spectra and molecular conformations of 1,5-dichloro- and 1,5-dibromopentanes and 1,6-dichloro-and 1,6-dibromohexanes

Abstract The Raman and IR spectra of 1,5-dichloro- and 1,5-dibromopentanes and 1,6-dichloro-and 1,6-dibromohexanes have been measured. The normal coordinates have been calculated for these molecules using a consistent set of force constants and the molecular conformations studied by analysing the spectra with reference to the results of the calculations. In the crystalline solid state, 1,5-dichloropentane assumes the trans-trans-trans-gauche form and 1,5-dibromopentane, 1,6-dichloro- and 1,6-dibromohexanes assume the all- trans form. The normal coordinate treatment with the well-established force field was of great help in determining the whole molecular form of the relatively large chain molecules.

Vibrational spectra and crystal structure of ethyl methyl sulfide-mercury(II) chloride complex

Abstract The crystal structure of the ethyl methyl sulfide-mercury(II) chloride complex, CH 3 SCH 2 CH 3 · HgCl 2 , has been determined by X-ray diffraction. The conformation about the CS-CC axis of the complex is trans , which is different from the conformation of crystalline ethyl methyl sulfide. The Raman and IR spectra of the complex have been measured. Observed wavenumbers of the CH 2 rocking and C-C stretching vibrations of the complex are close to those of the trans form of ethyl methyl sulfide in the liquid state, but the wavenumber of the C-S stretching vibration shifts on formation of the S-Hg bond.

Vibrational spectra and molecular conformations of alkoxy(alkylthio)methanes

Abstract The Raman and infrared spectra of methoxy(methylthio)methane, ethoxy(methylthio)methane and methoxy(ethylthio)methane have been measured in the liquid, glassy and crystalline states. Normal coordinate treatment of these molecules has been performed in order to analyse the spectra and determine the molecular conformations. Methoxy(methylthio)methane crystallized in the gauche-gauche conformation and ethoxy(methylthio)methane in the trans-gauche-gauche conformation about a series of axes C 2 H 5 OCH 2 SCH 3 . It is shown that many conformers are present in the liquid state of the molecules studied.

Raman spectra and normal vibrations of 2-substituted 2,4,4-trimethylpentanes (CH3)3CCH2C(CH3)2X (XCl, Br, SH and CH3) as model compounds of a hydrophobic group of triton X surfactants

Abstract Raman spectra of 2-chloro-2,4,4-trimethylpentane, 2-bromo-2,4,4-trimethylpentane and 2,2,4,4-tetramethylpentane were measured in the liquid and solid states. Normal coordinate calculations were made on these compounds together with 2,4,4-trimethyl-2-pentanethiol. The analysis has clarified the vibrational modes of the 1,1,3,3-tetramethylbutyl group which corresponds to a hydrophobic group of Triton X surfactants. Molecules of the Cl-, Br- and SH-substituted compounds take the gauche form in the solid state, but take both gauche and trans forms in the liquid state. On the basis of the spectral interpretation of these model compounds, the Raman spectra of Triton X-100 were examined and the bands associated with the hydrophobic 1,1,3,3-tetramethylbutyl group were identified.