Katsunosuke Machida

Microwave spectra of deuterated ethylenes: Dipole moment and rz structure

Abstract The pure rotational spectra of three deuterated ethylenes, CH2CD2, CH2CHD, and cis-CHDCHD, were observed by microwave spectroscopy, and the rotational and centrifugal distortion constants were determined precisely. The dipole moment of CH2CD2 was calculated from the Stark effects to be 0.0091 ± 0.0004 D. From the observed rotational constants the average structure was calculated to be r z (CC) = 1.3391 ± 0.0013 A , r z (CH) = 1.0869 ± 0.0013 A , θz(CCH) = 121.28 ± 0.10°, and r z (CH) - r z (CD) = 0.00137 ± 0.00037 A , where the errors include one standard deviation in the fitting and errors due to an uncertainty (±0.03°) in θz(CCH) - θz(CCD).

Infrared and Raman spectra of polyethyleneglycol dimethylethers in the liquid state

Abstract Infrared spectra of ethylene- through heptaethyleneglycol dimethylethers and Raman spectra of ethylene- through tetraethyleneglycol dimethylethers have been measured in the liquid state. Assignments of the vibrational frequencies have been made and the effect of the chain length on the spectra has been discussed with reference to the nature of vibrational modes. The CH 2 rocking and the CO and CC stretching modes are appreciably coupled. In the liquid state the internal rotation angles ( trans and gauche ) about the CC and the CO bonds of the molecular chain are randomly distributed.

Vibrational spectra and intermolecular potential of the α-form crystal of glycine

Abstract Polarized Raman and far i.r. spectra of glycine and N -deuterated glycine crystallized in the α-form were recorded. The normal coordinate analysis of the optical active intra- and intermolecular vibrations of the α-form crystal of glycine was carried out. A modified Urey—Bradley type intramolecular potential was adopted. The observed factor group splittings were elucidated fairly well by using the intermolecular potential including the exchange repulsion—dispersion interaction between non-bonded atoms and the Coulomb interaction. The stretching potential for the hydrogen bonds was found to contribute appreciably to the lattice frequencies.

Structural studies of copper(I) complexes with ethylene. Crystal structures of [Cu(2,2′-bipyridine)(ethylene)]ClO4 and [Cu(1,10-phenanthroline)(ethylene)]ClO4

Abstract The crystal structures of the complexes [Cu(2,2′-bipyridine)(ethylene)]ClO4 (I) and [Cu(1,10-phenanthroline)(ethylene)]ClO4 (II) have been determined from X-ray diffraction studies. Complex I crystallizes in the triclinic space group, P 1 , with four molecules in a unit cell of dimensions a 10.657(1), b 6.998(1), c 18.251(2) A, α 91.05(1), β 93.35(1), and γ 84.97(1)°. Complex II crystallizes in the monoclinic space group, P21/a, with four molecules in a unit cell of dimensions a 19.981(5), b 10.904(2), c 6.955(1) A, and β 103.90(2)°. Both structures were solved by heavy-atom methods, and refined by block-diagonal least-squares methods. The final R-values for I and II were 0.044 for 2225 observed reflections for I and 0.066 for 2005 observed reflections for II. In both crystals, the CuI ion is coordinated to two nitrogen atoms of 2,2′-bipyridine or 1,10-phenanthroline, and two carbon atoms of ethylene in an approximately planar form. The CC bond distances of the coordinated ethylene molecules, 1.360(13) and 1.346(18) A for I and 1.361(22) A for II, do not show marked lengthening compared with that for free ethylene, and may be explained by dπ(Cu) → dπ (ethylene) back-bonding between the Cu 3dπ orbital and the Rydberg 3dπ orbital of the ethylene molecule.

Vibrational spectra of nitrobenzene-d0, -p-d and -d5 and normal vibrations of nitrobenzene

Abstract Infrared and Raman spectra of nitrobenzene-p-d and -d5 have been recorded in the liquid state and sixty-seven of the seventy-two fundamental frequencies of the two isotopes have been assigned by referring to the isotopic frequency shifts, the Raman depolarization ratios and the assignments of sodium benzoate-p-d and -d5. A normal coordinate analysis has been carried out for the five isotopic nitrobenzenes, -d0, -p-d, -d5, -18O2 and -15N. The force constants have been refined by the method of least squares and a good fit between the observed and the calculated frequencies has been obtained.

Infrared spectra of poly(ethylene glycol) dimethyl ethers in the crystalline state

Abstract Infrared spectra of CH 3 O(-CH 2 CH 2 O-) p CH 3 ( p = 1–7) in the crystalline state have been measured in the region 4000-400 cm −1 . Assignments of absorption bands have been made with reference to the dispersion curves (wavenumber vs. phase difference) calculated for an infinite chain of poly(ethylene glycol). Normal coordinates have also been treated on some of these molecules in order to check the vibrational assignments. The band progression observed at 520–590 cm −1 has been analyzed on the basis of the coupled oscillator model. Chain conformation of these molecules in the crystalline state is similar to that of the high polymer.

Anharmonic potential function of formaldehyde

Abstract By using a simple anharmonic potential including 25 higher-order constants, the vibrational frequencies, vibration-rotation interaction constants, and centrifugal distortion constants of formaldehyde were calculated to agree well with the observed values. The harmonic part of the potential gives favorable signs of compliance constants for the C 2v -type dissociations into the methylene radical and into carbon monoxide, as well as for the C s -type dissociation into the formyl radical. The cubic constants have adequate signs to predict the changes of quadratic constants on the dissociation of the CH or the CO bonds. From the Morse parameter of the CH bond, the heat of dissociation for the process H 2 CO → CO + 2H is calculated to be 137 kcal/mole.

Polarized Raman spectra and intermolecular potential of l-alanine crystal

Abstract Polarized Raman spectra of l -alanine and N-deuterated l -alanine single crystals have been measured. A normal coordinate analysis has been made for the optical active intra- and intermolecular vibrations of l -alanine crystal. The large factor group splittings observed for the CH3 asymmetric deformation and the CH3 torsional modes were elucidated well by using the potential including only the non-bonded atom—atom repulsion interaction. A good agreement was obtained between the observed and the calculated lattice vibrational frequencies on addition of the terms due to the hydrogen bond stretching and long range Coulomb interaction to the intermolecular potential.

Anharmonic Stretch–Stretch Interaction Force Constants of Triatomic Molecules

A model is proposed which, using the generally accepted form of the potential‐energy surface in the two bond stretching coordinates, allows the prediction of the anharmonic stretch–stretch interaction force constants from the quadratic interaction force constant. The model is applied to CO2 and N2O. Hydrogen cyanide, OCS, and H2O are also discussed.

Anharmonic force field of ethylene

A simple anharmonic force field of ethylene is proposed. It includes the principal cubic and quartic stretching constants derived from appropriate Morse functions for individual bonds and two other higher‐order constants. The quadratic part consists of general valence type constants that show the characteristics of the Pulay‐Meyer Set II force field. The perturbation method including a general treatment of the first‐ and the second‐order resonances has been used, and about 190 vibrational frequencies of ethylene and six deuterated ethylenes have been calculated to agree fairly well with the experimental values. The proposed potential gives also reasonable values of the Coriolis coupling constants, the centrifugal distortion constants, and the 13C‐isotope shifts. The signs of the compliance constants are consistent with the assumption of monotone changes of internal coordinates on the dehydrogenation into acetylene and on the dissociation into two methylene radicals.