The microwave spectrum of 5-methylthiazole: methyl internal rotation, 14N nuclear quadrupole coupling and electric dipole moment

1988 ◽  
Vol 190 ◽  
pp. 295-305 ◽  
Author(s):  
W. Jäger ◽  
H. Mäder
Keyword(s):  
Dipole Moment ◽  
Internal Rotation ◽  
Electric Dipole Moment ◽  
Electric Dipole ◽  
Microwave Spectrum ◽  
Quadrupole Coupling ◽  
Nuclear Quadrupole

The Microwave Spectrum of 4-Methylisoxazole: 14N Nuclear Quadrupole Coupling, Methyl Internal Rotation and Electric Dipole Moment

1987 ◽  
Vol 42 (5) ◽  
pp. 501-506 ◽  
Author(s):  
W. Jäger ◽  
H. Dreizler ◽  
H. Mäder ◽  
J. Sheridan ◽  
C. T. Walls
Keyword(s):  
Dipole Moment ◽  
Internal Rotation ◽  
Electric Dipole Moment ◽  
Electric Dipole ◽  
Microwave Spectrum ◽  
Centrifugal Distortion ◽  
Frequency Range ◽  
Principal Axes ◽  
Quadrupole Coupling ◽  
Nuclear Quadrupole

The microwave spectrum of 4-methylisoxazole has been investigated in the frequency range from 8 to 40 GHz, employing both Stark and Fourier transform spectroscopy. We present the results from a 14N quadrupole hyperfine structure, a fourth-order centrifugal distortion and an IAM methyl internal rotation analysis. The components of the electric dipole moment with respect to the principal axes of inertia have been obtained from the Stark splittings of some rotational lines.

The Microwave Spectrum of Imidazole; Complete Structure and the Electron Distribution from Nuclear Quadrupole Coupling Tensors and Dipole Moment Orientation

1981 ◽  
Vol 36 (12) ◽  
pp. 1378-1385 ◽  
Author(s):  
Dines Christen ◽  
John H. Griffiths ◽  
John Sheridan
Keyword(s):  
Dipole Moment ◽  
Electric Dipole Moment ◽  
Electric Dipole ◽  
Electron Distribution ◽  
Ring Structure ◽  
Microwave Spectrum ◽  
Complete Structure ◽  
Quadrupole Coupling ◽  
Stark Effects ◽  
Nuclear Quadrupole

Spectra have been measured for eleven isotopic forms of imidazole, including single substitutions at each nucleus in turn. A complete rs-structure is obtained. The ring structure is: N(1)-C(2) = 1.364 Å, C(2)-N(3) = 1.314 Å, N(3)-C(4) = 1.382 Å, C(4)-C(5) = 1.364 Å, C(5)-N(1) = 1.377 Å, ≮N(1)C(2)N(3) = 112.0°, ≮C(2)N(3)C(4) = 104.9°, ≮N(3)C(4)C(5) = 110.7°, ≮C(4)C(5)N(1) = 105.5° and ≮C(5)N(1)C(2) = 106.9°. The N(1)-H(1) distance is 0.998 Å, while the C-H distances are all very close to 1.078 Å. The bonds N(1)-H(1) and C(2)-H(2) lie close to the external bisectors of the respective ring angles, but C(4)-H(4) and C(5)-H(5) are each displaced by several degrees from these bisectors towards N(3) and N(1) respectively. The electric dipole moment is established as 3.67 (5) D from Stark effects, directed almost parallel with the line joining the nitrogen nuclei. The properties and orientations of the two 14N-nuclear quadrupole tensors have been investigated, in particular through the spectra of the two mono-14N-imidazoles.

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