The microwave spectrum, barrier to internal rotation of the methyl group, and 14N nuclear quadrupole coupling constants in trans-crotononitrile

1971 ◽  
Vol 37 (1) ◽  
pp. 92-99 ◽  
Author(s):  
S.L. Hsu ◽  
W.H. Flygare
Keyword(s):  
Internal Rotation ◽  
Microwave Spectrum ◽  
Coupling Constants ◽  
Methyl Group ◽  
Quadrupole Coupling ◽  
In Trans ◽  
Nuclear Quadrupole

Nuclear Quadrupole Hyperfine Structure and Methyl Torsional Fine Structure in the Rotational Spectra of N,N-Dimethylformamide and N-Nitrosodimethylamine

1993 ◽  
Vol 48 (4) ◽  
pp. 570-576 ◽  
Author(s):  
N. Heineking ◽  
H. Dreizler
Keyword(s):  
Fourier Transform ◽  
Fine Structure ◽  
Hyperfine Structure ◽  
Internal Rotation ◽  
Amino Nitrogen ◽  
Coupling Constants ◽  
Methyl Group ◽  
Rotational Spectra ◽  
Quadrupole Coupling ◽  
Nuclear Quadrupole

Abstract The complicated nuclear quadrupole hyperfine structure and methyl torsional fine structure in the rotational spectra of N,N-dimethylformamide and N-nitrosodimethylamine have been studied using microwave Fourier transform spectroscopy. It has been found that both molecules are rather similar in terms of their parameters of methyl group internal rotation as well as in terms of their amino nitrogen quadrupole coupling constants.

Microwave Spectrum of N-Methyl Morpholine

1974 ◽  
Vol 52 (3) ◽  
pp. 434-439 ◽  
Author(s):  
S. C. Dass ◽  
R. Kewley
Keyword(s):  
Dipole Moment ◽  
Vibrational State ◽  
Microwave Spectrum ◽  
Coupling Constants ◽  
Vibrational States ◽  
Methyl Group ◽  
Ground Vibrational State ◽  
Chair Form ◽  
Quadrupole Coupling ◽  
Nuclear Quadrupole

The microwave spectrum of N-methyl morpholine has been investigated within the 8 to 40 GHz region. The observed rotational constants for the ground vibrational state are (in MHz), A = 4821.235(0.077), B = 2342.579(0.004), and C = 1719.452(0.003). The dipole moment components have been determined as (in D), μa = 1.21(0.02), μc = 0.10(0.03), and μ= 1.21(0.02). The values of these parameters show that the observed spectrum is due to the chair form with an equatorial methyl group. The 14N nuclear quadrupole coupling constants have the values (in MHz), χaa = 2.4(0.1), χbb =.6(0.3) and χcc = −5.0(0.2). Sets of rotational transitions due to six excited vibrational states have also been assigned.

The Microwave Spectrum of 4-Methylisothiazole

1991 ◽  
Vol 46 (7) ◽  
pp. 635-638 ◽  
Author(s):  
H.-W. Nicolaisen ◽  
J.-U. Grabow ◽  
N. Heineking ◽  
W. Stahl
Keyword(s):  
Fourier Transform ◽  
Internal Rotation ◽  
Molecular Beam ◽  
Microwave Spectrum ◽  
Coupling Constants ◽  
Fourier Transform Spectrometer ◽  
Methyl Group ◽  
Quadrupole Coupling ◽  
Internal Rotor ◽  
Rotor Axis

The microwave spectrum of 4-methylisothiazole was assigned by means of a pulsed molecular beam microwave Fourier transform spectrometer. Analysis of the spectrum yielded the rotational constants .4 = 7370.642(31) MHz, B = 2515.8461 (30) MHz, C = 1897.2863(33) MHz, a threefold barrier to internal rotation of the methyl group of V3 = 3170.81 (130) GHz≙ 105.7669(430) cm-1, a momentum of inertia of the methyl group of Iα = 3.16769(130) amu · Å2 and an angle between internal rotor axis and principal a-axis of Θ= 5.406(38)°. The nitrogen quadrupole coupling constants were determined to be χ+ = χbb + χcc = 1.4822(14) MHz, χ -= χbb-χcc = - 1.4353(25) MHz and χab= - 3.16(12) MHz.

Zum Mikrowellenspektrum des Isobutyronitrils

1967 ◽  
Vol 22 (4) ◽  
pp. 543-545 ◽  
Author(s):  
G. E. Herberich
Keyword(s):  
Lower Bound ◽  
Internal Rotation ◽  
Barrier Height ◽  
Microwave Spectrum ◽  
Coupling Constants ◽  
Methyl Groups ◽  
Kcal Mole ◽  
Rotational Constants ◽  
Quadrupole Coupling ◽  
Nuclear Quadrupole

The microwave spectrum of isobutyronitrile has been investigated in the region from 5 — 30 GHz. A and C type transitions have been observed. No splittings due to internal rotation of the methyl groups could be detected and a lower bound of 2.6 kcal/mole for the barrier height is established.Values for the rotational constants are 7.940 95 ± 0.000 04, 3.968 039 ± 0.000 010 and 2.901 030 ± 0.000 010 GHz.The nuclear quadrupole coupling constants are χαα=—3.905±0.010 MHz, χbb=2.077±0.02 MHz and χcc=1.828±0.017 MHz.

Microwave Spectrum and Nuclear Quadrupole Coupling of 2-Chloropyridine

1987 ◽  
Vol 42 (2) ◽  
pp. 197-206 ◽  
Author(s):  
M. Meyer ◽  
U. Andresen ◽  
H. Dreizler
Keyword(s):  
Excited State ◽  
Ground State ◽  
Microwave Spectrum ◽  
Coupling Constants ◽  
Vibrationally Excited ◽  
Isotopic Species ◽  
Quadrupole Coupling ◽  
Nuclear Quadrupole ◽  
Mo Theory

The microwave spectrum of 2-chloropyridine, 2-Cl(C5H4N), has been studied to determine the 35Cl, 37Cl and 14N nuclear quadrupole coupling constants. The results are discussed within a simple MO theory. We propose an approximate r0-structure under certain assumptions. In addition to the ground state we observed one vibrationally excited state of both chlorine isotopic species of 2-chloropyridine.

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