Spectroscopiċ investigations of hydrogen bonding interactions in the gas phase. X. Properties of the hydrogen-bonded heterodimer HCN∙ ∙ ∙HF determined from hyperfine coupling and centrifugal distortion effects in its ground-state rotational spectrum

1985 ◽  
Vol 401 (1821) ◽  
pp. 327-347 ◽  
Keyword(s):  
Nuclear Spin ◽  
Hyperfine Coupling ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Rotational Spectrum ◽  
Centrifugal Distortion ◽  
Hyperfine Coupling Constants ◽  
Rotational Spectra ◽  
Isotopic Species ◽  
Centrifugal Distortion Constants

The rotational spectra of six isotopic species of HCN∙ ∙ ∙HF in their vibrational ground states have been observed by pulsed-nozzle, Fourier-transform, microwave spectroscopy and have been analysed to yield the rotational constants B 0 , centrifugal distortion constants D J and various hyperfine coupling constants X i (D), X 3 ( 14 N) and D 4, 5 as follows (subscripts refer to the numbering scheme H (1) C (2) N (3) ∙ ∙ ∙H (4) F (5) ). isotopic species B 0 / MH Z D J /kH Z X i (D)/kH Z X 3 ( 14 N)/MH Z D 4, 5 (H, F)/kH Z HC 15 N∙ ∙ ∙HF 3573 5874(2) 6.97(2) ─ ─ –242(6) HC 15 N∙ ∙ ∙DF 3551.5110 6.83 269(4)( i = 4) ─ ─ HC 14 N∙ ∙ ∙HF 3591.1552 6.99 ─ –4.098(4) –218(6) HC 14 N∙ ∙ ∙DF 3569.6576 6.86 259(2)( i = 4) –4.096(1) ─ DC 15 N∙ ∙ ∙HF 3360.3549 5.85 186(5)( i = 1) ─ –244(4) DC 15 N∙ ∙ ∙DF 3338.0824 5.81 { 181(10) ( i = 1) ─ ─ 283(7) ( i = 4) The B 0 values lead to conclusions about the dimer geometry, the D J values allow the hydrogen bond stretching force constant k σ to be determined and the hyperfine coupling constants provide information about the internal dynamics of the subunits. An analysis of the D nuclear quadrupole coupling and H, F nuclear spin nuclear-spin coupling constants demonstrates that the H—F bond lengthens by 0.14 Å when the heterodimer HCN∙ ∙ ∙HF is formed. (1 Å = 10 –10 m = 10 –1 nm.)

Rotational Spectrum of Aminoborane: Centrifugal Distortion Constants and Boron and Nitrogen Hyperfine Structure

1991 ◽  
Vol 46 (9) ◽  
pp. 770-776 ◽  
Author(s):  
Kirsten Vormann ◽  
Helmut Dreizler ◽  
Jens Doose ◽  
Antonio Guarnieri
Keyword(s):  
Hyperfine Structure ◽  
Spin Rotation ◽  
Coupling Constants ◽  
Rotational Spectrum ◽  
Centrifugal Distortion ◽  
Rotational Spectra ◽  
Quadrupole Coupling ◽  
Wave Region ◽  
Nuclear Quadrupole ◽  
Centrifugal Distortion Constants

AbstractThe boron and nitrogen hyperfine structure in the rotational spectra of two aminoborane isotopomers, 11 BH2NH2 and 10BH2NH2, has been investigated and the quadrupole coupling constants of boron 10B, 11B and nitrogen 14N have been determined. We get the following results for the nuclear quadrupole coupling constants: χaa(11B) = -1.684 (14) MHz, χbb(11B) = -2.212 (11) MHz, χcc(11B) = 3.896(11) MHz, χaa(10B) = -3.481 (11) MHz, χbb(10B) = -4.623 (14) MHz, χCC(10B) = 8.104 (14) MHz and xaa(14N) = 0.095 (9) MHz, χbb(14N) = 2.091 (8) MHz, χcf4 (14N)=-2.186 (8) MHz. These nitrogen quadrupole coupling constants are those of the 11BH2 NH2 isotopomer. Additionally we were able to determine two out of the three spin rotation coupling constants caa, cbb, and ccc of boron, caa(11 B = 55.2 (26) kHz, cbb(11B) = 6.62 (36) kHz, caa (10B) = 15.26 (69) kHz and cbb(10B) = 4.94 (70) kHz. The spin rotation coupling constants ccc had to be fixed to zero in both cases. Furthermore we measured the rotational spectra in the mm-wave region to determine all quartic and several sextic centrifugal distortion constants according to Watson's A and S reduction

The Centimeter and Millimeter Microwave Spectrum of 1,1-Difluoro-2-Chloroethylene

1993 ◽  
Vol 48 (3) ◽  
pp. 514-518 ◽  
Author(s):  
Luis A. Leal ◽  
J. C. López ◽  
J. L. Alonso ◽  
A. Guarnieri
Keyword(s):  
Microwave Spectrum ◽  
Coupling Constants ◽  
Centrifugal Distortion ◽  
Frequency Range ◽  
Coupling Analysis ◽  
Rotational Spectra ◽  
First Order ◽  
Isotopic Species ◽  
Quadrupole Coupling ◽  
Centrifugal Distortion Constants

Abstract The rotational spectra of both 35Cl and 37Cl 1,1-difluoro-2-chloroethylene isotopomers have been measured in the frequency range 12-225 GHz. A first order quadrupole coupling analysis has been performed for both isotopic species. The calculated quadrupole coupling constants for the 37Cl species not previously reported are χaa = - 49.2 (2), χbb = 14.2 (1), and χcc = 28.7 (1). Accurate rotational constants, quartic and some sextic centrifugal distortion constants have also been determined for both isotopomers from the fit to the observed central frequencies.

Boron and Nitrogen Hyperfine Structure in the Rotational Spectrum of Aminodifluoroborane

1991 ◽  
Vol 46 (10) ◽  
pp. 909-913
Author(s):  
◽  
Helmut Dreizler
Keyword(s):  
Hyperfine Structure ◽  
Coupling Constants ◽  
Rotational Spectrum ◽  
Centrifugal Distortion ◽  
Rotational Spectra ◽  
Quadrupole Coupling ◽  
Nuclear Quadrupole ◽  
Centrifugal Distortion Constants

AbstractThe boron and nitrogen hyperfine structure in the rotational spectra of aminodifluoroborane has been investigated and the quadrupole coupling constants of 11B and nitrogen have been determined. We get the following results for the nuclear quadrupole coupling constants: Χaa(11B) = - 1.971 (6) MHz, Xbb(11B) = 0.500(11) MHz, Xcc(11B) - 2.471 (11) MHz, and Xaa(14N) = 0.890 (5) MHz, Xbb(14N) = 2.303 (7) MHz, Xcc(14N) = - 3.193 (8) MHz. Additionally we determined rotational and centrifugal distortion constants according to Watson's A reduction.

Vibronic Ground State Rotational Spectrum of 3-Bromothiophene

1983 ◽  
Vol 38 (11) ◽  
pp. 1238-1247 ◽  
Author(s):  
Dirk Hübner ◽  
Eckhard Fliege ◽  
Dieter H. Sutter
Keyword(s):  
Ground State ◽  
Coupling Constants ◽  
Fourier Transform Spectrometer ◽  
Rotational Spectrum ◽  
Centrifugal Distortion ◽  
Frequency Range ◽  
Isotopic Species ◽  
Quadrupole Coupling ◽  
Set Up ◽  
Centrifugal Distortion Constants

The rotational spectrum of 3-bromothiophene was investigated in the frequency range between 8 and 18 GHz by use of a microwave Fourier transform spectrometer. Both a- and b-type spectra were assigned for the vibronic ground state. Rotational constants, quartic centrifugal distortion constants and quadrupole coupling constants were obtained for the 79Br- and 81Br-isotopic species. For the analysis, the effective rotational Hamiltonian including centrifugal distortion in the form of Van Eijck's symmetric top reduction and bromine quadrupole coupling was set up in the coupled basis of the limiting symmetric top, J, K, I, F, MF>, and was diagonalized numerically. Spin rotation interaction was neglected

On the d-Orbital Influence in INDO Calculations of NMR and ESR Parameters of Sulphur Heterocyclics

1973 ◽  
Vol 28 (12) ◽  
pp. 1951-1953 ◽  
Author(s):  
V. Galasso
Keyword(s):  
Nuclear Spin ◽  
Hyperfine Coupling ◽  
The Self ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Indo Method ◽  
Hyperfine Coupling Constants ◽  
Self Consistent ◽  
Indo Calculations ◽  
Spin Coupling Constants

Comparative calculations by the self-consistent perturbed INDO method on thiophene and by the unrestricted HF INDO method on the 2-thenyl radical show that satisfactory reproduction of nuclear spin coupling constants and hyperfine coupling constants for sulphur heterocyclics can be obtained by considering the sp interaction only.

33S Nuclear Hyperfine Structure in the Rotational Spectrum of Thiazole

1993 ◽  
Vol 48 (12) ◽  
pp. 1219-1222 ◽  
Author(s):  
U. Kretschmer ◽  
H. Dreizler
Keyword(s):  
Fourier Transform ◽  
Hyperfine Structure ◽  
Molecular Beam ◽  
Microwave Spectroscopy ◽  
Coupling Constants ◽  
Rotational Spectrum ◽  
Centrifugal Distortion ◽  
Quadrupole Coupling ◽  
Nuclear Quadrupole ◽  
Centrifugal Distortion Constants

Abstract We investigated the 33S nuclear quadrupole coupling of thiazole- 33S in natural abundance by molecular beam Fourier transform microwave spectroscopy. In addition the 14N nuclear quadrupole coupling could be analyzed with high precision. We derived the rotational constants A = 8529.29268 (70) MHz, B = 5427.47098 MHz, and C = 3315.21676 (26) MHz, quartic centrifugal distortion constants and the quadrupole coupling constants of 33S χaa = 7.1708 (61) MHz and χbb= -26.1749 (69) MHz and of 14N χ aa = -2.7411 (61) MHz and χbb = 0.0767 (69) MHz.

The microwave spectrum of the ClS2 free radical

1994 ◽  
Vol 72 (11-12) ◽  
pp. 1043-1050 ◽  
Author(s):  
Masaharu Fujitake ◽  
Eizi Hirota
Keyword(s):  
Free Radical ◽  
Force Field ◽  
Electronic Spectroscopy ◽  
Spin Rotation ◽  
Rotational Spectrum ◽  
Centrifugal Distortion ◽  
Harmonic Force ◽  
Isotopic Species ◽  
Spin Resonance ◽  
Centrifugal Distortion Constants

The rotational spectrum of the ClS2 free radical in the gaseous phase has been observed in the millimetre- and submillimetre-wave regions. The ClS2 radical was generated by a dc glow discharge in either S2Cl2 or SCl2. Both a- and b-type R-branch transitions, most of which were split into two fine structure components, were detected for both of the 35Cl and 37Cl isotopic species in the ground vibronic state. As expected from the small hyperfine interaction constants reported by an electron spin resonance (ESR) study, the hyperfine structure was resolved for none of the transitions observed in the present study. Analysis of the observed transition frequencies yielded rotational and centrifugal distortion constants and also spin–rotation interaction constants with their centrifugal corrections. The spin–rotation interaction constants obtained in the present study were consistent with g values of the ESR study. The rotational constants of the two isotopic species led to the structure parameters r(S—S) = 1.906 (7) Å, r(S—Cl) = 2.071 (5) Å, and θ(SSCl) = 110.3 (4)°. A harmonic force field was derived from the observed centrifugal distortion constants and inertial defects combined with the ν1 frequency reported in literature on electronic spectroscopy. This harmonic force field yielded the ν2 and ν3 frequencies (445 (21) and 213.0 (2) cm−1, respectively, for 35ClS2), which differed considerably from the values reported previously.

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