ROTATIONAL SPECTRA AND NUCLEAR QUADRUPOLE COUPLING CONSTANTS OF IODOIMIDAZOLES

Abstract The microwave spectra of CF3CN, CH2FCN, CHDFCN, CD2FCN and CHF2CN have been measured and analysed. The nuclear quadrupole hyperfine splittings due to 14N have been measured by Microwave Fourier Transform spectroscopy. The nuclear quadrupole coupling constants, transformed to the bonding axis systems of the C-C ≡ N groups, are shown to be in accord with structural predictions of the p-electron populations at the nitrogen atom.

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Microwave Spectrum and Nuclear Quadrupole Interaction of 3-Bromothiophene in Excited Vibrational States

Zeitschrift für Naturforschung A ◽

10.1515/zna-1983-1206 ◽

1983 ◽

Vol 38 (12) ◽

pp. 1309-1319 ◽

Cited By ~ 7

Author(s):

Yoshiaki Sasada

Keyword(s):

Excited States ◽

Nuclear Quadrupole Interaction ◽

Coupling Constants ◽

Vibrational Modes ◽

Centrifugal Distortion ◽

Vibrational States ◽

Rotational Spectra ◽

Quadrupole Coupling ◽

Nuclear Quadrupole ◽

Centrifugal Distortion Constants

Abstract The rotational spectra of 3-bromothiophene in the excited states of two vibrational modes were observed and the rotational constants, the centrifugal distortion constants, and the nuclear quadrupole coupling constants were determined. The wave numbers of the two vibrational modes were evaluated to be 210 cm-1 and 320 cm-1 by measuring relative intensities of the ground and excited vibrational transitions. Variations in the inertia defect for each of the vibrational modes are compared with the results of the approximate calculation.

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

Zeitschrift für Naturforschung A ◽

10.1515/zna-1991-0905 ◽

1991 ◽

Vol 46 (9) ◽

pp. 770-776 ◽

Cited By ~ 1

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

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ab initio Calculation of 33S Quadrupole Coupling Constants. Reanalysis of the 33S Hyperfine Structure in the Rotational Spectrum of Thiirane

Zeitschrift für Naturforschung A ◽

10.1515/zna-1997-0401 ◽

1997 ◽

Vol 52 (4) ◽

pp. 297-305 ◽

Cited By ~ 9

Author(s):

Barbara Kirchner ◽

Hanspeter Huber ◽

Gerold Steinebrunner ◽

Helmut Dreizler ◽

Jens-Uwe Grabow ◽

...

Keyword(s):

Ab Initio Calculation ◽

Experimental Information ◽

Coupling Constants ◽

Basis Sets ◽

Rotational Spectrum ◽

Rotational Spectra ◽

Coupling Tensor ◽

Quadrupole Coupling ◽

Local Quality ◽

Nuclear Quadrupole

Abstract We present quantum chemical calculations on the MP4(SDQ) level with basis sets of high local quality to determine the nuclear quadrupole coupling tensor of 33S in a series of molecules, which were investigated up to now by microwave spectroscopy. The analysis of the nuclear quadrupole coupling in the rotational spectra provided experimental information on the tensors. As an example for such an analysis, improved values for thiirane, C2H433S, are given: χaa = - 32.9425(78) MHz, χbb = -16.402(14) MHz, χcc = 49.345(14) MHz.

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14N Nuclear Quadrupole Hyperfine Structure in the Microwave Spectrum of Methyl Azide, CH3N3

Zeitschrift für Naturforschung A ◽

10.1515/zna-1989-0711 ◽

1989 ◽

Vol 44 (7) ◽

pp. 669-674 ◽

Cited By ~ 24

Author(s):

N. Heineking ◽

M.C.L. Gerry

Keyword(s):

Hyperfine Structure ◽

Ab Initio Calculation ◽

Structural Information ◽

Microwave Spectrum ◽

Coupling Constants ◽

Rotational Spectra ◽

Isotopic Species ◽

Quadrupole Coupling ◽

Nuclear Quadrupole ◽

First Time

Abstract The 14N nuclear quadrupole hyperfine structure in the rotational spectra of three isotopic species of methyl azide, CH3 14N3, CH3 15N14N2, and CH3 14N2 15N, has been resolved using microwave Fourier transform spectroscopy. The quadrupole coupling constants of 14N at all three positions have been evaluated and are compared with those from an ab initio calculation in the literature.Since the spectra of the substituted species have been obtained for the first time, they have provided new structural information: the rotational constants are consistent with a structure in which the NNN chain is slightly bent.

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Boron and Nitrogen Hyperfine Structure in the Rotational Spectrum of Aminodifluoroborane

Zeitschrift für Naturforschung A ◽

10.1515/zna-1991-1011 ◽

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.

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

Zeitschrift für Naturforschung A ◽

10.1515/zna-1993-0406 ◽

1993 ◽

Vol 48 (4) ◽

pp. 570-576 ◽

Cited By ~ 13

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.

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Methyl Internal Rotation and 14N Nuclear Quadrupole Coupling from the Rotational Spectra of Ethyl Isocyanide, iso-Propyl Isocyanide and gauche- and trans-n-Propyl Isocyanide

Zeitschrift für Naturforschung A ◽

10.1515/zna-1992-1011 ◽

1992 ◽

Vol 47 (10) ◽

pp. 1067-1072 ◽

Cited By ~ 10

Author(s):

Michael Krüger ◽

Helmut Dreizler

Keyword(s):

Fourier Transform ◽

Internal Rotation ◽

Vibrational State ◽

Fourier Transform Spectroscopy ◽

Coupling Constants ◽

Ground Vibrational State ◽

Rotational Spectra ◽

Barrier Heights ◽

Quadrupole Coupling ◽

Nuclear Quadrupole

AbstractThe barrier heights (V3) hindering methyl internal rotation were determined with microwave Fourier transform spectroscopy from the ground vibrational state for the title molecules and found to be V3 = 3.336(52) kcal/mol for ethyl isocyanide, V3 > 3.1 kcal/mol for iso-propyl isocyanide, V3 = 2.894(23) kcal/mol for gauche-n-propyl isocyanide and V3 = 2.954(22) kcal/mol for transn- propyl isocyanide. The quadrupole coupling constants of iso-propyl isocyanide are χaa = 179.3(31) kHz, χbb = -140(15) kHz and χcc - 39(15) kHz; the constants of trans-n-propyl isocyanide were determined to be χaa = 268.1 (71) kHz, χbb = - 108(23) kHz and χcc = - 160(23) kHz.

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