Microwave spectrum, structure and nuclear quadrupole coupling constant tensor of ethyl chloride and vinyl chloride

Hayashi, Michiro; Inagusa, Toshihiro

doi:10.1016/0022-2860(90)80103-q

Cited by 53 publications

(34 citation statements)

References 7 publications

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“…The present data shows that the angle between the EFG-PA and the bond direction is 0.70°, and hence the second assumption is the more reasonable, with data as shown in Table 4. There is good agreement between the IA data and the present study for chloroethane, with similar angle 9 za 24.929 (compared with 26.9 from the averaged experimental data) [24], For both bromo-and iodo-ethane, the off-diagonal NQCC element x a b was determined, hence allowing the diagnonalisation of the tensor, and the EFG-PA to be determined without the assumptions for the chloro-compound. Again, the present results are in good agreement with experiment [29] [31].…”

Section: Quadrupole Coupling Constants In Relation To Structuresupporting

confidence: 80%

“…The ethyl halides provide the simplest non-axial symmetry cases; in the case of chloroethane, the difference in the two assumptions of (a) either zero asymmetry to enable the conversion of IA to EFG-PA data, or (b), assuming the EFG-PA to lie along the bond axis leads to results for the Xzz of -71.28 MHz and -68.84 MHz, respectively [24]. The present data shows that the angle between the EFG-PA and the bond direction is 0.70°, and hence the second assumption is the more reasonable, with data as shown in Table 4.…”

Section: Quadrupole Coupling Constants In Relation To Structurementioning

confidence: 99%

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Halogen Nuclear Quadrupole Coupling Constants in Non-axially symmetric Molecules; Ab initio Calculations, which Include Correlation, Compared with Experiment

Palmer

Blair-Fish

1998

Zeitschrift Für Naturforschung A

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Ab initio determination of the electric field gradient (EFG) tensors at halogen and other centres enabled determination of the nuclear quadrupole coupling constants (NQCC) for a diverse set of C 2v , C 3v and other symmetry molecules of general formula MH 2 X 2 and MHX 3 , where the halogen atoms (X) are Cl, Br and I, and the heavy central atoms (M) are C and Si. The study presents results at a standardised level of calculation, triple-zeta in the valence space plus polarisation functions (TZVP) for the equilibrium geometry stage; all-electron MP2 correlation is included in all these studies. For the bromo and iodo compounds, especially the latter, it is essential to allow core polarisation, by decontraction of the p,d-functions. This is conveniently done by initial optimization of the structure with a partly contracted basis, followed by reestablishment of the equilibrium structure with the decontracted basis.The NQCCs, derived from the EFGs, using the 'best' values for the atomic quadruple moments Cl, Br and I, lead to good agreement with the inertial axis (IA) data obtained from microwave spectroscopy. When the data from the present study is plotted against the values derived from the IA data, obtained by whatever approximations chosen by the MW authors, we obtain a linear regression for the data (85 points) with the slope 1.0365 and intercept -0.1737, with standard errors of 0.0042 and 0.2042, respectively; these are statistically identical results irrespective of whether the data is restricted to IA or EFG principal axis (PA) data.Since as in the C 3v MH 3 X compounds studied previously, a close correlation of the microwave spectral data with the calculations was observed using the 'best' current values for Q z , there seems no need to postulate that the values of Q Br for both 74 Br and M Br are seriously in error. A scaling downwards of Q z by about 5% for Br and I increases the agreement with experiment, but the contributions of relativistic effects are unknown, and could lead to further reassessment.Of the two common assumptions used in MW spectroscopy, to convert from IA to EFG-PA data, either (a) cylindrical symmetry of the NQCC along the bond direction, or (b) coincidence of the tensor principal element with the bond axis, the latter is found to be a much more realistic approximation.

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Section: Quadrupole Coupling Constants In Relation To Structuresupporting

confidence: 80%

Section: Quadrupole Coupling Constants In Relation To Structurementioning

confidence: 99%

Halogen Nuclear Quadrupole Coupling Constants in Non-axially symmetric Molecules; Ab initio Calculations, which Include Correlation, Compared with Experiment

Palmer

Blair-Fish

1998

Zeitschrift Für Naturforschung A

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“…The quadrupole coupling constants were calculated using the splittings of the three J = 2 ‹ 1 transitions. Their values (in MHz), v bb + v cc = 57.90 (16) and v bb À v cc = À6.72 (37) are close to the corresponding values of the ground state (57.21 (20) and À6.27 (24), respectively [6,21]). The experimental frequencies were corrected for the quadrupole hyperfine structure using these constants and the hypothetical unsplit frequencies were fitted using a WatsonHamiltonian in the A-reduction and I r representation.…”

Section: Introductionmentioning

confidence: 54%

“…Mode Description rotational constants [6] to yield the semi-experimental equilibrium rotational constants of Table 12. We have only used the constants of [6] because mixing sets of rotational constants is a questionable practice: a small incompatibility of the sets would affect the accuracy of the structure determination whereas the error practically compensates if all lines are measured and analyzed in the same way.…”

Section: Semi-experimental Equilibrium Structurementioning

confidence: 99%

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Microwave and high resolution infrared spectra of vinyl chloride, ab initio anharmonic force field and equilibrium structure

Demaison

Møllendal

Perrin

et al. 2005

Journal of Molecular Spectroscopy

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Molecular mechanics (MM3) studies of monochloroalkanes

Shim

Allinger

Bowen

1997

J. Phys. Org. Chem.

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Monochloroalkanes were studied using molecular mechanics and parameters were developed and incorporated into MM3. The new force field reproduces well molecular structures, conformational energy differences and vibrational frequencies. The compounds studied were methyl, ethyl, n‐propyl, isopropyl, n‐butyl, isobutyl, sec‐butyl, tert‐butyl, neopentyl, cyclopentyl and cyclohexyl chloride, 4‐tert‐butyl‐1‐chlorocyclohexane and 1‐chloroadamantane. The overall rms error for the averaged C—C and C—Cl bond lengths for the above set of compounds excluding sec‐butyl chloride, neopentyl chloride and 1‐chloroadamantane is 0·0047 Å, and the rms error for the vibrational frequencies is 377thinsp;cm−1. The moments of inertia (rg) are approximately 1% greater than the microwave values (ra0). Thermodynamic quantities are also compared with those observed using various experimental methods. © 1997 John Wiley & Sons, Ltd.

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Microwave spectrum, structure and nuclear quadrupole coupling constant tensor of ethyl chloride and vinyl chloride

Cited by 53 publications

References 7 publications

Halogen Nuclear Quadrupole Coupling Constants in Non-axially symmetric Molecules; Ab initio Calculations, which Include Correlation, Compared with Experiment

Halogen Nuclear Quadrupole Coupling Constants in Non-axially symmetric Molecules; Ab initio Calculations, which Include Correlation, Compared with Experiment

Microwave and high resolution infrared spectra of vinyl chloride, ab initio anharmonic force field and equilibrium structure

Molecular mechanics (MM3) studies of monochloroalkanes

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