Microwave spectrum, structure, nuclear quadrupole coupling constants of chlorine, and ab initio calculation of 2-chloropropionitrile

Ogata, Teruhiko; Yamashita, Noriko; Takata, Shigetoshi

doi:10.1016/s0022-2860(96)09740-2

Cited by 5 publications

(2 citation statements)

References 11 publications

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“…The optimized geometry of ( S )-2-chloropropionitrile (see Figure ) was determined using analytic energy gradients at the B3LYP 11,52,53 level of theory with the split-valence 6-311++G** basis set, ,− which is the same level used by Wiberg et al This optimized structure was confirmed to be a minimum on the potential energy surface via harmonic vibrational frequency calculations, carried out using analytic energy second-derivative methods. The computed rotational constants compare to within 1.3% with those determined by Ogata et al from the experimental microwave spectrum . The corresponding theoretical structure agrees reasonably well with that inferred from the microwave data, with C−C bond distances reproduced to within a few thousandths of an Angstrom.…”

Section: Resultssupporting

confidence: 83%

Ab Initio Optical Rotatory Dispersion and Electronic Circular Dichroism Spectra of (S)-2-Chloropropionitrile

2006

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Coupled-cluster and density-functional methods have been used to determine specific rotations and electronic circular dichroism (ECD) rotational strengths for (S)-2-chloropropionitrile. Coupled-cluster specific rotations using both the length- and velocity-gauge representations of the electric-dipole operator, computed with basis sets of triple-zeta quality containing up to 326 functions, compare very well with recently reported gas-phase cavity-ring-down polarimetry data. ECD rotational strengths for the six lowest-lying excited states are found to vary in sign, and the second excited state, which has a larger rotational strength than the first by a factor of 4, was found to yield a much larger contribution (by a factor of 10) to the overall negative specific rotation observed both experimentally and theoretically. However, both valence and Rydberg states appear to make substantial contributions to the total rotation, often of opposite sign from the converged/linear-response result. Furthermore, the sum-over-states approach was found to be inadequate for reproducing the specific rotations derived from the linear-response approach, even when 100 excited states (well beyond the estimated ionization limit) were included in the summation. Density-functional specific rotations using the B3LYP functional with basis sets of quadruple-zeta quality containing up to 588 functions are found to be too large compared to experiment by approximately a factor of 2. This error appears to be related to both the underestimation of the electronic excitation energies, as well as concomitant overestimation of the corresponding ECD rotational strengths. Although earlier studies reported good agreement between density-functional specific rotations and experiment when electric-field-dependent functions were used in conjunction with a double-zeta-quality basis set, the results reported here, which are near the basis-set limit, suggest that this agreement may be fortuitous.

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Section: Resultssupporting

confidence: 83%

Ab Initio Optical Rotatory Dispersion and Electronic Circular Dichroism Spectra of (S)-2-Chloropropionitrile

2006

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“…The structure and vibrational frequencies for 1 were calculated at the B3LYP/6-311++G** level, which usually gives very satisfactory estimates of the frequencies. 15 The structure is compared with that determined via microwave spectroscopy 16 in Table 3, and the vibrational frequencies are given in Table 4. The MP2 calculated structural parameters are in somewhat better agreement with the experimental structures than B3LYP.…”

Section: Vibrational Modes For Chloropropionitrile and Their Effect O...mentioning

confidence: 99%

Chiroptical Properties of 2-Chloropropionitrile

et al. 2005

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(S)-(-)-2-chloropropionitrile has been prepared from (S)-(+)-alanine, and the ORD curves have been obtained in several solvents and in the gas phase. A reaction field extrapolation of the solution data to the gas phase led to an estimated value of [alpha]D = -21 degrees, whereas the interpolated gas phase value is -8 degrees. The specific rotation was found to be temperature dependent in ethylcyclohexane solution over the range 0-100 degrees C. Although rotation of the methyl group leads to large calculated effects on the specific rotation, it does not lead to the temperature dependence. Rather, a low frequency mode at 224 cm(-1) was found to be responsible. This is a mixed mode involving methyl torsion and C-C[triple bond]N bending. The specific rotations calculated at the B3LYP/aug-cc-pVDZ level including electric field dependent functions are in very good agreement with the measured gas phase values.

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