The molecular structures of 2-, 3- and 4-chloropyridine and chloropyrazine in the gas phase by electron diffraction and ab initio calculations †

Smart, Bruce A.; Morrison, Carole A.; Papathomas, Paul M.; Brookman, Charles A.; Robertson, Heather E.; Rankin, David W. H.

doi:10.1039/a809882d

Cited by 9 publications

(2 citation statements)

References 14 publications

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“…It is seen from the tables that the theoretically calculated gas-phase data of the bond lengths and bond angles for both 2Clpy and 3Clpy agree nicely with the experimental data reported by Smart et al 36 The only disagreement observed is in the length of the C-Cl bond. The B3LYP/6-31CG(d,p) method seems to work precisely for these systems.…”

Section: Geometrical Structure and Interaction Energiessupporting

confidence: 77%

“…9 Vibrational dephasing of the C-Cl stretching mode of 2Clpy and 3Clpy in a methanol environment was carried out using polarized Raman and DFT calculations. 10 As explained by Torri, 11,12 the dipole derivative (υµ m /υq m ) is enhanced upon hydrogen bonding and consequently the infrared (IR) intensity, being proportional to (υµ m /υq m ), 2 becomes stronger owing to the interaction with the electric field of the surrounding molecules.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Raman and DFT study of hydrogen‐bonded 2‐ and 3‐chloropyridine with methanol

Singh

Vikram

Singh

et al. 2008

J Raman Spectroscopy

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Precise polarized Raman measurements of 2-chloropyridine (2Clpy) in the region 560-1060 cm −1 and 3-chloropyridine (3Clpy) in the region 680-1080 cm −1 at different concentrations in mole fraction of methanol were made to calculate the isotropic part of the Raman spectra, which has contributions only from vibrational dephasing. A detailed analysis of the Raman spectra was carried out to see the variation of peak position and linewidth. The dephasing is mode specific. The trigonal bending mode of 3Clpy has two components when it is mixed with methanol. The relative intensities of these two bands are used to calculate the equilibrium constants. The ring-breathing mode of 3Clpy, on the other hand, remains single in the mixture. The appearance of a new band corresponding to the trigonal bending mode, as well as the nonappearance of that of the ring-breathing mode, is also shown by the density functional theory (DFT) study of gas phase and methanol-solvated complexes. The vibrational dephasing time for the hydrogen-bonded ring-breathing mode is calculated from the linear Raman linewidth and peak position data. For other modes, it was not possible to calculate the dephasing time because of the nonavailability of a suitable theoretical model. Contrary to 3Clpy, in 2Clpy the ring-breathing mode becomes a doublet but the trigonal bending mode remains single. It is seen that the hydrogen-bonding capacity of chloropyridines is highly influenced by the position of the Cl atom. Single and double components of these modes are also explained by DFT calculations. We obtained excellent match of the experimental and theoretical spectra with the B3LYP/6-31+G (d,p) method.

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Section: Geometrical Structure and Interaction Energiessupporting

confidence: 77%

Section: Introductionmentioning

confidence: 99%