Vibrational spectra, phase transitions and conformers of 1,4‐dichlorobut‐2‐yne

Karlsson, Arne; Klæboe, P.; Nielsen, Claus J.

doi:10.1002/jrs.1250180703

Cited by 8 publications

(1 citation statement)

References 24 publications

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“…The former is more stable at high pressures, but metastable at low temperature/normal pressure, in which the gauche crystal' is the more stable. 13 Only one conformation (gauche) is observed in the crystal lattices of ClF, and with two fluorines the gauche conformation is preferred2' in all states of aggregation. The conformational preference apparently depends on the size and electronegativities of the halogen substituents.…”

Section: Crystal Phasementioning

confidence: 99%

Vibrational spectra and conformation of 1‐chloro‐4‐fluorobut‐2‐yne and ab initio calculations on 1,4‐dihalobut‐2‐ynes

Karlsson

Klæboe

Nielsen

1992

J Raman Spectroscopy

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Raman spectra were recorded in the 3200-5 cm-' range for l-chloro-Qfluorobut-2yne as a liquid at various temperatures and as amorphous and different crystalline solids at low temperature. In the liquid, the Raman spectra showed broad, asymmetrical band shapes as previously reported for other 1,4-dihalobut-Z-ynes. Additional IR and far-IR spectra were obtained of the liquid, vapour, amorphous and crystalline solids at low temperature, and of the compound isolated in argon and nitrogen matrices at 13 K. The vapour and liquid spectra were interpreted in terms of a low barrier to internal rotation and the crystal spectra of a single conformer, gauche. The unusual band shapes in the low-frequency Raman spectra of the l,ddihalobut-2-ynes are discussed and are reproduced fairly well by a simple model of a molecule exhibiting nearly free internal rotation. The agreement between the observed and calculated spectra is goad for all the molecules studied when ab initio potentials are applied in the model calculations. Temperature effects in the Raman spectra of liquid lchloro-4-fluorobut-2-yne can also be derived from the model. Internal rotation in l,Uifluoro-, 1,4-dichloro-, lchloro-Qfluoro-, 1,ddibromo-and 1,Q diiodobut-2-yne was studied with the aid of ub initio calculations. The barriers were found to be low and decreasing through the series from 1,Qdifluoro-to 1,4-diiodobut-2-yne accompanied by an increase in the equilibrium dihedral angle, X-CCCC-Y, from 101" in 1,4-difluorobut-2-yne to 180" in 1,4-diiodobut-2-yne. The systematic variations through the series were correlated with the local dipole moments of the halomethyl groups and the electronegativities of the halogen substituents.

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Section: Crystal Phasementioning

confidence: 99%

Vibrational spectra and conformation of 1‐chloro‐4‐fluorobut‐2‐yne and ab initio calculations on 1,4‐dihalobut‐2‐ynes

Karlsson

Klæboe

Nielsen

1992

J Raman Spectroscopy

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The conformers of chloromethylmethyldifluorosilane studied by vibrational spectroscopy andab initio methods

Aleksa

Klæboe

Nielsen

et al. 2000

J. Raman Spectrosc.

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Vibrational spectra and conformations of 1, 4‐dibromobut‐2‐yne and 1,4‐diiodobut‐2‐yne

Karlsson

Bauza

Klæboe

et al. 1992

J Raman Spectroscopy

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The Raman spectra of l,ddibromobut-%yne (BrBr) as a liquid at various temperatures and as an amorphous and crystalline solid at low temperatures were recorded in the 3200-10 cm-' region. IR spectra of the liquid at room temperature and of the amorphous and crystalline solids at low temperatures (4000-50 cm-') were obtained. Additional IR spectra of the vapour were recorded (4000-500 cm-I). The spectra of the liquid phase showed characteristic, broad bands below 500 cm-'. No temperature dependence was detected in these, and the spectra of the amorphous solid at 90 K are almost identical with the room temperature spectra of the liquid. A shoulder on the Rayleigh line was observed at cu. 20 cm-' in the Raman spectrum of the amorphous BrBr at 90 K which, tentatively, has been interpreted as the torsional mode. In the crystal an anti conformer was present, while the spectra of the vapour and the liquid were interpreted in terms of large torsional freedom. The Raman and IR spectra of the very unstable 1,4diiodobut-%yne (11) as a crystalline solid were recorded in the 4000-20 cm-' range at low temperatures. Spectra of carbon disulphide solutions at temperatures 250-260 K were obtained and additional IR spectra of I1 in Nujol mulls and in KBr pellets were also recorded. In the region below 500 cm-', where other 1,4-dihalobut-2-ynes have characteristic, broad bands, a high irregular background was observed in the Raman spectrum of I1 in solution. The spectra agree with an anti conformer present in the crystal and nearly free internal rotation in the liquid. The vibrational assignments are supported by force constant calculations and by a correlation diagram for the vibrations of the six skeletal bending modes in 1,4-dichlorobut-2-yne, BrBr and 11.

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Vibrational spectra, phase transitions and conformers of 1,4‐dichlorobut‐2‐yne

Cited by 8 publications

References 24 publications

Vibrational spectra and conformation of 1‐chloro‐4‐fluorobut‐2‐yne and ab initio calculations on 1,4‐dihalobut‐2‐ynes

Vibrational spectra and conformation of 1‐chloro‐4‐fluorobut‐2‐yne and ab initio calculations on 1,4‐dihalobut‐2‐ynes

The conformers of chloromethylmethyldifluorosilane studied by vibrational spectroscopy andab initio methods

Vibrational spectra and conformations of 1, 4‐dibromobut‐2‐yne and 1,4‐diiodobut‐2‐yne

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