Raman and infrared spectra, conformational stability, normal coordinate analysis and ab initio calculations of 3-chloro-1-butene

✍ Scribed by Min Joo Lee; Feng Fusheng; Seung Won Hur; Jian Liu; Todor K. Gounev; James R. Durig

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 185 KB
• Volume: 31
• Category: Article
• ISSN: 0377-0486
• DOI: 10.1002/(sici)1097-4555(200003)31:3<157::aid-jrs513>3.0.co;2-2

✦ Synopsis

The Raman and infrared spectra (3300-30 cm -1 ) of gaseous and solid 3-chloro-1-butene, H 2 C CHCCl (CH 3 )H, were recorded. Additionally, the Raman spectrum (3300-30 cm -1 ) of the liquid was recorded. All three conformers were observed in the fluid phases and the conformer with the hydrogen atom eclipsing the double bond (HE form) was identified as the most predominant. From variable-temperature measurements in liquified xenon, the enthalpy differences between the HE form and the two less stable conformers, i.e. the methyl group eclipsing the double bond (ME form) and the chlorine atom eclipsing the double bond (ClE form), were determined to be 75 ± 8 cm -1 (214 ± 23 cal mol -1 ) and 197 ± 37 cm -1 (563 ± 106 cal mol -1 ), respectively. Nearly complete vibrational assignments are proposed for all three conformers, which are consistent with the predicted wavenumbers utilizing the force constants from ab initio MP2/6-31G(d) calculations. Both the infrared intensities and the Raman activities and depolarization values were obtained from the ab initio calculations. Complete equilibrium geometries were determined by ab initio calculations employing the 6-31G(d) and 6-311YYG(d,p) basis sets with full electron correlation by the Möller-Plesset (MP2) perturbation method to second order. The structural parameters obtained with the larger basis set are comparable to those obtained from a previously reported electron diffraction study. The results are discussed and the theoretical values are compared with the experimental values when appropriate.