Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1232915 | Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy | 2009 | 11 Pages |
Abstract
The mid and far infrared and the Raman spectrum of 1,2-dibromopropane is reported in solid, liquid and gas. Several bands reported by earlier workers are not present in the spectrum of the purified material. Ab initio calculations of optimized geometry, energy, dipole moment, molar volume, vibrational spectrum and normal coordinate calculation were performed using the density functional B3LYP/6-311++g(3df,2pd), and the results used to assist a complete assignment of the 81 fundamental modes of vibrations of the three conformers of 1,2-dibromopropane. Relative energies found conformer A the lowest with G and Gâ² at 815.6 and 871.4 cmâ1 higher. The temperature dependence of the Raman spectrum of the liquid was investigated in the CCC bending region and the relative energies determined. It was found that the Gâ² and G conformers lie 236 ± 11 and 327 ±11 cmâ1, respectively above the A conformer, leading to the room temperature composition of the liquid as A, 65 ± 1; Gâ², 21 ± 1; G, 14 ± 1%. It is apparent that the calculated highest energy conformer Gâ² is stabilized more than the G conformer in the liquid. The Gâ² conformer has the lowest molar volume effectively changing the interaction distance between conformers in the liquid, and enhancing the effect of its dipole moment.
Related Topics
Physical Sciences and Engineering
Chemistry
Analytical Chemistry
Authors
Arthur J. LaPlante, Howard D. Stidham,