Article ID Journal Published Year Pages File Type
1238171 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2008 7 Pages PDF
Abstract

Infrared (4000–400 cm−1) and Raman (3500–50 cm−1) spectral measurements have been made for the solid sample of 7-methyl-4-bromomethylcoumarin. Electronic structure calculations at RHF/6-31G* and B3LYP/6-31G* levels of theory have been performed, giving equilibrium geometries, harmonic vibrational spectra and normal modes. Different orientations of bromomethyl group have yielded only two conformers, of which the most stable one lying lower from the other conformer by ∼7.99 kJ/mol, is non-planar with no symmetry. A complete assignment of the vibrational modes, aided by the calculations, has been proposed. Coupled vibrations are manifest in many modes. Some spectral features, compared to 6-methyl-4-bromomethylcoumarin, show changes across both IR and Raman spectra, involving mainly skeletal vibrations, and to a lesser degree, methyl and bromomethyl vibrations. Low-frequency vibrations below 150 cm−1 are assigned to lattice modes.

Related Topics
Physical Sciences and Engineering Chemistry Analytical Chemistry
Authors
, , , , ,