New insights into the vibrational spectroscopic investigation on S-cis & S-trans forms of 2-Methoxy benzoyl chloride

Abstract

The conformal stability of 2-Methoxy benzoyl chloride (2MBC) in its S-cis and S-trans forms was investigated using Density Functional Theory (DFT) calculations and Potential energy surface scan analysis. The experimental (FT-IR and FT-Raman) spectra were recorded in the condensed phase in order to perform detailed vibrational analysis. Different basis sets were adopted during optimization procedure and the suitable method was identified from the results obtained. The optimized geometry and vibrational wavenumbers were determined by using B3P86/6-31++G(d,p) level Density Functional Theory calculations and was found to be the most suitable one. The effect of scaling on the calculated wavenumbers was analyzed by employing unscaled, uniform scaling and selective scaling procedures. A detailed comparative analysis of the effect of hydrogen bonding on the geometry and structural parameters of both the conformers has been carried out using the results obtained from DFT level calculations. The results from the above studies reveal that, the presence of intramolecular hydrogen bond in S-cis conformer of 2MBC has significantly altered the geometrical parameters and hence the vibrational wavenumbers. The difference in electron transfer mechanism of the two different environments (S-cis and S-trans) was thoroughly investigated using Natural Bond Orbital analysis.