Conformational and vibrational analysis of S-(2-methoxyphenyl)-4-substituted-benzenecarbothioates, using X-ray, infrared and Raman spectroscopy and theoretical calculations

Abstract

Structural and conformational properties of S-(2-methoxyphenyl) 4-nitrobenzenecarbothioate ( I), S-(2-methoxyphenyl) 4-chlorobenzenecarbothioate ( II) and S-(2-methoxyphenyl) 4-methylbenzenecarbothioate ( III) are analyzed using data of two new structures obtained from X-ray diffraction, vibrational data and theoretical calculations. According to chemical quantum calculations, the synperiplanar and +anticlinal forms were found as the first and second more stable conformations, respectively, for the title compounds. The geometric parameters and normal modes of vibration have been calculated using a density functional theory method (B3LYP) and the 6-31+G ∗∗ basis set. The calculated parameters are in good agreement with the corresponding X-ray diffraction values. The combined experimental and theoretical approach allows a consistent assignment for most of the fundamental modes.