Vibrational spectroscopy and conformation of S-ethyl thioacetate: CH 3 COSCH 2 CH 3 and comparison with A C(O)S A and A C(O)O A compounds

M. E. DEFONSI LESTARD; M. E. TUTTOLOMONDO; A. BEN ALTABEF

SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY.

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2015 vol. 135 p. 907 - 914

1386-1425

The molecular structure and conformational properties of S-ethyl thioacetate, CH 3 COSCH 2 CH 3 , were determined in the gas phase by electron diffraction and vibrational spectroscopy (IR and Raman). The experimental investigations were supplemented by ab initio (MP2) and DFT quantum chemical calcula- tions at different levels of theory. Theoretical methods reveal two structures with C s ( anti , anti ) and C 1 ( anti , gauche ) symmetries. The infrared and Raman spectra for different phases were also recorded and the bands observed assigned to the vibrational normal modes. Liquid Raman and infrared spectra in liquid and gaseous state measurements revealed the presence of two conformations anti , anti ( C s symme- try) and anti , gauche ( C 1 symmetry). The study was completed using natural bond orbital (NBO) analysis. We have also analyzed the internal rotation barrier about the C(O)SCC dihedral angle using a variety of computational approaches and nat- ural bond orbital (NBO) analyses to understand the nature of the potential function and to explain the