Theoretical Conformational Studies of Thiol and Thione Forms of Thioacetic Acid

The theoretical conformational structure analyses were performed using density functional theory for thiol and thione tautomeric forms of thioacetic acid insert ignore into journalissuearticles values(TAA);. At the B3LYP/6-311++Ginsert ignore into journalissuearticles values(d,p); level, thiol [CH3insert ignore into journalissuearticles values(C=O);SH] and thione [CH3insert ignore into journalissuearticles values(C=S);OH] were found more stable than anti forms and the energy differences between these two forms were computed to be ca. 6.7 kJ mol−1 and ca. 27 kJ mol−1, respectively. Barrier energies for thiol and thione forms of thioacetic acid were calculated by using the density functional theory [DFTinsert ignore into journalissuearticles values(B3LYP);/6-311++Ginsert ignore into journalissuearticles values(d,p);] method contributing to more than 90% of the population in gas phase at room temperature and also reported a theoretical study on vibrational spectra of thiol and thione tautomeric forms of thioacetic acid obtained by the density functional theory.                       Key Words : thioacetic acid, DFT calculations,                   tautomerisation, PES, IR spectroscopy.