Theoretical Study on the Tautomeric Reaction of CH3S CH2SH

The tautomeric reaction of CH3S CH2SH has been studied by using the Density Function Theory (DFT) and Molecular Orbital (MO) ab initio. The geometries, frequencies, zero point energies (ZPE), total energies and relative energies of CH3S, CH2SH and Transition state (Ts) have been calculated on HF/B3LYP/MP2 theory levels with basis set 6-31G(d), respectively. In order to obtain the credibilitive vibration frequencies, ZPE, total energies, vibration frequencies analysis has been performed. Ts has been confirmed by the two criterions: Firstly, only one imaginary vibration frequency is in existence; secondly, Internal Reaction Coordinate (IRC) has been confirmed to connect the reactant and the product. At the same time, IRC was calculated based on the B3LYP theory level with the medium basis set 6-31G(d). The kinetic mechanism and properties of the tautomeric reaction have been studied in detail. In addition, the geometry parameters and spin contamination along IRC are discussed. From the calculated results of IRC, the Minimum Energy Potential (MEP) curve and the adiabatic energy potential curve were obtained. Participation functions and activation energy have been obtained from the result of Gaussian98 output on the B3LYP theory level and basis set 6-31G(d). On the basis of the result of Gaussian98 output, the rate constants and equlibrium constants from 200 K to 1000 K have been calculated by Conventional Transitional State Theory (CTST).