Theoretical studies on tautomerism of tetrazole 5-thion

Detailed investigation of the tautomerism of all possible forms of tetrazole thion (A and E) and its tetrazole forms (B–D) induced by proton transfer in the gas phase, in a continuum solvent, and in a microhydrated environment with 1 explicit water molecule was carried out by calculations at MP2, QCISD, CBS-Q, CBS-QB3, and density functional theory (DFT). It was found that in the gas phase and solvent tetrazole thion (form A) is the most stable isomer. In addition variation of dipole moments was studied in the gas phase and in the solvent. Water molecule was gradually put in different regions in the vicinity of five isomers. It was found that water can forms different hydrogen bonding with molecule.