THE EXISTENCE OF 2 ISOMERIC FORMS OF MONOFLUORINATED HYDROGEN-SULFIDE- A NEW THEORETICAL RATIONALE FOR EXPERIMENTALLY OBSERVED INFRARED-SPECTRUM

In order to explain the discrepancies between the matrix isolated IR s pectra of the products of the H2S + F-2 reaction and recent computatio nal studies of this system, we have analyzed the potential energy surf ace of monofluorinated hydrogen sulfide using high level post-Hartree- Fock methods. The molecular geometries and harmonic vibrational freque ncies were calculated at the DFT, MP2, and CCSD levels in conjunction with the 6-311++G(d,p) basis set. Besides the already proposed HSF iso mer which corresponds to the global energetic minimum, a local minimum corresponding to the HFS isomer as well as a transition state structu re between these minima have been also characterized. The calculated v ibrational frequencies fit well with the experimental IR spectra and a lso complement previous ntt initio calculations on the HSF isomer.