Rotational spectroscopy of a pre-reactive mixture of H2S and F2: detection and characterisation of the weakly bound complex H2S…F2

The rotational spectrum of a complex H2S…F2 was observed in a pre-reactive mixture of hydrogen sulphide and molecular fluorine by using a fast-mixing nozzle in a Balle-Flygare microwave spectrometer. Rotational constants 12(B + C) and centrifugal distortion constants ΔJ were determined for the ground state and a low-lying vibrationally excited state with ν = 1 of the isotopomers H2S…F2, HDS…F2 and D2S…F2. The vibrational satellite is probably associated with internal rotation of H2S about its local C2 axis. The complex is weakly bound (intermolecular stretching force constant kσ = 2.36 N m−1) and has a pyramidal configuration at S, with φ = 113(5)° and r(S…F) = 3.20(1) Å.