ROTATIONAL SPECTROSCOPY OF A PRE-REACTIVE MIXTURE OF H2S AND F2 - DETECTION AND CHARACTERIZATION OF THE WEAKLY-BOUND COMPLEX H2S CENTER-DOT-CENTER-DOT-CENTER-DOT F2

The rotational spectrum of a complex H2S ... F-2 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. Rotat ional constants 1/2(B + C) and centrifugal distortion constants Delta( J) were determined for the ground state and a low-lying vibrationally excited state with v = 1 of the isotopomers H2S ... F-2, HDS ... F-2 a nd D2S ... F-2. The vibrational satellite is probably associated with internal rotation of H,S about its local C, axis, The complex is weakl y bound (intermolecular stretching force constant k(sigma) = 2.36 N m( -1)) and has a pyramidal configuration at S, with theta= 113(5)degrees and r(S ... F) = 3.20(1) (A) over circle.