The Interaction of Dihalogens and Hydrogen Halides with Lewis Bases in the Gas Phase: An Experimental Comparison of the Halogen Bond and the Hydrogen Bond - Halogen Bonding: Fundamentals and Applications - page 29

Fig. 4 The experimentally determined geometries of H 2 S ClF drawn to

scale. The n-pair model of H 2 S, as discussed in the text, is shown for comparison. See
Fig. 1 for key to the colour coding of atoms

··· HCl and H 2 S ···

Fig. 5 The potential energy V ( φ ), expressed as a wavenumber, as a function of the angle φ

for a H 2 S ClF. These have been obtained using ab initio calculations,

by the method discussed in the text. Several vibrational energy levels associated with the
motion in

··· HCl and b H 2 S ···

= 0 is high in both molecules, so that in
each case the v =0and v = 1 vibrational energy levels are negligibly separated and hence
both molecules are pyramidal in the zero-point state and at equilibrium. The values of φ e
and the effective values

φ are also shown. The PE barrier at φ

φ 0 determined experimentally (see Fig. 4) are in good agreement.
SeeFig.1forkeytothecolourcodingofatoms