Molecular Structure of XeF6 and IF7

The deflection of molecular beams of XeF2, XeF4, XeF6, and IF7 in an inhomogeneous electric field has been examined. From the defocusing behavior of each of these species, it is concluded that the electric dipole moment μ is less than 0.03 D for XeF4, XeF6, and IF7 if these molecules have rigid structures. The upper limit for the polarity of nonrigid (inverting) structures is (μ / Δ1 / 2) < 0.1 D / (cm−1) / 2, where Δ is the separation between inversion doublets. These results imply molecular structures with symmetry-forbidden electric dipole moments for XeF4, XeF6, and IF7.