The millimeter- and submillimeter-wave spectrum of dichlorocarbene CCl2: Electronic structure estimated from the nuclear quadrupole coupling constants

Abstract

The pure rotational spectrum of CCl2 in the ground state was observed for the first time in the millimeter- and submillimeter-wave region. The CCl2 molecule was generated directly in a free space cell by a dc glow discharge in CCl4 . Several transitions showed hyperfine splittings arising from the nuclear quadrupole coupling of two Cl atoms. Analysis of the observed spectrum yielded the rotational, centrifugal distortion, and nuclear quadrupole coupling constants of the C35 Cl2 species. The r0 structure was derived from the rotational constants to be r0 (C–Cl)=1.7157 Å and θ0 (ClCCl)=109.2°. The ionic and π character of the C–Cl bond were estimated from the nuclear quadrupole coupling constants to be 0.26 and 0.32, respectively.