Dibromine Monoxide, Br2O: The Rotational Spectrum and Molecular Properties

The rotational spectra of (79)Br2O, (79)BrO(81)Br, and Br2O in their ground vibrational states as well as (79)BrO(81)Br in its v (sub 2) = 1 state have been studied in selected regions between 90 and 523 GHz. Transitions involving a large range of quantum numbers, 6 less than or equal to J less than or equal to 123 and 0 less than or equal to K (sub a) less than or equal to 12, have been observed permitting precise rotational and a large set of centrifugal distortion constants to be determined. All isotopic species as well as the excited state data were fit simultaneously. Ground-state effective and average structural parameters as well as an estimate of the equilibrium structure have been derived. The quartic distortion constants were used for a calculation of the harmonic force field. The complete quadrupole tensor has been determined. Its diagonalization reveals a largely covalent BrO bond with little pi-bonding. The derived properties of Br2O are compared with those of related compounds such as Cl2O, HOBR, and HOCl.