Microwave spectrum, molecular structure, and force field of HBO

Abstract

The HBO molecule was generated as a transient intermediate in the reaction of diborane with oxygen induced by a dc discharge. The J = 3 ← 2 transition was observed for H10BO and was combined with the spectra already reported to derive the rotational, centrifugal distortion, and nuclear quadrupole coupling constants for this species. The rotational and centrifugal distortion constants were determined also for D11BO, D10BO, H11B18O, and H10B18O. The measurements were extended to rotational transitions of H11BO and H10BO in the ν1, ν2, 2ν2, and ν3 states and to those of D11BO and D10BO in the ν2, 2ν2, and ν3 states. The vibrational frequencies and the rotational, vibration-rotation, l-type doubling, and centrifugal distortion constants thus determined for the six isotopic species were simultaneously analyzed to derive the equilibrium molecular structure and the harmonic and third-order anharmonic potential constants of the HBO molecule. The equilibrium bond lengths thus obtained are re(HB) = 1.166 67(41) Å and re(BO) = 1.200 68(10) Å, and the substituted, average, and effective structures were also calculated for comparison.