MICROWAVE SPECTRUM AND STRUCTURE OF $HBr-SO_{3}$ AND THE QUADRUPOLE COUPLING CONSTANT OF $Ar-^{33}SO_{3}$

Abstract

We report the microwave spectrum and structure of $HBr-SO_{3}$ as determined by pulsed nozzle Fourier transform microwave spectroscopy. Like its previously studied HF- and HCI analogs, the complex exhibits a symmetric top spectrum and has a structure in which the halogen approaches the sulfur along the $C_{3}$ axis of the $SO_{3}$ The S-Br distance is 3.24 A and the HBr submit forms an angle of approximately 73 deg. (or 107 deg.) with the a-axis of the complex. The: structures of the threeHX-$SO_{3}$ complexes are compared. We also report A measurement of the $^{33}S$ nuclear quadrupole coupling constant in Ar-33 $SO_{3}$. The value obtained (-15.296(14) MHz is compared with a recent theoretical calculation of the monomer value and discussed in terms of the angular oscillations of the $SO_{3}$ unit.