ROTATIONAL SPECTRUM SPECTRUM AND COUPLED-CLUSTER CALCULATIONS OF SILICON OXYSULFIDE, O=Si=S

Abstract

Silicon oxysulfide, OSiS, and seven of its minor isotopic species have been characterized for the first time in the gas phase at high spectral resolution by means of Fourier-transform microwave spectroscopy. The equilibrium structure of OSiS has been determined from a combination of experimental ground state rotational constants and calculated vibrational corrections to those. The structural parameters %($r_{O-Si}$=1.5064 \AA\ and $r_{Si-S}$=1.9133 \AA) are in good agreement with values from high-level quantum-chemical calculations using coupled-cluster techniques together with sophisticated additivity and extrapolation schemes. %The bond distances in OSiS are very short in comparison to SiO and SiS. This unexpected finding is explained by the partial charges %calculated for OSiS via a natural population analysis. %The results convey that electrostatic effects rather than multiple bonding are the key to understand the bonding situation in OSiS. %The data presented provide the spectroscopic information needed for radio-astronomical searches for OSiS in space.