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

Author Institution: I. Physikalisches Institut, Universitat zu Koln, 50937 Koln, Germany; Institut fur Physikalische Chemie, Universitat Mainz, 55099 Mainz, Germany; Dipartimento di Chimica Fisica e Inorganica, Universita di Bologna, I-40136 Bologna, Italy; Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, and School of Engineering and Applied Science, Harvard University, Cambridge, MA 02138Silicon 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