Silicon Oxysulfide, OSiS: Rotational Spectrum, Quantum-Chemical Calculations, and Equilibrium Structure

• Published in: The journal of physical chemistry letters Vol. 2; no. 11; pp. 1228 - 1231
• Main Authors: Thorwirth, Sven, Mück, Leonie Anna, Gauss, Jürgen, Tamassia, Filippo, Lattanzi, Valerio, McCarthy, Michael C
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 02-06-2011
• Subjects: Molecular Structure, Quantum Chemistry, General Theory; quantum-chemical calculations; equilibrium structure; radio astronomy; bonding; rotational spectroscopy
• ISSN: 1948-7185; 1948-7185
• DOI: 10.1021/jz200368x

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 the experimental data using calculated vibration–rotation interaction constants. The structural parameters (r O–Si = 1.5064 Å and r Si–S = 1.9133 Å) are in very 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 with those in SiO and SiS. This unexpected finding is explained by the partial charges calculated for OSiS via a natural population analysis. The results suggest that electrostatic effects rather than multiple bonding are the key factors in determining bonding in this triatomic molecule. The data presented provide the spectroscopic information needed for radio astronomical searches for OSiS.