An ab initio characterization of diphosphorus trisulfide, P 2S 3

Abstract

We have carried out ab initio electronic structure calculations at the HF 6-31 G∗ and MP2 6-31 G∗ levels using the Turbomole and ACES II programs for the diphosphorus trisulfide molecule, P 2S 3. We have located 10 stationary points, six of which correspond to stable equilibria (local minima), the remaining four having at least one imaginary vibrational frequency. Three structures are found to be within 1 kJ mol −1 in energy at the MP2 DZP level. These structures are a planar trans -trans form with the connectivity SPSPS and C 2v symmetry, its planar trans-cis rotomer, also having the connectivity SPSPS but only C s symmetry, and a non-planar four-membered ring with one exocyclic S atom and C s symmetry. The third of these structures is best viewed as a bound but non-bonded adduct between PS and PS 2, which lies higher in energy than the other two at coupled-cluster levels of calculation, and is thus not the likely structure of P 2S 3. These results differ from our earlier findings for P 2O 3, for which the preferred HF 6-31 G∗ geometry possesses the same connectivity as the preferred P 2S 3 structures, namely OPOPO, but is non-planar with only C 2 symmetry.