ChemInform Abstract: Vibrational Spectra and ab initio Quantum Mechanical Calculation of Energy, Geometry and Vibrational Frequencies of the Oxothiophosphate Ions PO3S3-, PO2S3- 2 and POS3- 3

Water-free samples with the stoichiometries Na 3 PO 3 S, Na 3 PO 2 S 2 and Na 3 POS 3 have been prepared, and from vibrational spectra the ions PO 3 S 3− and PO 2 S 3− 2 have been found. POS 3− 3 seems to be unstable towards disproportionati under these conditions. Some distinct differences are seen between the vibrational spectra of water-free and water-containing samples. Ab initio calculations (SCF/triple split valence basis, MP2 energy) have been used to study the relative stability, geometry and vibrational spectra of the oxothiophosphate anions PO 3 S 3− , PO 2 S 3− 2 and POS 3− 3 . The significant deviations between calculated and experimental geometry, especially for PO 3 S 3− , are found to be due to the neglect of the counterions. The effect of several counterions is investigated, and based on these results a corrected resonance hydridization scheme for PO 3 S 3− is presented. By scaling the force constants in accordance with the observed inaccuracies in the calculated geometry a good fit to experimental frequencies is obtained, and the potential energy distribution (PED) is calculated. The scaling for PO 3 S 3− is supported by calculation of the influence of one Na + cation on the vibrational spectra.