Spectroscopic Properties, Conformation and Structure of Difluorothiophosphoryl Isocyanate in the Gaseous and Solid Phase

Abstract

Difluorothiophosphoryl isocyanate, F 2 P(S)NCO was characterized with UV/vis, NMR, IR (gas and Ar-matrix), and Raman (liquid) spectroscopy. Its molecular structure was also established by means of gas electron diffraction (GED) and single crystal X-ray diffraction (XRD) in the gas phase and solid state, respectively. The analysis of the spectroscopic data and molecular structures is complemented by extensive quantumchemical calculations. Theoretically, the C s symmetric syn-conformer is predicted to be the most stable conformation. Rotation about the PÀ N bond requires about 9 kJ mol À 1 and the predicted existence of an anti-conformer is dependent on the quantum-chemical method used. This syn-orientation of the isocyanate group is the only one found in the gas phase and contained likewise in the crystal. The overall molecular structure is very similar in gas and solid, despite in the solid state the molecules arrange through intramolecular O•••F contacts into layers, which are further interconnected by S•••N, S•••C and C•••F contacts. Additionally, the photodecomposition of F 2 P(S)NCO to form CO, F 2 P(S)N, and F 2 PNCO is observed in the solid Armatrix.