FP=S in the gas-phase: Detection by rotationally resolved infrared and millimetre-wave spectra assisted by ab-initio calculations

Pyrolysis of F2PSPF2 at about 1400 degrees C in Ar flow provides a new and practical method for synthesising short-lived FP=S (with side product PF3). Cooperation between infrared and millimetre-wave (MMW) spectroscopy assisted by reliable ab-initio calculations at the MP2 and CCSD(T) levels has led to the gas-phase detection of this elusive species and enabled its spectral characterisation. The excellent agreement of all methods confirms the identification. The IR data provide parameters for the v(1)=1 vibrational state. From the MMW data it was possible to calculate precise ground state parameters up to the sextic centrifugal distortion terms.