The microwave spectrum, spin-rotation coupling constants, and structure of thiocarbonyl fluoride, SCF2, observed with a cavity microwave Fourier transform spectrometer

Abstract

The microwave spectrum of thiocarbonyl fluoride, SCF2, has been investigated in the frequency range of 6.7–18.4 GHz using a pulsed molecular-beam microwave Fourier transform spectrometer. Twelve a-type transitions of the 32S12C19F2 isotopomer with J between 0 and 9, including ΔKa=2 transitions, as well as eight transitions of the 34S12C19F2 isotopomer with J between 0 and 9, have been assigned. The rotational constants and quartic centrifugal distortion constants have been determined. A 19F nuclear spin-rotation interaction, as well as a rather large direct 19F nuclear spin–spin interaction, have been observed. The three diagonal elements of the spin-rotation tensor at the 19F nuclei have been determined to be Maa=22.9(9) kHz, Mbb=10.4(4) kHz, and Mcc=5.4(3) kHz for 32S12C19F2 and Maa=20.9(9) kHz, Mbb=10.7(4) kHz, Mcc=6.4(4) kHz for 34S12C19F2, respectively. For 32S13C19F2, seven transitions with J between 0 and 6 have been assigned and rotational constants and two quartic centrifugal distortion constants have been derived. The splitting patterns due to the two 19F nuclei and the 13C nucleus have been observed but not completely resolved. A ground-state average structure has been determined for 32S12C19F2 as rz(CS)=1.5870(20) Å, rz(CF)=1.3182(13) Å, and ∢(FCF)=106.89(11)°.