Microwave Investigation of Methyl Sulfone and Methane Sulfonyl Fluoride

Abstract

Rotational constants for the ground state of methyl sulfone and for the ground and first excited torsional state of methane sulfonyl fluoride have been derived from microwave spectra observed in the 18 000–37 000-MHz region. Molecular dipole moments of 4.50 ± 0.10 D for (CH3)2SO2 and 3.88 ± 0.04 D for CH3SO2F were measured. Relative intensity measurements place the barrier to methyl rotation in CH3SO2F at 880 ± 120 cm−1 (2.52 ± 0.35 kcal/mole). Alternative structures for (CH3)2SO2, based on assumption of either the SO or the SC bond length from a recent electron diffraction study, are presented. Both reveal a significant discrepancy between the microwave and diffraction values for the OSO angle.