Methanesulfenyl Fluoride, CH3SF, a Missing Link in the Family of Sulfenyl Halides: Formation and Characterization through the Matrix Photochemistry of Methyl Thiofluoroformate, FC(O)SCH3

Matrix‐isolation experiments have afforded the means of preparing the hitherto unknown sulfur(II) fluoride, methanesulfenyl fluoride, CH3SF. Broadband UV‐visible irradiation of methyl thiofluoroformate, FC(O)SCH3, isolated in a solid Ar matrix results, first, in photoisomerization of the syn into the anti form of the molecule, and, subsequently, in the elimination of CO with the concomitant formation of CH3SF. Continued irradiation brings about tautomerization of this product with the detachment and migration of a hydrogen from the methyl group to give the molecular complex H2CS⋅⋅⋅HF. The changes have been monitored and the photoproducts detected and identified by the IR spectra of the matrices, and the conclusions confirmed: 1) with reference to the corresponding behavior of the perdeuterated molecule FC(O)SCD3; 2) by analogy with the properties of related molecules, for example, ClC(O)SCH3, CH3SCl, and H2CS⋅⋅⋅HCl, and; 3) by comparison with the vibrational properties simulated for the different molecules by ab initio and density functional theory methods. Broadband UV‐visible irradiation of FC(O)SCH3 isolated in a solid Ar matrix results, first, in photoisomerization of the syn into the anti form of the molecule, and subsequently, in the formation of CH3SF with the concomitant elimination of CO. Continued irradiation gives the molecular complex H2CS⋅⋅⋅HF (see picture).