Theoretical and experimental studies on the novel thiazylfluoroformate, FC(O)SN

Abstract

FC(O)SCl reacts with (CH₃)₃SiN₃ to give a polymeric product with the formula [FC(O)SN]_x. Thiazylfluoroformate (nitrilo-λ⁴-sulfanecarbonyl fluoride) is formed during this reaction and can be trapped by the addition of hexachlorocyclopentadiene (C₅Cl₆). Before polymerization, FC(O)SN can be trapped by C₅Cl₆ to give a 1 : 1 adduct. This adduct is hexachloro-3-cyclopentenylideneamino sulfanecarbonyl fluoride, C₅Cl₆NSC(O)F, as mainly identified by mass spectroscopy. Ab initio calculations at various levels of theory (HF/3-21G*, HF/6-31G*, MP2/6-31G*) are performed for the free molecule FC(O)SN in the gas phase. Thereby, the anti(CO bond in anti position with respect to the SN bond) and syn forms are taken into account. The calculated relative stabilities of FC(O)SN and of the isomeric compound FS(O)CN are discussed. In addition, the ab initio results are compared to density functional theory calculations at the local and non-local level of approximation.