Sulfur Cyanate Pentafluoride, SF5OCN

Seppelt et al. 170) reported the first synthesis of SF5OCN by the sequence of reactions below. 

The identification of isomers i and ii is made on the basis of NMR data (170). Only isomer i undergoes further chlorine elimination in the presence of mercury to afford the desired product in 10% yield. Isomer ii under similar conditions decomposes to give SOF4 and CICN. The IR and N NMR spectra (170, 172) are used to differentiate between SF5 cyanate and SFg isocyanate. 

The first successful synthesis of SFgCN (5% yield) by fluorination of (SCN)2 in FCI2CCF2CI with elemental fluorine diluted with N2 (1 10) at -20°C is reported by Losking and Willner (178). It is a stable, colorless gas at room temperature (b.p., -25°C). It does not isomerize as suggested in the earlier literature (177). It does not decompose even on pyrolysis at 350°C. The IR and F NMR spectral data and molecular weight data are consistent with the structure (178). The molecular structures obtained by gas-phase electron diffraction and microwave spectroscopy concur (179). 

The preparation of SFgNC in about 5% yield by the following sequence of reactions is reported by Thrasher (180). 

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