SF5 Substituents

Although the chemical shifts of most commonly encountered orga-nofluorine compounds are upheld of CFC13 and thus have negative values, there are a number of structural situations for fluorine that lead to positive chemical shifts (downfield from CFC13). These include acyl and sulfonyl fluorides as well as the fluorines of SF5 substituents. 

This chapter will also include discussion of the SF5 substituent, which is a thermally and hydrolytically stable substituent now attracting much attention with respect to its impact on biological activity of compounds of pharmacological and agrochemical interest. 

All of the different types of sulfur fluorides will be touched upon in this section, with the special SF5 substituent being taken up in detail in the following section. 

Three-bond coupling to vicinal hydrogens generally leads to a pentet signal, meaning that coupling to the equatorial fluorines of the SF5 substituent, as mentioned earlier, is much greater than to its axial fluorine. 

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