In synthetic method development, the most rewarding path is seldom a straight line. While our initial entry into pentafluorosulfanyl (SF5 ) chemistry did not go according to plan (due to inaccessibility of reagents such as SF5 Cl at the time), a detour led us to establish mild and inexpensive oxidative fluorination conditions that made aryl-SF5 compound synthesis more accessible. The method involved the use of potassium fluoride and trichloroisocyanuric acid (TCICA)-a common swimming pool disinfectant-as opposed to previously employed reagents such as F2 , XeF2 , HF, and Cl2 . Thereafter, curiosity led us to explore applications of TCICA/KF as a more general approach to the synthesis of fluorinated Group 15, 16, and 17 heteroatoms in organic scaffolds; this, in turn, prompted SC-XRD, VT-NMR, computational, and physical organic studies. Ultimately, it was discovered that TCICA/KF can be used to synthesize SF5 Cl, enabling SF5 chemistry in an unexpected way.

The analysis of crystal structures of SF5 - or SF4 -containing molecules revealed that these groups are often surrounded by hydrogen or other fluorine atoms. Even though fluorine prefers F⋅⋅⋅H over F⋅⋅⋅F contacts, the latter appeared to be important in many compounds. In a significant number of datasets, the closest F⋅⋅⋅F contacts are below 95 % of the van der Waals distance of two F atoms. Moreover, a number of repeating structural motifs formed by contacts between SF5 groups was identified, including different supramolecular dimers and infinite chains. Among SF4 -containing molecules, the study focused on SF4 Cl compounds, including the first solid-state structure analyses of these reactive species. Additionally, electrostatic potential surfaces of a series of Ph-SF5 derivatives were calculated, pointing out the substituent influence on the ability of F⋅⋅⋅X contact formation (X=F or other electronegative atom). Interaction energies were calculated for different dimeric arrangements of Ph-SF5 , which were extracted from experimental crystal structure determinations.

We report a mild approach to the synthesis of difluoro(aryl)-λ3-iodanes (aryl-IF2 compounds) and tetrafluoro(aryl)-λ5-iodanes (aryl-IF4 compounds) using trichloroisocyanuric acid (TCICA) and potassium fluoride (KF). Under these reaction conditions, selective access to either the I(iii)- or I(v)-derivatives is predictable based solely on the substitution pattern of the iodoarene starting material. Moreover, the discovery of this TCICA/KF approach prompted detailed dynamic NMR, kinetic, computational, and crystallographic studies on the relationship between the IF2 group and the ortho-substituents on carefully designed probe molecules. It was during these experiments that the role of the ortho-substituent in inhibiting further oxidative fluorination of I(iii)-compounds to I(v)-compounds during the reaction with TCICA and KF was revealed. Additionally, a notable exception to this empirical trend is discussed herein.