The pentafluorosulfanyl (SF5) group is situated on an exclusive list of fluorinated functional groups with documented utility that remain shrouded in obscurity. The reason for this dissonance is attributed to limited pentafluorosulfanylation methods and reagents, particularly with respect to introducing the SF5 group to aliphatic frameworks. For instance, SF5Cl gas -one of the few reliable sources of SF5 radicals with applications in C(sp 3 )-SF5 synthesis -has been historically difficult to synthesize and handle, thus preventing widespread adoption of the chemistry and impeding further innovation. This contrasts with the relative accessibility of its Ar-SF4Cl congeners, which are analogous sources of Ar-SF4 radicals with applications in C(sp 3 )-SF4Ar synthesis. However, as part of a larger effort to make polyfluorinated groups more accessible in 2019, one of us disclosed the first user-friendly, gas-reagent free synthesis of SF5Cl in the patent literature through oxidative fluorination of S8 using inexpensive trichloroisocyanuric acid (TCICA) and potassium fluoride. In 2021, Qing and co-workers reported an optimized workup protocol for this TCICA/KF approach whereby SF5Cl can be extracted directly into hexanes to produce a storable stock solution, thus obviating the need to handle SF5Cl as a gas. Together, these recent advancements not only enable the broader chemical community to synthesize their own SF5Cl solution more safely, but facilitates the invention of pentafluorosulfanylation reactions and the study of heretofore unknown SF5-containing motifs. 10 To date, the known methods of forming C(sp 3 )-SF5 and C(sp 3 )-SF4Ar bonds from either SF5 or Ar-SF4 radicals involve formal addition to p-systems (Figure ). Alternatively, we sought opportunities to add SF5Cl and Ar-SF4Cl compounds across other types of bonds such as the central bond in [1.1.1]propellane. Conceptually, the result of combining SF5 radical chemistry with strain-release functionalization would enable investigation of the structural consequences of merging a bioisosteric replacement for phenyl groups or alkynes (i.e., bicyclopentane, or "BCP") with a bioisosteric surrogate for trifluoromethyl or tert-butyl groups (i.e., SF5). Additionally, appending an Ar-SF4 moiety with a BCP ring would provide access to another type of hybrid isostere that may be of interest in the design of materials, such as liquid crystals. Herein, we report a mild, radical pentafluorosulfanylation and tetrafluoro(aryl)sulfanylation of [1.1.1]propellane. Based on a detailed structural analysis of this unusual SF5-BCP motif, we also found that the resulting transannular C•••C distance in SF5-BCP-Cl is one of the shortest allegedly nonbonding C•••C distances reported in the CSD (see Supporting Information for search details). This prompted synthesis of a suite of tetrafluoro(aryl)sulfanyl derivatives and extensive single-crystal X-ray diffraction (SC-XRD) and NMR comparative analyses. Furthermore, the nature of the dramatic impact of the SF5 group on the BCP ring scaffold was studied further using density functional theory (DFT).