Ennobling an Old Molecule: Thiazyl Trifluoride (NSF3), a Versatile Synthon for Xe–N Bond Formation

The fields of sulfur-nitrogen-fluorine chemistry and noble-gas chemistry have been significantly extended by the syntheses and characterizations of four new Xe–N-bonded cations derived from NSF3. The adduct-cation, F3SNXeF+, has provided the entry point to a significant chemistry through HF solvolysis of the coordinated NSF3 ligand and HF-catalyzed and solid-state rearrangements of F3SNXeF+. The HF solvolyses of [F3SNXeF][AsF6] in anhydrous HF (aHF) and aHF/BrF5 solutions yield the F4SNXe+ cation, which likely arises from an HF-catalyzed mechanism. The F4SNXe+ cation, in turn, undergoes HF displacement to form F4SNH2 + and XeF2, as well as HF addition to the SN bond to form F5SN(H)Xe+. Both cations undergo further solvolyses in aHF to form the F5SNH3 + cation. The F4SNXe+ and F4SNH2 + cations were characterized by NMR spectroscopy and single-crystal X-ray diffraction and exhibit high barriers to rotation about their SN double bonds. They are the first cations known to contain the F4SN– group and significantly extend the chemistry of this ligand. The solid-state rearrangement of [F3SNXeF][AsF6] at 22 °C has yielded [F4SNXe][AsF6], which was characterized by Raman spectroscopy, providing the first examples of xenon bonded to an imido nitrogen and of the F4SN– group bonded to a noble-gas element. The rearrangement of [F3SNXeF][AsF6] in a NSF3 solution at 0 °C also yielded [F4SNXe---NSF3][AsF6], which represents a rare example of a N–Xe–N linkage and the first to be characterized by X-ray crystallography. Solvolysis of NSF3 in aHF was previously shown to give the primary amine F5SNH2, whereas solvolysis in the superacid medium, AsF5/aHF, results in amine protonation to give [F5SNH3][AsF6]. Complete structural characterizations were not available for either species. Isolation of F5SNH2·nHF from the reaction of NSF3 with HF has provided a structural characterization of F5SNH2 by Raman spectroscopy. Crystal growth by sublimation of F5SNH2·nHF at −30 to −40 °C has resulted in the X-ray crystal structure of F5SNH2·2[F5SNH3][HF2]·4HF and structural characterizations of F5SNH2 and F5SNH3 +. The redox decomposition of [F4SNXe---NSF3][AsF6] in NSF3 at 0 °C generated Xe, cis-N2F2, and [F3S(NSF3)2][AsF6].