Carbon−Fluorine Bond Cleavage in the Preparation of Osmium(III) and Osmium(IV) Fluorothiolate Complexes. Fluorine by Fluorine NMR-Assignment and Fluxional Processes

Reactions of OsO4 with HSR (R = C6F5, C6F4H-4,) in refluxing ethanol afford (1)
and (2), which involve the rupture of C−F bonds. At room temperature,
the compound [Os(SC6F5)3(PMe2Ph)2] or [Os(SC6F5)4(PMe2Ph)] reacts with KOH(aq) in acetone, giving rise to
(3), through a process involving the rupture of two C−F bonds, while
the compound [Os(SC6F4H)4(PPh3)] reacts with KOH(aq) in acetone to afford
(4), which also implies a C−F bond cleavage. Single-crystal X-ray diffraction studies of 1, 2, and 4 indicate that
these compounds include five-coordinated metal ions in essentially trigonal-bipyramidal geometries, whereas these
studies on the paramagnetic compound 3 show a six-coordinated osmium center in a distorted octahedral geometry.
19F, 1H, 31P{1H}, and COSY 19F−19F NMR studies for the diamagnetic 1, 2, and 4 compounds, including variable-temperature 19F NMR experiments, showed that these molecules are fluxional. Some of the activation parameters
for these dynamic processes have been determined.