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 OsO with HSR (R = CF, CFH-4,) in refluxing ethanol afford [Os(SC F)(SCF(SC F)-2)] (1) and [Os(SCFH-4) (SCFH-4-(SCFH-4)-2)] (2), which involve the rupture of C-F bonds. At room temperature, the compound [Os(SCF)(PMePh)] or [Os(SCF)(PMePh)] reacts with KOH(aq) in acetone, giving rise to [Os(SCF)(SC F(SCFO-2)-2)(PMe Ph)] (3), through a process involving the rupture of two C-F bonds, while the compound [Os(SCFH) (PPh)] reacts with KOH(aq) in acetone to afford [Os(SCFH-4)(SCF H-4-0-2)(PPh)] (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. F, H, P{H}, and COSY F-F NMR studies for the diamagnetic 1, 2, and 4 compounds, including variable-temperature F NMR experiments, showed that these molecules are fluxional. Some of the activation parameters for these dynamic processes have been determined. © 2007 American Chemical Society.