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 [Os(SC6F5)3(SC6F4(SC6F5)-2)] (1) and [Os(SC6F4H-4)3(SC6F3H-4-(SC6F4H-4)-2)] (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 [ Os(SC6F5)(SC6F4(SC6F4O-2)-2)(PMe2Ph)2] (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 [Os(SC6F4H-4)2(SC6F3H-4-O-2)(PPh3)] (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.
Arroyo
Maribel
M
Centro de Química del Instituto de Ciencias de la BUAP, Edificio 193 del Complejo de Ciencias, Ciudad Universitaria, San Manuel, 72570 Puebla, Puebla, Mexico. slarroyo@siu.buap.mx
Bernès
Sylvain
S
Cerón
Margarita
M
Cortina
Verónica
V
Mendoza
Consuelo
C
Torrens
Hugo
H
D002244:Carbon / Q000737:chemistry*; D018360:Crystallography, X-Ray; D005461:Fluorine / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D017892:Osmium Compounds / Q000138:chemical synthesis* / Q000737:chemistry
D017892:Osmium Compounds; D005461:Fluorine; D002244:Carbon