Carbon-Fluorine Bond Activation in Thermolysis Reactions of the Osmium(IV) Perfluorothiolate Compounds [Os(SC6F5)4(P(C6H4X-4)3)] (X = CF3, Cl, F, H, CH3, and OCH3)

Thermolysis reactions of [Os(SC6F5)(4)(P(C6H4X-4)(3))] (X = CF3 I, Cl 2, F3, Fl 4, CH(3)5, and OCH(3)6) in refluxing toluene yield compounds [OsF(SC6F5)(2)(SC6F4(SC6F5)-2)(P(C6H4X-4)(3))] (1a-6a) and [Os(SC6F5)(2)(SC6F4(SC6F5)-2)(C6H4X-4)] (1b-6b). In addition, [Os(SC6F5)(3)(SC6F4(SC6F5)-2)] (c) is yielded from 1-4 and 6, compounds [OsF(SC6F5)(3)(P(C6H4X-4)(3))] [X = CF3 (1e), X = Cl (2e)] are also identified as products of the thermolysis reactions of 1 and 2, while [Os(SC6F5)(2)(S2C6F4)- (P(C6H4CH3-4)(3))] (5d) is obtained from 5. Compounds c, e, and d are produced in low yields (ca. 2-4%). Formation of all products involves the rupture of ortho C-F bonds. The first complexes systematically detected in these thermolysis reactions are compounds a, which are isomers of the starting complexes. Thus, the C I: activation involves the metal-mediated generation of the covalent Os F bond. Single-crystal X-ray diffraction studies of the new compounds 4a, 5a, 2b-6b, 2e. and 5d indicate that these compounds consist of five-coordinated metal ions in essentially trigonal-bipyramidal geometries. In addition, thermolysis of the isolated compound [OsF(SC6F5)2(SC6F4(SC6F5)-2)(P(C6H4CH3-4)(3))] (5a) in relluxing toluene gives rise to [Os(SC6F5)(2)(SC6F4(SC6F5)-2)(C6H4CH3-4)] (5b) and [Os(SC6F5)(2)(S2C6F4)(P(C6H4CH3-4)(3))] (5d), confirming that compounds a can generate compounds b when the thermolysis is prolonged. Compounds 1a-6a, 2b-6b, le, and 2e are investigated in solution by NM R studies, including variable-temperature (19) F NM R experiments. These molecules are fluxional. Some of the activation parameters for the dynamic processes are determined.