Thermolysis reactions of [Os(SC 6 F 5 ) 4 (P(C 6 H 4 X-4) 3 )] (X = CF 3 1, Cl 2, F 3, H 4, CH 3 5, and OCH 3 6 ) in refluxing toluene yield compounds [OsF(SC 6 F 5 ) 2 (SC 6 F 4 (SC 6 F 5 )-2)(P(C 6 H 4 X-4) 3 )] ( 1a − 6a ) and [ Os(SC 6 F 5 ) 2 (SC 6 F 4 ( SC 6 F 5 )-2)(C 6 H 4 X-4)] ( 1b − 6b ). In addition, [ Os(SC 6 F 5 ) 3 (SC 6 F 4 ( SC 6 F 5 )-2)] ( c ) is yielded from 1 − 4 and 6, compounds [OsF(SC 6 F 5 ) 3 (P(C 6 H 4 X-4) 3 )] [X = CF 3 ( 1e ), X = Cl ( 2e )] are also identified as products of the thermolysis reactions of 1 and 2, while [Os(SC 6 F 5 ) 2 (S 2 C 6 F 4 )(P(C 6 H 4 CH 3 -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−F 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(SC 6 F 5 ) 2 (SC 6 F 4 (SC 6 F 5 )-2)(P(C 6 H 4 CH 3 -4) 3 )] ( 5a ) in refluxing toluene gives rise to [ Os(SC 6 F 5 ) 2 (SC 6 F 4 ( SC 6 F 5 )-2)(C 6 H 4 CH 3 -4)] ( 5b ) and [Os(SC 6 F 5 ) 2 (S 2 C 6 F 4 )(P(C 6 H 4 CH 3 -4) 3 )] ( 5d ), confirming that compounds a can generate compounds b when the thermolysis is prolonged. Compounds 1a − 6a, 2b − 6b, 1e, and 2e are investigated in solution by NMR studies, including variable-temperature 19 F NMR experiments. These molecules are fluxional. Some of the activation parameters for the dynamic processes are determined.
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Mendoza et al. (2010) studied this question.