Dynamic NMR studies of ferrocenylsulphide-palladium(II) and -platinum(II) complexes

The stereodynamics of ferrocenylsulphide-palladium(II) and -platinum(II) complexes, Fe(C₅H₄SR)₂MX₂, (M = Pd^II, Pt^II; X = Cl, Br; R = Ph, i-Pr and i-Bu), have been examined by variable temperature NMR. At temperatures down to ca. ?100° C, the pyramidal inversion of the S atoms could be slowed down sufficiently to yield accurate energy data, while the reversal of the ferrocenophane ring remained fast on the NMR time scale. ΔG^≠ data for the S inversion process were in the range 47 to 65 kJ mol^?1 and were influenced to varying extents by the nature of the transition metal, the halogen, and the R substituent on the sulphur.