Inversion of sulphur and the trans-effect in sulphide (thioether) complexes of platinum(II) and palladium(II)

Abstract

Variable-temperature ¹H n.m.r. spectra have been recorded for (RSC₂H₄SR) MX₂(R = Me, Et, Prⁿ, Prⁱ, or Buⁿ; M = Pt or Pd; X = Cl, Br, or I). The pyramidal conformation at sulphur allows the detection of meso and (±)-isomeric forms at low temperatures. At higher temperatures, rapid interconversion of these isomers leads to the observation of ‘averaged’ spectra corresponding to a weighted mean of the parameters of the individual conformers. The interconversion process is inversion at single sulphur atoms. The rate of inversion increases as the trans-influence of X increases, and this appears to be an inductive effect. Inversion in the palladium compounds is more rapid than in the platinum derivatives.