Synthesis and spectroscopic studies of palladium and platinum complexes of methylene-backboned dithio-, diseleno- and ditelluro-ether ligands, RECH2ER (R = Me or Ph; E = S, Se or Te)

Abstract

The complexes [ML₂Cl₂](M = Pd or Pt; L = PhSCH₂SPh, MeSCH₂SMe, PhSeCH₂SePh or MeSeCH₂SeMe), which are square planar with monodentate sulfur or selenium ligands, have been prepared. In the solid state, on the basis of IR and Raman data, the palladium complexes are trans and the platinum cis, whilst in solution multinuclear NMR spectroscopy (¹H, ¹⁹⁵Pt-{¹H}, and ⁷⁷Se-{¹H}) reveal that both cis and trans isomers and meso and DLenantiomers are present, the isomer populations varying with L and M in a systematic way. The complexes [ML₂Cl₂] are stable in solution for L = PhSCH₂SPh, but the other complexes lose L to precipitate polymeric [(MLCl₂)n] complexes. The ditelluroethers, MeTeCH₂TeMe and PhTeCH₂TePh, form only the latter type of complex. The crystal structure of trans-[Pd(PhSCH₂SPh)₂Cl₂] has been determined and contains a trans square-planar palladium atom with one co-ordinated and one free sulfur atom associated with each dithioether ligand [Pd–Cl 2.292(1) and Pd–S 2.329(1)Å].