Spectroscopic Studies of Alkyl Sulfoxide Complexes of Platinum(II) and Palladium(II)

A number of sulfoxide complexes of platinum(II) and palladium(H) have been synthesized, and their infrared and proton magnetic resonance spectra indicate that sulfur is the donor atom. The Pt(II) complexes are of the type PtCl2L2 (L =sulfoxide) and far-ir data suggest all have cis configurations except the diisopropyl sulfoxide complex. The Pd(II) complexes PdCl2L2: are trans in the solid state but in solution most appear to revert to the halo-bridged binuclear structures Pd2Cl4L2. The pmr spectra of the Pt(II) complexes have been analyzed, and the values of 185Pt-H coupling constants have been rationalized in terms of preferred conformations about the C S bonds. In suitable sulfoxides, e.g., diethyl, it is clear that S coordination to Pt(II) or Pd(II) results in a significant increase in the degree of methylene proton inequivalence. Magnetic anisotropic effects in these d8 square-planar structures are suggested to be responsible.