The S 2p binding energies of a series of nickel(II), palladium(II), and platinum(II) complexes of 1,2-ethanedithiol and benzenethiol occur between 163.5 and 161.5 eV. A comparison between data for the square-planar sulfur-bridged polymers [Ni(SCH2CH2S)]n and [M(SPh)2]n, where M = Ni, Pd, or Pt, and square-planar monomers of the type Ni(SCH2CH2S)L2 and M(SPh)2L2, where L = C6H11NC, PMe2Ph, or 1/2 dppe, shows that the bridging sulfur atoms usually have S 2p binding energies which are higher than those of sulfur atoms in terminal thiol ligands (i.e., R-Sb- ≳ R-St-). For the ligand methionine, which contains a thioether moiety, coordination of the sulfur atom to platinum(II) causes a S 2p chemical shift of +1.2eV. However, in methionine complexes of cobalt(II), nickel(II), copper(II), and zinc(II), in which the sulfur atoms are not complexed, the S 2p binding energies (S 2p3/2 = 163.0 eV) are unchanged from that of the free ligand. Related data for molecules such as [Fe(SCH3)(CO)3]2, [Fe(SC2H5)(NO)2]2 and a variety of dithiocarbamate- and dithiene-metal complexes have also been obtained. These results are discussed in the light of some recent XPS results for several sulfur-containing metalloproteins.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry