X-ray photoelectron spectroscopy studies of novel Π-conjugated ethynyl thiophene containing Pd(II) complexes and of their interaction with chromium

Abstract

The structure of some novel oligomeric thiophene-containing π-conjugated Pd(II) complexes, recently prepared in our laboratory, Cl–Pd(PBu3)2-C≡C–C4H2S-C≡C–C4H2S–C≡C–C4H2S–C≡C-Pd(PBu3)2Cl or Pd–TRI and Cl[–Pd(PBu3)2–C≡C–C4H2S–C≡C–]3–Pd(PBu3)2Cl or Pd–DET, were studied by means of x-ray photoelectron spectroscopy. The interface formation between chromium and the organometallic π-conjugated polymer films was also investigated. Chromium was evaporated stepwise in situ onto the surface of the polymer films and the XPS core-level spectra of the polymer and of the metal overlayer were studied as a function of Cr coverage. A charge-transfer reaction from the deposited metal atoms to the substrate material was evidenced by the modifications taking place in the polymer spectra upon Cr deposition. A comparison with the surface reactivity towards chromium of [–Pd(PBu3)2–C≡C–C6H4–C6H4–C≡C–]n, Pd–DEBP, a related polymer where benzene groups replace thiophene in the organic conjugated moiety, will be discussed.