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

The structure of some novel oligomeric thiophene-containing pi-conjugated P d(II) complexes, recently prepared in our laboratory, Cl-Pd(PBu3)(2)-C=C-C4 H2S-C=C-C4H2S-C=C-C4H2S-C=C-Pd(PBu3)(2)Cl or Pd-TRI and Cl[-Pd(PBu3)(2)-C=C -C4H2S-C=C-](3)-Pd(PBu3)(2)Cl Or Pd-DET, were studied by means of x-ray pho toelectron spectroscopy. The interface formation between chromium and the o rganometallic rr-conjugated polymer films was also investigated. Chromium w as evaporated stepwise in situ onto the surface of the polymer films and th e XPS core-level spectra of the polymer and of the metal overlayer were stu died as a function of Cr coverage. A charge-transfer reaction from the depo sited metal atoms to the substrate material was evidenced by the modificati ons taking place in the polymer spectra upon Cr deposition. A comparison wi th 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. (C) 2000 American Vacu um Society. [S0734-2101(00)03801-X].