Ylide–Metal Complexes. X. An X-Ray Photoelectron Spectroscopic Study of Triphenylmethylenephosphorane and Gold- and Copper–Phosphorane Complexes

Triphenylmethylenephosphorane, the bis(triphenylmethylenephosphorane)gold chloride and the corresponding copper chloride have been studied by X-ray photoelectron spectroscopy. For the phosphorane, the binding energies, EB, for P 2s and P 2p peaks were observed at 190.1 and 132.6 eV, respectively. The EB value for the P 2p peak agrees with that (132.6 eV) for the phosphonium ion in triphenylmethylphosphonium bromide. The C 1s spectrum was separated into two peaks at EB=285.0 and 283.9 eV, assuming a ratio of 18:1. The peak at 285.0 eV corresponds to the phenyl carbons, and that at 283.9 eV can be assigned to the electronrich methylene carbon. Thus, the structure of the phosphorane is considered to be an ylide formula, (Remark: Graphics omitted.). In gold phosphorane complexes, EB of the C 1s, P 2s, and P 2p peaks were close to those for the phosphorane. The EB of the Cl 2p3⁄2, Au 4f7⁄2, and Au 4f5⁄2 peaks coincided with those for bis(triphenylphosphine)gold chloride. These results indicate the structure of the gold complex to be (Remark: Graphics omitted.). The XPS results also indicate that the structure of the copper complex is similar to that of the gold complex.