Gas-phase ultraviolet photoelectron spectra of [{Ni(η-C5H5)}2(µ-C2R2)](R = H or CF3) complexes

Abstract

The u.v. photoelectron (p.e.) spectra of [{Ni(η-C₅H₅)}₂(µ-C₂H₂)] and [{Ni(η-C₅H₅)}₂{µ-C₂(CF₃)₂}] are reported. For the first time p.e. spectral features which are related to ionizations from molecular orbitals involved in metal–alkyne back-donation have been detected. The analysis of p.e. results for the CF₃ derivative allow us to discuss in detail the mechanism of interaction between an alkyne and two metallic centres.