Study of the Electronic Structure of Ni(eta(5)-C(5)H(5))(NO) by Variable-Photon-Energy Photoelectron Spectroscopy and Density Functional Calculations.

Photoelectron spectra, with photon energies varying from 18 to 120 eV, have been measured for Ni(η5-C5H5)(NO). Relative partial photoelectron cross sections and branching ratios have been evaluated for the first three valence ionization bands. He I and He II photoelectron spectra have been remeasured for Ni(η5-C5H5)(NO) and Ni(η5-C5H4CH3)(NO). In the latter case, the fine structure on the first band differs from that in the previously published spectrum. Density functional calculations have been carried out to determine the ionization potentials of the lowest lying states of Ni(η5-C5H5)(NO) as well as the corresponding photoionization cross sections and the resulting branching ratios using the LCGTO-DF and LDKL-DF methods, respectively. Both experimental and theoretical investigations lead to an ion state ordering 2E1 < 2E2 ∼ 2A1< 2E1 and an assignment of 2E1 states to the first and third bands with the 2A1 and 2E2 states comprising the second band. This differs from the original assignment in the literat...