UV photoelectron spectra of the title compounds are reported. Assignments are made with the help of He(I)/He(II) intensity differences, shift effects upon substitution and comparison with related molecules. Previously drawn conclusions about the electronic structure of similar complexes also hold for the compounds. It is indicated that the ionization energy for the symmetric metal-metal bond strongly depends on the overlap between transition and post-transition metals.
He(I) and He(II) photoelectron spectra are reported for (η5-C5H5)2MLX (M = Nb, Ta; L = H, CO; X - propene, 1-butene, propyl) and some methylcyclopentadienyl deriva-tives. Also the spectra of some π-allyl and dihalide complexes are reported. Unambiguous assignments could be made of the metal d a1 orbital, the Cp orbitals, the olefin π ionization and the M-hydride and π-allyl orbitals. Very regular trends are observed in the ionization energies upon substitution of the ligands. The olefin π ionization is found at very low energy indicating that the π backbonding to the olefin is very important. He(I)/He(II) cross section differences show clearly differences in metal character of the various M.O.'s.
By means of UV photoelectron spectroscopy (UPS) the electronic structures of [Feη3.C3H5(CO)3X], [Feη3-(2-CH3C3H4)(CO)3X] (X = Cl, Br, I) and [Co(C3H5)(CO)3] have been studied. Detailed assignments are possible and surprisingly low ionization energies (as low as 8.19 eV) are found for iodine lone pair type Orbitals. From the spectra a large difference in π backbonding is found between the cobalt and iron complexes
UV photoelectron spectra of the title compounds are reported. Assignments based on He(I)/He(II) intensity differences, shift effects, and comparison with related molecules allow an assignment of the upper valence bands. Electronic differences between nickel and both platinum and palladium are reflected in the spectra, especially with respect to bands due to ionization of electrons from the metal.
Strong evidence is found for π interaction of the ligand phenyl system with metal orbitals
The He(I) and He(II) photoelectron spectra of L3MCo(CO)4 complexes (M = Si, Ge, Sn, and Pb and L = Cl, Brand CH3) are reported. Bands attributable to the metal-cobalt bond, cobalt 3d and CO orbitals are assigned in agreement with a qualitative MO model. Relativistic effects and He(I)/He(II) intensity ratios prove to be important in assigning these ultraviolet photoelectron spectra.
The He(I) and He(II) photoelectron spectra of M[Co(CO)4]2 and M[Mn(CO)5]2 complexes (M = Zn, Cd, Hg) are reported. Bands attributable to metal-metal bonds, metal d-levels and CO orbitals are assigned in agreement with a semi-ionic model, i.e. M2+ and [M'(CO)n]-. Relativistic effects prove to be important in assigning these ultraviolet photoelectron spectra.