He(I) and He(II) Photoelectron Spectra of Some Mixed Sandwich Compounds of Titanium, Zirconium and Hafnium

The He(I) and He(II) photoelectron spectra are reported for two series of transition metal mixed sandwich complexes of general formula LaMLb (M = Ti, La = η5-C5H5, η5-CH3C5H4, η5-C5(CH3)5; M = Zr, Hf, La = η5-C5(CH3)5; Lb = η7-C7H7 (series I); M = Ti, La = η5-CH3C5H4, η5-C5(CH3)5; M = Zr, La = η5-C5(CH3)5; Lb = η8-C8H8 (series II)). Assignments were made of the metal d, cyclopentadienyl and carbocylic π orbitals on the basis of He(I)/He(II) intensity ratios and shift effects and by comparison with UP data for related compounds. For series I no influence of the central metal upon the IEs of the highest occupied molecular orbital e2 was observed. The IE of the non-bonding metal dz2 orbital of Ti or Zr (5.28 and 4.70 eV, respectively) in the complexes of series II (La = η5-C5(CH3)5) is very low