He I and He II Photoelectron Studies of Bis(cyclopentadienyl)vanadium(III) Complexes

He I and He II photoelectron spectra have been obtained for a series of bis(η5-cyclopentadienyl)vanadium(III) halides, alkyls, and aryls, V(η-C5H5)2X, where X = Cl, Br, I, Me, CH2SiMe3, CH2CMe3, C6F5, C6H5, o-C6H4Me, m-C6H4Me, and 2,6-C6H3Me2. Assignments are made principally on the basis of variations of band intensity with photon energy, ionization energy trends, and a generalized molecular orbital scheme. Evidence is presented for weak but significant π interactions between metal d and halogen p orbitals in the halide complexes and a π-donor effect in the alkyls