Binding energies and isomerization in metallocene ions from threshold photoelectron photoion coincidence spectroscopy.

Metallocene ions (Cp(2)M(+), M = Cr, Co, Ni) were studied by threshold photoelectron photoion coincidence spectroscopy (TPEPICO) to investigate the mechanism, energetics, and kinetics of the ionic dissociation processes. The examined energy-selected Cp(2)M(+) ions fragment by losing the neutral cyclopentadienyl ligand. In addition, CH and C(2)H(2) losses appear as minor channels, while the cobaltocene ion also loses an H atom.

Photoelectron spectroscopy and thermochemistry of tert-butylisocyanide-substituted cobalt tricarbonyl nitrosyl.

A new organometallic complex, Co(CO)2NOtBuNC, was synthesized and investigated by photoelectron spectroscopy (PES) and threshold photoelectron photoion coincidence (TPEPICO) spectrometry in order to determine its ionization energy as well as the bond energies in the ionic forms. The assignment of the nine peaks in the PES was based on Kohn-Sham molecular orbital energies, and an adiabatic ionization energy of 7.30 +/- 0.

Donor-acceptor properties of isonitriles studied by photoelectron spectroscopy and electron transmission spectroscopy.

Some alkyl and aryl isonitriles, considered as CO analogue sigma-donor and pi-acceptor ligands in transition metal chemistry, were studied by means of HeI photoelectron spectroscopy and electron transmission spectroscopy, in order to evaluate their donor-acceptor properties from the measured ionization energies (IE) and vertical electron attachment energies (VAE). The investigated molecules were 2-propyl, 1-butyl, tert-butyl, 1-pentyl, cyclohexyl, 2,6-dimethylphenyl, 4-methoxyphenyl and 4-chorophenyl isonitrile. By interpreting the spectra on the basis of literature data and quantum chemical calculations, the spectral features associated with the molecular orbitals mainly involved in coordination and back-donation were identified.

Unexpected reactivity difference between iodo-alkene moieties of steroids possessing remote lactame or cycloalkane structural units: a theoretical approach.

The steroidal ring A possessing cyclohexane vs. delta-valerolactame structures shows a 'long-range effect' on the reactivity of the 'iodovinyl' functionality of the ring D. The strikingly different reactivity of 17-iodo-16-ene functionality of steroids is explained on the basis of the redistribution of kinetic energy of the system.

Intramolecular electron transfer in heterosubstituted benzene derivatives as probed by dissociative electron attachment.

The electron transmission and dissociative electron attachment spectra of the 1-chloroalkyl benzene derivatives, C(6)H(5)(CH(2))(3)Cl and C(6)H(5)(CH(2))(4)Cl, and of the sulfur and silicon derivatives, C(6)H(5)SCH(2)Cl, C(6)H(5)Si(CH(3))(2)CH(2)Cl and C(6)H(5)CH(2)Si(CH(3))(2)CH(2)Cl, are presented for the first time. The relative Cl(-) fragment anion currents generated by electron attachment to the benzene pi* LUMO are measured in the series C(6)H(5)(CH(2))(n)Cl, with n = 1-4, and in the heteroatomic compounds. The Cl(-) yield reflects the rate of intramolecular electron transfer between the pi-system and the remote chlorine atom, which in turn depends on the extent of through-bond coupling between the localized pi* and sigma*(Cl-C) orbitals.