Werner Schäfer

Reversal in the sequence of two highest occupied molecular orbitals in the series thiophen, selenophen, and tellurophen

It is shown by photoelectron spectroscopy that the two highes occyupied MOs reverse their sequence from thiophen [π(1a2)/π(2b1)] through selenophen to tellurophen [π(2b1)/π(1a2)].

On the nature of the “free electron pair” on phosphorus in aromatic phosphorus compounds: The photoelectron spectrum of 2-phosphanaphthalene☆

Abstract The electronic structure of the 2-phosphanaphthalene system has been studied by photoelectron spectroscopy. The assignment of bands in the PE spectra of 2-phosphanaphthalene and 3-methyl-2-phosphanaphthalene has been performed with the aid of two useful generalisations, one pertaining to the energies of the the π ionizations, and the other to the phosphorus n ionization, as well as by calculations using the extended CNDO/S method. The n ionization of the 2-phosphanaphthalenes can be observed as a well separated single band. From the breadth of this n band the “lone pair” is seen to have considerable bonding character resulting from orbital mixing with other σ-orbitals of the molecule. This appears to be the first evidence of appreciable delocalization of ldlone pair” phosphorus electrons in aromatic molecules, which, judging from the breadth of the bands, is almost as large as with pyramidal phosphorus atoms.

Notizen: Monitoring Chemical Reactions by Variable Temperature Photoelectron Spectroscopy. A New Thermal Reaction

Abstract Variable temperature photoelectron (vtpe) spectroscopy is applied to ethane-1,2-dithiol. Thereby it is shown that this molecule thermally reacts to thiirane and hydrogen sulphide at the very low pressure applied in the pe experiment.