Erzeugung und Untersuchung des Cyclopentadienons mit der Methode der temperaturabhängigen Photoelektronenspektroskopie / Preparation and Investigation of Cyclopentadienone by Variable Temperature Photoelectron Spectroscopy (VTPES)

Abstract

Using our VTPES technique cyclopentadienone is generated in the gas phase at 500-600 °C from the three different precursors cyclobutene-3,4-dicarboxylic acid anhydride, o-phenylene sulfite and o-benzoquinone and its PE spectrum is recorded. The PE spectrum and also the PE spectra of the various precursors as well as of the cyclopentadienone dimer are interpreted on the basis of our recently developed PERTCI method (i. e. performing large scale perturbation configuration interaction calculations in connection with selection procedures). The agreement between measured and calculated ionization potentials is good.

The ionisation energy of cyclopentadienone: a photoelectron–photoion coincidence study

“…Those observed in typical aldehydes and ketones [12] are nπ * , resulting from the excitation of a non-bonding electron to the anti-bonding π orbital in the carbonyl group, whereas in C 5 H 4 =O, the lowest lying electronic transition is a ππ * transition localised largely within the ring. The earlier, pioneering photoelectron studies [13,14] identified the ground state of the C 5 H 4 =O cation as X + 2 A 2 and the first excited states of the cation as A + 2 B 2 and B + 2 B 1 , as would be predicted from the molecular orbital diagram in Figure 1, thereby tending to corroborate the proposal that the highest occupied molecular orbital of the neutral is a π orbital in the ring of a 2 symmetry. Cyclopentadienone not only presents an interesting chemical problem with intriguing electronic structure questions, it is also a system with practical importance.…”

Polarized Matrix Infrared Spectra of Cyclopentadienone: Observations, Calculations, and Assignment for an Important Intermediate in Combustion and Biomass Pyrolysis

“…At low pyrolysis temperatures (900–1100 K) the appearance of m / z 48 and m / z 80 indicate the conversion of o -phenylene sulfite to SO ( m / z 48) + CO ( m / z 28) + C 5 H 4 O ( m / z 80). The measured ionization energy (IE) of SO is 10.294 ± 0.004 eV, while that of C 5 H 4 O has been measured at 9.49 ± 0.02 eV and 9.40 eV . At higher pyrolysis temperatures (>1100 K), the C 5 H 4 O signal is attenuated and m / z 52, vinylacetylene (HCCCHCH 2 ), grows.…”

“…The Journal of Physical Chemistry A 52 (IE) of SO is 10.294 ± 0.004 eV, while that of C 5 H 4 O has been measured at 9.49 ± 0.02 eV 26 and 9.40 eV. 27 At higher pyrolysis temperatures (>1100 K), the C 5 H 4 O signal is attenuated and m/z 52, vinylacetylene 53 (HCCCHCH 2 ), grows.…”

“…The UV/vis spectrum , of C 5 H 4 O showed UV band maxima at 195 and 360 nm, in good agreement with the predicted ππ* low-energy transitions. The photoelectron spectrum , of C 5 H 4 O has been reported and assigned the symmetry of the ground state cation as X̃ 2 A 2 (π), while the first excited state was assigned as à 2 B 2 (n).…”