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The He(Iα) PE spectra and electronic absorption spectra of hexafluorocyclobutanone and of tetrafluoro‐1,2‐cyclobutane‐dione
Author(s) -
Gleiter Rolf,
Schang Peter,
Bloch Martin,
Heilbronner Edgar,
Bünzli JeanClaude,
Frost David C.,
Weiler Larry
Publication year - 1985
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19851180532
Subject(s) - chemistry , spectral line , ionization energy , absorption spectroscopy , ionization , homo/lumo , cyclobutane , cyclobutanone , crystallography , ion , molecule , ring (chemistry) , physics , organic chemistry , quantum mechanics , astronomy
The He(Iα) PE and the electronic absorption spectra of hexafluorocyclobutanone ( 3 ) and tetrafluoro‐1,2‐cyclobutanedione ( 4 ) have been recorded. The assignment of the observed bands in both types of spectra is mainly based on the correlation with the corresponding spectra of the parent compounds cyclobutanone ( 1 ) and 1,2‐cyclobutanedione ( 2 ), and in addition on the results of semiempirical calculations. As a result of the perfluoro effect, the bands in the PE spectra of 3 and 4 are shifted towards higher ionization energies by 1.6 eV and 1.5 eV relative to the corresponding bands in the PE spectra of 1 and 2 . A comparison of the positions of the first band in the electronic spectra of 1 and 3 , as well as of 2 and 4 , shows that this band is shifted bathochromically by about 5000 cm −1 as a consequence of the perfluoro substitution. This is explained as being due to a stronger lowering of the LUMO (π*) energy than that of the HOMO (n) energy, induced by the replacement of the H‐by F‐atoms.