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Ionization Energies of 1‐R‐2,2‐dimesitylethenols, 1,2‐Dimesityl‐2‐phenylethenol, and Some of their Keto Tautomers
Author(s) -
Lecoultre Jacques,
Heilbronner Edgar,
Biali Silvio E.,
Rappoport Zvi
Publication year - 1986
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19860690835
Subject(s) - chemistry , tautomer , ionization , keto–enol tautomerism , enthalpy , enol , ionization energy , spectral line , mass spectrum , molecule , computational chemistry , adiabatic process , mass spectrometry , stereochemistry , organic chemistry , thermodynamics , chromatography , ion , physics , astronomy , catalysis
The He(Iα) PE spectra of the two pairs of 1 (Ph)‐ 3 and 2–4 have been recorded and assigned by comparison with spectra of related molecules, or by using simple MO arguments. This analysis shows that the PE spectra are in agreement with the assumption that the twist angles observed in the crystalline state are more or less conserved in the gas phase. The observed first adiabatic ionization energies I I aallow the calculation of the molar reaction enthalpy Δ r H m θwhich accompanies the enolization of the radical cations of the title compounds. It is found that Δ r H m θ≈ –−70 kJ mol −1 is roughly the same for both keto/enol pairs, in qualitative and quantitative agreement with expectation. These results complement and correct ionization energies determined previously by mass spectrometric methods and conclusions based on them.