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Quantum mechanical investigation of effects in formation of carbonyl and thiocarbonyl cations. Part I. Fragmentation reactions of 1,2‐hemithiodione radical cations
Author(s) -
Nevalainen Vesa,
Vainiotalo Pirjo
Publication year - 1987
Publication title -
organic mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 0030-493X
DOI - 10.1002/oms.1210220907
Subject(s) - chemistry , radical , hydrogen atom abstraction , formaldehyde , unpaired electron , fragmentation (computing) , photochemistry , ionic bonding , decomposition , medicinal chemistry , oxygen , hydrogen atom , radical ion , ion , organic chemistry , group (periodic table) , computer science , operating system
In order to study decomposition reactions of ionic oxygen and sulphur‐containing compounds, such as hemithiodione radical cations, a quantum chemical investigation of the formation of formyl, thioformyl, acyl and thioacyl cations and radicals was performed. Calculations were carried out mainly at the 6–31G * level involving complete geometry optimizations. In the ionization of aldehydes and thioaldehydes, no important energy differences were found between the oxygen and sulphur analogues studied. A stepwise generation of formyl and thioformyl cations from formaldehyde and thioformaldehyde, by hydrogen atom abstraction followed by expulsion of unpaired electrons from the resulting radicals, showed the radicalization of formaldehyde to be only 12.6 kJ mol −1 more favoured than that of thioformaldehyde. The electron expulsion from formyl radical was 23.8 kJ mol −1 more favoured than that from thioformyl radical. Substitution of hydrogens of formyl and thioformyl groups by methyls lowered the total formation energies of carbonyl and thiocarbonyl cations 119.2 and 96.2 kJ mol −1 . The formation energy difference between acyl and thioacyl cations was also very small.