Beta-heterosubstituted acrylonitriles--electronic structure study by UV-photoelectron spectroscopy and quantum chemical calculations.
Beta-heterosubstituted acrylonitriles correspond to the formal addition of nucleophiles on cyanoacetylene. Acrylonitriles substituted with an amino, methoxy, mercapto group, or halogeno atom have been synthesized. Rearrangements between Z and E stereoisomers or tautomerizations have been studied by NMR spectroscopy and by quantum calculations. The photoelectron spectra were recorded and analyzed with the aid of a time-dependent density functional theory, ab initio OVGF, and so-called "corrected" ionization energy calculations. The electronic structure of the studied species was determined, and strong differences between beta-heterosubstituted acrylonitriles and the corresponding nitrile-free heteroalkenes were clearly documented. A "push-pull" effect was noticed, due to the combined donor effect of the substituent on one side of the carbon-carbon double bond and the electron-withdrawing effect of the nitrile group on the other side. Thus, the presence of a nitrile group strongly stabilizes the electronic structure. The efficient pi-donor contribution of the NH(2) and SH groups was evidenced.
Chrostowska
Anna
A
Institut Pluridisciplinaire de Recherche sur l'Environnement et les Materiaux, Universite de Pau et des Pays de l'Adour-CNRS-UMR 5254, 64000 Pau, France. anna.chrostowska@univ-pau.fr
Nguyen
Thi Xuan Mai
TX
Dargelos
Alain
A
Khayar
Saïd
S
Graciaa
Alain
A
Guillemin
Jean-Claude
JC