ELECTRONIC STRUCTURE AND CONFORMATIONAL PROPERTIES OF THE AMIDE LINKAGE

Article abstract of DOI:10.1016/0022-2860(89)87013-9

The photoelectron spectra of N-vinyllactams 4-6 have been obtained.Based on band shape analyses and AM1 calculations the ionization potentials are assigned to molecular orbitals.The sequence of the three highest occupied MOs was found to be: ?₃ (HOMO), n₀, ?₂.The MOs ?₃ and ?₂ are essentially linear combinations of ?_N and ?_C=C.Some conformational properties of N-vinyllactams have been studied by AM1 calculations on N-methyl-N-vinylacetamide (1) as a model compound for torsions of the vinyl and the acetyl group.Planar forms (ap and sp) were found as stable conformers.For 3-6 AM1 calculations also revealed essen tially planar vinyllactam units, while the α-lactam derivative 2 has a pyramidal nitrogen atom.