DETERMINATION OF THE N1S AND O1S CORE ENERGIES IN PLANAR AND DISTORTED LACTAMS AND AMIDES - RELATIONSHIPS WITH THE CONCEPT OF RESONANCE

The core ionization energies of three, strained lactams have been measured and compared with those of model lactams, amides, amines, and ketones In general. the high values for N1s and the low values for O1s in planar amide (lactam) linkages compared to those in model amines and ketones are consistent with traditional resonance arguments. The N1s and O1s data for the distorted lactams 1,3-di-tert-butylaziridinone and 1-azabicyclo-[3.3.1]nonan-2-one are consistent with a reduced positive charge on nitrogen and a reduced negative charge on oxygen in accord with the classical resonance viewpoint. They are also consistent with other spectroscopic data for distorted lactams. The carbonyl C 1 s ionization energies are lower in distorted lactams than in planar lactams. The explanation may lie in the relative electronegativities of the nitrogen atoms. ESCA data also suggest the presence of more C+-O- character in ketones than in amides. Although 1-pyrrolidinecarboxaldehyde has a distorted amide linkage, its ESCA data are not unambiguously interpretable in terms of reduced resonance. The dependencies of core electron ionization energies upon different amide distortion modes need to be explored using a much expanded set of amides and lactams. The relationships between the resulting experimental ESCA data with various calculations of atomic charge need to be examined.