title: Structures of cycloserine and 2-oxazolidinone probed by X-ray photoelectron spectroscopy: theory and experiment.
abstract: The electronic structures and properties of 2-oxazolidinone and the related compound cycloserine (CS) have been investigated using theoretical calculations and core and valence photoelectron spectroscopy. Isomerization of the central oxazolidine heterocycle and the addition of an amino group yield cycloserine. Theory correctly predicts the C, N, and O 1s core spectra, and additionally, we report theoretical natural bond orbital (NBO) charges. The valence ionization energies are also in agreement with theory and previous measurements. Although the lowest binding energy part of the spectra of the two compounds shows superficial similarities, further analysis of the charge densities of the frontier orbitals indicates substantial reorganization of the wave functions as a result of isomerization. The highest occupied molecular orbital (HOMO) of CS shows leading carbonyl π character with contributions from other heavy (non-H) atoms in the molecule, while the HOMO of 2-oxazolidinone (OX2) has leading nitrogen, carbon, and oxygen pπ characters. The present study further theoretically predicts bond resonance effects of the compounds, evidence for which is provided by our experimental measurements and published crystallographic data.
authors.affiliation: eChemistry Laboratory, Department of Chemistry and Biotechnology, School of Science, Faculty of Science, Engineering and Technology, Swinburne University of Technology , Melbourne, Victoria 3122, Australia.
authors.forename: Marawan
authors.initials: M
authors.lastname: Ahmed
authors.forename: Feng
authors.initials: F
authors.lastname: Wang
authors.forename: Robert G
authors.initials: RG
authors.lastname: Acres
authors.forename: Kevin C
authors.initials: KC
authors.lastname: Prince
mesh_terms: D003523:Cycloserine / Q000737:chemistry*; D015394:Molecular Structure; D023303:Oxazolidinones / Q000737:chemistry*; D056951:Photoelectron Spectroscopy; D011789:Quantum Theory
chemical_list: D023303:Oxazolidinones; D003523:Cycloserine