| Popis: |
Resonance and tautomerism by proton transfer were studied by N and 0 K-XANES spectroscopy in two systems with coupled NH and CO groups: amides and salicylideneaniline derivatives. In amides, where tautomerism is mostly absent with OH form dominating the equilibrium, effect of resonance clearly appears in the N K-XANES spectra as the 1s → π* resonance showing the double bond nature of the CN bond. In salicylidenaniline derivatives, N and 0 K-XANES spectra gave consistent results about the tautomerism in N,N'-disalicylidene-1,6-pyrenediamine (DSPY) and di(2-hydroxy-1-naphthylidene)-p-phenylenediamine (DNP), with DSPY primarily in OH form and DNP in both OH and NH forms. These results are consistent with those from X-ray diffraction and NMR measurements, showing the usefulness of XANES as a method of studying resonance and tautomerism in organic systems. |
