X-ray Absorption Near-Edge Structure Spectroscopy of a Stable 6-Oxoverdazyl Radical and Its Diamagnetic Precursor
| Autor: | Tsun-Kong Sham, Zhiqiang Wang, Joseph A. Paquette, Viktor N. Staroverov, Joe B. Gilroy |
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| Rok vydání: | 2018 |
| Předmět: |
010304 chemical physics
Chemistry chemistry.chemical_element Electronic structure 010402 general chemistry 01 natural sciences Nitrogen XANES Spectral line 0104 chemical sciences Crystallography Unpaired electron 0103 physical sciences Diamagnetism Physical and Theoretical Chemistry Absorption (chemistry) Spectroscopy |
| Zdroj: | The Journal of Physical Chemistry A. 123:323-328 |
| ISSN: | 1520-5215 1089-5639 |
| Popis: | The electronic structure of 1,3,5-triphenyl-6-oxoverdazyl, a heteroatom-rich stable organic radical, and its diamagnetic 1,3,5-triphenyl-6-oxotetrazane precursor are probed using X-ray absorption near-edge structure (XANES) spectroscopy. The N K-edge XANES spectra of the 6-oxoverdazyl radical contain strong N 1s → π* resonances for each set of equivalent nitrogen atoms. The fact that these resonances are absent from the analogous spectra of the 6-oxotetrazane, whereas the O K-edge and C K-edge XANES spectra of both species are very similar, demonstrates that the unpaired electron of the radical is localized primarily on the N atoms of the 6-oxoverdazyl heterocycle. The O K-edge XANES spectra of both species contain strong O 1s → π* (C═O) peaks, but the peak of the radical is red-shifted by 0.5 eV relative to that of the 6-oxotetrazane, which indicates that the C═O bond in the radical is part of a larger π-conjugated system. The proposed interpretations of the XANES spectra are aided by density-functional calculations. |
| Databáze: | OpenAIRE |
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