EPR and ENDOR studies on monoanionic complexes of 1,2-semiquinones with 52Cr, 53Cr(III)
| Autor: | Mario Branca, Maria Antonietta Zoroddu, Salvatore Sau, Michelina Fruianu |
|---|---|
| Rok vydání: | 1996 |
| Předmět: |
Chromate conversion coating
Radical Inorganic chemistry chemistry.chemical_element Biochemistry law.invention Inorganic Chemistry Metal Crystallography Chromium chemistry Unpaired electron law visual_art Octahedral molecular geometry visual_art.visual_art_medium Molecular orbital Electron paramagnetic resonance |
| Zdroj: | Journal of Inorganic Biochemistry. 62:223-230 |
| ISSN: | 0162-0134 |
| DOI: | 10.1016/0162-0134(95)00156-5 |
| Popis: | Monoanionic complexes of chromium(III) like [Cr(sq)2(cat)]−, where the ligands are anionic radicals such as 1,2-semiquinones and catecholates unsubstituted and 3,5-di-tert-butyl-substituted were detected after interaction of chromate anion (Cr(VI), natural isotope, I = 0 or 53Cr-enriched isotope, I = 32 with 1,2-catechol or 3,5-di-tert-butyl-1,2-catechol in methanolic, ethanolic, or aqueous solution under both anaerobic and aerobic conditions. The very low 〈g〉 values (g = 1.972) obtained in methanol for both complexes, and the very strong metal hyperfine coupling, A53Cr = 25.71 G and A53Cr = 25.17 G for the complex with the ligands 1,2-catechol eand 3,5-di-tert-butyl-1,2-catechol, respectively, suggest a ground state localized on the metal ion. The unpaired electron could be localized in a molecular orbital with a large metal character. The isotropic spectra obtained at room temperature as well as at low temperature suggest an essential octahedral arrangement around the chromium ion. The 1H ENDOR spectra confirm the octahedral geometry of the complexes. |
| Databáze: | OpenAIRE |
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