The effect of charged axial ligands on the EPR parameters in oxovanadium(IV) compounds: An unusual reduction of the A(z)(V-51) values

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dc.contributor.authorTolis, E. J.en
dc.contributor.authorTeberekidis, V. I.en
dc.contributor.authorRaptopoulou, C. P.en
dc.contributor.authorTerzis, A.en
dc.contributor.authorSigalas, M. P.en
dc.contributor.authorDeligiannakis, Y.en
dc.contributor.authorKabanos, T. A.en
dc.date.accessioned2015-11-24T16:50:23Z
dc.date.available2015-11-24T16:50:23Z
dc.identifier.issn0947-6539-
dc.identifier.urihttps://olympias.lib.uoi.gr/jspui/handle/123456789/9600
dc.rightsDefault Licence-
dc.subjectab initio calculationsen
dc.subjectcoordination modesen
dc.subjectepr spectroscopyen
dc.subjectimidazoleen
dc.subjectvanadiumen
dc.subjectelectron-spin-echoen
dc.subjectenvelope modulation spectroscopyen
dc.subjectvanadium-protein interactionsen
dc.subjecteffective core potentialsen
dc.subjectparamagnetic-res characterizationen
dc.subjectray-absorption-spectroscopyen
dc.subjectactive-site structureen
dc.subjectmetal-bindingen
dc.subjectmolecular calculationsen
dc.subjectmodel investigationsen
dc.titleThe effect of charged axial ligands on the EPR parameters in oxovanadium(IV) compounds: An unusual reduction of the A(z)(V-51) valuesen
heal.abstractTwo series of octahedral oxovanadium(IV) compounds, containing charged or neutral axial ligands, with the tetradentate amidate molecules Hcapca and H(2)capcah of the general formulae trans-[(VOX)-O-IV(capca)](0/4) (where X = Cl- (1 . CH2Cl2),SCN- (2), N-3 (3), CH3C- OO- (4), PhCOO (5), imidazole (6 . CH3NO2), and eta -nBuNH(2) (7)) and cis-[(VOX)-O-IV(Hcapcah)](0/4) where X= Cl- (8 . 0.5 CH2Cl2), SCN- (9), N-3(-) (10 . 2CH(3)OH), and imidazole (11)), were synthesized and characterized by X-ray crystallography (1 . CH3OH, 8 . CHCl3, 9 . 2 CH3CN, 10 . CH3CN and cis-[VO(imidazole)(Hcapcah)](+)) and continuous-wave electron paramagnetic resonance (cw EPR) spectroscopy. In addition to the synthesis, crystallographic and EPR studies, the optical, infrared and magnetic properties (room temperature) of these compounds are reported. Ab initio calculations were also carried out on compound 8 . CHCl3 and revealed that this isomer is more stable than the trans isomer, in good agreement with the experimental data. The cw EPR studies of compounds 1-5, that is, the (VO2+)-O-IV species containing monoanionic axial ligands, revealed a novel phenomenon of the reduction of their A, components by about 10% relative to the N-4 reference compounds ([(VO)-O-IV(imidazole)(4)](2+) and [(VO)-O-IV(2,2-bi-pyririne)(2)](2+), see reference [46]). In marked contrast, such a reduction is not observed in compounds 6 CH3NO2-11, which contain neutral axial ligands Based on the spin-Hamiltonian formalism a theoretical explanation is put forward according to which the observed reduction of A, is due to a reduction of the electron - nuclear dipolar coupling (P). The present findings bear strong relevance to cw EPR studies of oxovanadium(IV) in vanadoproteins, (VO2+)-O-IV-substituted proteins, and in (VO2+)-O-IV; model compounds, since the hyperfine coupling constant, A(2), has been extensive used as a benchmark for identification of equatorial-donor-atom sets in oxovanadium(IV) complexes.en
heal.accesscampus-
heal.fullTextAvailabilityTRUE-
heal.identifier.secondary<Go to ISI>://000169492400022-
heal.identifier.secondaryhttp://onlinelibrary.wiley.com/store/10.1002/1521-3765(20010618)7:12<2698::AID-CHEM26980>3.0.CO;2-2/asset/26980_ftp.pdf?v=1&t=h0dvy4qx&s=a9e48166a54cafede1bbe8a3cca8358dc4741f36-
heal.journalNameChemistry-a European Journalen
heal.journalTypepeer reviewed-
heal.languageen-
heal.publicationDate2001-
heal.publisherWiley-VCH Verlagen
heal.recordProviderΠανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Χημείαςel
heal.typejournalArticle-
heal.type.elΆρθρο Περιοδικούel
heal.type.enJournal articleen

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