The effect of charged axial ligands on the EPR parameters in oxovanadium(IV) compounds: An unusual reduction of the A(z)(V-51) values
Φόρτωση...
Ημερομηνία
Συγγραφείς
Tolis, E. J.
Teberekidis, V. I.
Raptopoulou, C. P.
Terzis, A.
Sigalas, M. P.
Deligiannakis, Y.
Kabanos, T. A.
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Τίτλος τόμου
Εκδότης
Wiley-VCH Verlag
Περίληψη
Τύπος
Είδος δημοσίευσης σε συνέδριο
Είδος περιοδικού
peer reviewed
Είδος εκπαιδευτικού υλικού
Όνομα συνεδρίου
Όνομα περιοδικού
Chemistry-a European Journal
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Σειρά βιβλίου
Έκδοση βιβλίου
Συμπληρωματικός/δευτερεύων τίτλος
Περιγραφή
Two 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.
Περιγραφή
Λέξεις-κλειδιά
ab initio calculations, coordination modes, epr spectroscopy, imidazole, vanadium, electron-spin-echo, envelope modulation spectroscopy, vanadium-protein interactions, effective core potentials, paramagnetic-res characterization, ray-absorption-spectroscopy, active-site structure, metal-binding, molecular calculations, model investigations
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Σύνδεσμος
<Go to ISI>://000169492400022
http://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
http://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
Γλώσσα
en
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Γενική Περιγραφή / Σχόλια
Ίδρυμα και Σχολή/Τμήμα του υποβάλλοντος
Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Χημείας