期刊
EUROPEAN JOURNAL OF INORGANIC CHEMISTRY
卷 -, 期 17, 页码 1805-1816出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/ejic.201800090
关键词
Vanadium; Oxides; EPR spectroscopy; Density functional calculations; Redox chemistry
资金
- Fondazione di Sardegna (FdS15Garribba)
- Universitat Autnoma de Barcelona
- Fuel Cycle Research and Development Campaign (FCRD)/Fuel Resources Program, Office of Nuclear Energy, the U.S. Department of Energy (USDOE) at Lawrence Berkeley National Laboratory (LBNL) [DE-AC02-05CH11231]
Complexation of V-IV in aqueous solution with glutaroimide-dioxime (H3L), a ligand proposed for the possible sequestration of uranium from seawater, was studied by the combined application of spectroscopic (EPR and UV/Vis), spectrometric (ESI-MS), electrochemical (CV), and computational (DFT) techniques. The results indicate that a rare non-oxido V-IV species, with formula [(VL2)-L-IV](2-), is formed in the pH range 3-5. It transforms into a usual (VO)-O-IV complex, [(VOL)-O-IV(OH)](2-), at pH > 6. The non-oxido species is characterized by a type 3 EPR spectrum with A(z) approximate to 126 x 10(-4) cm(-1) and a UV/Vis signal with epsilon > 2000 m(-1)cm(-1) in the visible region. The detection of V-V species by ESI-MS spectrometry was related to two possible oxidation processes, the first one in solution and the second one in-source during the recording of the spectra. The cyclic voltammogram of [(VL2)-L-IV](2-) shows two quasi-reversible processes, at E-1/2 = -0.75 V and E-1/2 = 0.03 V, assigned to the V-IV/V-III reduction and V-IV/V-V oxidation, respectively. All the experimental results were verified by DFT calculations, which indicated that the geometry of the non-oxido V-IV complex is intermediate between an octahedron and a trigonal prism and allowed us to predict its V-51 hyperfine coupling (HFC) tensor A, the electron absorption spectrum, the two redox processes in the cyclic voltammogram, and the electronic structure that, in turn, determines its EPR and UV/Vis behavior.
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