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V IV O and V IV Species Formed in Aqueous Solution by the Tridentate Glutaroimide–Dioxime Ligand – An Instrumental and Computational Characterization
Author(s) -
Sanna Daniele,
Ugone Valeria,
Sciortino Giuseppe,
Parker Bernard F.,
Zhang Zhicheng,
Leggett Christina J.,
Arnold John,
Rao Linfeng,
Garribba Eugenio
Publication year - 2018
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201800090
Subject(s) - chemistry , electron paramagnetic resonance , aqueous solution , ligand (biochemistry) , redox , octahedron , electrochemistry , hyperfine structure , analytical chemistry (journal) , crystallography , inorganic chemistry , nuclear magnetic resonance , crystal structure , biochemistry , physics , receptor , electrode , quantum mechanics , chromatography
Complexation of V IV in aqueous solution with glutaroimide–dioxime (H 3 L), 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 [V IV L 2 ] 2– , is formed in the pH range 3–5. It transforms into a usual V IV O complex, [V IV OL(OH)] 2– , at pH > 6. The non‐oxido species is characterized by a “ type 3 ” EPR spectrum with A z ≈ 126 × 10 –4 cm –1 and a UV/Vis signal with ε > 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 [V IV L 2 ] 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 51 V 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.