Structural and spectroscopic studies of a rare non-oxido V(v) complex crystallized from aqueous solution

Abstract

A non-oxido V(v) complex with glutaroimide-dioxime (H3L), a ligand for recovering uranium from seawater, was synthesized from aqueous solution as Na[V(L)2]·2H2O, and the structure determined by X-ray diffraction.

VIVO and VIV Species Formed in Aqueous Solution by the Tridentate Glutaroimide–Dioxime Ligand – An Instrumental and Computational Characterization

“…The comparison between the experimental and calculated isotopic pattern of the peaks due to [H 2 L] – , [V V O(OH)L] – /[V V O 2 L+H] – and [V V L 2 ] – ions is reported in Figures S4–S6 of the Supporting Information, in which the satellite peaks, due to the natural abundance of 13 C isotope, are separated by m/z ≈ 1.00 for these fragments with charge of –1 and allowed us to confirm the attribution proposed. The two V V complexes were observed in a recent paper, and their existence in aqueous solution was related to the use of NaV V O 3 as the metal salt . In contrast, using V IV OSO 4 , one would expect signals ascribable to V IV adducts, which – instead – were not detected even if the latter were well visible in the EPR spectra in Figure .…”

“…When the pH is raised to about 3, new signals appear and indicate the formation of new species (resonances II in Figure ). The small value of 51 V hyperfine coupling constant A (126.4 × 10 –4 cm –1 ) for this species would suggest it is a non‐oxido V IV complexes, structurally analogous to the compound revealed in the system containing V V . If the ligand is indicated with H 3 L, to this complex the formula [V IV L 2 ] 2– , with 2 × (O – , N – , O – ) coordination, could be assigned.…”

“…The values for p K a2 and p K a3 indicate that the deprotonation of these groups is not completely independent. [31a] The deprotonation of the imide group –NH in the neutral form cannot be measured in water and is induced by complexation with metal ions , …”

“…Very recently, some of us demonstrated that glutaroimide–dioxime (H 3 L) (shown in Scheme ) forms a very stable bare V V complex with composition [V V L 2 ] – in aqueous solution, isolable also in the solid state, which has important implications in the interference of vanadium during the recovery of uranium from seawater through specific ligands such as poly(amidoximes). The logical consequence is to try to synthesize a possible bare vanadium species from solutions containing V IV .…”

Gas‐phase complexes formed between amidoxime ligands and vanadium or iron investigated using electrospray ionization mass spectrometry

“…In addition, Leggett et al . have synthesized a 1:2 vanadium(V)–DHIP complex and showed that stepwise displacement of the vanadyl oxygen atoms occurs upon complexation of vanadate (HVO 4 2 − ) by DHIP in solution, creating a ‘bare’ 1:2 vanadium(V)–DHIP complex, V V L 2 , with loss of water (L here indicates deprotonated DHIP).…”