V^IVO and V^IV Species Formed in Aqueous Solution by the Tridentate Glutaroimide–Dioxime Ligand – An Instrumental and Computational Characterization

Abstract

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 [a]

A hydrolytically stable Ce(iv) complex of glutarimide-dioxime

“…Similar calculations involving Ce(IV) or H 3 A have been reported previously. 16,21,28,[30][31][32] The optimized structure exhibited good overall agreement with crystallographic data. The major differences involved the Ce-N bonds, exhibiting deviations up to 0.05 Å between the computational and experimental results.…”

“…H 3 A was originally known to extract uranyl (U VI [14][15][16][17][18] H 3 A was then developed to readily chelate simple metal ions, such as Ca(II), 19 Mg(II), 19 Cu(II), 20 Pb(II), 20 Ni (II), 20 Mn(II), 21 Fe(III), 20 Eu(III), 22 Nd(III), 22 and metals of high oxidation states, such as Th(IV), 23 Np(IV), 23 Pu(IV), 24 Np(V), 25 and V(V). [26][27][28] We reasoned it would similarly stabilize the Ce (IV) cation as in the high oxidation state metal complexes cases (Scheme 1). Complexation of glutarimide-dioxime (H 3 A) with tetravalent cerium is of potential interest from applied and fundamental chemistry perspectives.…”

Synthesis, structural and physicochemical characterization of a new type Ti6-oxo cluster protected by a cyclic imide dioxime ligand

“…The ligand H3pidiox in its mono/di and tri-deprotonated form acts as a tridentate chelator in its metal complexes with U VI , {[U VI O2(Hpidiox)2]}, 31 Fe III , {[Fe III (Hpidiox)(H2pidiox)]} 32 and V IV/V , {[V IV/V (pidiox)2] 2−/− }. 33,34 The hydrolytic stability of the ligand H3pidiox was reported by Hay and coworkers. 35…”

“…3a), 36,37 and the second one consisting of two planar {Ti3O3} units parallel to each other (Fig. 3b); 12,[27][28][29][30][31][32][33][34][35][36][37][38][39]42 (ii) six configurations with the six Ti IV lying almost on a planar arrangement {Ti6 55 and {Ti6(μ2-O)9} ( Fig. 3f), 56 exhibiting two {Ti3(μ2-O)3} units parallel to each other; and (iv) {Ti6(μ3-O)2(μ2-O)2} ( Fig.…”

“…This assignment was supported by the UVvis spectra of the mononuclear metal-H3pidiox complexes, which exhibit strong absorption at similar wavelengths. 32,34 The broad intense peak at 383 nm was assigned to O-Ti IV LMCT transitions.…”