The vanadium-vanadium interactions in the polygonal aggregates of d¹ vanadium(IV) atoms, with a total of 4k + 2 vanadium electrons (k an integer) imbedded in an electronically inactive borate matrix in certain vanadoborate structures are analogous to the ring carbon-carbon interactions in diamagnetic planar cyclic hydrocarbons. They thus represent a high-spin analogue of aromaticity. Thus, the ...

the possibility of application of 4-nitrocatechol (4-nc) - tetrazolium salt - organic solventsystems for liquid-liquid extraction-spectrophotometric vanadium (iv and v) speciation wasstudied. six commercially available tetrazolium salts (2,3,5-triphenyltetrazolium chloride (ttc),3-(2-naphtyl)-2,5-diphenyltetrazolium chloride (tetrazolium violet, tv); 3-(4,5-dimethyl-2-thiazol)-2,5-diphenyltetra...

The effect of the point of zero charge (PZC) of the support oxide (Al2O3,Nb2O5, SiO2 and ZrO2) on the molecular structure of hydrated vanadium oxide specieshas been investigated with EXAFS spectroscopy for low-loaded vanadium oxidecatalysts. It was found that the degree of clustering (i.e., the V---V coordinationnumber) and the V---V distance increase with decreasing PZC of ...

Vanadium silicates such as V-Al-analcime, V-analcime, V-magediite and V-ZSM-11 were synthesized using vanadium pentoxide or vanadyl sulfates. Vanadium silicates with analcime structure with and without aluminum (V-Al-analcime, V-analcime) were prepared as pure phase by hydrothermal crystallization from a gel with molar composition of (1 SiO2; 0.2 V2O5; 1 Na2O; 0.034 Al2O3; 35.7 H2O) and (1 SiO2...

Isostructural vanadium, niobium and tantalum complexes of bis(3,5-di-tert-butyl-2-phenol)amine ([ONO]H3), were prepared and characterized to evaluate the impact of the metal ion on redox-activity of the ligand platform. New vanadium and niobium complexes with the general formula, [ONO]MCl2L (M = V, L = THF, 1-V; M = Nb, L = Et2O, 1-Nb) were prepared and structurally analysed by X-ray crystallog...

Solid-state wide-line, magic-angle spinning (MAS) and pulse excitation (nutation) NMR techniques are applied in a study of local environmeots in two-dimensional vanadium(V) oxide surface layers on titania and alumina supports. Two main surface vanadium oxide species with different bonding environments are detected, which are, on the basis of their anisotropic chemical shift and nuclear electric...

Reactions of the salicylaldehyde 4-phenylthiosemicarbazone (H(2)L) with selected vanadium(iv) and vanadium(v) precursors ([VO(acac)(2)], [VO(OAc)(2)], VOSO(4), [V(2)O(4)(acac)(2)]) were investigated under aerobic conditions in different alcohols (methanol, ethanol, propanol). In all examined cases mononuclear alkoxo vanadium(v) complexes [VOL(OR)] (1) (OR = OMe, OEt, OPr) were isolated as major...

This paper examines vanadium chloride solutions as electrolytes for an all-vanadium redox flow battery. The chloride solutions were capable of dissolving more than 2.3 M vanadium at varied valence states and remained stable at 0-50 °C. The improved stability appeared due to the formation of a vanadium dinuclear [V(2)O(3)·4H(2)O](4+) or a dinuclear-chloro complex [V(2)O(3)Cl·3H(2)O](3+) in the s...

A mild and efficient synthesis of polysubstituted dihydro-2-oxypyrroles has been developed for the one-pot, four-component domino condensation of dialkyl acetylenedicarboxylate, formaldehyde and aromatic amines using Vanadium (V) oxide as the catalyst at ambient temperature. The use of Vanadium (V) oxide makes this process simple, more convenient, and environmentally friendly.