Oxovanadium ion

The e.s.r. spectra of oxovanadium ions in redox systems have been reported. The interaction of free-radicals generated using the reactions of cerium(iv) or ferrous ions with hydrogen peroxide with oxovanadium(v), produces a complex which decays in a first-order manner (k = 6-2 s at 22 °C) with the formation of vanadium(iv). The oxidation of phenetidines by bromate is catalysed by vanadium(v) and kinetic parameters involved in the interactions of various substrates with vanadium(v) have been correlated with electron configurations. The redox behaviour of oxo-3,5-disulphocatecholatovanadium(v) has been studied and the acidity dependence in the reaction with phenylethyl alcohol reported. In the... 

Hinkle KR, Jameson CJ, Murad S (2014) Transport of Vanadium and Oxovanadium Ions Across Zeolite Membranes AMolecular. J Phys Chem C 118 23803-23810. doi 10.1021/jp507155s... 

Analogs of Transition States for Phosphoryl Transfer - The transition states for most enzymatic phosphoryl transfer reactions are probably very much like a trigonal bipyramid of pentacovalent phosphorus, with the entering and leaving groups (X, Y) in apical positions (28). A comidex between oxovanadium ion (IV) and uridine binds very tightly to the enzyme ribonuclease (P = 1700),... 

In the higher oxidation states partially hydrolysed species dominate the aqueous chemistry, the most important being the oxovanadium(IV), or vanadyl, ion This gives the sul-... 

Reeder and Rieger6 used ESR spectra to identify complex ions and to estimate formation constants for aqueous oxovanadium(iv) complexes with lactic acid, thiolactic acid, glycolic acid, and thioglycolic acid. Through the use of second-harmonic detection, which produces second-derivative spectra, the resolution was good enough that several of the individual species could be separately... 

The ability of vanadium(II) chloride to facilitate sulfoxide deoxygenation has been discussed (Section IV,C), and it appears that vana-dium(III) sulfoxide complexes may be prepared by air oxidation of van-adium(II) salts in the presence of the sulfoxide. In this manner, [V(Me2S0)6][C104]3 was prepared from vanadium(II) perchlorate (119) and the kinetics of substitution with thiocyanate ion detailed. Care is necessary in handling the pure compound, as it is reported to be sensitive to detonation. A large number of oxovanadium(IV) species have... 

Exchange of varying quantities of the oxovanadium(IV) ion on Mg hectorlte resulted In hydrolysis of V at low levels of adsorption (53). The hydrolyzed product that was adsorbed on the clay surface was interpreted as having a ligand environment that was partially aqueous and partially hydroxide in nature. With increasing V... 

In the ESR spectra of adsorbed oxovanadium(IV) ions on minerals, Information on the nature of the adsorbed species is obtained from the g-values and V hyperfine coupling constants, but ligand hyperfine structure is seldom, if ever, observed. With ENDOR much smaller hyperfine splittings can be observed than with ESR and it is possible to measure hyperfine coupling from nuclear spins in... 

Metal ions like copper(II), oxovanadium(IV), titanium(III), silver(II) have electron-spin quantum number equal to 1/2, like radicals. Therefore, they have no ZFS. These systems can be divided into three classes, according to the spin orbit interaction of the paramagnetic center ... 

The electron relaxes through modulation of the A and g anisotropy. Typical examples are copper(II), oxovanadium(IV) and silver(II) aqua ions. The electronic relaxation times are relatively long (10 -10 ° s at room temperature) and the hyperfine coupling with the metal nuclear spin is usually present. No field dependence of the electron relaxation time is usually evident up to 100 MHz. 

The presence of second-sphere water molecules could be considered also for other metal aqua ions, like iron(III) and oxovanadium(IV) aqua ions, where the reorientational time is found to be longer than expected. However, in the other cases increases much less than for the chromium(III) aqua ion, thus suggesting that second-sphere water molecules are more labile, their lifetime being of the order of the reorientational time. 

Oxovanadium(IV) complexes with dithiophosphate ligands have been extensively examined <8,121.161,252,386) x typical ESR spectrum is shown in Fig. 7. In addition to the eight vanadium 1=112 hyperfine lines phosphorus (/ = 1/2) superhyperfine splitting is also observed. The phosphorus superhyper-fine splitting can be considered a bit unusual since the phosphorus is located about 3 A or more away from the metal ion. P and As superhyperfine splitting has been observed in the ESR spectra of ill-defined vanadium phosphine 388) and arsine 389) complexes but in those cases, presumably, direct V-P and V—As interactions occur. ESR parameters have been tabulated for a large number of dithiophosphate 121,252) dithiophosphinate 121.252) complexes. Evaluation 3i) of the fractional 3s character of unpaired electron in dithiophosphate complexes yielded a value of 1.35%. The vanadyl(IV) complexes possess approximate C2V symmetry. The unpaired d electron resides... 

The same authors later on presented their results of the epoxidation of various cyclic and acyclic olefins employing a heterogeneous catalyst with an oxovanadium(IV) ion incorporated on a sulfonic acid ion-exchange resin and TBHP as oxidant . Selectivities... 

This oxidation state is the most stable under ordinary conditions.353 Important compounds contain the V02+ unit (vanadyl(IV) ion or oxovanadium(IV) ion), which can persist through a variety of reactions and is considered the most stable oxycation of the first row transition ions.354 It forms stable anionic, cationic and neutral complexes with all types of ligands, and has one coordination position occupied by the vanadyl oxygen (Figure 15). 

Figure 20 Different substitution rates at various coordination sites of oxovanadium(IV) ion (see text), with approximate first-order rate constants at room temperature...

Alternative stripping procedures using concentrated solutions containing chloride or nitrate ions to displace the vanadate from the loaded solvent, or sulfur dioxide to reduce the vanadium(V) to the oxovanadium(IV) cation have been proposed.210... 

Stankiewicz, PJ. and A.S. Tracey. 1995. Stimulation of enzyme activity by oxovanadium complexes. Met. Ions Biolog. Syst. 31 259-285. 

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