Electron paramagnetic resonance vanadium

The reaction of bis(benzene)vanadium [12129-72-5] with TCNE affords an insoluble amorphous black soHd that exhibits field-dependent magnetization and hysteresis at room temperature, an organic-based magnet (12). The anion radical is quite stable in the soHd state. It is paramagnetic, and its intense electron paramagnetic resonance (epr) spectmm has nine principal lines with the intensity ratios expected for four equivalent N nuclei (13) and may be used as an internal reference in epr work (see Magnetic spin resonance). 

Bogomolova, L.D., Jachkin, V.A., Lazukin, V.N., Pavlushkina, T.K., and Shmuckler, V.A. 1978. The electron paramagnetic resonance and optical spectra of copper and vanadium in phosphate glasses. Journal of Non-Crystalline Solids 28 375-389. 

The spectrum for LaY impregnated with vanadyl naphthenate shows a characteristic band at 365 nm that loses most of its intensity after calcination, Figs. 5a, 5b. This is not surprising since Pompe et al (30), using TGA/DTA data,have shown that the oxidative decomposition of the vanadyl naphthenate is complete at 500°C. Electron paramagnetic resonance (EPR) studies have shown that vanadium (after calcination) is stabilized mainly in the form of vanadyl (V02+) cations in the zeolite supercages (29). 

SIMS (61,64,86), microscopy (65), XPS (56), electron microprobe techniques (14,66), electron paramagnetic resonance (EPR) (67) and luminescence experiments (68) have been successfully employed to probe and study V mobility and reactivity on a catalyst surface. TEM, STEM and energy dispersive X-ray emission (EDX) measurements have indicated that V interaction with REY-crystals induced vanadate clusters formation (65). Vanadium was also found capable of reacting with rare-earths outside the zeolite cavities to form LaVQ4... 

Analysis of vanadium-loaded model materials (such as EuY, amorphous aluminosilicate gels and EuY-gel mixtures) by electron paramagnetic resonance (EPR) has provided information concerning metal oxidation state and stereochemistry (67). EPR data has indicated that when vanadyl cations are introduced in the form of vanadyl naphthenate, they were stabilized in a zeolite with the faujasite structure as pseudo-octahedral V02+ even after calcination at 540°C. Upon steaming, these V02+ cations were then converted almost entirely to V+5 species (67). The formation of EuV04 was verified but the concentration of this vanadate was never proportional to the total rare-earth content of the zeolite. In EuY-gel mixtures the gel preferentially sorbed vanadium where it was stabilized mainly in the form of V205. 

Degani, H., M. Gochin, SJ.D. Karlish, and Y. Shechter. 1981. Electron paramagnetic resonance studies and insulin-like effects of vanadium in rat adipocytes. Biochemistry 20 5795-9. 

Dikanov, S.A., B.D. Liboiron, and C. Orvig. 2002. Two-dimensional (2D) pulsed electron paramagnetic resonance study of V02+-triphosphate interactions Evidence for tridentate triphosphate coordination, and relevance to bone uptake and insulin enhancement by vanadium pharmaceuticals. J. Am. Chem. Soc. 124 2969-2978. 

Components of fluidized cracking catalysts (FCC), such as an aluminosilicate gel and a rare-earth (RE) exchanged zeolite Y, have been contaminated with vanadyl naphthenate and the V thus deposited passivated with organotin complexes. Luminescence, electron paramagnetic resonance (EPR) and Mossbauer spectroscopy have been used to monitor V-support interactions. Luminescence results have indicated that the naphthenate decomposes during calcination in air with generation of (V 0)+i ions. After steam-aging, V Og and REVO- formation occurred. In the presence of Sn, Tormation Of vanadium-tin oxide species enhance the zeolite stability in the presence of V-contaminants. 

Thus, x-ray powder diffraction, electron paramagnetic resonance, luminescence and Mossbauer data suggest that a complex of Sn, V0+ and oxygen forms that leads to the passivation of vanadium when deposited on the zeolite, and on zeolite/gel mixtures. This complex may be a compound like VpSnO, or similar higher molecular weight species. Evidence of Sn/V all oy formation has not been found from Mossbauer spectroscopy. 

By using non-invasive techniques, it is possible to determine the concentration and oxidation state of vanadium in living cells. In A. ceratodes, EXAFS (X-ray absorption fine structure) techniques showed that 90% of the vanadium is in the form of V(III), 10% is V(IV)84. In A. nigra, EPR (electron paramagnetic resonance) spectroscopy showed that 95% of the vanadium is in the V(III) form, and 5% is V(IV)85. ... 

Tris[bis(trimethylsilyl)amido] vanadium(III) crystallizes from benzene as dark-brown, soft needles, extremely sensitive to air and moisture. This complex is paramagnetic 2.4 BM) but does not show electron paramagnetic resonance absorption at temperatures above that of liquid nitrogen. The compound is thermally unstable but gives a mass spectrum containing the parent molecular ion. Infrared spectra and electronic absorption spectra are given in Table II. The crystalline complex has the same trigonal structure as the Fe compound. ... 

Goodman, B. A. and Cheshire, M. V. (1975). The bonding of vanadium in complexes with humic acid An electron paramagnetic resonance study. Geochim. Cosmochim. Acta 39, 1711-1713. 

Ye S, Neese F, Ozarowski A et al (2010) Family of V(ni)-tristhiolato complexes relevant to functional models of vanadium nitrogenase synthesis and electronic structure investigations by means of high-frequency and -field electron paramagnetic resonance coupled to quantum chemical computations. Inorg Chem 49 977-988... 

Insulin-Enhancing Vanadium Pharmaceuticals The Role of Electron Paramagnetic Resonance Methods in the Evaluation OF Antidiabetic Potential... 

Chasteen ND, Lord EM, Thompson HJ. 1985. Vanadium metabolism vanadyl(IV) electron paramagnetic resonance spectroscopy of selected rat tissues in the rat. In Frontiers in bioinorganic chemistry, pp. 133-141. Ed A Xavier. Weinheim, Germany VCH. 

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