Cations vanadium

No homoleptic isocyanide complexes of niobium, tantalum, titanium, zirconium, and halfnium have yet been synthesized. The vanadium cation... 

Bisbenzene vanadium and bismesitylene vanadium have been synthesized by the Fischer-Hafner method 53, 133). The reaction is thought to proceed via formation of the bisarene vanadium cation, e.g.. 

The kinetics of acrolein oxidation is of first order with respect to acrolein, which can be easily understood by the competition of strongly adsorbed acrylic acid and less strongly adsorbed acrolein. The reduced rate of acrolein oxidation at elevated acrolein concentration is interpreted by adsorption of acrolein on reduced sites and consequently described by a negative reaction order with respect to acrolein in the reoxidation term r(02). In this context the independence of the acrolein oxidation rate from acrylic acid concentration is surprising. This result may be understood by the reaction mechanism proposed by T.V. Andrushkevich in which formed acrylate anions are shifted to sites on vanadium cations and after protonation are desorbed as acrylic acid. Parallel to the protonation the reduced sites are reoxidized. 

S. Akita and T. Iwahori, Energy storage, Karyoku Genshiryoku Hatsuden (The thermal and Nuclear Power), 2001, 52, 1344 D-G. Oei, Permeation of vanadium cations through anion and cation exchange membranes, J. Appl. Electrochem., 1985,15, 231. 

While there has been great interest in the preparation of nanofibers, the studies on metal-oiganic polymers are rare. In the most recent investigation in this field, the growth of MOF (MIL-47) on electrospun polyacrylonitrile (PAN) mat was studied using in situ microwave irradiation [18]. MIL-47 consists of vanadium cations associated to six oxygen atoms, forming chains connected by terephthalate linkers (Fig. 6). 

Fig. 6. Relationship between selectivity in ammoxidation of 3-picoline to nicotinonitrile and concentration of reduced vanadium cations. Reprinted with permission from Ref (92)., Copyright (1985), American Chemical Society.

Fig. 23.13 Correlation of V/Sn ratio with (a) sensor response to CO and XPS data related to (b) Sn3d and Ols binding energy (BE) and (c) vanadium cation fraction (Data extracted from Wang et al. 2011a, b)...

In addition to cupric and ferric ions, manganese, nickel and vanadium cations are also active catalysts of these reactions [28, 29]. The catalytic oxidation of adrenaline, in the presence of Mn ions, has been studied recently and the reaction found to be inhibited by ascorbic acid [47]. 

Many attempts have been made to block the cross-diffusion of vanadium cations through polyelectrolyte membranes, in order to modify the water-filled channels... 

The ionic radii of the vanadium cations are 0.79 and 0.64 A for vanadium(II) and vanadium(III), respectively (Shannon, 1976), and with apparent ionic radii of 0.56 and 0.50 A for the hydrolysis species of vanadium(IV) and vanadium(V), respectively (see discussion in Brown and Wanner (1987) in relation to the derivation of the apparent ionic radii for oxo-cations). 

The bis- i-mesitylene vanadium cation may then undergo hydrolytic disproportionation. As shown below, the extent of the hydrolytic disproportionation depends on the basicity of the solution [28]. 

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