Electrochemical Investigations of the Complexes Resulting from the Acid-Promoted Deoxygenation and Dimerization of (N,N'-Ethylenebis(salicylideneaminato))oxovanadium(IV)

Abstract

Electrochemical confirmation that (7V,7V-ethylenebis(saiicylideneaminato))oxovanadium(IV), VO(salen), reacts with trifluoromethanesulfonic acid (CF3SO3H) or triphenylmethyl tetrafluoroborate (Ph3C(BF4)) to form a deoxygenated complex, VIV(salen)2+, and a µ-oxodinuclear complex, [(salen)VOV(salen)]X2, (X = CF3SO3™ or BF4-) is presented. Cyclic voltammograms of VO(salen) in the presence of CF3SO3H or Ph3C(BF4) exhibit reversible waves with formal potentials near 0.5 and 0.8 V (vs Ag/AgCl). The cathodic wave at 0.5 V is argued to arise from the combined reduction of V(salen)2+ and the µ-dimeric complex and the wave at 0.8 V from the oxidation of the V(salen)2+ complex. The diffusion coefficients of these three complexes in acetonitrile were determined. The dimerization of VO(salen) is initiated by deoxygenation of the V=0 center by H+ or Ph3C+ to produce V(salen)2+ which enters into an equilibrium with a second VO(salen) complex to produce the µ-dimer. The kinetics of

Salophen and salen oxo vanadium complexes as catalysts of sulfides oxidation with H2O2: Mechanistic insights

“…The synthesis of these complexes was accomplished by a procedure slightly different form that reported in the literature [34]. For all compounds 1 H NMR spectra are in agreement with the structure (in CD 3 CN, aromatic protons resonate in the range 7.1-7.8 ppm, CH N protons in the range 8.2-8.9 ppm, and CH 2 protons of salen complexes are around 4.4 ppm).…”

“…A number of the vanadium derivatives used in the literature were tested as precursors, i.e. VO(acetylacetonate) 2 [31], vanadyl sulfate di-hydrate [29,33], and V(acetylacetonate) 3 [34]. The best results were obtained with V III (acac) 3 , in terms of reproducibility of the reaction and solubility of complexes.…”

“…The various ligands have been subsequently used to synthesize all V IV and V V complexes in very good yields (see Section 2), following slightly modified literature procedures [27,31,32,34] and the species obtained have been identified by comparison of their properties with literature data.…”

A journey into the electrochemistry of vanadium compounds

“…The electrochemical properties of all the oxidovanadium(V) complexes, examined in MeCN by cyclic voltammetry, consisted in a quasi-reversible response in the potential range 0.29-0.36 V vs Ag + /Ag, involving single electron V(V) → V(IV) reduction (Table 5, entries [77][78][79].…”

Investigation of VO–salophen complexes electronic structure

“…A number of vanadium derivatives were tested as precursors, i.e. VO(acac) 2 (acac = acetylacetonate) [19], vanadyl sulfate di-hydrate [21,22], and V(acac) 3 [23]. The best results in terms of reproducibility and solubility of the complexes were obtained with V(acac) 3 .…”