Oxovanadium complexes

Spin-spin coupling in oxovanadium complexes. A. Syamal, Coord. Chem. Rev., 1975, 16, 309-339... 

Organometallic compounds asymmetric catalysis, 11, 255 chiral auxiliaries, 266 enantioselectivity, 255 see also specific compounds Organozinc chemistry, 260 amino alcohols, 261, 355 chirality amplification, 273 efficiency origins, 273 ligand acceleration, 260 molecular structures, 276 reaction mechanism, 269 transition state models, 264 turnover-limiting step, 271 Orthohydroxylation, naphthol, 230 Osmium, olefin dihydroxylation, 150 Oxametallacycle intermediates, 150, 152 Oxazaborolidines, 134 Oxazoline, 356 Oxidation amines, 155 olefins, 137, 150 reduction, 5 sulfides, 155 Oxidative addition, 5 amine isomerization, 111 hydrogen molecule, 16 Oxidative dimerization, chiral phenols, 287 Oximes, borane reduction, 135 Oxindole alkylation, 338 Oxiranes, enantioselective synthesis, 137, 289, 326, 333, 349, 361 Oxonium polymerization, 332 Oxo process, 162 Oxovanadium complexes, 220 Oxygenation, C—H bonds, 149... 

Gautier, A., Mulatier, J. C., Crassous, J., Dutasta, J. P., Chiral trialkanolamine-based hemicryptophanes Synthesis and oxovanadium complex. Org. Lett. 2005, 7, 1207-1210. 

Electrochemical and structural studies of oxovanadium complexes with Schiff-base ligands attract particular attention because of their reversible redox behavior, which allows possible applications to electrocatalysts. VO(salen) and its oxidized product VvO(salen)Cl04 crystallize readily and their x-ray structures have been solved [108,109],... 

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

Ramachandran, B. and S. Subramanian. 2005. Amelioration of diabetic dyslipidemia by macrocyclic binuclear oxovanadium complex on streptozotocin induced diabetic rals. Mol. Cell. Biochem. 272 157-64. 

Figure 1. Structures of porphyrins found in petroleum. The species in petroleum are the nickel arid oxovanadium complexes.

In dinuclear oxovanadium complexes, the two oxovanadium centres may be bridged through one or two ligands. These can be 0 (jjl—0), halides, in particular CP, or alcoholate functions OR. The doubly bonded oxo group also can act as a bridging ligand (with a reduction in bond order as discussed above), mainly so if the mononuclear units are based on d/oxovanadium species. The bridging mode can be symmetric in... 

Configurations of the central V=0(/tt—0) 2 and (V=0)2/t-—O cores in binuclear oxovanadium complexes. The classifications follow the orientations of the terminal oxo gronps with respect to the plane (edge-sharing units) or the V-O-V fragment (corner-sharing nnits), partly following ref. 36. 

Chemical shifts 6( V) for oxovanadium complexes carrying the innocent ligand salicyli-deneaminatoethylimidazole and (centre and right) the noninnocent methylhydroxamate and bis(tert-butyl)catecholate. The noninnocent ligands induce downfield shifts (deshielding). ... 

Finally here it is worth noting that substitution by a fluorine atom does not always produce beneficial effects. For example, Chipperfield has synthesized the symmetric salen complexes shown in the Figure 32 containing copper(II), nickel(II) and oxovanadium(IV) [63]. Fluorination reduces the clearing point, as expected, in all but the oxovanadium complex with n = 6 where it remains constant. However, the mesophases are severely destabilized either disappearing completely or becoming monotropic. 

Chiral (salen)oxovanadium complexes for sulfide oxidation were first investigated by Fujita [29,43]. In the presence of 4 mol % of the catalyst optically active sulfoxides were obtained in good yields, however, the enantiomeric excesses remained only moderate (up to 40%). 

The reaction of [VO(Ph-acac)2] with Tp and Tp gave [VO(Ph-acac)(Tp)]-2H20 and [V0(Ph-acac)(Tp )]-2H20, respectively. The oxovanadium complex [V204(Tp)]2-2CH3CN was obtained by the reaction of V0S04-3H20 with Tp in MeOH.25... 

Insulin-like model complexes Synthesis, spectra characterization and crystal structure of two novel oxovanadium complexes with poly(pyrazolyl)borate ligands VO(HB(pz)3)(H2B(pz)2) and VO(B(pz)4)2... 

Synthesis, structure and non-thermal decomposition kinetics of scorpionates oxovanadium complexes with carboxyl acid ligand >V ° H J - 75... 

New scorpionate oxovanadium complexes Syntheses and crystal structures of a series of vanadium(V) complexes with mixed ligands of poly(pyrazolyl)borates and substituted acetylacetonates i i n)9y N O R R = Me, Et 82... 

A series of j8-diketonate Schiff base complexes (87 M = Ni, Cu, Pd, VO n=10, 12, 16) having a half disc-shape, was synthesised [164]. All the complexes, except the oxovanadium complexes, were mesomorphic (Colh), at relatively low temperatures. This approach was also applied to half-discshaped homodinuclear and heterodinuclear 1,3,5-triketonate Schiff base complexes, 88, and 1,3,5,7-tetraketonate Schiff base dicopper complexes, 89 [165]. The homodinuclear complexes 88, with M = M = Cu, X = OR, were mesomorphic showing Colh phases, whereas those with four chains (88 X = H) were not liquid-crystalline. Amongst the five heterodinuclear prepared (88 X = OR,n=14, Y = —CH2—CH2—, M = Cu, Pd, Ni, Mn, Co and M =Ni), only those with M = Cu, M = Ni and M = Pd, M =Ni, showed a mesophase, namely a Colh phase. A Colh phase was also observed for a structurally related compound, 89, (n=12, X = OR). 

Stimulation of Enzyme Activity by Oxovanadium Complexes Paul J. Stankiewicz and Alan S. Tracy... 

A number of a-substituted-j8-diketone ((200) R = R" = Me), a-substituted-j8-ketoaldehyde ((200) R = Me, R" = H), and a-substituted-yS-dialdehyde ((200) R = R" = H) complexes were investigated to evaluate their liquid crystalline properties. Whereas none of the diketone and ketoalde-hyde copper(II) complexes was mesomorphic, bis(4-alkoxyphenylmalonaldehyde)copper and oxovanadium(rV) complexes " ((200) R = R" = H R = OC H2 +i, m > 8 for M = Cu and n > 10 for M=VO) and bis(4-alkoxyphenylmalonaldehyde)copper complexes ((200) M = Cu R = R" = H R = C H2 +i, ra>5) displayed a narrow-temperature-range ( 10°Q nematic phase above 200 °C. Some nickel complexes were also prepared but extensive decomposition hampered mesophase characterization. Fliiorination and/or chlorination at the 2- or 3-position was found to lower the transition temperature substantially in the copper complexes without destroying the nematic phase, but to inhibit mesophase formation in nickel and oxovanadium complexes. 

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