Vanadium complexes imidazole

Andersson, I., S J. Angus-Dunne, O.W. Howarth, and L. Pettersson. 2000. Speciation in vanadium bioinorganic systems 6. Speciation study of aqueous peroxovanadates, including complexes with imidazole. J. Inorg. Biochem. 80 51-58. 

Vanadium(II) heterocyclic amine complexes of the type [VX2L4] and [VL6]X2 (L = heterocyclic amine, e g. pyrazole, imidazole, 2-methylimidazole, benzimidazole, isoquinoline X = anionic ligand) have been known for some time and more recent examples of such complexes include polypyridyl V complexes of the type [V(terpy)(bipy)L] +. Such complexes are obtained as a result of the disproportionation reaction of [V (terpy)Cl3], which yields [V (terpy)2] + and [V 0] + in CH2CI2 suspensions. ... 

Attempts to model the structure of the V-dependent bromoperoxidase enzyme have resnlted in the characterization by X-ray crystallography of a great number of VO + complexes having N,N,N,N-donor atoms. The imidazole group is thought to mimic the protein enviromnent and complexes such as [VO(SALIMH)(acac)(MeOH)], [VO(SALIMH)SAL], and [VO(SALIMH)2(EtOH)], have been prepared " (see Vanadium in Biology). 

Fignre 3 Vanadium-51 chemical shifts for the complexes [CpV(CO)3L], where L is a neutral ligand (g = 0) or an anionic ligand (9=— ). Curly brackets indicate functionalities py = pyridine im = imidazole... 

Aromatic amines, such as pyridine and imidazole, have been found to form weak complexes with vanadate.100 104 2 7 The fact that no vanadium(V) complexes with aliphatic amines, in the absence of stabilizing ligands, have been reported supports the expectation that such complexes will have low stability in aqueous solution. In the presence of ancillary ligands, both aliphatic119 and aromatic73 amines form stable ternary complexes in solution. 

Complexes of ligands with O-donors and two or three N-donors are known. The kinetics of the outer-sphere oxidation of cis-aq uaoxovanad i u m (IV) complexes of [2-(pyridylmethyl)imino]diacet-ate and its derivatives were determined.675 Complexes with Schiff bases have been used to mimic the structure and chemistry of vanadium bromoperoxidase.275 The ligation of an imidazole functionality in the ligand has been found to readily dissociate, and is important to the functional aspects of this complex.275 A variety of five-coordinate complexes with tridentate Schiff base complexes have been prepared, several of which have been found to form supramolecular polymeric structures through association between the V=0 groups in a V=0 V=0 V=0 pattern (140).627... 

Vanadium(V), which does not contain d electrons, obviously is restricted to intra-ligand and LMCT absorptions. Simple compounds such as vanadate are colourless, because the LMCT bands lie in the UV region. Decavanadate, and also vanadate-dependent haloper-oxidases (which contain vanadate additionally coordinated to a side-chain imidazole of the protein matrix), are yellow, because the LMCT tails from the UV into the violet range. More complex vanadium(V) complexes can be very colourful when the LMCT... 

Vanadium. The interactions betwen vanadate, uridine, and imidazole have been studied using C, 0, and V NMR spectroscopy. Complex formation between HSCH2CHOHCHOHCH2SH and vanadate has been investigated using V NMR spectroscopy. V NMR spectroscopy has been used to study the interaction of vanadate oligomers with a 90 kDa heat shock protein, Hsp90. The interaction of vanadate with aquatic humic substance has been studied using V NMR spectroscopy. ... 

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