Vanadium complexes hydroxy acids

Hambley, T.W., R.J. Judd, and P.A. Lay. 1992. Synthesis and crystal structure of a vanadium(V) complex with a 2-hydroxy acid ligand A structural model of both vanadium(V) transferrin and ribonuclease complexes with inhibitors. Inorg. Chem. 31 343-345. 

This book does not follow a chronological sequence but rather builds up in a hierarchy of complexity. Some basic principles of 51V NMR spectroscopy are discussed this is followed by a description of the self-condensation reactions of vanadate itself. The reactions with simple monodentate ligands are then described, and this proceeds to more complicated systems such as diols, -hydroxy acids, amino acids, peptides, and so on. Aspects of this sequence are later revisited but with interest now directed toward the influence of ligand electronic properties on coordination and reactivity. The influences of ligands, particularly those of hydrogen peroxide and hydroxyl amine, on heteroligand reactivity are compared and contrasted. There is a brief discussion of the vanadium-dependent haloperoxidases and model systems. There is also some discussion of vanadium in the environment and of some technological applications. Because vanadium pollution is inextricably linked to vanadium(V) chemistry, some discussion of vanadium as a pollutant is provided. This book provides only a very brief discussion of vanadium oxidation states other than V(V) and also does not discuss vanadium redox activity, except in a peripheral manner where required. It does, however, briefly cover the catalytic reactions of peroxovanadates and haloperoxidases model compounds. 

Somewhat surprisingly, maltol (2-methyl-3-hydroxy-4-pyrone), an aromatic analogue to a-hydroxy carboxylic acids, shows little inclination toward formation of dimeric complexes. Rather, the chemistry is more in parallel with that of oxalate, and an x-ray structure of the bismaltolato complex [25] shows a cis octahedral coordination similar to that found for the oxalate complex. Under mildly acidic to moderately basic solution, the major complexes are mono- and bisligand derivatives. The corresponding vanadium chemical shifts are -509 and -496 ppm, respectively [25,26], The closely related amines, 2-methyl-3-hydroxy-4-pyridinone and its N-... 

In 1972 Bayer and Kneifel isolated (98) a pale blue compound from A. muscaria containing vanadium, which they named amavadine. They proposed (98,99) that it consisted of a complex of AT-hydroxyimino-a,a -dipropionic acid with in a 2 1 ratio. From a comparison of the EPR spectra of segments of frozen mushrooms with those of vanadyl complexes of various amino acids, it was concluded (100,101) that this proposal was not very likely. However, Krauss et al. (102) synthesized amavadine and compared its EPR properties with the complex extracted from the mushroom and concluded that it was the same. Others were unable to reproduce the synthesis (103), although models analogous to amavadine were reported. The synthesis of the ligand N-hydroxy-a,a -iminodipropionic acid, and related compounds was, however, later confirmed (104-106). The stereochemistry and total synthesis of the vanadium compound of A. muscaria has now been elucidated (107). 

The use of the complex with A -substituted-phenylstyrylacrylohydroxamic acid and Aliquat 336 for the determination of V in alloys, rock, environmental and clinical samples has recently been reported [1]. Studies on the complexation of V(V) with PAR on the solid phase of a fibrous sorbent filled with an anion exchanger were described [2]. The DL of of 3-4 ng ml V was achieved. The effect of modification of a solid support with 8-hydroxyquinoline and 8-hydroxyquinoline-5-sulfonic acid on analytical characteristics of the reaction of vanadium(V) with PAR on a solid phase was studied [3]. Extraction of V with the use of 3-hydroxy-2-(4-methoxyphenyl)-6-methyl-4//-chromen-4-one was employed to detect V in flue dust and steel [4]. 

Magnetic exchange interactions have also been identified in the oxovanadium-(iv) complexes with the Schiff bases derived from 2-hydroxy-l-naphthaldehyde and ethanolamine or propanolamine. Such complexes can accommodate two further donor atoms per metal and [VO(A)(L)] (A = bipy or phen HjL = Schiff base from salicylaldehyde or 2-hydroxy-l-naphthaldehyde with glycine, alanine, anthranilic acid, or o-aminophenol) complexes have been shown to involve six-co-ordinate vanadium. Similarly, VOL,B [HjL = 2-hydroxy-naphthylideneamino-acid, B = HjO, phen, or (py)2 HjL = 2-hydroxy-naphthylidene-o-aminophenol, B = phen] have normal magnetic moments ifi = 1.70—1.74 BM) at room temperature. The complex VOL (HjL = 6,ll-dimethyl-7,10-diazahexadeca-6,10-diene-2,4,13,15-tetrone) has been prepared from V0(0H)2, heptane-2,4,6-trione, and en in MeOH. The structure... 

We therefore determined the complex stability constants of a larger variety of ligands related to HIDP, which are shown for the V(IV)- and Cu(II)-chelates in table 2. Only N-hydroxy-iminodiacetic acid forms a vanadium compound with similar stability as amavadin. All other ligands like the isomeric compound N-hydroxy-D,D -iminodipropionic acid or the bidentate ligand N-hydroxy- -alanine form much weaker complexes. 

In these reactions the tested organic substance and an inorganic salt give a more or less stable strong color due to a complex salt. In Part 2 of this monograph a series of such reactions is described, such as, for example, the reaction of hydroxamic acids with ferric salts (p. 276), the reaction of phenols with ferric chloride (p. 188), the reaction of molybdenum with o-dihydro-xybenzenes (p. 191), of diacetyl dioxime with nickel salts (p. 227), of phenols with Millon s reagent (p. 196), alcohols with ceric ammonium nitrate (p. 170), alcohols with vanadium-hydroxy quinoline complex (p. 171), and the reaction of cis-enols of )5-dicarbonylic compounds and a-dicarbonyl compounds with ferric chloride, (p. 294.)... 

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