Vanadium coordination compounds chelating ligands

Diols derived from substituted monosaccharides have also been shown to bind as chelated heteroligands to L-amino acid-derived Shifif base complexes [17]. The coordination about vanadium in these complexes is octahedral, with the sixth coordination site occupied by an oxo ligand. Vanadium-5 NMR spectra from nonaqueous solvent show the coordination is retained in solution. Evidently, the compound is stable... 

Vanadium-5 NMR spectroscopy has shown there are a number of complexes of varying stoichiometry and coordination formed in aqueous solution. These can clearly be seen in Figure 5.4 for the Af,A-dimethylhydroxylamine ligand. Of the complexes formed, two chelate complexes have VL stoichiometry (—670 ppm). These compounds are both monoanionic at neutral pH, and one complex, if not both complexes, can give up an additional proton under basic conditions [21], The observation of two chelate monoligand products clearly shows that there are two distinct coordination geometries for the VL complexes. Presumably, these are based on the coordination of the VL2 complexes. An additional monohydroxylamine complex that apparently is coordinated end-on via the hydroxylamine OH has been found [6,7],... 

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