Molybdenum complexes hydroxamic acids

Dutta, R. L. Metal complexes of hydroxamic acids. Colored complexes of iron, vanadium and molybdenum with isonicotinohydroxamic acids and their analtyical uses. J. Ind. Chem. Soc. 36, 285 (1959). 

Molybdenum(VI) complexes citric acid, 476 IR spectra, 469 guanidine, 283 hydroxamic adds, 506 maleic add, 475 conformation, 467 crystal structure, 476 tartaric add, 479 NMR, 468... 

Enantiomerically pure manganese complexes using ligands other than the salen structure have been reported, but so far with lower enantioselectiv-ities. Better results have been achieved using molybdenum complexes bearing hydroxamic acid ligands and TBHP or cumylhydroperoxide as oxidant. This system has been used to effect the epoxidation of a range of olefins with up to 96% ee. 

Secondary amides are oxidized, as their iV-trimethylsilyl derivatives, to the corresponding hydroxamic acids by a molybdenum oxide-HMPA complex. NN-disubstituted thiocarbamoyl chlorides or bromides are easily prepared by direct reaction of the corresponding thioformamides with elemental halogen. 

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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