Reactivity of μ-Peroxo-Bridged Dimeric Vanadate in Bromoperoxidation

Macromolecular peroxo complexes of Vanadium(V) and Molybdenum(VI): Catalytic activities and biochemical relevance

“…61 The findings are consistent with the previous suggestion implicating formation of a peroxobridged divanadate intermediate as active brominating species at neutral pH. 5,127,128 Scope of using the pV complexes for mediating bromination of various other organic substrates has also been explored in aqueous-organic media. 61 Smooth conversion of several activated aromatics into their corresponding bromo-organics were achieved by stirring a solution of the substrate in presence of PV 1 or PV 4 in CH 3 CN:H 2 O (1:1) for 7-10 h at ambient temperature.…”

“…Vanadium has a chemical versatility that is useful to biological systems [1][2][3][4][5][6][7] and is redox active under physiological conditions. 8,9 One of the most fascinating domains of vanadium chemistry is its peroxo chemistry.…”

Density functional studies on structure and reactivity of a dinuclear peroxovanadate(V) complex

“…1). The distances of all the six hydrogen bonds present in the complex are given in Table 2 compounds lend support to our earlier suggestion that the amino acid and peptide ligands impart stability to the highly reactive 'VOOV' species by inter-ligand interaction possibly hydrogen bonding, affording their isolation into solid state [10][11][12][13]. It is significant to note that such dimeric compounds could be isolated only in the presence of coligands with ability to form H-bond, such as amino acids and peptides.…”

“…The proposed reaction pathway based on our experiments and work of some other laboratories conferred the status of a selective bromide oxidant, at physiological pH, on VOOV group [10][11][12][13][14][15]. The l-peroxo group of the VOOV moiety appears to be amenable for reductive cleavage by bromide which produces a bromination competent intermediate, postulated to be -BrOVO(O 2 ), that can transfer the bromine atom to the substrate [10][11][12][13][14]. However, the cause of this greater reactivity of a peroxobridged divanadate moiety compared to a g 2 -peroxo group, in an oxidative bromination reaction was not completely clear.…”

“…Contrary to natural V-BPO which is most efficient at pH 5.5-7, most of the synthetic peroxovanadate compounds studied as functional model of the V-BPO were found to be catalytically active only in acid medium [1,4,7]. Significantly, a series of pV compounds with the distinctive feature of having a l-peroxo group and amino acids or small peptides serving as ancillary ligands, of the type [V 2 O 2 (O 2 ) 3 (L) 3 ] Á H 2 O (L = asn, gln, gly-gly, gly-ala or gly-asn) synthesized by us [10][11][12], could act as powerful bromide oxidant at physiological pH [10][11][12][13], an essential requirement of a biomimetic model. Diperoxovanadate compounds with exclusively g 2 -peroxo groups in its co-ordination sphere were found to be catalytically incompetent in bromide oxidation at neutral pH [12].…”