Synthesis, characterization and crystal structure of a stable aqua-dioxo-tetraperoxodivanadate(V) with a cation of macrocyclic tetraamine

Histidine-Containing Bisperoxovanadium(V) Compounds: Insight Into the Solution Structure by an ESI-MS and 51V-NMR Comparative Study

“…6.8 shows in 51 V-NMR the known distri-identified as the bisperoxovanadium compound. [20] Furthermore, species having a peroxo-tovanadium ratio higher than two have been detected at m/z 315 and 361. [17] In particular the prevailing species are monomeric, peaks can be attributed to bisperoxo species containing different solvent molecules in the coordination sphere: [VO 5 ] Ϫ dimeric and tetrameric metavandates, respectively, indicated by the resonances at δ ϭ Ϫ559, Ϫ572, and Ϫ577, in agree-(m/z 131, 100%), the solvent bound species [VO 5 Ϫ m/z 223, the latter in much lower relative intensity.…”

Towards hydroperoxovanadium complexes: the X-ray crystal structure of a peroxovanadium(v) complex containing a V(O2)(RCO2H)(H2O)2 cluster with hydrogen bond inter-linkages

“…§ Although only O2 of the peroxide is involved in this H-bonding network to a sizable extent, there are no significant differences in the V-O (peroxide) bond lengths. Bonding parameters [d(V-O1) 1.8734 (16), d(V-O2) 1.8827(16) Å; angle O1-V-O2 = 44.48 (7)°] are comparable to those in other peroxovanadium complexes; 9,13,[23][24][25]29 the O-O bond length, 1.421 (3), is inbetween the margins noted for [V 2 O 2 (O 2 ) 4 H 2 O] 22 13 and [VO(O 2 )(tp)(pz)] (tp = tris(pyrazolyl)borate, pz = pyrazole). 30 This special arrangement of carboxylic acid, water and peroxide provides a basis for a mechanism for rapid -and reversible -transfer of a proton to the activated (by coordination to vanadium) peroxo function, and hence a mechanism by which the electrophilicity of this site can be adapted to an appropriate substrate to be oxidised, such as bromide; cf.…”

“…10 The asymmetric side-on coordination of RO 2 2 has previously been reported for 22 . 13 Based on kinetic investigations, hydroperoxo intermediates have also been made plausible in oxo transfer reactions to metal-centred thiolates using [VO(O 2 ) 2 (pic)] 22 , 14 and peroxidative halogenations with [VO(O 2 )(bpg)] (bpgH = N,N-bis(2-pyridylmethyl)glycine). 5,9 An additional point of considerable interest in the context of peroxovanadium complexes is their ability to inhibit phosphotyrosine phosphatases and thus act as insulin mimetics.…”

Histidine-Containing Bisperoxovanadium(V) Compounds: Insight Into the Solution Structure by an ESI-MS and51V-NMR Comparative Study

“…It is worth of noting that very recently the crystal structure of this latter dimeric compound has been solved. [20] Furthermore, species having a peroxo-tovanadium ratio higher than two have been detected at m/z 315 and 361. As far as the possibility of observing the formation of the previously reported [19] triperoxo compound is concerned, under such experimental conditions even Ϫ (m/z 201, < 5%), water, 1:1, pH 6.9 we could not confirm its nature with collision induced-decomposition experiments (MS n ) because of the low intensity of the signal.…”