Structure, Physicochemical and Biological Properties of an Aqua (2,2′,2′′‐Nitrilotriacetato)‐oxidovanadium(IV) Salt with 4‐Methylpyridinium Cation

Abstract

The crystal structure of a nitrilotriacetate (nta) oxidovanadium(IV) salt with 4-methylpyridinium cation, [4-Me(Py)H] + , of [4-Me(Py)H][VO(nta)(H 2 O)] stoichiometry was determined. The complex comprises a discrete mononuclear [VO(nta)(H 2]coordination entity that can be rarely found among other known compounds containing nitrilotriacetate oxidovanadium(IV) moieties. The complex was characterized by spectroscopic (IR and EPR) methods, magnetic measurements, and thermogravimetry (TG-FTIR). The stability of the title compound in aqueous solutions was investigated by using the potentiometric titration method. Furthermore, spectrophotometric (UV/Vis) studies have revealed that the compound is capable to scavenge the

Magnetic and relaxation properties of vanadium(iv) complexes: an integrated 1H relaxometric, EPR and computational study

“…This is in good agreement with the X-ray structures reported in the literature. 34,35 Again, the inclusion of explicit second-sphere water molecules causes a shortening of the V–O water distance, as observed previously for Mn( ii ) and Gd( iii ) complexes. 51,52…”

“…This is in good agreement with the X-ray structures reported in the literature. 34,35 Again, the inclusion of explicit second-sphere water molecules causes a shortening of the V-O water distance, as observed previously for Mn(II) and Gd (III) complexes. 51,52 DFT calculations yield two minimum energy geometries for the [VO(acac)(H 2 O)] system characterized by cis and trans coordination of the water molecule.…”

“…32 The X-ray crystal structures of the [VO(ox) 2 ] 2− and [VO(nta)] − complexes show that a water molecule is coordinated to the metal ion in the cis position with respect to the oxo group. 33–35 The X-ray structure of the [VO(H 3 DTPA)] complex evidences coordination of the ligand through two amine N atoms and three oxygen atoms of carboxylate groups, and thus this complex lacks any coordinated water molecule. 36…”

“…32 The X-ray crystal structures of the [VO(ox) 2 ] 2− and [VO(nta)] − complexes show that a water molecule is coordinated to the metal ion in the cis position with respect to the oxo group. [33][34][35] The X-ray structure of the [VO(H 3 DTPA)] complex evidences coordination of the ligand through two amine N atoms and three oxygen atoms of carbox-ylate groups, and thus this complex lacks any coordinated water molecule. 36 Variable temperature EPR experiments EPR spectra were recorded in aqueous solutions in the temperature range 294-353 K. Under these circumstances, the anisotropic gand A-tensors are averaged out depending on the rate of motion of the complex, which in turn depends on the temperature.…”

“…This suggests that the [VO(nta)] − complex contains a coordinated water molecule, as observed in the solid state. 35 The complex with H 5 DTPA likely lacks any coordinated water molecule, with the observed relaxivity being a consequence of the outer-sphere mechanism. The decrease in relaxivity with temperature is therefore likely related to a faster diffusion.…”