NMR and theoretical study on the linking properties of peroxovanadium(V) complexes with the 3-aminomethyl-pyridine derivatives

<p>To understand the substitution effects of 3-aminomethyl-pyridine on the reaction equilibrium, the interactions between a series of 3-aminomethyl-pyridine derivatives and peroxovanadium(V) complex [OV(O₂)₂(D₂O)]⁻/[OV(O₂)₂(HOD)]⁻ in solution were explored by the combined use of multinuclear (¹H, ¹³C, and ⁵¹V) magnetic resonance spectroscopy together with HSQC in 0.15 M NaCl ionic medium for mimicking the physiological conditions. Some direct NMR data are given for the first time. The relative reactivity among the 3-aminomethyl-pyridine derivative ligands are <i>N</i>-(pyridin-3-ylmethyl)acetamide (<b>1</b>) ≈ <i>N</i>-(pyridin-3-ylmethyl)propionamide (<b>2</b>) > <i>N</i>-(pyridin-3-ylmethyl)pivalamide (<b>3</b>) > <i>t</i>-butyl(pyridin-3-ylmethyl)carbamate (<b>4</b>). The competitive coordination results in the formation of a series of new six-coordinate peroxovanadium species [OV(O₂)₂L]⁻ (L = <b>1</b>–<b>4</b>). The results of density functional calculations indicated that the solvation effects play an important role in these reactions, providing a reasonable explanation on the relative reactivity of the 3-aminomethyl-pyridine derivatives.