Metallation of Ligands with Biological Activity: Synthesis and X‐Ray Characterization of [UO₂(PN)₂(H₂O)]Cl₂{PN = vitamin B₆ pyridoxine[2‐methyl‐3‐hydroxy‐4, 5‐bis(hydroxymethyl) pyridine]}

Abstract

Abstract Chloridrate of pyridoxine (vitamin B 6 ) reacts with UO 2 (NO 3 ) 2 ·6H 2 O in acetonitril containing triethylamine to give the complex salt [UO 2 (PN) 2 (H 2 O)]Cl 2 . The structure of the novel compound was analyzed by single crystal X‐ray diffraction affording the centrosymmetric triclinic space group ${\rm P}{\bar 1}$ . In [UO 2 (PN) 2 (H 2 O)] 2+ two zwitterionic pyridoxine molecules complex the uranium atom in a planar manner with a water molecule achieving the coordination of a semi planar pentagon. The two uranyl oxo ligands set the axis of a distorted pentagonal bipyramide. The ability of vitamin B 6 pyridoxine to react with UO 2 2+ allowing the chelation of one uranium atom represents a very specific model of assimilation of uranium by living beings. It could also explain the serious damages caused by heavy or radioactive metals like uranium since their complexation “in vivo” by enzymatic systems like pyridoxal phosphate‐containing enzymes would lead to a modification of the prosthetic groups of the metalloenzymes with loss of their catalytic activities.