Phenol ring nitration induced by the unprecedented reduction of the Cu(II) centre by nitrogen dioxide.

Nitrogen dioxide (˙NO2) induces tyrosine nitration through a radical mechanism in biological systems. Two copper(II) complexes, 1 and 2, with ligands L₁ and L₂ [L₁ = 2,4-di-tert-butyl-6-(((2-(dimethylamino)ethyl)(isopropyl)amino)methyl)phenol; L₂ = 6,6'-(((2-(dimethylamino)ethyl)azanediyl)bis(methylene))bis(2,4-di-tert-butylphenol)], respectively, have been made to react with ˙NO2. In both cases, the reduction of the copper(II) center was observed in the presence of ˙NO2 which induces phenol ring nitration through nitronium ion (NO2(+)) formation.