Direct Resonance Raman Characterization of a Peroxynitrito Copper Complex Generated from O2 and NO and Mechanistic Insights into Metal-Mediated Peroxynitrite Decomposition.

We report the formation of a new copper peroxynitrite (PN) complex [CuII (TMG3 tren)(κ1 -OONO)]+ (PN1) from the reaction of [CuII (TMG3 tren)(O2.- )]+ (1) with NO.(g) at -125 °C. The first resonance Raman spectroscopic characterization of such a metal-bound PN moiety supports a cis κ1 -(- OONO) geometry. PN1 transforms thermally into an isomeric form (PN2) with κ2 -O,O'-(- OONO) coordination, which undergoes O-O bond homolysis to generate a putative cupryl (LCuII -O. ) intermediate and NO2. . These transient species do not recombine to give a nitrato (NO3- ) product but instead proceed to effect oxidative chemistry and formation of a CuII -nitrito (NO2- ) complex (2).