Reaction of a Copper−Dioxygen Complex with Nitrogen Monoxide (•NO) Leads to a Copper(II)−Peroxynitrite Species

• Published in: Journal of the American Chemical Society 2008-05, Vol.130 (21), p.6700-6701
• Main Authors: Maiti, Debabrata, Lee, Dong-Heon, Narducci Sarjeant, Amy A, Pau, Monita Y. M, Solomon, Edward I, Gaoutchenova, Katya, Sundermeyer, Jörg, Karlin, Kenneth D
• Format: Article
• Language: English
• Subjects: Cations, Divalent; Copper - chemistry; Electron Spin Resonance Spectroscopy; Nitric Oxide - chemistry; Organometallic Compounds - chemistry; Oxygen - chemistry; Peroxynitrous Acid - chemistry; Spectrometry, Mass, Electrospray Ionization
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja801540e

A discrete peroxynitrite−copper(II) complex, [(TMG3tren)CuII(−OONO)]+ (3), has been generated in solution (ESI-MS, m/z = 565.15; tetragonal EPR) by reacting •NO(g) with superoxo complex [(TMG3tren)CuII(O2 •−)]+ (2). Complex 3 undergoes a thermal transformation to give CuII−nitrite complex [(TMG3tren)CuII(−ONO)]+ (4) (X-ray) along with ca. 0.5 molar equiv dioxygen. A DFT calculation derived structure with cyclic bidentate k2-O,O′-OONO bound peroxynitrite moiety and d x 2 −y 2 ground state is proposed. Experiments using 18O2 suggest that the adjacent peroxo oxygen atoms in 3 are derived from molecular oxygen. Further, 18O2 containing 3 undergoes O−O bond cleavage to form singly 18-O-labeled 4. The results suggest the viability of biological CuI/O2/(•NO) peroxynitrite formation and chemistry, that is, not coming from free superoxide plus •NO reaction.