Generation of a Peroxynitrato Metal Complex from Nitrogen Dioxide and Coordinated Superoxide

The reaction between photogenerated N02 radicals and a superoxochromium(lll) complex, CraqOO occurs with rate constants k = (2.8 ± 0.2) x 10 M s- (20 vol % acetonitrile in water) and k = (2.6 ± 0.5) x Ms (40 vol % acetonitrile) in aerated acidic solutions and ambient temperature. The product was deduced to be a peroxynitrato complex, CraqOONC)2 which undergoes homolytic cleavage of an N-O bond to return to the starting materials, the rate constants in the two solvent mixtures being k = 172 ± 4 s and k = 197 ± 7 s. NC)2 reacts rapidly with 10-methyl-9,10-dihydroacridine, k = 2.2 x M s- k = (9.4 ± 0.2) x 10 M- s-, and with N.N.N-tetramethylphenylenediamine, k = (1.84 ± 0.03) x 10 M- s-