Reaction of Nitrogen Monoxide with a Macrocyclic Superoxorhodium(III) Complex Produces an Observable Nitratorhodium Intermediate

Abstract

The rapid (k > or = 10(6) M(-1) s(-1)) reaction between NO and L(2)(H(2)O)RhOO(2+) (L(2) = meso-Me(6)-[14]ane-N(4)) generates two strongly oxidizing, scavengeable intermediates, believed to be NO(2) and L(2)(H(2)O)RhO(2+). A mechanism is proposed whereby a peroxynitrito complex L(2)(H(2)O)RhOONO(2+) is formed first. The homolysis of O-O bond produces NO(2) and L(2)(H(2)O)RhO(2+) which were trapped with ABTS(2)(-) and Ni([14]aneN(4))(2+). In the absence of scavengers, the decomposition of L(2)(H(2)O)RhOONO(2+) produces both free NO(3)(-) and a rhodium nitrato complex L(2)(H(2)O)RhONO(2)(2+), which releases NO(3)(-) in an inverse acid-dependent process. The total yield of L(2)(H(2)O)RhONO(2)(2+) is 70%. In a minor, parallel path, NO and L(2)(H(2)O)RhOO(2+) react to give nitrite and the hydroperoxo complex L(2)(H(2)O)RhOOH(2+).

Visible Light‐Induced Release of Nitrogen Monoxide from a Nitrosylrhodium Complex

“…Complexes with a good combination of chemical stability and high quantum yield for photochemical release of NO upon irradiation with visible light in aqueous solutions are rare. Here we report that a simple macrocyclic nitrosylrhodium complex [L 2 [14] [24] The identity of the intermediate was further confirmed by its decay kinetics. The value of the rate constant at 0.014 m H + was 1.2 10 À4 s À1 , and at 0.14 m, 1.4 10 À5 s À1 .…”

Oxidative Homolysis of a Nitrosylchromium Complex

“…[47] Gaseous NO (Matheson) was purified by passage through Ascarite, sodium hydroxide and water. [48] Stock solutions of NO were prepared by bubbling the purified gas through argonsaturated 0.10 m or 1.0 m HClO 4 for 30 min. [48] Such solution typically contained 1.7 mm NO and 0.…”

“…[48] Stock solutions of NO were prepared by bubbling the purified gas through argonsaturated 0.10 m or 1.0 m HClO 4 for 30 min. [48] Such solution typically contained 1.7 mm NO and 0. 3 + (2 mm) by exposing the sample to Pyrex-filtered sunlight.…”

“…[3,[10][11][12] Among metal complexes, iron-porphyrins have received most attention, [11,13,14] but non-porphyrin complexes of a number of metal ions have also provided important mechanistic data on the formation and chemistry of metal nitrosyls. [10,12,[15][16][17] Thermal and photochemical cleavage of a metal À NO bond, and the low pH-induced dissociation of NO from NONOates are among the most common ways of generating NO for chemical and biological purposes. Several other mechanisms for NO release exist, and it is quite likely that some of them may be advantageous under some circumstances.…”

Reactivity of Inorganic Radicals in Aqueous Solution

“…204 In other examples, NO reacts with superoxo complexes of Rh(III) and Cr(III) to produce peroxonitrito intermediates that decompose in complicated ways. 205,206 NO adds to oxo complexes, including CrO 2 þ and MbFe IV O, to form nitrito complexes. 203 Similar reactions of the ferryl(V) moiety in various metalloproteins are likely to become an important physiological consideration.…”