Reactivity of Reduced Nitroprusside, [Fe(CN)5NO]3-, toward Oxygen
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- 作者：Mariela Videla ; Federico Roncaroli ; Leonardo D. Slep ; José ; A. Olabe
- 刊名：Journal of the American Chemical Society
- 出版年：2007
- 出版时间：January 17, 2007
- 年：2007
- 卷：129
- 期：2
- 页码：278 - 279
- 全文大小：40K
- 年卷期：v.129,no.2(January 17, 2007)
- ISSN：1520-5126
文摘
In the reaction of [Fe(CN)5NO
f">]3- with O2 (4:1 stoichiometry), the nitroprusside ion [Fe(CN)5NO]2- (NP) was quantitatively produced. The rate law was -1/4d[Fe(CN)5NOf">3-]/dt = k2[Fe(CN)5NOf">3-][O2], with k2 = (3.5 ± 0.2) × 105 M-1 s-1 at 25.0 
f">C. The rate was insensitive to pH (range 9-11) and ionic strength (I = 0.1-1 M). Excess cyanide was used for minimizing the production of [Fe(CN)4NO]2-, which appeared to be much less reactive. Addition of O2 to the NOf"> group is proposed to generate peroxynitrite bound to Fe(III), which reacts rapidly with [Fe(CN)5NOf">]3- to yield [Fe(CN)5NO2f">]3-. Reaction between the latter radical ions leads to the final product, NP. Comparison with the autoxidation rates for other NOf"> complexes reveals that the rate constants decrease with an increase in ENO+/NO, the redox potentials of the bound NO+/NOf"> couples. Six-coordination appears to be necessary for attaining reasonable electrophilic rates for the NOf"> ligand, as with other heme and non-heme complexes.
f">]3- with O2 (4:1 stoichiometry), the nitroprusside ion [Fe(CN)5NO]2- (NP) was quantitatively produced. The rate law was -1/4d[Fe(CN)5NOf">3-]/dt = k2[Fe(CN)5NOf">3-][O2], with k2 = (3.5 ± 0.2) × 105 M-1 s-1 at 25.0 f">C. The rate was insensitive to pH (range 9-11) and ionic strength (I = 0.1-1 M). Excess cyanide was used for minimizing the production of [Fe(CN)4NO]2-, which appeared to be much less reactive. Addition of O2 to the NOf"> group is proposed to generate peroxynitrite bound to Fe(III), which reacts rapidly with [Fe(CN)5NOf">]3- to yield [Fe(CN)5NO2f">]3-. Reaction between the latter radical ions leads to the final product, NP. Comparison with the autoxidation rates for other NOf"> complexes reveals that the rate constants decrease with an increase in ENO+/NO, the redox potentials of the bound NO+/NOf"> couples. Six-coordination appears to be necessary for attaining reasonable electrophilic rates for the NOf"> ligand, as with other heme and non-heme complexes.