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artículo con referato
"Kinetics of the reaction of nitric oxide with polypyridylamine iron(II) complexes"
Federico Roncaroli and Roland Meier
J. Coord. Chem. 68(17-18) (2015) 2990-3002, Special Issue to Honour Professor Dr. Rudi van Eldik on the occasion of his 70th birthday
The reactions of three polypyridylamine ferrous complexes, [Fe(TPEN)]2+, [Fe(TPPN)]2+, and [Fe(TPTN)]2+, with nitric oxide (NO) (where TPEN = N,N,N′,N′-tetrakis(2-pyridylmethyl)ethylenediamine, TPPN = N,N,N′,N′-tetrakis(2-pyridylmethyl)-1,2-propylenediamine, and TPTN = N,N,N′,N′-tetrakis(2-pyridylmethyl)trimethylenediamine) were investigated. The first two complexes, which are spin-crossover systems, presented second-order rate constants for complex formation reactions (kf) of 8.4 × 103 and 9.3 × 103 M-1 s-1, respectively (pH 5.0, 25 °C, I = 0.1 M). In contrast, the [Fe(TPTN)]2+ complex, which is in low-spin ground state, did not show any detectable reaction with NO. kf values are lower than those of high-spin Fe(II) complexes, such as [Fe(EDTA)]2- (EDTA = ethylenediaminetetraacetate) and [Fe(H2O)]2+, but higher than low-spin Fe(II) complexes, such as [Fe(CN)5(H2O)]3- and [Fe(bipyridine)3]2+. The release of NO from the [Fe(TPEN)NO]2+ and [Fe(TPPN)NO]2+ complexes were also studied, showing the values 15.6 and 17.7 s-1, respectively, comparable to the high-spin aminocarboxylate analogs. A mechanism is proposed based on the spin-crossover behavior and the geometry of these complexes and is discussed in the context of previous publications.
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