Radical Reactivity of the Fe(III)/(II) Tetramesitylporphyrin Couple: Hydrogen Atom Transfer, Oxyl Radical Dissociation, and Catalytic Disproportionation of a Hydroxylamine.

ABSTRACT: The chemistry of low-valent iron porphyrin complexes with oxyl radical reagents has been explored. (Meso-tetramesityl porphyrinato) iron(III) hydroxide, (TMP)Fe^III(OH) reacts with the hydroxylamine TEMPO-H (1-hydroxy-2,2,6,6-tetramethylpiperdine) to yield the ferrous porphyrin, (TMP)Fe^II, together with H₂O and TEMPO. This reaction has a second order rate constant k₁ = 76 ± 5 M^-1 1 s^-1 and likely occurs by concerted e^-/H⁺ transfer. Hydrazines PhNHNHPh and PhNHNH₂ similarly yield (TMP)Fe^II. A subsequent reaction between TEMPO (2,2,6,6-tetramethylpiperdinyl radical) and (TMP)Fe^II is observed to reversibly form the TEMPO-ligated ferric porphyrin, (TMP)Fe

SUBMITTER: Porter TR 

PROVIDER: S-EPMC3981745 | biostudies-literature | 2014 Jan

REPOSITORIES: biostudies-literature