β-Nitro Derivatives of Iron Corrolates

Abstract

Two different methods for the regioselective nitration of different meso-triarylcorroles leading to the corresponding β-substituted nitrocorrole iron complexes have been developed. A two-step procedure affords three Fe(III) nitrosyl products - the unsubstituted corrole, the 3-nitrocorrole and the 3,17-dinitrocorrole. In contrast, a one-pot synthetic approach drives the reaction almost exclusively to formation of the iron nitrosyl 3,17-dinitrocorrole. Electron-releasing substituents on the meso-aryl groups of the triarylcorroles induce higher yields and longer reaction times than what is observed for the synthesis of similar triarylcorroles with electron-withdrawing functionalities, and these results can be confidently attributed to the facile formation and stabilization of an intermediate iron corrole π-cation radical. Electron-withdrawing substituents on the meso-aryl groups of triarylcorrole also seem to labilize the axial nitrosyl group which, in the case of the pentafluorophenylcorrole derivative, results in the direct formation of a disubstituted iron μ-oxo dimer complex. The influence of meso-aryl substituents on the progress and products of the nitration reaction was investigated. In addition, to elucidate the most important factors which influence the redox reactivity of these different iron nitrosyl complexes, selected compounds were examined by cyclic voltammetry and thin-layer UV-visible or FTIR spectroelectrochemistry in CH2Cl2.

Photometric Detection of Nitric Oxide Using a Dissolved Iron(III) Corrole as a Sensitizer

“…The lowest‐energy absorption that can be identified in the experimental spectra appears around 730 nm in all solvents tested and has a weak intensity with an extinction coefficient between 2500 and 3000 m −1 cm −1 (Table ). This absorption feature has been reported for 1 and similar complexes but for many iron(III) corroles it is too weak to be observed . According to our time‐dependent (TD)‐DFT calculations, this absorption is dominated by iron d x − y →d z transitions, which possess only small oscillator strength as reflected in the stick spectrum at 776 nm (Figure ).…”

“…This absorption feature has been reported for 1 [16] and similarc omplexes [61] but for many iron(III) corroles it is too weak to be observed. [62][63][64][65] According to our time-dependent (TD)-DFT calculations, this absorption is dominated by iron dx 2 Ày 2 !dz 2 transitions, which possess only small oscillator strength as reflected in the stick spectrum at 776 nm ( Figure 3). At even lower photon energies, weaka bsorptions due to furtherd -d transitions are predictedb yT D-DFT calculations.…”

Infrared Spectroelectrochemistry of Iron-Nitrosyl Triarylcorroles. Implications for Ligand Noninnocence

“… 4 Similar voltammetric behavior has also been observed for other corrole derivatives. 2 , 5 − 7 Autret et al interpreted the first reduction wave to be due to the reduction of a ferric complex to a ferrous complex. 4 The visible spectroelectrochemical reduction led to a shift in the Soret band from 376 to 412 nm and of the band at 536 to 577 nm, with a small band at 538 nm.…”

“… 6 The visible spectroelectrochemistry of the tris(4-nitrophenyl) complex showed a red-shift of the Soret band from 382 to 395 nm, while in the longer wavelength region the 544 nm band split into two bands at 524 and 662 nm. Nardis et al 5 observed strongly split Soret bands in the UV–visible spectra of β-nitrocorrole derivatives which were significantly different from the unsubstituted derivatives.…”

Phenyl Derivative of Iron 5,10,15-Tritolylcorrole

“… 5 We have recently exploited the π-cation radical nature of the complex for the preparation of β-nitrocorrole iron complexes, obtained upon nucleophilic attack of the nitrite ion on the chloro–iron corrole complex. 8 , 9 …”