81567-13-7Relevant academic research and scientific papers
PHOTOREDUCTION OF HYDROXO(TETRAMESITYLPORPHINATO)IRON(III) IN AROMATIC HYDROCARBONS AND THE CONCURRENT GENERATION OF HYDROXYL RADICAL
Tohara, Akira,Sato, Mitsuo
, p. 153 - 156 (1989)
Hydroxo(tetramesitylporphinato)iron(III) in degassed benzene, toluene, and ethylbenzene is confirmed to be reduced to the four coordinate ferrous complex upon irradiation with light λ > 300 nm.Production of diphenyl and solvent dependence of photoreduction rates support the concurrent generation of hydroxyl radical along with the ferrous complex production.
Examination of the Magneto-Structural Effects of Hangman Groups on Ferric Porphyrins by EPR
Nehrkorn, Joscha,Bonke, Shannon A.,Aliabadi, Azar,Schwalbe, Matthias,Schnegg, Alexander
, p. 14228 - 14237 (2019/10/19)
Ferric hangman porphyrins are bioinspired models for haem hydroperoxidase enzymes featuring an acid/base group in close vicinity to the metal center, which results in improved catalytic activity for reactions requiring O-O bond activation. These functional biomimics are examined herein with a combination of EPR techniques to determine the effects of the hanging group on the electronics of the ferric center. These results are compared to those for ferric octaethylporphyrin chloride [Fe(OEP)Cl], tetramesitylporphyrin chloride [Fe(TMP)Cl], and the pentafluorophenyl derivative [Fe(TPFPP)Cl], which were also examined herein to study the electronic effects of various substituents. Frequency-domain Fourier-transform THz-EPR combined with field domain EPR in a broad frequency range from 9.5 to 629 GHz allowed the determination of zero-field splitting parameters, revealing minor rhombicity E/D and D values in a narrow range of 6.24(8) to 6.85(5) cm-1. Thus, the hangman porphyrins display D values in the expected range for ferric porphyrin chlorides, though D appears to be correlated with the Fe-Cl bond length. Extrapolating this trend to the ferric hangman porphyrin chlorides, for which no crystal structure has been reported, indicates a slightly elongated Fe-Cl bond length compared to the non-hangman equivalent.
Studies of iron(III) porphyrinates containing silanethiolate ligands
Meininger, Daniel J.,Caranto, Jonathan D.,Arman, Hadi D.,Tonzetich, Zachary J.
, p. 12468 - 12476 (2013/11/19)
The chemistry of several iron(III) porphyrinates containing silanethiolate ligands is described. The complexes are prepared by protonolysis reactions of silanethiols with the iron(III) precursors, [Fe(OMe)(TPP)] and [Fe(OH)(H 2O)(TMP)] (TPP = dianion of meso-tetraphenylporphine; TMP = dianion of meso-tetramesitylporphine). Each of the compounds has been fully characterized in solution and the solid state. The stability of the silanethiolate complexes versus other iron(III) porphyrinate complexes containing sulfur-based ligands allows for an examination of their reactivity with several biologically relevant small molecules including H2S, NO, and 1-methylimidazole. Electrochemically, the silanethiolate complexes display a quasi-reversible one-electron oxidation event at potentials higher than that observed for an analogous arenethiolate complex. The behavior of these complexes versus other sulfur-ligated iron(III) porphyrinates is discussed.
Models of nitric oxide synthase: Iron(III) porphyrin-catalyzed oxidation of fluorenone oxime to nitric oxide and fluorenone
Wang, Charles C.-Y.,Ho, Douglas M.,Groves, John T.
, p. 12094 - 12103 (2008/10/08)
Nitric oxide synthase (NOS) is a heme-containing monoxygenase that catalyzes the oxidation of L-arginine to L-citrulline and NO in two steps. In the second step of the NOS reaction, citrulline and NO are generated from the heme-catalyzed 3-electron oxidation of L-N-hydroxyarginine. To model this unusual reaction, iron porphyrin-catalyzed oxygenations of oximes with O2 were investigated. The oxidation of fluorenone oxime and a stoichiometric amount of hydroxoiron(III) porphyrin (Fe(OH)P, P = TMP and TPFPP) with O2 in benzene generated Fe(NO)P, fluorenone, and O-(9-nitro-9-fluorenyl)fluorenone oxime. The X-ray crystal structure of the oxime ether product suggests that it originated from the dimerization of the fluorenyl iminoxy radicals. Detailed analysis of this reaction showed that the oxime reacted first with Fe(OH)P to generate a 5-coordinate, high-spin oximatoiron(III) porphyrin species [Fe(oximate)P]. The X-ray crystal structure of oximatoiron(III) tetrakis(2,6-dichlorophenyl)porphyrin [Fe(oximate)TDCPP] showed that the oximate ligand was monodentate, O-bound to Fe(III)P. The aerobic oxidation of Fe(oximate)P followed the characteristic kinetics of a metalloporphyrin- catalyzed radical-type autoxidation. O2 surrogates, the π-acids NO and CO, induced the homolysis of Fe(oximate)P to generate Fe(NO)P or Fe(CO)P and the iminoxy radical, implicating a similar reaction mode for O2 with Fe(oximate)P. Fe(oximate)TMP reacted with 18O2 to generate predominantly 18O-labeled fluorenone (75% yield), while the reaction conducted under 16O2 and H218O generated only 16O-labeled fluorenone. This reaction is proposed to proceed via an Fe-O bond homolysis of Fe(oximate)TMP followed by O2 insertion to generate 9-nitroso-9-fluorenylperoxyFe(III)TMP, which decomposes via an O-O bond homolysis to generate NO, fluorenone, and oxoFe(IV)P. The implications of this system for the NOS reaction mechanism are discussed.
Preparation, characterization, and reactions of novel iron(III) porphyrin dication complexes
Tsurumaki, Hiroshi,Watanabe, Yoshihito,Morishima, Isao
, p. 11784 - 11788 (2007/10/02)
A dication complex of (meso-tetramesitylporphynato)iron(III) (FeIIITMP) has been prepared by the reaction of FeIIITMP N-oxide with trifluoroacetic acid in toluene at low temperature. The electronic structure of the complex is characterized to be ferric high spin with rhombic symmetry on the basis of iodometric titration and UV-vis, 2H NMR, and EPR spcctroscopies. A value of E/D, which shows rhombicity of the heme environment, was estimated to be 0.29 by EPR measurement. An unusually high E/D value indicates that the symmetry of the ligand field around the iron is rather similar to those of nonheme ferric complexes, and the porphyrin ring could exhibit large nonplanarity. While tetraphenylporphyrin dication complexes of Zn, Mg, and Ni are known to react with methanol to afford the corresponding isoporphyrins, the dication complex of FeIIITMP was found to react with methanol to yield FeIIITMP N-methoxide, possibly due to the sterric barrier of the o-methyl groups of mesitylene. The FeIIITMP dication is not thermally stable and is readily reduced to the FeIIITMP π-cation radical even at -25 °C in toluene. The dication complex of (meso-tetrakis(2,6-dichlorophenyl)porphynato)iron(III) (FeIIITDCPP) was also prepared by the same reaction. The preparation of the dication complex of Fe(III) porphyrin demonstrates possible manipulation of the two-electron-oxidized equivalent in various forms by Fe porphyrin, i.e., the O=Fe(IV) porphyrin π-cation radical, O=Fe(V) porphyrin, Fe(III) porphyrin N-oxide, and the Fe(III) porphyrin dication.
Oxygenation Patterns for Iron(II) Porphyrins. Peroxo and Ferryl (FeIVO) Intermediates Detected by 1H Nuclear Magnetic Resonance Spectroscopy during the Oxygenation of (Tetramesitylporphyrin)iron(II)
Balch, Alan L.,Chan, Yee-Wai,Cheng, Ru-Jen,Mar, Gerd N. La,Latos-Grazynski, Lechoslaw,Renner, Mark W.
, p. 7779 - 7785 (2007/10/02)
The reaction between unligated (tetramesitylporphyrin)iron(II) (TMPFeII) and dioxygen in a toluene solution has been examined by 1H NMR spectroscopy.At -70 deg C, TMPFeII reacts with O2 to yield TMPFeIIIOOFeIIITMP that has spectroscopic properties similar to those of other peroxo-bridged complexes.On warming, TMPFeIIIOOFeIIITMP decomposes to yield a second intermediate (identified as TMPFeIVO) and TMPFeIIIOH, the final, stable product.TMPFeIIIOOFeIIITMP reacts with N-methylimidazole (N-MeIm) to produce (N-MeIm)TMPFeO2 and (N-MeIm)2TMPFeII.The former has been independently prepared from (N-MeIm)2TMPFeII and dioxygen at -50 deg C. TMPFeIVO reacts with N-MeIm to form (N-MeIm)TMPFeIVO that has been identified by comparison with other FeIVO complexes.TMPFeIVO reacts with triphenylphosphine at -50 deg C to yield triphenylphosphine oxide while TMPFeIIIOOFeIIITMP is unreactive toward triphenylphosphine under these conditions.TMPFeII is a catalyst for the oxidation of triphenylphosphine by dioxygen. 1H NMR spectra and resonance assignments for each species are described.
