19496-18-5Relevant academic research and scientific papers
Temperature effects on structure: Five-coordinate (nitrosyl)(tetratolylporphinato)iron(II)
Silvernail, Nathan J.,Oliver, Allen G.,Scheidt, W. Robert
, p. 717 - 724 (2020)
We have prepared crystals of [Fe(TTP)(NO)] (TTP = tetratolylporphyrin), a five-coordinate nitrosyl complex and determined its crystal and molecular structure at two temperatures. The crystal structure at 100 K reveals two independent molecules in the asymmetric unit of the structure. One molecule is completely ordered and the second molecule has a moderately disordered nitrosyl ligand. Both molecules show similar structural features: a substantial off-axis tilt of the Fe-N(NO) bond and an asymmetry of the equatorial Fe-Np bonds that is correlated with the tilt. The axial Fe-N(NO) bond distances are 1.7230 (9) and 1.7210 (10) ?; the Fe-N-O bond angles are 141.62 (8) and 140.04 (10). Determination of the structure at ambient temperature (293 K) showed an unexpected phase change, a crystal structure with one molecule per asymmetric unit containing the superposition of the two molecules at lower temperature. However, there was an increase in the NO disorder.
Synthesis, electrochemical and spectroelectrochemical characterization of iron(III) tetraarylporphyrins containing four β, β ′-butano and β, β ′-benzo fused rings
Xu, Weijie,Fang, Yuanyuan,Ou, Zhongping,Chen, Mingyuan,Kadish, Karl M.
, p. 521 - 534 (2018/05/14)
Six iron(III) tetraarylporphyrins containing four b,b?-butano or b,b?-benzo fused rings were synthesized and characterized by electrochemistry and spectroelectrochemistry in nonaqueous media. The examined compounds are represented as butano(TpYPP)FeCl and
Iron-based metalloporphyrins as efficient catalysts for aerobic oxidation of biomass derived furfural into maleic acid
Xie, Yongdi,Huang, Yi,Wu, Chunyan,Yuan, Wenwen,Xia, Yongmei,Liu, Xiang,Wang, Haijun
, p. 20 - 27 (2018/04/05)
A series of porphyrin type catalysts with the metal active sites of Fe were prepared and investigated in aerobic oxidation of biomass-based furfural to maleic acid (MAD) in aqueous phase. The catalytic performance of meso-tetrakis(4-bromophenyl)porphyrin iron (III) chloride (FeT(p-Br)PPCl) immobilized on different supports was evaluated. It was interesting to find that the catalytic activity varied with the supports and followed the trend: FeT(p-Br)PPCl/SBA–15 > FeT(p-Br)PPCl/meso-ZSM–5 > FeT(p-Br)PPCl/MCM-41. The effect of reaction conditions were discussed in detail over FeT(p-Br)PPCl/SBA-15 catalyst, and 56.1% yield and 73.8% selectivity of MAD were obtained from renewable furfural under the optimal conditions. Moreover, the FeT(p-Br)PPCl/SBA-15 catalyst could be reused five times without a significant decrease of activity in recycling examinations.
Catalytic Aerobic Oxidation of Biomass-based Furfural into Maleic Acid in Aqueous Phase with Metalloporphyrin Catalysts
Huang, Yi,Wu, Chunyan,Yuan, Wenwen,Xia, Yongmei,Liu, Xiang,Yang, Huamei,Wang, Haijun
, p. 786 - 794 (2017/07/24)
Catalytic oxidation of renewable furfural into valuable maleic acid in aqueous solutions using metalloporphyrin catalysts was investigated for the first time. The synthesized catalysts were characterized by FT-IR, UV–vis, 1H NMR, elemental analysis, and TGA. The catalysts varied in metal active sites and functional groups, which had different effects on their catalytic activity. Furthermore, the effects of temperatures, reaction time, catalyst loading, and oxygen pressure were studied in detail. Maleic acid could be achieved in 44% yield by using FeT(p-Cl)PPCl as catalyst under optimal conditions. Finally, FeT(p-Cl)PPCl could be reused in five consecutive runs without a significant loss of activity.
Influence of substituents in meso-aryl groups of iron μ-oxo porphyrins on their catalytic activity in the oxidation of cycloalkanes
Tabor, Edyta,Po?towicz, Jan,Pamin, Katarzyna,Bas?g, Sylwia,Kubiak, W?adys?aw
, p. 342 - 349 (2016/10/09)
The aim of this work was to study the effect of substituents on the catalytic activity of iron μ-oxo porphyrins in oxidation of cycloalkanes. Electron-donating or electron-withdrawing substituents were introduced in meso-aryl groups of iron μ-oxo porphyrins. An important part of the work was the characterization of the catalysts, in particular their redox properties. Catalytic performance and selectivity were evaluated using cyclopentane, cyclohexane, and cyclooctane as model compounds. It was shown that not only electron-withdrawing but also electron-donating substituents improved the catalytic performance of iron μ-oxo complexes. Moreover, catalytic activity of iron μ-oxo porphyrins with electron-withdrawing substituents correlated with the half-wave potential E1/2while the catalytic activity of iron μ-oxo porphyrins with electron-donating substituents increased with the decrease of reduction potential ERED.
β-Nitro-substituted free-base, iron(III) and manganese(III) tetraarylporphyrins: Synthesis, electrochemistry and effect of the NO 2 substituent on spectra and redox potentials in non-aqueous media
Yang, Shuibo,Sun, Bin,Ou, Zhongping,Meng, Deying,Lu, Guifen,Fang, Yuanyuan,Kadish, Karl M.
, p. 857 - 869 (2013/09/24)
Two free-base and four metal derivatives of substituted tetraarylporphyrins containing a nitro-substituent on the β-pyrrole position of the macrocycle were synthesized and characterized by UV-vis, FTIR, 1H NMR and mass spectrometry as well as e
Synthesis, characterization and spectral properties of substituted tetraphenylporphyrin iron chloride complexes
Sun, Zhi-Cheng,She, Yuan-Bin,Zhou, Yang,Song, Xu-Feng,Li, Kai
experimental part, p. 2960 - 2970 (2011/06/21)
A series of substituted tetraphenylporphyrin iron chloride complexes [RTPPFe(III)Cl, R=o/p-NO2, o/p-Cl, H, o/p-CH3, o/p-OCH3] were synthesized by a novel universal mixed-solvent method and the spectral properties of free b
The electronic and magnetic properties of iron(III) derivatives of selected substituted meso-tetraphenyl porphyrins: ESR spectroscopic study
Skrzypek,Madejska,Habdas
, p. 91 - 97 (2008/10/09)
The electronic and magnetic behaviour of the nonsolvated ferric complexes of: (a) meso-tetratolyl-, (b) meso-tetra-4-hydroxyphenyl-, (c) meso-tetra-4-carboxyphenyl-, and (d) 5-(4-carboxyphenyl)-10,15,20-tritolyl-porphyrins was studied by ESR spectroscopy in the temperature range between 300 and 4 K. The complexes exhibit predominant contribution from the low-spin iron species at high temperature and a drastic shift toward the high-spin iron species at the low-temperature limit. These paramagnetic species are in different proportions at different temperatures, as well as in porphyrins with different substituents. The examined porphyrins obtained as disordered solids contain iron complexes with continuous short-range disorder which is additionally sensitive to change of temperature.
Reactions of aryl-iron(III) porphyrins with dioxygen. Formation of aryloxy-iron(III) and aryl-iron(IV) complexes
Arasasingham, Ramesh D.,Balch, Alan L.,Hart, Rebecca L.,Latos-Grazyński, Lechos?aw
, p. 7566 - 7571 (2007/10/02)
The reaction of dioxygen with low-spin, five-coordinate complexes, PFeIIIAr (P, porphyrin dianion; Ar, aryl group) has been examined for comparison with previous work (Arasasingham, R. D. et al. J. Am. Chem. Soc. 1989, 111, 4357) on the corresponding alkyl complexes which showed that peroxo complexes PFeIIIOOR formed initially and then decomposed to form PFeOH and an aldehyde or ketone when R was a primary or secondary alkyl group. Dioxygen addition to TTPFeIII(C6H4CH3-ρ) at 25 °C in toluene yields the phenoxide complex, TTPFe(OC6H4CH3-ρ), as the principle product, while addition to TTPFeIIIC6H5 at -30 °C yields TTPFeIIIOC6H5 and small amounts of TTPFeIII(OC6H4OH-ρ) and TTPFeIIIOC6H4OFeIIITTP. These reactions have been monitored by both 1H NMR and ESR spectroscopies. No intermediates have been detected in the formation of these products. Mechanisms for the formation of these products have been formulated in terms of the initial insertion of dioxygen into the Fe-C bond followed by rapid homolysis to form PFeIV=O and .OAr, with subsequent reactions yielding the final products. Addition of dioxygen to a solution of TTPFeIII(C6H4CH3-ρ) in chloroform at -60 °C yields a mixture of [TTPFeIV(C6H4CH3-ρ)]+ and TTPFeIIICl with no evidence for the formation of the phenoxide complexes. In this case electron transfer to yield the oxidized iron porphyrin and Superoxide ion is driven by the solvent polarity and the ability of the solvent to destroy Superoxide ion as it is formed.
Identification of High-Valent Fluoroiron Porphyrin Intermediates Associated with the Electrocatalytic Functionalization of Hydrocarbons
Hickman, David L.,Nanthakumar, Alaganandan,Goff, Harold M.
, p. 6384 - 6390 (2007/10/02)
The difluoroiron(III) tetraphenylporphyrin complex undergoes a one-electron oxidation at 0.68 V (SCE) in contrast with values of 1.1 V measured for the monofluoroiron(III) porphyrin and the other five-coordinate iron(III) porphyrin complexes.Cyclic voltammetric oxidation of the difluoroiron(III) species in dichloromethane solution is quasi-reversible as a consequence of an EC mechanism.Reversible waves are favored at high scan rates and lower temperatures.Increased water content serves to make the oxidative cyclic voltammetric process irreversible presumably due to a disproportionation process.In the presence of added olefin substrates, this EC process permits efficient electrocatalytic oxidation to the epoxide, allylic alcohol, and enone.Tertiary carbon units are converted to the corresponding alcohol.Utilization of fluoride ion permits generation and low-temperature spectroscopic identification of a highly oxidized iron porphyrin species.The high-valent complex is produced at -78 deg C through addition of m-chloroperbenzoic acid to monofluoroiron(III) tetraarylporphyrins or by fluoride ion promoted disproportionation of the dication radical μ-oxo dimeric iron(III) porphyrin derivative.The oxidized iron porphyrin species is competent to effect olefin epoxidation at -78 deg C.Low-temperature 1H and 2H NMR spectroscopies demonstrate the porphyrin ?-cation radical nature of the high-valent species, in that porphyrin phenyl resonances are drastically shifted in alternating upfield and downfield directions.The electron spin resonance spectrum is consistent with an S = 3/2 ground state, and the high-valent intermediate is assigned a tentative fluorooxoiron(IV) porphyrin ?-cation radical formulation.
