98715-91-4Relevant academic research and scientific papers
Hydrogen atom abstraction and hydride transfer reactions by iron(IV)-oxo porphyrins
Jeong, Yu Jin,Kang, Yaeun,Han, Ah-Rim,Lee, Yong-Min,Kotani, Hiroaki,Fukuzumi, Shunichi,Nam, Wonwoo
, p. 7321 - 7324 (2008)
(Chemical Equation Presented) True identity revealed: The C-H bond activation of alkyl aromatics by synthetic iron(IV)-oxo porphyrin species and the hydride transfer of NADH analogues to them occur through H-atom abstraction and proton-coupled electron-transfer mechanisms, respectively. Mechanistic studies revealed that iron(IV)-oxo porphyrin π, not iron(IV)-oxo porphyrin pradical cations, are the true oxidant.
Acid-catalyzed disproportionation of oxoiron(IV) porphyrins to give oxoiron(IV) porphyrin radical cations
Pan, Zhengzheng,Newcomb, Martin
, p. 968 - 970 (2011/06/27)
Disproportionation of oxoiron(IV) porphyrin (Compound II) to oxoiron(IV) porphyrin radical cation (Compound I) was studied in three P450 model systems with different electronic structures. Direct conversion of Compound II to Compound I has been observed f
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.
Factors which affect the catalytic activity of iron(III) meso tetrakis(2,6-dichlorophenyl) porphyrin chloride in homogeneous system
Iamamoto, Yassuko,Assis, Marilda D.,Ciuffi, Katia J.,Sacco, Herica C.,Iwamoto, Lidia,Melo, Andrea J.B.,Nascimento, Otaciro R.,Prado, Cynthia M.C.
, p. 189 - 200 (2008/10/09)
An optimization study of the reaction conditions of Fe(TDCPP)Cl when it is used as catalyst in the hydroxylation of cyclohexane by iodosylbenzene (PhIO) has been carried out. It was found that Fe(TD CPP)Cl follows the classical PhIO mechanism described for Fe(TPP)Cl, which involves the monomeric active species Fe(IV)(O)P+ (I). In the optimized condition ([Fe(TDCPP) = 3.0 x 10-4 mol-1 in 1,2-dichloroethane (DCE); ultrasound stirring at 0°C; PhIO/FeP molar ratio = 100), this PeP led to a yield of cyclohexanol (C-ol) of 96% and a turnover number of 96. Therefore, Fe(TDCPP)Cl may be considered a good biomimetic model and a very stable, resistant and selective catalyst, which yields C-ol as the sole product. DCE showed to be a better solvent than dichloromethane (DCM), I DCE:I MeOH mixture or acetonitrile (ACN). Since the Fe(IV)(O)P+ is capable of abstracting hydrogen atom from (DCM), MeOH or ACN, the solvent competes with the substrate. Presence of O2 lowers the yield of C-ol, as it can further oxidize this alcohol to carboxylic acid in the presence of radicals. Presence of H2O also causes a decrease in the yield, since it converts the active species I into Fe(IV)(OH)P, which cannot oxidize cyclohexane. Addition of excess imidazole or OH to the system results in a decrease in the yield of C-ol, due to the formation of the hexacoordinated complexes Fe(TDCPP)Im2/+ (low-spin, β2= 2.5 x 108 mol-2 l2) and Fe(TDCPP)(OH) 2/- (high-spin, β2 = 6.3 x 107 mol-2 l2). The formation of both Fe(TDCPP)lm+ and Fe(TDCPP)(OH)2/- complexes were confirmed by EPR studies. The catalytic activities of Fe(TDCPP)Cl and Fe(TFPP)Cl were compared. The unusually high yields of C-ol with Fe(TFPP)Cl obtained when ultrasound, DCM and 02 atmosphere were used, suggest that a parallel mechanism involving the μ-oxo dimer form, O2 and radicals may also be occurring with this FeP, besides the Phi() mechanism.
Ligand-centered redox processes for MnL3, FeL3, and CoL3 complexes (L = acetylacetonate, 8-quinolinate, picolinate, 2,2′-bipyridyl, 1,10-phenanthroline) and for their tetrakis(2,6-dichlorophenyl)porphinato complexes [M(Por)]
Richert, Silvia A.,Tsang, Paul K. S.,Sawyer, Donald T.
, p. 2471 - 2475 (2008/10/08)
The potentials for the ML3-/ML3 couple of MnL3, FeL3, and CoL3 complexes (L = acetylacetonate, 8-quinolinate, picolinate, 2,2′-bipyridyl, 1,10-phenanthroline) occur at substantially less positive values than those for their zinc analogues and are clearly ligand-centered. The negative shift in potential for these ligand oxidations is proportional to their metal-ligand covalent-bond energies. The reductions for the bipyridyl and phenanthroline complexes of these transition metals also are ligand-centered. Electrochemical characterization of tetrakis(2,6-dichlorophenyl)porphine and of its neutral porphinato complexes with Zn, Mn, Fe, and Co indicates that electron transfer occurs within the porphyrin ring and that the metal-porphyrin bonding involves covalent σ bonds between dnsp valence electrons of the neutral metal (or hydrogen atoms of porphine) and two pyrrole p electrons of the uncharged porphyrin.
Formation, Characterization, and Reactivity of the Oxene Adduct of iron(III) Perchlorate in Acetonitrile. Model for the Reactive Intermediate of Cytochrome P-450
Sugimoto, Hiroshi,Tung, Hui-Chan,Sawyer, Donald T.
, p. 2465 - 2470 (2007/10/02)
Combination of iron(III) perchlorate with pentafluoroiodosobenzene, m-chloroperbenzoic acid, or ozone in acetonitrile at -35 deg C yields a green porphyrin-oxene adduct.This species, which has been characterized by spectroscopic, magnetic, and electrochemical methods, cleanly and stereospecifically epoxidizes olefins (>99percent exo-norbornene oxide).The reaction chemistry and electronic characterization of the adduct are consistent with an oxygen atom covalently bound to an iron(II)-porphyrin radical center (Por.-)FeII(O)+>.The latter has the spectral, magnetic, and redox characteristics of compound I of horseradish peroxidase (HRP) and the selective stereospecific oxygenase character of the reactive intermediate for cytochrome P-450.Reduction of the green species by one electron equivalent yields a red species, PorFeII(O), which has the spectral characteristics and reactivity of compound II of HRP.The iron(III)-porphyrin is an efficient catalyst for (a) the stereospecific epoxidation of olefins and (b) the oxidative cleavage of α-diols by F5PhIO and m-ClPhC(O)OOH; with H2O2, there is extensive attack on the porphyrin ring and no significant reaction with olefins or α-diols.
