12582-61-5Relevant academic research and scientific papers
Structure of the deoxymyoglobin model [Fe(TPP)(2-MeHIm)] reveals unusual porphyrin core distortions
Ellison, Mary K.,Schulz, Charles E.,Scheidt, W. Robert
, p. 2173 - 2181 (2002)
The preparation and characterization of the deoxymyoglobin model (2-methylimidazole)(tetraphenylporphinato)iron-(II) is described. The preparation and crystallization from chlorobenzene leads to a new crystalline phase that has been structurally character
Reversal of H2O and OH- ligand field strength on the magnetochemical series relative to the spectrochemical series. Novel 1-equiv water chemistry of iron(III) tetraphenylporphyrin complexes
Evans, Daniel R.,Reed, Christopher A.
, p. 4660 - 4667 (2000)
Contrary to expectations based on the spectrochemical series, H2O is found to be a significantly weaker field ligand than OH- in the magnetochemical series ranking of ligand field strengths based on the spin states of iron(III) tetraphenylporphyrin complexes. The preparation and characterization of the [Fe(H2O)(TPP)]+ ion and the spectroscopic identification of Fe(OH)(TPP) have made this assessment possible. These two species were previously thought to be unattainable because of the facile formation of the well-known μ-oxo dimer, (TPP)Fe-O-Fe(TPP). However, the special characteristics of single equivalents of water under high acidity, relevant to metalloenzyme active sites and superacidity, make them accessible in benzene solution. Their 1H NMR β-pyrrole chemical shifts at -43 and +82 ppm indicate admixed-intermediate S = 3/2, 5/2 and high S = 5/2 spin states for the aqua and hydroxo species, respectively. The X-ray crystal structure of the aqua complex has been determined for [Fe(H2O)(TPP)] [CB11H6Cl6] and is consistent with the high degree of S = 3/2 character indicated by the NMR measurement, Mossbauer spectroscopy (ΔE(q) = 3.24 mm·s-1), and magnetic susceptibility (μ(eff) = 4.1 μ(B)). The anhydrous precursor to these species is the 'nearly bare' iron(III) porphyrin complex Fe(CB11H6Br6)(TPP). Judged by its magnetic parameters (δ(pyrrole) = -62 ppm, ΔE(q) = 3.68 mm·s-1, μ(eff) = 4.0 μ(B)) it attains the long sought essentially 'pure' S = 3/2 spin state. The magnetochemical ranking of ligand field strengths in five-coordinate high-spin and admixed-intermediate-spin iron(III) porphyrins is useful because it more closely reflects the intuitive field strengths of crystal field theory than does the usual spectrochemical ranking, which is controlled largely by π effects in octahedral low-spin d(π)6 complexes.
COMPLEXES DE LA FERROTETRAPHENYLPORPHYRINE AVEC DES HALOGENOALKYLCARBENES: Fe
Guerin, Philippe,Battioni, Jean-Paul,Chottard, Jean-Claude,Mansuy, Daniel
, p. 201 - 209 (1981)
Stable carbeneiron(II) complexes with halocarbenes having an alkyl group (CH3 or C(OH)R'R'') have been isolated and their structures established by 1H and 13C NMR, IR and mass spectroscopy.Their ability to coordinate ligands such as alcohols or pyridine i
Dioxygen Insertion into Iron(III)-Carbon Bonds. NMR Studies of the Formation and Reactivity of Alkylperoxo Complexes of Iron(III) Porphyrins
Arasasingham, Ramesh D.,Balch, Alan L.,Cornman, Charles R.,Latos-Grazynski, Lechoslaw
, p. 4357 - 4363 (1989)
The behavior of PFeIIICHR2 (P is a porphyrin dianion) in solution especially in the presence of dioxygen has been examined by (1)H and (2)H NMR measurements.Evidence for the photolytic Fe-C bond homolysis with the formation of PFeII is presented.Addition of dioxygen to PFeCH2R produces two unstable intermediates, PFeIIIO2CH2R and PFeIIIOH, which may be directly observed at low temperatures.These form and decompose through the following reactions: PFeIIICH2R + O2 -> PFeIIIO2CHR2; PFeIIIO2CHR2 -> PFeIIIOH + O=CR2; 2PFeIIIOH -> PFeIIIOFeIIIP + H2O.The formation of the product aldehyde or ketone has been established for methyl, ethyl, isopropyl, n-propyl, and benzyl ligands axially coordinating iron.The dioxygen insertion is retarded by the coordination of N-methylimidazole to the sixth iron coordination site or by employing a sterically encumbered porphyrin.PFeIIIOH catalyzes the decomposition of ethyl hydroperoxide to give acetaldehyde as the major organic product.
The oxidation of bromide ion by [(FeTPP)2O]+SbF6- In dichloromethanej
Hubbard, Colin D.,Jones, John G.,McKnight, John
, p. 3143 - 3148 (2000)
The oxidation of cetyltrimethylammonium bromide (CTAB) by mono-oxidised iron(m) tetraphenylporphyrin u-oxo-dimer, [(FeTPPOSbF, ; , has been found to be much slower than the corresponding oxidation of iodide ion, but can still be studied by stopped-flow techniques. The stoichiometry of the reaction has been established as 2 [Fe(TPP)2O]+ + 3Br -> 2(FeTPP)2O + Br3-. The rate law for the reaction is d [(FeTPP)2O]/df = [Fe(TPP)2O+] (kf [CTAB] -A'r). The rate constant for the first term has been identified with the rate determining forward process, the formation of the unstable Br2-, and the second term with the attack of Br2- on the uncharged u-oxo-dimer. A subsequent process involves what appears to be the rapid oxidation of Br2- in the presence of Br- to give Br3 . At 298 K kf is 737(±30) NT1 s-1 and k, is 0.80(±0.16) s-1. For kf, Δ = 58.8(±1.6) kJ mol-1, AS = 8.62(10.45) J K-1 moP1; for k, , ΔH = 43.6(110.8) kJ mol-1, AS = -97.8(136.0) J K-1 mol-1. The addition of cetyltrimethylammonium perchlorate (inert to reaction with the oxidised u-oxo-dimer) slowed the reaction in a manner which indicated competition between perchlorate and bromide for the formation of ion pairs with the oxidised iron(m) dimer, the bromide ion pair being the reactive one. The Royal Society of Chemistry 2000.
Comparison of Variable-Temperature 1H NMR Spectra of Five-Coordinate High-Spin (S=5/2) Iron(III) Porphyrins and Chlorins
Pawlik, M. J.,Miller, P. K.,Sullivan, E. P.,Levstik, M. A.,Almond, D. A.,Strauss, S. H.
, p. 3007 - 3012 (1988)
Variable-temperature 1H NMR spectra are reported for five different five-coordinate high-spin (S=5/2) iron(III) chlorin complexes.The complexes are Fe(TPC)X (X-=Cl-, OTeF5-) and Fe(OEC)X (X-=Cl-, OTeF5-, NCS-), where TPC=tetraphenylchlorinate dianion and OEC=octaethylchlorinate dianion.For completeness, variable-temperature spectra are also reported for the five homologous porphyrin complexes, although with one exception, Fe(OEP)(NCS), these porphyrin data have been reported by others.Spectra and Curie plots for the two classes of complexes are compared and spectral characteristics that are unique to chlorins are discussed.Our data show that the various types of pyrrole protons in the TPCcomplexes and the various types of pyrrole methylene protons in the OEC complexes exhibit a large range of isotropic shifts, ca. 30 ppm at ca. 300 K.The average temperature dependence of the resonances (i.e., Curie plot slopes) is similar to the temperature dependence of the resonance(s) for porphyrin protons in chemically similar positions.For both sets of chlorin complexes, pyrroline proton or methylene proton isotropic shifts are substantially smaller than pyrrole isotropic shifts, while pyrroline proton or methylene proton line widths are larger than pyrrole proton line widths.Large deviations in Curie plot 1/T=0 intercepts from diamagnetic chemical shifts are observed for many of the chlorin proton resonances.This behavior has been observed for all paramagnetic iron(II,III) hydroporphyrins studied to date.The different axial ligands greatly influence the range of isotropic shifts for the pyrrole protons or pyrrole methylene protons for a given chlorin and the temperature dependence (Curie plot slopes and intercepts) of the pyrroline protons for the TPC complexes.
Spontaneous Formation of Reactive Oxometal Porphyrins by Oxygen Atom Transfer from Dioxirane
Wolowiec, S.,Kochi, J. K.
, p. 1782 - 1784 (1990)
Oxygen atom transfer to manganese(II) tetraphenylporphyrin (tpp) and iron(II) tetramesitylporphyrin (tmp) is readily effected at IV(tpp) and O=Fe
Synthesis and Magnetic Exchange Properties of Linear Trinuclear Oxo- Bridged M(III)ORu(IV)OM(III) Complexes (M = Fe, Cr, Mn) Formed by Two-Electron Redox Reactions
Berry, Kevin J.,Moubaraki, Boujemaa,Murray, Keith S.,Nichols, Peter J.,Schulz, Lewis D.,West, Bruce O.
, p. 4123 - 4133 (1995)
The two-electron reductions of various porphyrin complexes Ru(VI)(O)2(P) by Fe(II), Cr(II), and Mn(II) compounds of porphyrins and salicylaldimines result in the formation of heterotrimetallic oxo-bridged complexes (L)M(III)ORu(IV)(P)OM(III)(L) (M = Fe(III), Cr(III), Mn(III); P is the dianion of 5,10,15,20-tetraarylporphyrins, such as tetraphenylporphyrin (TPP), tetrakis(p-methoxyphenyl)porphyrin (TMP), or 2,3,7,8,12,13,17,18-octaethylporphyrin (OEP); L is TPP, TMP, or OEP or the dianions of N,N'-(4-methyl-4-azaheptane-1,7-diyl)bis(salicylaldimine) (salmah) or N,N'-ethane-1,2-diylbis(salicylaldimine) (salen). A detailed study of the temperature- and field-dependent magnetic properties of this rather novel series of (L)M(III)ORu(IV)(P)OM(III)(L) compounds has been made. The spin-states of the constituent metal centers are as follows: Ru(IV), SRu = 1 (d(4)); Fe(III), SFe = 5/2 (d(5)); Cr(III), SCr = 3/2 (d(3)); Mn(III), SMn= 4/2 (d(4)). The spin-state and coordination geometry of the (L)Fe(III) groups were confirmed by Moessbauer spectral measurements. Trinuclear combinations of the present kind give rise to unusual coupled spin-stateenergy levels which, in the case of (L)Fe(III)ORu(IV)(P)OFe(III)(L) compounds, result in "ferromagnetic-like" plots of magnetic moment versus temperature, particularly at low temperatures. The following best-fit values of parameters were deduced from the magnetic moment data, obtained in 1 T fields over the temperature range 4.2-300 K. (salmah)FeORu(TPP)OFe(salmah): g = 1.97, J12 = -19.7 cm**-1, J13 = +6.5 cm**-1, α = J13/J12 = -0.33, ground-state S = 4; (TMP)FeORu(TPP)OFe(TMP): g = 1.95, J12= -23.4 cm**-1, J13 = 5.4 cm**- 1, α = -0.23, ground-state S = 4.(TPP)FeORu(TPP)OFe(TPP): g = 2.0, J12 = -35.7 cm**-1, J13 = 11.2 cm**-1, α = -0.31, ground-state S = 4, [(TPP)Fe]2O impurity = 13%, zero-field splitting of the S = 4 state (D ~ 5 cm**-1). (TMP)MnORu(TPP)OMn(TMP): g = 1.93, J12 = -17.4 cm**-1, J13 = 9.6 cm**-1, α = -0.55, ground-state S = 3. (TPP)CrORu(TPP)OCr(TPP): g = 1.98, J12 = -25.3 cm**-1, J13 = -11.1 cm**-1, α = 0.44, ground-state S = 1. Possiblereasons for the small sizes of the J12 values, in comparison to those of related M(III)OM(III) and Ru(IV)ORu(IV) compounds, are discussed.
Meso-Tetraphenylporphyrin Iron Chloride Catalyzed Selective Oxidative Cross-Coupling of Phenols
Shalit, Hadas,Libman, Anna,Pappo, Doron
supporting information, p. 13404 - 13413 (2017/10/05)
A novel catalytic system for oxidative cross-coupling of readily oxidized phenols with poor nucleophilic phenolic partners based on an iron meso-tetraphenylporphyrin chloride (Fe[TPP]Cl) complex in 1,1,1,3,3,3-hexafluoropropan-2-ol (HFIP) was developed. The unique chemoselectivity of this reaction is attributed to the coupling between a liberated phenoxyl radical with an iron-ligated phenolic coupling partner. The conditions are scalable for preparing a long list of unsymmetrical biphenols assembled from a less reactive phenolic unit substituted with alkyl or halide groups.
Replacement of imidazoles by azide at an iron(III) porphyrin center: Part 1 replacement of N-methylimidazole in bis-(N-methylimidazole) tetraphenylporphyrinato iron(III)
Jones, John G.,McKnight, John,Twigg, Martyn V.
experimental part, p. 2766 - 2778 (2010/12/25)
Addition of tetra-n-butylammonium azide to acetone solutions of the tetraphenylporphyrinato iron(III) complex [Fe(TPP)(MeIm)2] +N-3 formed in situ from the reaction of N-methylimidazole and [Fe(TPP)N3] afforded equilibrium amounts of [Fe(TPP)(MeIm)2]+ and [Fe(TPP)(MeIm)N3]. Equilibrium experiments made using a range of known concentrations of added tetra-n-butylammonium azide and N-methylimidazole using stopped-flow apparatus gave an estimate of about 50 for the equilibrium constant for the formation of [Fe(TPP)(MeIm)N3] from the addition of azide to [Fe(TPP)(MeIm) 2]+. Kinetic studies indicated that the substitution of azide ion by N-methylimidazole is a dissociative process, and the results were interpreted using a stationary state approach in which [Fe(TPP)(MeIm)] + was the transient intermediate that discriminated in favor of the reaction with azide as opposed to the reaction with N-methylimidazole by about a factor of two. Loss of N-methylimidazole from [Fe(TPP)(MeIm)2] + is at least 50 times faster than that from the product [Fe(TPP)(MeIm)N3]. Using calculated values of free azide concentrations from experimentally determined ion-pair formation constants led to success in rationalizing results obtained under different conditions.
