55290-32-9Relevant academic research and scientific papers
Axial base-controlled catalytic activity, oxidative stability and product selectivity of water-insoluble manganese and iron porphyrins for oxidation of styrenes in water under green conditions
Zakavi, Saeed,Hashemi-Amiri, Akbar,Asadi, Fatemeh
, (2017/11/30)
A series of water-insoluble iron(III) and manganese(III) porphyrins, FeT(2-CH3)PPCl, FeT(4-OCH3)PPCl, FeT(2-Cl)PPCl, FeTPPCl, MnT(2-CH3)PPOAc, MnT(4-OCH3)PPOAc, MnT(2-Cl)PPOAc and MnTPPOAc, in the presence of imidazole (ImH), F?, Cl?, Br? and acetate were used as catalysts for the aqueous-phase heterogeneous oxidation of styrenes to the corresponding epoxides and aldehydes with sodium periodate. Also, the effect of various reaction parameters such as reaction time, molar ratio of catalyst to axial base, type of axial base, molar ratio of olefin to oxidant and nature of metal centre on the activity and oxidative stability of the catalysts and the product selectivity was investigated. Higher catalytic activities were found for the iron complexes. Interestingly, the selectivity towards the formation of epoxide and aldehyde (or acetophenone) was significantly influenced by the type of axial base. Furthermore, Br? and ImH were found to be the most efficient co-catalysts for the oxidation of olefins performed in the presence of the manganese and iron porphyrins, respectively. The optimized molar ratio of catalyst to axial base was different for various axial bases. Also, the order of co-catalyst activity of the axial bases obtained in aqueous medium was different from that reported for organic solvents. The use of a convenient axial base under optimum reaction catalyst to co-catalyst molar ratio in the presence of the manganese porphyrin gave the oxidative products with a conversion of ca 100% in a reaction time of less than 3?h. However, the catalytic activity of the iron porphyrins could not be effectively improved by increasing the catalyst to co-catalyst molar ratio.
Magnetocaloric effect and heat capacity of high-spin manganese complexes in a disperse state
Korolev,Aref'Ev,Lomova,Klyueva,Zakharov,Korolev
, p. 1631 - 1635 (2011/01/08)
Magnetothermal properties of high-spin chloro(2,3,7,8,12,13,17,18- octaethylporphyrinato)manganese(III), chloro(5,10,15,20-tetraphenylporphyrinato) manganese(III), bromo(5,10,15,20-tetraphenylporphyrinato)manganese(III), and (acetato)(5,10,15,20-tetraphenylporphyrinato)manganese(III) complexes as 6% water suspensions were determined by the microcalorimetric method at 298 K in a magnetic field of 0-1.0 T. It was established that when the magnetic field was applied, the temperature of the systems increases, leading to positive values of the magnetocaloric effect: the higher the magnetic field induction, the higher the values. It is shown that the dependences of the heat capacity of the complexes' solid particles on the magnetic field induction are of an extreme nature with a heat capacity in the area above 0.6 T less than that in the zero field. The regularities of the dynamics of the numerical values of the change in enthalpy and magnetic entropy of the manganese complexes when a growing magnetic field was applied and the regularities of the influence of the acidoligand in pentacoordinated complexes on their magnetothermal properties were considered.
Spectroscopic study of the interaction of nitrogen dioxide with sublimed layers of manganese(II) mesotetraphenylporphyrins
Kurtikyan,Stepanyan,Martirosyan,Kazaryan,Madakyan
, p. 345 - 348 (2008/10/08)
The methods of 15NO2-isotope-substituted IR and electronic absorption spectroscopy were used to show that the interaction of nitrogen dioxide with sublimed layers of manganese(II) meso-tetraphenyporphyrin (MnTPP) has a complicated character and results in the Mn(III)TPP · NO3/- nitrato complex. The coordination of an additional axial ligand brings about noticeable shifts of several bands corresponding to the vibrations of porphyrin macrocycle. It is shown that the literature IR spectra of Mn(III)TPP · NO3/- recorded in KBr pellets are distorted because of the anion exchange by the solid-phase reaction Mn(III)TPP · NO3/- + KBr = Mn(III)TPP · Br- + KNO3.
The use of perchlorato(tetraphenylporphinato)manganese(III) as a reagent for the spectrophotometric determination of anions in nonaqueous solvents
Hinman, A. Scott,McGarty, Karen,Tang, Clement,Pavelich, Brad J.
, p. 545 - 550 (2007/10/02)
Perchlorato(tetraphenylporphinato)manganese(III) (TPPMnClO4) is shown to be a useful reagent for the determination of a variety of anions in nonaqueous media.The analysis is based on the displacement of coordinated perchlorate by more strongly coordinating anions as monitored spectrophotometrically.The procedure is demonstrated for the determination of tetra-alkylammonium salts of nitrate, nitrite, chloride, bromide, iodide, acetate, trifluoroacetate, cyanate, and thiocyanate in acetonitrile.Relative precisions and accuracies of the order of five parts per thousand are indicated.Key words: perchlorato(tetraphenylporphinato)manganese(III), spectrophotometric determination of anions, anions in nonaqueous media.
Electrochemical reactivity of manganese(II) porphyrins. Effects of dioxygen, benzoic anhydride, and axial ligands
Creager,Murray, Royce W.
, p. 2612 - 2618 (2008/10/08)
Currents for electrochemical reductions of manganese(III) porphyrins in oxygenated, aprotic media correspond to passage of between one and two electrons per porphyrin, depending on the experimental time scale, the axial base present, and the particular porphyrin. The two-electron process corresponds to an ECE reaction sequence involving formation and subsequent reduction of an intermediate Mn(II)-dioxygen adduct. The formal potential of the second electron step is shown to be ca. -0.17 V vs. NaSCE for Mn(TPP)benzoate. Passage of the second electron is suppressed by strong axial bases and by competitive axial binding but is promoted by use of an axial anion that gives the most negative potential for passage of the first electron, Mn(TPP)benzoate being a specific example. The overall rate constant for the intermediate chemical step is estimated. In the presence of the added electrophile benzoic anhydride, and on a slower time scale, reduction by more than two electrons occurs by a process postulated to involve heterolysis of the O-O bond by the electrophile, producing an even more easily reduced, high-valent manganese-oxo porphyrin. The rate of electrophile attack is slower than that for dioxygen binding.
Isolation and characterization of a five-coordinate manganese(III) porphyrin cation. Crystal and molecular structure of aquo(tetraphenylporphinato)manganese(III) triflate
Williamson, Michael M.,Hill, Craig L.
, p. 4668 - 4671 (2008/10/08)
Five-coordinate cationic manganese(III) porphyrin complexes exist in nonpolar organic media in the presence of a limiting amount of water. Slow diffusion of heptane into a benzene solution of (tetraphenylporphinato)manganese(III) triflate containing 1 equiv of water produces crystals of aquo(tetraphenylporphinato)manganese(III) triflate, [(H2O)MnIIITPP]+OTf- (1), the first unequivocal and isolated example of a five-coordinate cationic manganese(III) porphyrin complex. Solvate-free crystals of 1 crystallize in space group P1. The unit cell has a = 11.1735 (47) ?, b = 13.0503 (80) ?, c = 13.8998 (121) ?, α = 81.102 (60)°, β = 79.476 (53)°, γ = 75.312 (41)°, V = 1915.07 (2.17) ?3, and Z = 2. The structure was solved by conventional heavy-atom methods and converged to a final R = 0.0746. Complex 1 has a dMn-O of 2.105 (4) ?, and the Mn atom resides 0.17 and 0.19 ? above the mean 24-atom plane and the mean N4 plane, respectively. The molecular stereochemistry and the electronic spectra for 1 clearly establish the Mn to be in the high spin, S = 2, state. Complex 1 reacts only with a large excess of iodosylbenzene to form one or more high-valent Mn porphyrin species. The five-coordinate cationic form of MnIII porphyrins is accessible under the literature conditions for both the homogeneous catalytic oxygenation of hydrocarbons and the homogeneous oxidation of water by Mn porphyrins.
Study of (Tetraphenylporphinato)manganese(III)-Catalyzed Epoxidation and Demethylation Using p-Cyano-N,N-dimethylaniline N-Oxide as Oxygen Donor in a Homogeneous System. Kinetics, Radiochemical Ligation Studies, and Reaction Mechanism for a Model of Cytochrome P-450
Powell, Michael F.,Pai, Emil F.,Bruice, Thomas C.
, p. 3277 - 3285 (2007/10/02)
Oxygen transfer from p-cyanodimethylaniline (p-CNDMANO) to cyclohexene as well as "intramolecular" oxygen transfer accompained by demethylation to yield p-cyanomonomethylaniline (p-CNMMA) are strongly catalyzed by ligated (tetraphenylporphinato)MnIII (i.e., XMnIIITPP).These reactions have been studied in dry, oxygen-free benzonitrile.Radiochemical studies show that H2O (or TOH) is not bound to XMnIIITPP in aprotic solvents so that the MnIII moiety is pentacoordinate.Oxygen transfer occurs through the reversible formation of the hexacoordinated species p-CNDMANO*MnIII(X)TPP.This species decomposes to p-cyanodimethylaniline (p-CNDMA) + O=MnV(X)TPP.Reactions of cyclohexene with O=MnV(X)TPP yields cyclohexene epoxide and XMnIIITPP whereas p-CNMMA is formed directly from the p-CNDMANO*MnIII(X)TPP complex.The rates of product formation are shown to be dependent upon the nature of the ligand (X- = F-, Cl-, Br-, I-, OCN-).In the absence of the axial ligand X-, the rates of reaction are extremely slow.Thus, the MnIII C2-cap-porphyrin (XMnIIICAPTPP), which can only form an O=MnV porphyrin species wherein the Mn moiety is not complexed to X- as a sixth ligand, shows almost no tendency to act as a catalyst for oxygen transfer.The necessary presence of the axial ligand X- and the dependence of rate upon X- requires the structure of the oxygen transfer species to be quivalent to O=MnV(X)TPP.A kinetic analysis is presented (Scheme III) which has allowed the determination of the influence of the ligands X- upon the various rate constants (Table IV) involved in the overall oxidations.By employing p-CNDMANO as oxygen donor, multiple catalytic turnovers without loss of porphyrin have been realized.
Isolation, Purification, and Characterization of Intermediate (Iodosylbenzene)metalloporphyrin Complexes from the (Tetraphenylporphinato)manganese(III)-Iodosylbenzene Catalytic Hydrocarbon Functionalization System
Smegal, John A.,Schardt, Bruce C.,Hill, Craig L.
, p. 3510 - 3515 (2007/10/02)
A second-type of high-valent complex has been isolated from the reaction of (tetraphenylporphinato)manganese(III) derivatives, XMnIIITPP, with iodosylbenzene.This new type of complex, isolated from the XMnIIITPP-iodosylbenzene system
