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1.
Catalytic activity of Mn(III) and Fe(III) complexes of meso-tetra(n-propyl)porphyrin, MnT(n-Pr)P(X) and FeT(n-Pr)P(X) (X = Cl, SCN, OAc) in oxidation of olefins with tetra-n-butylammonium periodate at room temperature has been studied. The influence of different parameters including the molar ratio of catalyst to imidazole, type of counter ion (X) and oxidative stability of metalloporphyrins on the efficiency of the catalysts was investigated. The results of competitive oxidation of cis- and trans-stilbene suggest the presence of a high-valent Mn-oxo as the predominant oxidant species in equilibrium with a six coordinate complex, MnT(n-Pr)P(ImH)(IO4) in the case of MnT(n-Pr)P(OAc). An unusual preference for trans-stilbene over cis-stilbene was observed in the reaction catalyzed by FeT(n-Pr)P(OAc). Control reaction indicated a significant cis- to trans-isomerization (81%) in oxidation of cis-stilbene catalyzed by FeT(n-Pr)P(OAc) which may explain the observed unusual cis to trans-stilbene oxide ratio. While oxidation of cyclooctene and styrene led to the exclusive formation of the corresponding epoxides, oxidation of cyclohexene gave 2-cyclohexe-1-ol and cyclohexene oxide as the products. However, the results of this study clearly demonstrate the key role played by the group substituted at the meso positions of metalloporphyrins on their catalytic activity, apart from the electron-donating or electron-withdrawing properties of the substituents. 相似文献
2.
Gholamhossein Grivani Aliakbar Dehno KhalajiVida Tahmasebi Kazuma GotohHiroyuki Ishida 《Polyhedron》2012,31(1):265-271
The Schiff base ligand N-salicylidin-2-bromoethylimine (L) and its vanadium(IV) complex, VOL2 (1), were synthesized and characterized by using X-ray, CHN, 1H NMR and FT-IR methods. X-ray analysis shows the Schiff base ligand L acts as a bidentate (O, N) chelating ligand and coordinates via imine nitrogen and phenolato oxygen atoms to the V(IV) center. The coordination geometry around the V(IV) center in 1 is approximately square pyramidal, as indicated by the unequal metal-ligand bond distances and angles, with the basal plane formed by the N2O2 donors of the two bidentate Schiff base ligands, the two phenolato O atoms and the two imine N atoms are in the trans position. The coordination sphere of the V(IV) is completed by one oxygen atom in apical position. In the Schiff base ligand, L, there are some classical intramolecular O1-H1?N1 and non-classical intermolecular C9-H9b?O1 hydrogen bonds, while in 1, there are two non-classical intermolecular C7-H7?O3 and C8-H8b?O3 hydrogen bonds. The catalytic activity of 1 in epoxidation of cyclooctene was investigated in different conditions to obtain optimum conditions. The effects of solvent, oxidant, catalyst concentration and alkene/oxidant ratio were studied and the results showed that in CCl4 in the presence of tert-butylhydroperoxide in 1:3 alkene/oxidant ratio, high epoxide yield was obtained. The epoxidation of alkenes was also carried out in optimized conditions that high catalytic activity and selectivity were obtained. 相似文献
3.
《Journal of Coordination Chemistry》2012,65(5):845-853
Two new Fe(III)(salen) complexes, FeL1ClO4·2H2O (1) and FeL2ClO4 (2) [L1 = N,N′-ethylenebis(3-formyl-5-methylsalicylaldimine) and L2 = N,N′-cyclohexenebis(3-formyl-5-methylsalicylaldimine)], have been synthesized and characterized. The catalytic activity of the complexes for epoxidation of alkenes has been investigated in the presence of two terminal oxidants PhIO and NaOCl, with two solvents CH3CN and CH2Cl2. As alkenes styrene and (E)-stilbene have been chosen for investigation; styrene is a better substrate than electron-rich (E)-stilbene. The study also suggests that unlike their Mn(III) counterparts, 1 and 2 are poor epoxidation catalysts; catalysis proceeds with formation of one intermediate, rather than forming more than one intermediate depending on the terminal oxidant used. Use of exogenous neutral donor ligands such as Py, PyNO and 1-MePy is effective to improve catalytic behavior. 相似文献
4.
Mojtaba Bagherzadeh Reza Latifi Laleh Tahsini 《Journal of molecular catalysis. A, Chemical》2006,260(1-2):163-169
The catalytic activity of two manganese(III)-oxazoline complexes [Mn(phox)2(CH3OH)2]ClO4 and Mn(phox)3 (Hphox = 2-(2′-hydroxylphenyl)oxazoline), was studied in the epoxidation of various olefins. All of epoxidation reactions were carried out in (1:1) mixture of methanol:dichloromethane at room temperature using urea hydrogen peroxide (UHP) as oxidant and imidazole as co-catalyst. The epoxide yields clearly demonstrate the influence of steric and electronic properties of olefins, the catalysts and nitrogenous bases as axial ligand. [Mn(phox)2(CH3OH)2]ClO4 catalyst with low steric properties has higher catalytic activity than Mn(phox)3. The highest epoxide yield (95%) was achieved for indene at the presence of [Mn(phox)2(CH3OH)2]ClO4 within 5 min. The proximal and distal interactions of strong π-donor axial ligands such as imidazole with the active intermediate are efficiently increased activity of the catalytic system. 相似文献
5.
Synthesis and catalytic activity of binuclear Mn(III,III)–BINOL complexes for epoxidation of olefins
The novel binuclear complexes [Mn2(III, III)(BINOL)3L2]2H2O, where, L = 2, 2′‐bipyridine (Bpy) or 1,10‐phenanthroline (Phen) and BINOL = 1, 1′‐bi‐2‐naphthol were synthesized and characterized by elemental analyses, magnetic susceptibility and various spectral methods. The catalytic activity of these complexes was studied for the epoxidation reaction of unfunctionalized olefins like styrene, 1‐hexene, 1‐octene and 1‐decene. The products thus obtained were analyzed by GC. The epoxidation reactions were carried out, in the presence of catalyst with different oxidants, to study the effect of the nature of the oxidant on the reactions. The different oxidants used were the peroxide oxygen donor (e.g. TBHP and H2O2), mono oxygen donor (e.g. PhIO) and dioxygen donor (e.g. molecular O2). TBHP was found to be the best oxidant for the epoxidation reaction. To study the effect of the solvent on the epoxidation, the reactions were carried out in different media, such as a polar media (e.g. with CH3OH as solvent), non‐polar media (e.g. with CH2Cl2 and C6H6 as solvents) and coordinating solvent (e.g. CH3CN). The maximum epoxide formation was observed in CH2Cl2 medium. The epoxidation reactions with optically active BINOL catalysts under optimum established conditions were carried out to examine the enantioselectivity of the catalysts. The complexes were, however, found not to be enantioselective. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
6.
Epoxidation of various alkenes in low to high yields (29-100%) and good to excellent selectivities (75-100%) was performed with tetrabutylammonium monopersulfate in the presence of meso-tetrakis(pentafluorophenyl)porphyrin as catalyst and tetrabutylammonium acetate or fluoride or imidazole as co-catalysts in CH2Cl2, in less than 10 min at room temperature (∼25 °C). 相似文献
7.
《Journal of Coordination Chemistry》2012,65(22):4082-4101
A new gadolinium(III) complex of 5-aminoorotic acid (HAOA) was synthesized by reaction of the respective inorganic salt in molar ratio of 1:3 to ligand. The structure of the complex was determined by elemental analysis, FT-IR, and FT-Raman spectroscopies. Significant differences in the IR and Raman spectra of the complex were observed as compared to the spectra of the free ligand. Detailed vibrational analysis of HAOA and Gd(III)-AOA systems revealed that the binding mode in the complex was bidentate through the carboxylic oxygens. The newly synthesized gadolinium(III) complex of 5-aminoorotic acid (GdAOA) showed antioxidant properties. The antioxidant activity of both HAOA and GdAOA was related with their electron donor properties. 相似文献
8.
Adamantia Kagkelari Giannis S. Papaefstathiou Catherine P. Raptopoulou Theodoros F. Zafiropoulos 《Polyhedron》2009
The reactions of Ga(acac)3 with N-salicylidene-o-aminophenol (saphH2) and its 5-methyl (5MesaphH2) and 5-bromo (5BrsaphH2) derivatives in alcohols afforded the complexes [Ga(acac)(saph)(EtOH)] (1), [Ga(acac)(5Mesaph)(MeOH)] (2) and [Ga(acac)(5Brsaph)(EtOH)] (3), respectively, in good yields. The crystal structures of 1 and 2 have been solved by single-crystal X-ray crystallography. All three complexes are mononuclear with the GaIII atoms being surrounded by a dianionic tridentate Schiff base ligand, one bidentate acac− ligand and a terminal alcohol molecule. Characteristic IR data are discussed in terms of the nature of bonding and the structures of the three complexes. 相似文献
9.
Duraiswamy SukanyaDuraisamy Senthil Raja Nattamai S.P. BhuvaneshKaruppannan Natarajan 《Polyhedron》2011,30(6):1108-1113
New hexa-coordinated Ru(III) complexes of the type [Ru(H2Pzdc)(EPh3)3X2] have been synthesized by reacting 3,5-pyrazole dicarboxylic acid (H3Pzdc) with the appropriate starting complexes [RuX3(EPh3)3] (where X = Cl or Br; E = P or As). The ligand behaves as a bidentate monobasic chelate. All the complexes have been characterized by analytical and spectroscopic (IR, electronic and EPR) data. Single-crystal X-ray analysis of the complex [Ru(H2Pzdc)(PPh3)2Cl2]·C6H6·C2H5OH revealed that the coordination environment around the ruthenium center consists of an NOP2Cl2 octahedron. The planar ligand occupies the equatorial position along with two chlorine atoms, while the triphenylphosphine groups occupy the axial positions. The electrochemical behavior of the new complexes was studied using cyclic voltammetry. The new mononuclear ruthenium complexes are capable of acting as catalysts for the oxidation of alcohols. 相似文献
10.
《Journal of Coordination Chemistry》2012,65(13):2321-2328
A ruthenium(III) complex containing ethylenediaminetetraacetate (edta), [{Ru(Hedta)}2(Pyz)]?·?8H2O (1) (Pyz?=?pyrazine), has been synthesized by the reaction between K[Ru(Hedta)Cl]?·?1.5H2O and pyrazine. The structure of the complex was determined by single X-ray diffraction. Complex 1 crystallizes in the triclinic space group P 1 with a?=?7.293(9)?Å, b?=?10.575(14)?Å, c?=?12.742(16)?Å, α?=?104.044(19)°, β?=?91.893(19)°, γ?=?93.35(2)°, Z?=?1. The product was also characterized by IR, UV-Vis, EPR spectrum and magnetic techniques. 相似文献
11.
《Journal of Coordination Chemistry》2012,65(19):3187-3197
New Sm(III) and Gd(III) complexes of deprotonated 4-hydroxy-3[1-(4-nitrophenyl)-3-oxobutyl]-2H-1-benzopyran-2-one (Acenocoumarol) were synthesized and characterized using FT-IR, FT-Raman, NMR spectra, and elemental analyses. The vibrational study gave evidence for the coordination of ligand to lanthanide ions. The ligand and its lanthanide(III) complexes were tested for their cytotoxic/cytostatic activity against two tumor cell lines and peritoneal mouse macrophages. The Sm(III) and Gd(III) complexes exhibit good activity against melanoma B16 and fibrosarcoma L929 and are stronger inhibitors of tumor cell proliferation than the ligand. Besides their cytotoxicity to tumor cells, Acenocoumarol and its gadolinium(III) and samarium(III) complexes modulate NO generation in activated macrophages. 相似文献
12.
Risa Matsumoto 《合成通讯》2013,43(15):1807-1816
The Mn(III)-based oxidation of a tertiary alkylamine, such as nitrilotris(ethane-2,1-diyl) tris(3-oxobutanoate) (1) with 1,1-diphenylethene (2a), effectively proceeded in an acetic acid–formic acid mixed solvent to give nitrilotris(ethane-2,1-diyl) tris(2-methyl-5,5-diphenyl-4,5-dihydrofuran-3-carboxylate) (3). Other typical Mn(III)-based reactions of various β-diketo esters 4a–e, 2,4-pentanedione (6a), malonic acid (6b), and diethyl malonate (6c) with 1,1-diarylthenes 2a–d were also investigated in a similar acetic acid–formic acid mixed solvent and the reaction rate was accelerated and the product yield increased. 相似文献
13.
A new azido derivative of a NNO donor tridentate Schiff-base copper(II) complex, [CuL(μ1,1-N3)]n (1) (HL = 1-(N-ortho-hydroxyacetophenimine)-2-(N-ethyl)aminoethane), containing a single end-on μ1,1-azido bridged 1D infinite chain has been synthesized and characterized. X-ray single crystal structure analysis reveals that the complex [CuL(μ1,1-N3)]n (1) is a 1D chain in which neighboring Cu(II) chromophores are related by glide planes and linked by single azido bridges in the EO mode. No measurable magnetic interaction was evidenced in the complex [CuL(μ1,1-N3)]n (1) through variable temperature magnetic susceptibility measurements (10–300 K). The complex was used as an active catalyst for the epoxidation of cyclooctene using tert-butyl-hydroperoxide as an oxidant. The catalytic activity of the complex has been compared in a series of solvents. The results show that in acetonitrile medium, the epoxide was produced in high yield with high selectivity. 相似文献
14.
Chullikkattil P. Pradeep Panthapally S. Zacharias Samar K. Das 《Journal of Chemical Sciences》2006,118(4):311-317
The open air reaction of the chiral Schiff base ligand H2L, prepared by the condensation of L-phenylalaninol and 5-bromosalicylaldehyde, with MnII(CH3COO)2.4H2O yielded dark brown complex [MnIV L2]·0·5 DMF (1). Compound 1 was characterized by elemental analysis, IR, UV-visible, CD and EPR spectroscopy, cyclic voltammetry
and room temperature magnetic moment determination. Single-crystal X-ray analysis revealed that compound 1 crystallises in
the monoclinicP2
1 space group with six mononuclear [MnIV L2] units in the asymmetric unit along with three solvent DMF molecules. In the crystal structure, each Mn(IV) complex, acting
as the building unit, undergoes supramolecular linking through C-H...0 bonds leading to an intricate hydrogen bonding network. 相似文献
15.
A new, highly sensitive and simple kinetic method for the determination of thyroxine was proposed. The method was based on the catalytic effect of thyroxine on the oxidation of As(III) by Mn(III) metaphosphate. The kinetics of the reaction was studied in the presence of orthophosphoric acid. The reaction rate was followed spectrophotometrically at 516 nm. It was established that orthophosphoric acid increased the reaction rate and that the extent of the non-catalytic reaction was extremely small. A kinetic equation was postulated and the apparent rate constant was calculated. The dependence of the reaction rate on temperature was investigated and the energy of activation and other kinetic parameters were determined.
Thyroxine was determined under the optimal experimental conditions in the range 7.0 × 10−9 to 3.0 × 10−8 mol L−1 with a relative standard deviation up to 6.7% and a detection limit of 2.7 × 10−9 mol L−1. In the presence of 0.08 mol L−1 chloride, the detection limit decreased to 6.6 × 10−10 mol L−1. The proposed method was applied for the determination of thyroxine in tablets. The accuracy of the method was evaluated by comparison with the HPLC method. 相似文献
16.
《Journal of Coordination Chemistry》2012,65(6):923-930
A mononuclear ruthenium(III) complex containing ethylenediaminetetraacetate (edta), [Ru(Hedta)(Htrz)] · 4H2O (1) (Htrz = 1H-1,2,4-triazole), has been synthesized and the structure was determined by single-crystal X-ray diffraction. The complex crystallizes in the triclinic space group P 1, with the unit cell parameters a = 7.212(3) Å, b = 9.873(4) Å, c = 13.806(6) Å, α = 91.945(6)°, β = 100.078(6)°, γ = 97.230(7) and Z = 2. The complex was also characterized by elemental analysis, IR, UV–Vis and ESR spectra. Cyclic voltammetry for the complex shows a ruthenium(III)/ruthenium(IV) oxidation and a ruthenium(III)/ruthenium(II) reduction within the range of ?1.5–0.5 V. Magnetic susceptibility data give an effective moment of 1.81 B.M. at room temperature. 相似文献
17.
[M(SRaaiNR′)Cl3] (M = Rh(III), Ir(III) and SRaaiNR′ = 1-alkyl-2-{(o-thioalkyl)phenylazo}imidazole) complexes are described in this article. The single crystal X-ray structure of one of the complexes, [Rh(SMeaaiNEt)Cl3] (3b), shows a tridentate chelation of SMeaaiNEt via N(imidazole), N(azo) and S(thioether) donor centres. Spectral characterization has been done by IR, UV–Vis and 1H NMR data. The electronic structure, redox properties and spectra are well supported by DFT and TDDFT computation on the complexes. 相似文献
18.
In the current work, two triazine‐based multidentate ligands (H2L1 and H2L2) and their homo‐dinuclear Mn (II), mononuclear Ln (III) and hetero‐dinuclear Mn (II)/Ln (III) (Where Ln: Eu or La) complexes were synthesized and characterized by spectroscopic and analytical methods. Single crystals of a homo‐dinuclear Mn (II) complex {[Mn (HL1)(CH3OH)](ClO4·CH3OH}2 ( 1 ) were obtained and the molecular structure was determined by X‐ray diffraction method. In the structure of the complex, each Mn (II) ion is seven‐coordinate and one of the phenolic oxygen bridges two Mn (II) centre forming a dimeric structure. The UV–Vis. and photoluminescence properties of synthesized ligands and their metal complexes were investigated in DMF solution and the compounds showed emission bands in the UV–Vis. region. The catecholase enzyme‐like activity of the complexes were studied for 3,5‐DTBC → 3,5‐DTBQ conversion in the presence of air oxygen. Homo‐dinuclear Mn (II) complexes ( 1 and 4 ) were found to efficiently catalyse 3,5‐DTBC → 3,5‐DTBQ conversion with the turnover numbers of 37.25 and 35.78 h?1 (kcat), respectively. Mononuclear Eu (III) and La (III) complexes did not show catecholase activity. 相似文献
19.
Sofia M. Bruno Salete S. Balula Anabela A. Valente Filipe A. Almeida Paz Martyn Pillinger Carla Sousa Jacek Klinowski Cristina Freire Paulo Ribeiro-Claro Isabel S. Gonalves 《Journal of molecular catalysis. A, Chemical》2007,270(1-2):185-194
The monomeric cis-dioxomolybdenum(VI) complexes [MoO2(oep-saldpen)] and [MoO2Cl2(oep-H2saldpen)], with a tetradentate [N2(imine)O2] and bidentate [N2(imine)] salen-type ligand functionalised with two pyrrole derivative pendant arms [oep-H2saldpen = 1,2-diphenylethylenebis(3-oxyethylpyrrole)salicylideneimine], were synthesised and characterised by 1H NMR, IR and Raman spectroscopy. The solid-state structure of the free ligand oep-H2saldpen was determined by single crystal X-ray diffraction. Assignment of the vibrational spectra of the molybdenum complexes was supported by carrying out ab initio calculations for the possible isomers using [MoO2(salen)] and [MoO2Cl2(H2salen)] as model compounds [H2salen = N,N′-ethylenebis(salicylideneimine)]. The oep-saldpen complexes were examined as catalysts for the epoxidation of cyclooctene, (R)-(+)-limonene, styrene, α-pinene, and cis and trans-β-methylstyrene, with tert-butyl hydroperoxide as the oxidant. Both complexes exhibited high selectivity for the epoxidation reaction, with the bis(chloro) complex being always the more active of the two. 相似文献
20.
Manikyanahally N. Kumara Dase Gowda Channe Gowda Kanchugarakoppal S. Rangappa 《Reaction Kinetics and Catalysis Letters》2001,72(2):331-342
Synthesis and characterization of the dipeptides(DP) namely Glycyl-Proline (Gly-Pro), Alanyl-Proline (Ala-Pro) and Valyl-Proline (Val-Pro), were made. Kinetics of oxidation of these DP by Mn(III) have been studied in the presence of sulfate ions in acidic medium at 26C. The reaction was followed spectrophotometrically at max = 500 nm. A first order dependence of rate on both Mn(III) and DP was observed. The rate is independent of the concentration of reduction product, Mn(II) and hydrogen ions. Effects of varying dielectric constant of the medium and addition of anions such as sulfate, chloride and perchlorate were studied. Activation parameters have been evaluated using Arrhenius and Eyring plots. The oxidation products were isolated and characterized. A mechanism involving the reaction of DP with Mn(III) in the rate limiting step is suggested. 相似文献