Effect of bulky substitution on catalytic activity of a manganese salen complex used in biomimetic alkene epoxidation and alkane hydroxylation with sodium periodate

Mirkhani, Valiollah; Tangestaninezhad, S; Bahramian, Bahram

doi:10.1007/bf03245991

Cited by 11 publications

(3 citation statements)

References 40 publications

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“…The results obtained in the oxidation with the axial ligands are contradictory to other oxidation and epoxidation reactions involving salen as catalyst [86][87][88], where rate enhancement is observed. In such cases, the rate enhancement is explained on the basis of easy transfer of oxygen atom from oxo-salen intermediates to the substrate which is facilitated by the binding of donor ligands to salen.…”

Section: Discussioncontrasting

confidence: 91%

Role of Iron(III)-salen Chloride as Oxidizing Agent with Thiodiglycolic Acid: The Effect of Axial Ligands

Subramaniam¹,

Vanitha²,

Kodispathi³

et al. 2017

J. Mex. Chem. Soc.

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The sulfoxidation of thiodiglycolic acid with iron(III)-salen chloride, which acts as an oxidizing agent without any terminal oxidant, in 50% aqueous acetonitrile medium has been studied. A substantial red shift in the λmaxvalue of FeIII-salen was observed in aqueous medium. The spectrophotometric kinetic study indicates that [FeIII(salen)]+ is the active oxidizing species and the reaction follows Michaelis-Menten kinetics with respect to the substrate. The rate of the reaction is highly sensitive to the medium. A reaction mechanism involving electron transfer from sulfur atom of thiodiglycolic acid to the central iron atom of [FeIII(salen)]+ is proposed. The presence of nitrogenous bases like pyridine, imidazole and 1-methylimidazole shows a retarding effect on the reaction rate. This can be explained on the basis of binding of these ligands to the coordination sphere of [FeIII(salen)]+ prior to the reaction with the substrate. The observed order of reactivity, pyridine > 1-methylimidazole > imidazole, is in accordance with the inverse of π-donating ability of nitrogen bases.

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Section: Discussioncontrasting

confidence: 91%

Role of Iron(III)-salen Chloride as Oxidizing Agent with Thiodiglycolic Acid: The Effect of Axial Ligands

Subramaniam¹,

Vanitha²,

Kodispathi³

et al. 2017

J. Mex. Chem. Soc.

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“…Depending on the chemical nature of the N and O donor atoms, salen-type ligands may offer thermodynamic and kinetic stability to a large variety of metal centers [2][3][4][5][6]. The presence of bulky substituents in the phenolate rings may provide additional stereochemical protection [7][8][9]. Moreover, the incorporation of chiral centers within the salen backbone reveals an important role in enantioselective catalysis [9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Synthesis and characterization of Ti(IV), Zr(IV) and Al(III) salen-based complexes

Hipólito¹,

Alves²,

Martins³

2021

Eur J Chem

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New Ti(IV), Zr(IV) and Al(III) salen-based complexes of formulae [(L)TiCl2], 2, [(L)ZrCl2], 3, and [(L){Al(CH2CH(CH3)2)2}2], 4, where L = meso-(R,S)-diphenylethylene-salen, were synthesized in high yields. [(L){Al(CH2CH(CH3)2)2}2] is a bimetallic complex that results from the reaction of H2L with either 1 or 2 equivalent of Al(CH2CH(CH3)2)3. The solid-state molecular structures of compounds 2 and 4·(C7H8) were obtained by single-crystal X-ray diffraction. Crystal data for C44H54Cl2N2O2Ti, (2a): monoclinic, space group C2/c (no. 15), a = 27.384(1) Å, b = 12.1436(8) Å, c = 28.773(2) Å, β = 112.644(2)°, V = 8830.6(9) Å3, Z = 8, μ(MoKα) = 0.350 mm-1, Dcalc = 1.146 g/cm3, 26647 reflections measured (5.204° ≤ 2Θ ≤ 50.7°), 8072 unique (Rint = 0.0967, Rsigma = 0.1241) which were used in all calculations. The final R1 was 0.0640 (I > 2σ(I)) and wR2 was 0.1907 (all data). Crystal data for C62H72Cl2N2O2Ti (2b): monoclinic, space group P21/c (no. 14), a = 19.606(1) Å, b = 12.793(1) Å, c = 23.189(2) Å, β = 105.710(4)°, V = 5599.0(7) Å3, Z = 4, μ(MoKα) = 0.291 mm-1, Dcalc = 1.182 g/cm3, 37593 reflections measured (3.65° ≤ 2Θ ≤ 50.928°), 10304 unique (Rint = 0.0866, Rsigma = 0.1032) which were used in all calculations. The final R1 was 0.0593 (I > 2σ(I)) and wR2 was 0.1501 (all data). Crystal data for C67H97Al2N2O2 (4·(C7H8)): triclinic, space group P-1 (no. 2), a = 10.0619(9) Å, b = 16.612(2) Å, c = 21.308(2) Å, α = 67.193(5)°, β = 78.157(6)°, γ = 77.576(5)°, V = 3176.8(6) Å3, Z = 2, μ(MoKα) = 0.088 mm-1, Dcalc = 1.063 g/cm3, 42107 reflections measured (5.382° ≤ 2Θ ≤ 51.624°), 12111 unique (Rint = 0.0624, Rsigma = 0.0706) which were used in all calculations. The final R1 was 0.0568 (I > 2σ(I)) and wR2 was 0.1611 (all data). The solid-state molecular structure of [(L){Al(CH2CH(CH3)2)2}2] reveals that both metal centres display a slightly distorted tetrahedral geometry bridged by the salen ligand. Both [(L)TiCl2] and [(L)ZrCl2] complexes display octahedral geometry with trans-chlorido ligands.

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“…There are several methods for structural modification of the salen ligands, including the substitution on the phenoxy groups or the ethylene bridge [132][133][134] and the metalation to give a complex called a metallosalen. Metallosalens were well known as chemical catalyst in various reactions such as enantioselective pinacol coupling 47 , copolymerization, [135][136][137] enantioselective Nazarov cyclization, 138 asymmetric sulfimidation and sigmatropic rearrangement.…”

Section: Figure Ii-3: a General Structure Of The Salen Ligandmentioning

confidence: 99%

Metallosalen-based polymers for reduction of carbon dioxide

Kaewyai

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In this research, a series of novel asymmetric copper- and nickel-salens bearing thiophene-based substituents were successfully synthesized and characterized by nuclear magnetic resonance spectroscopy and mass spectrometry.? Homogeneous electrocatalytic activities of these monomers toward reduction of CO2 were investigated using cyclic voltammetry technique.? Electrochemical studies showed these salen monomers are able to serve as?catalysts in the electrochemical reduction of CO2?due to the significantly increase of the current observed under CO2-saturated condition,?compared?with those found under the N2-saturated one.? Results also revealed that?insertion of the carbon-carbon triple-bond between the thiophene-based substituents?and the salen core led to the lower required reduction potential, while the additional thiophene rings did not significantly influence?in this aspect.? Furthermore, addition of 3% of H2O as a proton source resulted in even higher current enhancement?in the reduction of CO2.? Electropolymerization of the target monomers?through their thiophene-based units gave desirable metallosalen-based polymers in most cases.? In?the polymerization process, results?showed that the introduction of bithiophenyl rings led to the lower required oxidation potential, while the derivatives containing?carbon-carbon triple-bond spacers required higher oxidation potential than those having the thiophene-based substituents directly linked to the salen cores.? However, further optimization of the polymerization condition is required to obtain more efficient films for the reduction of CO2.

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Effect of bulky substitution on catalytic activity of a manganese salen complex used in biomimetic alkene epoxidation and alkane hydroxylation with sodium periodate

Cited by 11 publications

References 40 publications

Role of Iron(III)-salen Chloride as Oxidizing Agent with Thiodiglycolic Acid: The Effect of Axial Ligands

Role of Iron(III)-salen Chloride as Oxidizing Agent with Thiodiglycolic Acid: The Effect of Axial Ligands

Synthesis and characterization of Ti(IV), Zr(IV) and Al(III) salen-based complexes

Metallosalen-based polymers for reduction of carbon dioxide

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