Designing ligands to achieve robust oxidation catalysts. Iron based systems

Bartos, Michael J.; Gordon‐Wylie, Scott W.; Fox, Brian G.; Wright, L. James; Weintraub, Susan T.; Kauffmann, Karl; Münck, Eckard; Kostka, Kimberly L.; Uffelman, Erich S.; Rickard, Clifton E. F.; Noon, Kathleen R.; Collins, Terrence J.

doi:10.1016/s0010-8545(98)00142-8

Cited by 73 publications

(60 citation statements)

References 36 publications

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“…The ellipsoids are drawn at the 50% probability level. [33]. This complex was initially observed during the activation of the a-C-H bond of a nitrile solvent by [Fe III (DCB)Cl] 2À in the presence of t BuOOH.…”

Section: S = 1 Complex With Metal Centered Oxidationmentioning

confidence: 99%

High-valent iron complexes with tetraamido macrocyclic ligands: Structures, Mössbauer spectroscopy, and DFT calculations

Chanda

Popescu

Oliveira

et al. 2006

Journal of Inorganic Biochemistry

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Section: S = 1 Complex With Metal Centered Oxidationmentioning

confidence: 99%

High-valent iron complexes with tetraamido macrocyclic ligands: Structures, Mössbauer spectroscopy, and DFT calculations

Chanda

Popescu

Oliveira

et al. 2006

Journal of Inorganic Biochemistry

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“…The X-ray structure of the monoligated 1-methylimidazole (MeIm) adduct (Ia-MeIm) is shown in Scheme 3.4 [19]. A square pyramidal environment is typical of Fe III -TAMLs in the solid state [8,14,25]. Imidazole does not change the coordinative arrangement of Fe III -TAMLs from that observed with axial water or chloride.…”

Section: ð3:1þmentioning

confidence: 99%

“…This suggests that the aromatic components of Fe III -TAML catalysts are vulnerable to oxidative degradation. The six-membered ring is the primary site for degradation in organic solvents when this is substituted with ethyl groups, which are the initiation site of degradation based on a methylene H-atom abstraction [14]. Substitution with methyl groups slows the rate significantly because the methyl CÀH bonds are stronger than the methylene CÀH bonds and this iteration in the design of our catalysts [7] allowed for the generation of useful catalysts.…”

Section: Kinetic Model For Parameterizationmentioning

confidence: 99%

“…The FeÀCl bond distance is much longer (2.359 and 2.361 Å in 1i Cl and 1l Cl , respectively) than in [FeCl 4 ] À (2.182-2.187 Å) [9,10] and Fe III porphyrins (2.218 [11], 2.192 [12] and 2.223 Å [13]). The metal cation in a one-electron oxidized analogue of 1i Cl (where the oxidation site is ligand centered) is more deeply immersed into the macrocyclic cavity (0.04 Å displacement) and the FeÀCl bond length drops to 2.203 Å [14]. The Fe III ÀCl bond is elongated in 1 Cl due to the groundstate destabilization of the axial s-bonding orbitals by the four deprotonated strong s-donor amido-N ligands.…”

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confidence: 99%

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Chemistry and Applications of Iron–TAMLCatalysts in Green Oxidation Processes Based on Hydrogen Peroxide

Collins

Khetan

Ryabov

2010

Handbook of Green Chemistry

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Iron–tetraamido macrocyclic ligand (TAML) activators have been designed and developed to provide small‐molecule mimics, the peroxidase enzymes. Fe–TAML activators are proving to be highly active catalysts that function effectively at very low concentrations from nanomolar to low micromolar. Notably, they are capable of performing many thousands of turnovers per minute under ambient conditions, of functioning over a broad pH range from acidic and most notably for iron catalyst to basic and even to highly basic, of presenting a broad range of selectivities and oxidative aggression determined by the conditions of use and the choice of catalyst over the 14 catalysts presented. The catalysts have fulfilled the design criteria and now provide the basis of platform technology for myriad applications. Published kinetics and mechanistic interpretations are reviewed to illustrate the success of the design protocol. Published applications are briefly described. A highly developed field of use involves the use of Fe–TAML–peroxide for the purification of water of persistent pollutants and hardy pathogens.

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“…The Fe III -TAML activators are predominantly five-coordinate complexes in the solid phase. [23][24][25][26] In water, they turn into six-coordinate species of À1 charge with two axial aqua ligands. One aqua ligand loses a proton to form a species of À2 charge in the range of pH 9.0-10.5 depending on the nature of 1 (Scheme 4 a).…”

Section: Introductionmentioning

confidence: 99%

The Impact of Surfactants on Fe^III–TAML‐Catalyzed Oxidations by Peroxides: Accelerations, Decelerations, and Loss of Activity

Banerjee

Apollo

Ryabov

et al. 2009

Chemistry A European J

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Iron(III) complexes of tetraamidato macrocyclic ligands (TAMLs), [Fe{4-XC(6)H(3)-1,2-(NCOCMe(2)NCO)(2)CR(2)}(OH(2))](-), 1 (1 a: X = H, R = Me; 1 b: X = COOH, R = Me); 1 c: X = CONH(CH(2))(2)COOH, R = Me; 1 d: CONH(CH(2))(2)NMe(2), R = Me; 1 e: X = CONH(CH(2))(2)NMe(3) (+), R = Me; 1 f: X = H, R = F), have been tested as catalysts for the oxidative decolorization of Orange II and Sudan III dyes by hydrogen peroxide and tert-butyl hydroperoxide in the presence of micelles that are neutral (Triton X-100), positively charged (cetyltrimethylammonium bromide, CTAB), and negatively charged (sodium dodecyl sulfate, SDS). The previously reported mechanism of catalysis involves the formation of an oxidized intermediate from 1 and ROOH (k(I)) followed by dye bleaching (k(II)). The micellar effects on k(I) and k(II) have been separately studied and analyzed by using the Berezin pseudophase model of micellar catalysis. The largest micellar acceleration in terms of k(I) occurs for the 1 a-tBuOOH-CTAB system. At pH 9.0-10.5 the rate constant k(I) increased by approximately five times with increasing CTAB concentration and then gradually decreased. There was no acceleration at higher pH, presumably owing to the deprotonation of the axial water ligand of 1 a in this pH range. The k(I) value was only slightly affected by SDS (in the oxidation of Orange II), but was strongly decelerated by Triton X-100. No oxidation of the water-insoluble, hydrophobic dye Sudan III was observed in the presence of the SDS micelles. The k(II) value was accelerated by cationic CTAB micelles when the hydrophobic primary oxidant tert-butyl hydroperoxide was used. It is hypothesized that tBuOOH may affect the CTAB micelles and increase the binding of the oxidized catalysts. The tBuOOH-CTAB combination accelerated both of the catalysis steps k(I) and k(II).

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Designing ligands to achieve robust oxidation catalysts. Iron based systems

Cited by 73 publications

References 36 publications

High-valent iron complexes with tetraamido macrocyclic ligands: Structures, Mössbauer spectroscopy, and DFT calculations

High-valent iron complexes with tetraamido macrocyclic ligands: Structures, Mössbauer spectroscopy, and DFT calculations

Chemistry and Applications of Iron–TAMLCatalysts in Green Oxidation Processes Based on Hydrogen Peroxide

The Impact of Surfactants on Fe^III–TAML‐Catalyzed Oxidations by Peroxides: Accelerations, Decelerations, and Loss of Activity

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Designing ligands to achieve robust oxidation catalysts. Iron based systems

Cited by 73 publications

References 36 publications

High-valent iron complexes with tetraamido macrocyclic ligands: Structures, Mössbauer spectroscopy, and DFT calculations

High-valent iron complexes with tetraamido macrocyclic ligands: Structures, Mössbauer spectroscopy, and DFT calculations

Chemistry and Applications of Iron–TAMLCatalysts in Green Oxidation Processes Based on Hydrogen Peroxide

The Impact of Surfactants on FeIII–TAML‐Catalyzed Oxidations by Peroxides: Accelerations, Decelerations, and Loss of Activity

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The Impact of Surfactants on Fe^III–TAML‐Catalyzed Oxidations by Peroxides: Accelerations, Decelerations, and Loss of Activity