Novel iron(III) complexes with phenolate containing tripodal tetradentate ligands as model systems for catechol 1,2-dioxygenases

Merkel, M.; Müller, Felizitas K.; Krebs, Bernt

doi:10.1016/s0020-1693(02)01082-4

Cited by 66 publications

(92 citation statements)

References 24 publications

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“…These bond lengths are similar to the Fe-O phenolato bond lengths observed in related distorted octahedral iron(III) complexes possessing phenolato ligands. [24,77,80,81] They are, however, longer than the average Fe-O bond length in trigonal bipyramidal or square pyramidal complexes, as expected because of the higher coordination number. [22,23,78,82,83] [23,24,82] The Fe-O-C bond angles of complex 1 are 138.4(2)°for Fe1-O1-C1 and 137.8(2)°for Fe1-O1-C34.…”

Section: Structural Characterizationmentioning

confidence: 67%

“…The geometries of the Fe III centers in both complexes are distorted octahedral. In complex 2, the O1-Fe1-N2, O4-Fe1-N1, and O2-Fe1-O3 angles are 160.43 (16) [24,77,80,81] as well as those in complex 1. The two nitrogen donor atoms in the ligand showed bond lengths of 2.192(4) Å and 2.290(4) Å for Fe1-N1 and Fe1-N2, respectively, in 2, and lengths of 2.120(6) Å and 2.263(5) Å for Fe1-N1 and Fe1-N2, respectively, in 3.…”

Section: Structural Characterizationmentioning

confidence: 94%

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Synthesis, Structure, and C–C Cross‐Coupling Activity of (Amine)bis(phenolato)iron(acac) Complexes

2011

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A series of (amine)bis(phenolato)iron(III)acac complexes has been prepared and characterized. Reaction of Fe(acac)3 with the diprotonated linear tetradentate proligand N,N′‐bis(4,6‐di‐tert‐butyl‐2‐methylphenol)‐N,N′‐dimethyl‐1,2‐diaminoethane, H2[L1], and tripodal tetradentate ligand precursors dimethylaminoethylamino‐N,N‐bis(2‐methylene‐4,6‐di‐tert‐butylphenol), H2[L2], dimethylaminoethylamino‐N,N‐bis(2‐methylene‐4‐methyl‐6‐tert‐butylphenol), H2[L3], 2‐methoxyethylamino‐N,N‐bis(2‐methylene‐4,6‐di‐tert‐butylphenol), H2[L4], 2‐methoxyethylamino‐N,N‐bis(2‐methylene‐4‐methyl‐6‐tert‐butylphenol), H2[L5], and 2‐methoxyethylamino‐N,N‐bis(2‐methylene‐4,6‐dimethylphenol), H2[L6], produces the distorted octahedral FeIII complexes [L1]Fe(acac) (1), [L2]Fe(acac) (2), [L3]Fe(acac) (3), [L4]Fe(acac) (4), [L5]Fe(acac) (5), and [L6]Fe(acac) (6). In all of these complexes, the phenolato oxygen atoms are cis‐oriented. The paramagnetic FeIII complexes 1–6 were also characterized by UV/Vis and IR spectroscopy, mass spectrometry, cyclic voltammetry, and magnetic measurements. Single crystal X‐ray molecular structures have been determined for complexes 1, 2, 3, 5, and the proligand H2[L6]. Preliminary investigations of complexes 1–6 for catalytic cross‐coupling reactions of aryl Grignard reagents with cyclic and acyclic secondary alkyl halides and benzyl halides were performed. While the activity for cyclohexyl chlorides and bromides was high, cross‐coupling of benzyl halides was moderate and 2‐bromo‐ and 2‐chlorobutane gave poor yields of cross‐coupled product.

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Section: Structural Characterizationmentioning

confidence: 67%

Section: Structural Characterizationmentioning

confidence: 94%

Synthesis, Structure, and C–C Cross‐Coupling Activity of (Amine)bis(phenolato)iron(acac) Complexes

2011

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“…As for the manganese complexes, two absorptions are attributed to L Ǟ M charge transfer transitions. [7,28,39,40] The absorption around 280 nm could be due to the π 3 -π 4 transition of the acac ligand (as it was assigned in the manganese complexes). However, the same absorption was reported for a similar iron(III) complex with a bis(phenolate) ligand without a β-diketonate ligand; [39] and could thus also be due to a tripodal ligand π-π* absorption.…”

Section: Fementioning

confidence: 80%

“…In the complexes 3 and 10 this absorption is obscured by very intense π-π* charge-transfer transitions, due to the phenyl rings of the dbm ligand for 3 and the nitro groups on the dnpppy ligand for 10. [7,39] All manganese complexes show an absorption at around 230-260 nm, which is attributed to a π-π* transition originating from the (substituted) pppy ligand.…”

Section: Electronic Absorption Spectroscopymentioning

confidence: 99%

“…Chelating ligands in which one or more of the "arms" consist of phenol groups have been used extensively for the preparation of copper complexes that model the active site of the enzyme galactose oxidase, [1][2][3][4][5] and also in the synthesis of iron and manganese complexes to model the active sites of various dioxygenase and phosphatase enzymes. [6][7][8][9][10][11] Lipoxygenases are nonheme, non-sulfur iron or manganese dioxygenases that act on lipid substrates containing one or more (Z,Z)-1,4-pentadiene moieties. [12] Common polyunsaturated fatty acids, such as linoleic, linolenic and arachidonic acids are the natural substrates for these enzymes, which are widely distributed among plants and animals.…”

Section: Introductionmentioning

confidence: 99%

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The Synthesis, Structures and Characterisation of New Mixed‐Ligand Manganese and Iron Complexes with Tripodal, Tetradentate Ligands

et al. 2008

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The preparation of new manganese and iron complexes with the general formula [M(tripod)(anion)] is described, where M = Fe III or Mn III , "tripod" is a dianionic tetradentate tripodal ligand and the anion is a chelating β-diketonate, 8-oxyquinoline or acetate. The synthesis of this type of complexes was found to be straightforward, which allows for the preparation of a large variety of such coordination compounds. The complexes are characterised by X-ray crystallography, infrared spectroscopy, UV/Vis spectroscopy, cyclic voltammetry and elemental analysis. A correlation between the ligand sets and the electron density at the metal centre in the complexes is

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Catalytic promiscuity of an iron(II)–phenanthroline complex

De¹,

Garai²,

Yadav

et al. 2016

Applied Organom Chemis

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A mononuclear iron(II) complex, [Fe(phen) 3 ]Cl 2 (1) (phen =1,10-phenanthroline), has been synthesized in crystalline phase and characterized using various spectroscopic techniques including single crystal X-ray diffraction. Crystal structure analysis revealed that 1 crystallizes in a monoclinic system with C2/m space group. Complex 1 acts as a functional model for a biomimetic catalyst promoting the aerobic oxidation of 3,5-di-tert-butylcatechol (3,5-DTBC) through radical pathways with a significant turnover number (k cat =3.55 × 10 3 h À1 ) and exhibits catechol dioxygenase activity towards the same 3,5-DTBC substrate at room temperature in oxygen-saturated ethanol medium. The existence of an isobestic point at 610 nm from spectrophotometric data indicates the presence of Fe 3+ À3,5-DTBC adduct favouring an enzyme-substrate binding phenomenon. Upon stoichiometric addition of 3,5-DTBC pretreated with two equivalents of triethylamine to the iron complex, two catecholate-to-iron(III) ligand-to-metal charge transfer bands (575 and 721 nm) are observed and the in situ generated catecholate intermediate reacts with dioxygen (k obs =9.89 × 10 À4 min À1 ) in ethanol medium to afford exclusively intradiol cleavage products along with a small amount of benzoquinone, and a small amount of extradiol cleavage products, which provide substantial evidence for a substrate activation mechanism.

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Novel iron(III) complexes with phenolate containing tripodal tetradentate ligands as model systems for catechol 1,2-dioxygenases

Cited by 66 publications

References 24 publications

Synthesis, Structure, and C–C Cross‐Coupling Activity of (Amine)bis(phenolato)iron(acac) Complexes

Synthesis, Structure, and C–C Cross‐Coupling Activity of (Amine)bis(phenolato)iron(acac) Complexes

The Synthesis, Structures and Characterisation of New Mixed‐Ligand Manganese and Iron Complexes with Tripodal, Tetradentate Ligands

Catalytic promiscuity of an iron(II)–phenanthroline complex

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