Synthesis and Characterization of Iron(II) Quinaldate Complexes

Houghton, Dylan T.; Gydesen, Nicholas W.; Arulsamy, Navamoney; Mehn, Mark P.

doi:10.1021/ic901464b

Cited by 13 publications

(7 citation statements)

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“…Similar observations have been made elsewhere. 64, 65 The structure of 3(b)-Cl , with two equatorial carboxylates cis to a labile ligand site, demonstrates that by careful ligand design complexes that act as structural mimics of the active site of mononuclear nonheme iron enzymes can be obtained (Scheme 1, Figure 2). …”

Section: Resultsmentioning

confidence: 99%

A mononuclear carboxylate-rich oxoiron(iv) complex: a structural and functional mimic of TauD intermediate ‘J’

McDonald

Guo

et al. 2012

Chem. Sci.

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The pentadentate ligand nBu-P2DA (2(b), nBu-P2DA = N-(1′,1′-bis(2-pyridyl)pentyl)iminodiacetate) was designed to bind an iron center in a carboxylate-rich environment similar to that found in the active sites of TauD and other α-ketoglutarate-dependent mononuclear non-heme iron enzymes. The iron(II) complex nBu4N[FeII(Cl)(nBu-P2DA)] (3(b)-Cl) was synthesized and crystallographically characterized to have a 2-pyridine-2-carboxylate donor set in the plane perpendicular to the Fe-Cl bond. Reaction of 3(b)-Cl with N-heterocyclic amines such as pyridine or imidazole yielded the N-heterocyclic amine adducts [FeII(N)(nBu-P2DA)]. These adducts in turn reacted with oxo-transfer reagents at −95 °C to afford a short-lived oxoiron(IV) complex [FeIV(O)(nBu-P2DA)] (5(b)) in yields as high as 90% depending on the heterocycle used. Complex 5(b) exhibits near-IR absorption features (λmax = 770 nm) and Mossbauer parameters (δ = 0.04 mm/s; ΔEQ = 1.13 mm/s; D = 27±2 cm−1) characteristic of an S = 1 oxoiron(IV) species. Direct evidence for an Fe=O bond of 1.66 Å was found from EXAFS analysis. DFT calculations on 5(b) in its S =1 spin state afforded a geometry-optimized structure consistent with the EXAFS data. They further demonstrated that the replacement of two pyridine donors in [FeIV(O)(N4Py)]2+ (N4Py = N,N-(bis(2-pyridyl)methyl)N-bis(2-pyridylmethyl)amine) with carboxylate donors in 5(b) decreased the energy gap between the ground S = 1 and the excited S = 2 states, reflecting the weaker equatorial ligand field of 5(b) and accounting for its larger D value. Complex 5(b) reacted readily with dihydrotoluene, methyldiphenylphosphine and ferrocene at −60 °C, and in all cases was approximately a 5-fold more reactive oxidant than [FeIV(O)(N4Py)]2+. The reactivity differences between these two complexes may arise from a combination of electronic and steric factors. Carboxylate-rich 5(b) represents the closest structural mimic reported thus far of the oxoiron(IV) intermediate (‘J’) found in TauD and provides us with vital insights into the role carboxylate ligands play in modulating the spectroscopic and reactivity properties of the non-heme oxoiron(IV) moiety.

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Section: Resultsmentioning

confidence: 99%

A mononuclear carboxylate-rich oxoiron(iv) complex: a structural and functional mimic of TauD intermediate ‘J’

McDonald

Guo

et al. 2012

Chem. Sci.

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“…Structurally characterized complexes with quinaldinate reveal a bidentate chelating manner through pyridine nitrogen and carboxylate oxygen as a prevailing coordination mode [12][13][14][15][16][17][18][19][20][21][22]. Examples of a bridging mode through two or all three donor atoms are not very common [23][24][25][26]. The quinaldinate was introduced into our reaction system through the [Cu(quin)2(H2O)] starting material, one of the rare copper(II) quinaldinate compounds known prior to this report [27].…”

Section: Introductionmentioning

confidence: 99%

Beyond the Simple Copper(II) Coordination Chemistry with Quinaldinate and Secondary Amines

2020

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Copper(II) acetate has reacted in methanol with quinaldinic acid (quinoline-2-carboxylic acid) to form [Cu(quin)2(CH3OH)]∙CH3OH (1) (quin− = an anionic form of the acid) with quinaldinates bound in a bidentate chelating manner. In the air, complex 1 gives off methanol and binds water. The conversion was monitored by IR spectroscopy. The aqua complex has shown a facile substitution chemistry with alicyclic secondary amines, pyrrolidine (pyro), and morpholine (morph). trans-[Cu(quin)2(pyro)2] (2) and trans-[Cu(quin)2(morph)2] (4) were obtained in good yields. The morpholine system has produced a by-product, trans-[Cu(en)2(H2O)2](morphCOO)2 (5) (morphCOO− = morphylcarbamate), a result of the copper(II) quinaldinate reaction with ethylenediamine (en), an inherent impurity in morpholine, and the amine reaction with carbon dioxide. (pyroH)[Cu(quin)2Cl] (3) forms on the recrystallization of [Cu(quin)2(pyro)2] from dichloromethane, confirming a reaction between amine and the solvent. Similarly, a homologous amine, piperidine (pipe), and dichloromethane produced (pipeH)[Cu(quin)2Cl] (11). The piperidine system has afforded both mono- and bis-amine complexes, [Cu(quin)2(pipe)] (6) and trans-[Cu(quin)2(pipe)2] (7). The latter also exists in solvated forms, [Cu(quin)2(pipe)2]∙CH3CN (8) and [Cu(quin)2(pipe)2]∙CH3CH2CN (9). Interestingly, only the piperidine system has experienced a reduction of copper(II). The involvement of amine in the reduction was undoubtedly confirmed by identification of a polycyclic piperidine compound 10, 6,13-di(piperidin-1-yl)dodecahydro-2H,6H-7,14-methanodipyrido[1,2-a:1′,2′-e][1,5]diazocine.

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“…In the literature, detailed crystallographic data related to similar complexes can be found in the following references. [42] Antioxidant Studies…”

Section: Xrd Analysis Of Ni(ii) Complexmentioning

confidence: 99%

Spectroscopic and Structural Characterization, Enzyme Inhibitions, and Antioxidant Effects of New Ru(II) and Ni(II) Complexes of Schiff Base

Buldurun

Turan

Aras

et al. 2019

Chemistry & Biodiversity

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The new complex compounds [RuLCl(p‐cymene)] ⋅ 3H2O and [NiL2(H2O)2] ⋅ 3H2O (L: 1‐{4‐[(2‐hydroxy‐3‐methoxybenzylidene)amino]phenyl}ethanone) were prepared and characterized using FT‐IR, 1H‐ and 13C‐NMR, mass spectroscopy, TGA, elemental analysis, X‐ray powder diffraction and magnetic moment techniques. Octahedral geometry for new Ni(II) and Ru(II) complexes was proposed. Thermal decomposition confirmed the existence of lattice and coordinated water molecule in the complexes. To determine the antioxidant properties of Schiff base ligand and its Ni(II), Ru(II) metal complexes, FRAP, CUPRAC, ABTS and DPPH methods of antioxidant assays were used. Moreover, enzyme inhibition of complexes was evaluated against carbonic anhydrase I and II isoenzymes (CA I and CA II) and acetylcholinesterase (AChE). For CA I and CA II, the best inhibition enzymes, was the Ni(II) complex with 62.98±18.41, 86.17±23.62 Ki values, whereas this inhibition effect showed ligand with 24.53±2.66 Ki value for the AChE enzyme.

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Synthesis and Characterization of Iron(II) Quinaldate Complexes

Cited by 13 publications

References 61 publications

A mononuclear carboxylate-rich oxoiron(iv) complex: a structural and functional mimic of TauD intermediate ‘J’

A mononuclear carboxylate-rich oxoiron(iv) complex: a structural and functional mimic of TauD intermediate ‘J’

Beyond the Simple Copper(II) Coordination Chemistry with Quinaldinate and Secondary Amines

Spectroscopic and Structural Characterization, Enzyme Inhibitions, and Antioxidant Effects of New Ru(II) and Ni(II) Complexes of Schiff Base

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