Synthesis and reactivity of the five-coordinate {Fe(NO)2}9 [(TMEDA)Fe(NO)2I]

Chen, Chien‐Hong; Ho, Yi-Chieh; Lee, Gene‐Hsiang

doi:10.1016/j.jorganchem.2009.06.040

Cited by 17 publications

(15 citation statements)

References 37 publications

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“…57 Fe-labeled complexes 1 and 2 were synthesized in a manner analogous to that for the unlabeled complexes from 57 Fe(OTf) 2 , generated in situ via metathesis of 57 FeCl 2 with Ag(OTf) as previously described . [ 57 Fe(μ-I)(NO) 2 ] 2 , generated from 57 Fe powder, was used to synthesize [ 57 Fe(TMEDA)(I)(NO) 2 ] ( 5 ) following literature procedures. , Reduction of 5 with CoCp 2 following a literature procedure afforded the complex [ 57 Fe(TMEDA)(NO) 2 ] ( 4 ).…”

Section: Methodsmentioning

confidence: 99%

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Unusual Synthetic Pathway for an {Fe(NO)₂}⁹Dinitrosyl Iron Complex (DNIC) and Insight into DNIC Electronic Structure via Nuclear Resonance Vibrational Spectroscopy

et al. 2016

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Dinitrosyl iron complexes (DNICs) are among the most abundant NO-derived cellular species. Monomeric DNICs can exist in the {Fe(NO)2}(9) or {Fe(NO)2}(10) oxidation state (in the Enemark-Feltham notation). However, experimental studies of analogous DNICs in both oxidation states are rare, which prevents a thorough understanding of the differences in the electronic structures of these species. Here, the {Fe(NO)2}(9) DNIC [Fe(dmp)(NO)2](OTf) (1; dmp = 2,9-dimethyl-1,10-phenanthroline) is synthesized from a ferrous precursor via an unusual pathway, involving disproportionation of an {FeNO}(7) complex to yield the {Fe(NO)2}(9) DNIC and a ferric species, which is subsequently reduced by NO gas to generate a ferrous complex that re-enters the reaction cycle. In contrast to most {Fe(NO)2}(9) DNICs with neutral N-donor ligands, 1 exhibits high solution stability and can be characterized structurally and spectroscopically. Reduction of 1 yields the corresponding {Fe(NO)2}(10) DNIC [Fe(dmp)(NO)2] (2). The Mössbauer isomer shift of 2 is 0.08 mm/s smaller than that of 1, which indicates that the iron center is slightly more oxidized in the reduced complex. The nuclear resonance vibrational spectra (NRVS) of 1 and 2 are distinct and provide direct experimental insight into differences in bonding in these complexes. In particular, the symmetric out-of-plane Fe-N-O bending mode is shifted to higher energy by 188 cm(-1) in 2 in comparison to 1. Using quantum chemistry centered normal coordinate analysis (QCC-NCA), this is shown to arise from an increase in Fe-NO bond order and a stiffening of the Fe(NO)2 unit upon reduction of 1 to 2. DFT calculations demonstrate that the changes in bonding arise from an iron-centered reduction which leads to a distinct increase in Fe-NO π-back-bonding in {Fe(NO)2}(10) DNICs in comparison to the corresponding {Fe(NO)2}(9) complexes, in agreement with all experimental findings. Finally, the implications of the electronic structure of DNICs for their reactivity are discussed, especially with respect to N-N bond formation in NO reductases.

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Section: Methodsmentioning

confidence: 99%

“…22 [ 57 Fe(μ-I)(NO) 2 ] 2 , generated from 57 Fe powder, was used to synthesize [ 57 Fe(TMEDA)-(I)(NO) 2 ] (5) following literature procedures. 23,24 Reduction of 5 with CoCp 2 following a literature procedure 24 afforded the complex [ 57 Fe(TMEDA)(NO) 2 ] (4).…”

Section: [Fe(dmp)(no) 2 ] (2)mentioning

confidence: 99%

Unusual Synthetic Pathway for an {Fe(NO)₂}⁹Dinitrosyl Iron Complex (DNIC) and Insight into DNIC Electronic Structure via Nuclear Resonance Vibrational Spectroscopy

et al. 2016

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“…31 While there exists a variety of four-coordinate {Fe(NO) 2 } 9 synthetic DNIC models in the inorganic chemistry literature, several reports have also presented the rare, ve-coordinate counterparts. [36][37][38] Our work focuses on developing understanding of mixed ligand environments and mechanisms of ligand exchange processes that might regulate switches in redox levels.…”

Section: Introductionmentioning

confidence: 99%

Hammett correlations as test of mechanism of CO-induced disulfide elimination from dinitrosyl iron complexes

et al. 2014

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The displacement of RSc from [(NHC)(SPh)Fe(NO) 2 ] (NHC ¼ N-heterocyclic carbene) by carbon monoxide follows associative kinetics, rate ¼ k [CO] 1 [(NHC)(SPh)Fe(NO) 2 ] 1 , resulting in reduction of the oxidized form of the dinitrosyliron unit, {Fe(NO) 2 } 9 (Enemark-Feltham notation) to {Fe(NO) 2 } 10 . Thermodynamically driven by the release of PhS-SPh concomitant with formation of [(NHC)(CO)Fe(NO) 2 ], computational studies suggested the reactant dinitrosyliron unit serves as a nucleophile in the initial slanted interaction of the p* orbital of CO, shifting into normal linear Fe-CO with weakening of the Fe-SPh bond. The current study seeks to experimentally test this proposal. A series of analogous {Fe(NO) 2 } 9 [(NHC)(p-S-C 6 H 4 X) Fe(NO) 2 ] complexes, with systematic variation of the para-substituents X from electron donor to electron withdrawing groups was used to monitor variation in electron density at the Fe(NO) 2 unit via Hammett analyses. Despite the presence of non-innocent NO ligands, data from n(NO) IR spectroscopy and cyclic voltammetry showed consistent tracking of the electron density at the {Fe(NO) 2 } unit in response to the aryl substituent. The electronic modifications resulted in systematic changes in reaction rates when each derivative was exposed to CO. A plot of the rate constants and the Hammett parameter s p is linear with a negative slope and a r value of À0.831; such correlation is indicative of rate retardation by electron-withdrawing substituents, and provides experimental support for the unique role of the delocalized frontier molecular orbitals of the Fe(NO) 2 unit. † Electronic supplementary information (ESI) available: Experimental methods, additional spectroscopic, cyclic voltammetric and kinetic details, X-ray crystallographic data (CIF) from the structure determination and full list of metric parameters for complexes 1a-1e. CCDC 1004078-1004081. For crystallographic data in CIF or other electronic format see a Average distance or angles. The maximum deviations from the average distances and angles are shown in the table. Full lists of metric parameters are available in the ESI.This journal is

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“… As shown in Scheme a and Figure S2, oxidation of {Fe(NO) 2 } 10 1-Me by [Cp 2 Fe][BF 4 ] in CH 2 Cl 2 afforded the nonclassical five-coordinate {Fe(NO) 2 } 9 [( Me DDB)Fe(NO) 2 ][BF 4 ] ( 2-Me ) with the F atom of [BF 4 ] − anion weakly coordinated to Fe metal (Fe---F = 2.28 Å), characterized by IR (ν NO 1834 s, 1769 s cm –1 (CH 2 Cl 2 )) and single-crystal X-ray diffraction (Figure S3). In a similar fashion, oxidation of {Fe(NO) 2 } 10 DNIC 1-Me by [Cp 2 Fe][BF 4 ] in CH 3 CN afforded the five-coordinate {Fe(NO) 2 } 9 [( Me DDB)Fe(NO) 2 (CH 3 CN)][BF 4 ] ( 4 ) with CH 3 CN coordinated to {Fe(NO) 2 } 9 core, characterized by IR (ν NO 1801 s, 1724 s cm –1 (CH 3 CN)) and an EPR g -value ( g av = 2.019 at 77 K) (Scheme c), compared to the previous reports of Fe-based oxidation of {Fe(NO) 2 } 10 [(sparteine)Fe(NO) 2 ], yielding the unstable four-coordinate {Fe(NO) 2 } 9 [(sparteine)Fe(NO) 2 ][BF 4 ] with Δν NO shift 125 cm –1 and EPR g av = 2.032. , …”

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confidence: 99%

“…13 As shown in Scheme 1a and Figure S2, oxidation of {Fe(NO) ] with Δν NO shift 125 cm −1 and EPR g av = 2.032. 15,16 Inspired by the formation of complex 4 with {Fe(NO) 2 } 9 core coordinated by α-diimine and CH 3 CN, we injected dry NO (1.5-fold excess) into the CH 2 Cl 2 solution of complex 2-Me (complex 2-Et) with a gastight syringe, as shown in Scheme 1b. The reaction solution was stirred under N 2 atmosphere at ambient temperature for 5 min.…”

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confidence: 99%

{Fe(NO)₂}⁹ Dinitrosyl Iron Complex Acting as a Vehicle for the NO Radical

Chen

Tsai

et al. 2016

J. Am. Chem. Soc.

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To carry and deliver nitric oxide with a controlled redox state and rate is crucial for its pharmaceutical/medicinal applications. In this study, the capability of cationic {Fe(NO)} dinitrosyl iron complexes (DNICs) [(DDB)Fe(NO)] (R = Me, Et, Iso; DDB = N,N'-bis(2,6-dialkylphenyl)-1,4-diaza-2,3-dimethyl-1,3-butadiene) carrying nearly unperturbed nitric oxide radical to form [(DDB)Fe(NO)(NO)] was demonstrated and characterized by IR, UV-vis, EPR, NMR, and single-crystal X-ray diffractions. The unique triplet ground state of [(DDB)Fe(NO)(NO)] results from the ferromagnetic coupling between two strictly orthogonal orbitals, one from Fe d and the other a π* orbital of a unique bent axial NO ligand, which is responsible for the growth of a half-field transition (ΔM = 2) from 70 to 4 K in variable-temperature EPR measurements. Consistent with the NO radical character of coordinated axial NO ligand in complex [(DDB)Fe(NO)(NO)], the simple addition of MeCN/HO into CHCl solution of complexes [(DDB)Fe(NO)(NO)] at 25 °C released NO as a neutral radical, as demonstrated by the formation of [SFe(NO)] from [SFe(μ-S)FeS].

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Synthesis and reactivity of the five-coordinate {Fe(NO)2}9 [(TMEDA)Fe(NO)2I]

Cited by 17 publications

References 37 publications

Unusual Synthetic Pathway for an {Fe(NO)₂}⁹Dinitrosyl Iron Complex (DNIC) and Insight into DNIC Electronic Structure via Nuclear Resonance Vibrational Spectroscopy

Unusual Synthetic Pathway for an {Fe(NO)₂}⁹Dinitrosyl Iron Complex (DNIC) and Insight into DNIC Electronic Structure via Nuclear Resonance Vibrational Spectroscopy

Hammett correlations as test of mechanism of CO-induced disulfide elimination from dinitrosyl iron complexes

{Fe(NO)₂}⁹ Dinitrosyl Iron Complex Acting as a Vehicle for the NO Radical

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Synthesis and reactivity of the five-coordinate {Fe(NO)2}9 [(TMEDA)Fe(NO)2I]

Cited by 17 publications

References 37 publications

Unusual Synthetic Pathway for an {Fe(NO)2}9Dinitrosyl Iron Complex (DNIC) and Insight into DNIC Electronic Structure via Nuclear Resonance Vibrational Spectroscopy

Unusual Synthetic Pathway for an {Fe(NO)2}9Dinitrosyl Iron Complex (DNIC) and Insight into DNIC Electronic Structure via Nuclear Resonance Vibrational Spectroscopy

Hammett correlations as test of mechanism of CO-induced disulfide elimination from dinitrosyl iron complexes

{Fe(NO)2}9 Dinitrosyl Iron Complex Acting as a Vehicle for the NO Radical

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Unusual Synthetic Pathway for an {Fe(NO)₂}⁹Dinitrosyl Iron Complex (DNIC) and Insight into DNIC Electronic Structure via Nuclear Resonance Vibrational Spectroscopy

Unusual Synthetic Pathway for an {Fe(NO)₂}⁹Dinitrosyl Iron Complex (DNIC) and Insight into DNIC Electronic Structure via Nuclear Resonance Vibrational Spectroscopy

{Fe(NO)₂}⁹ Dinitrosyl Iron Complex Acting as a Vehicle for the NO Radical