共查询到20条相似文献,搜索用时 31 毫秒
1.
Dr. Shanti G. Patra Dr. Erzsébet Illés Dr. Amir Mizrahi Prof. Dr. Dan Meyerstein 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(3):711-720
CoII salts in the presence of HCO3−/CO32− in aqueous solutions act as electrocatalysts for water oxidation. It comprises of several key steps: (i) A relatively small wave at Epa≈0.71 V (vs. Ag/AgCl) owing to the CoIII/II redox couple. (ii) A second wave is observed at Epa≈1.10 V with a considerably larger current. In which the CoIII undergoes oxidation to form a CoIV species. The large current is attributed to catalytic oxidation of HCO3−/CO32− to HCO4−. (iii) A process with very large currents at >1.2 V owing to the formation of CoV(CO3)3−, which oxidizes both water and HCO3−/CO32−. These processes depend on [CoII], [NaHCO3], and pH. Chronoamperometry at 1.3 V gives a green deposit. It acts as a heterogeneous catalyst for water oxidation. DFT calculations point out that Con(CO3)3n−6, n=4, 5 are attainable at potentials similar to those experimentally observed. 相似文献
2.
Jean-Noël Rebilly Christian Herrero Katell Snchal-David Rgis Guillot Tanya Inceoglu Hlne Maisonneuve Frdric Banse 《Chemical science》2021,12(47):15691
Redox metalloenzymes achieve very selective oxidation reactions under mild conditions using O2 or H2O2 as oxidants and release harmless side-products like water. Their oxidation selectivity is intrinsically linked to the control of the oxidizing species generated during the catalytic cycle. To do so, a second coordination sphere is used in order to create a pull effect during the activation of O2 or H2O2, thus ensuring a heterolytic O–O bond cleavage. Herein, we report the synthesis and study of a new non-heme FeII complex bearing a pentaazadentate first coordination sphere and a pendant phenol group. Its reaction with H2O2 generates the classical FeIIIOOH species at high H2O2 loading. But at low H2O2 concentrations, an FeIVO species is generated instead. The formation of the latter is directly related to the presence of the 2nd sphere phenol group. Kinetic, variable temperature and labelling studies support the involvement of the attached phenol as a second coordination sphere moiety (weak acid) during H2O2 activation. Our results suggest a direct FeII → FeIVO conversion directed by the 2nd sphere phenol via the protonation of the distal O atom of the FeII/H2O2 adduct leading to a heterolytic O–O bond cleavage.A new FeII complex with a phenol group attached as a second coordination sphere moiety activates H2O2 to yield FeIVO following a mechanism reminiscent of peroxidase enzymes. 相似文献
3.
Jing Xu Qiang Zhang Xin Gao Peifang Wang Huinan Che Chunmei Tang Yanhui Ao 《Angewandte Chemie (International ed. in English)》2023,62(32):e202307018
Piezo-catalytic self-Fenton (PSF) system has been emerging as a promising technique for wastewater treatment, while the competing O2 reductive hydrogen peroxide (H2O2) production and FeIII reduction seriously limited the reaction kinetics. Here, we develop a two-electron water oxidative H2O2 production (WOR−H2O2) coupled with FeIII reduction over a FeIII/BiOIO3 piezo-catalyst for highly efficient PSF. It is found that the presence of FeIII can simultaneously initiate the WOR−H2O2 and reduction of FeIII to FeII, thereby enabling a rapid reaction kinetics towards subsequent Fenton reaction of H2O2/FeII. The FeIII initiating PSF system offers exceptional self-recyclable degradation of pollutants with a degradation rate constant for sulfamethoxazole (SMZ) over 3.5 times as that of the classic FeII-PSF system. This study offers a new perspective for constructing efficient PSF systems and shatters the preconceived notion of FeIII in the Fenton reaction. 相似文献
4.
Lidie Rousseau Dr. Christian Herrero Dr. Martin Clémancey Arnaud Imberdis Dr. Geneviève Blondin Dr. Guillaume Lefèvre 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(11):2417-2428
Ate-iron(II) species such as [Ar3FeII]− (Ar=aryl) are key intermediates in Fe-catalyzed couplings between aryl nucleophiles and organic electrophiles. They can be active species in the catalytic cycle, or lead to Fe0 and FeI oxidation states, which can themselves be catalytically active or lead to unwished organic byproducts. Analysis of the reactivity of the intermediates obtained by step-by-step displacement of the mesityl groups in high-spin [Mes3FeII]− by less hindered phenyl ligands was performed, and uncovered the crucial role of both steric and electronic parameters in the formation of the Fe0 and FeI oxidation states. The formation of quaternized [Ar4FeIIMgBr(THF)]− intermediates allows the bielectronic reductive elimination energy required for the formation of Fe0 to be reduced. Similarly, the small steric pressure of the aryl groups in [Ar3FeII]− enables the formation of aryl-bridged [{FeII(Ar)2}2(μ-Ar)2]2− species, which afford the FeI oxidation state by bimetallic reductive elimination. These results are supported by 1H NMR, EPR, and 57Fe Mössbauer spectroscopies, as well as by DFT calculations. 相似文献
5.
Beatrice Battistella Dr. Thomas Lohmiller Dr. Beatrice Cula Prof. Dr. Peter Hildebrandt Dr. Uwe Kuhlmann Prof. Dr. Holger Dau Dr. Stefan Mebs Prof. Dr. Kallol Ray 《Angewandte Chemie (International ed. in English)》2023,62(12):e202217076
In class Ib ribonucleotide reductases (RNRs) a dimanganese(II) cluster activates superoxide (O2⋅−) rather than dioxygen (O2), to access a high valent MnIII−O2−MnIV species, responsible for the oxidation of tyrosine to tyrosyl radical. In a biomimetic approach, we report the synthesis of a thiolate-bound dimanganese complex [MnII2(BPMT)(OAc)2](ClO)4 (BPMT=(2,6-bis{[bis(2-pyridylmethyl)amino]methyl}-4-methylthiophenolate) ( 1 ) and its reaction with O2⋅− to form a [(BPMT)MnO2Mn]2+ complex 2 . Resonance Raman investigation revealed the presence of an O−O bond in 2 , while EPR analysis displayed a 16-line St=1/2 signal at g=2 typically associated with a MnIIIMnIV core, as detected in class Ib RNRs. Unlike all other previously reported Mn−O2−Mn complexes, generated by O2⋅− activation at Mn2 centers, 2 proved to be a capable electrophilic oxidant in aldehyde deformylation and phenol oxidation reactions, rendering it one of the best structural and functional models for class Ib RNRs. 相似文献
6.
Xenia Engelmann Deesha D. Malik Teresa Corona Katrin Warm Erik R. Farquhar Marcel Swart Wonwoo Nam Kallol Ray 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(12):4052-4056
The generation of a nonheme oxoiron(IV) intermediate, [(cyclam)FeIV(O)(CH3CN)]2+ ( 2 ; cyclam=1,4,8,11‐tetraazacyclotetradecane), is reported in the reactions of [(cyclam)FeII]2+ with aqueous hydrogen peroxide (H2O2) or a soluble iodosylbenzene (sPhIO) as a rare example of an oxoiron(IV) species that shows a preference for epoxidation over allylic oxidation in the oxidation of cyclohexene. Complex 2 is kinetically and catalytically competent to perform the epoxidation of olefins with high stereo‐ and regioselectivity. More importantly, 2 is likely to be the reactive intermediate involved in the catalytic epoxidation of olefins by [(cyclam)FeII]2+ and H2O2. In spite of the predominance of the oxoiron(IV) cores in biology, the present study is a rare example of high‐yield isolation and spectroscopic characterization of a catalytically relevant oxoiron(IV) intermediate in chemical oxidation reactions. 相似文献
7.
Prof. Ryo Ohtani Hiromu Matsunari Prof. Takafumi Yamamoto Prof. Koji Kimoto Prof. Masaaki Isobe Dr. Kotaro Fujii Prof. Masatomo Yashima Dr. Susumu Fujii Dr. Akihide Kuwabara Dr. Yuh Hijikata Prof. Shin-ichiro Noro Prof. Masaaki Ohba Prof. Hiroshi Kageyama Prof. Shinya Hayami 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(43):19416-19421
Metal node design is crucial for obtaining structurally diverse coordination polymers (CPs) and metal–organic frameworks with desirable properties; however, FeII ions are exclusively six-coordinated. Herein, we present a cyanide-bridged three-dimensional (3D) CP, FePd(CN)4, bearing four-coordinate FeII ions, which is synthesized by thermal treatment of a two-dimensional (2D) six-coordinate FeII CP, Fe(H2O)2Pd(CN)4⋅4 H2O, to remove water molecules. Atomic-resolution transmission electron microscopy and powder X-ray and neutron diffraction measurements revealed that the FePd(CN)4 structure is composed of a two-fold interpenetrated PtS topology network, where the FeII center demonstrates an intermediate geometry between tetrahedral and square-planar coordination. This four-coordinate FeII center with the distorted geometry can act as a thermo-responsive flexible node in the PtS network. 相似文献
8.
Dr. Jin-Xia Liang Prof. Dr. Jian Lin Prof. Dr. Jingyue Liu Prof. Dr. Xiaodong Wang Prof. Dr. Tao Zhang Prof. Dr. Jun Li 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(31):12968-12975
Herein, we report a theoretical and experimental study of the water-gas shift (WGS) reaction on Ir1/FeOx single-atom catalysts. Water dissociates to OH* on the Ir1 single atom and H* on the first-neighbour O atom bonded with a Fe site. The adsorbed CO on Ir1 reacts with another adjacent O atom to produce CO2, yielding an oxygen vacancy (Ovac). Then, the formation of H2 becomes feasible due to migration of H from adsorbed OH* toward Ir1 and its subsequent reaction with another H*. The interaction of Ir1 and the second-neighbouring Fe species demonstrates a new WGS pathway featured by electron transfer at the active site from Fe3+−O⋅⋅⋅Ir2+−Ovac to Fe2+−Ovac⋅⋅⋅Ir3+−O with the involvement of Ovac. The redox mechanism for WGS reaction through a dual metal active site (DMAS) is different from the conventional associative mechanism with the formation of formate or carboxyl intermediates. The proposed new reaction mechanism is corroborated by the experimental results with Ir1/FeOx for sequential production of CO2 and H2. 相似文献
9.
Olga V. Makhlynets Prof. Dr. Elena V. Rybak‐Akimova 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(47):13995-14006
Mechanism of substrate oxidations with hydrogen peroxide in the presence of a highly reactive, biomimetic, iron aminopyridine complex, [FeII(bpmen)(CH3CN)2][ClO4]2 ( 1 ; bpmen=N,N'‐dimethyl‐N,N'‐bis(2‐pyridylmethyl)ethane‐1,2‐diamine), is elucidated. Complex 1 has been shown to be an excellent catalyst for epoxidation and functional‐group‐directed aromatic hydroxylation using H2O2, although its mechanism of action remains largely unknown. 1 , 2 Efficient intermolecular hydroxylation of unfunctionalized benzene and substituted benzenes with H2O2 in the presence of 1 is found in the present work. Detailed mechanistic studies of the formation of iron(III)–phenolate products are reported. We have identified, generated in high yield, and experimentally characterized the key FeIII(OOH) intermediate (λmax=560 nm, rhombic EPR signal with g=2.21, 2.14, 1.96) formed by 1 and H2O2. Stopped‐flow kinetic studies showed that FeIII(OOH) does not directly hydroxylate the aromatic rings, but undergoes rate‐limiting self‐decomposition producing transient reactive oxidant. The formation of the reactive species is facilitated by acid‐assisted cleavage of the O? O bond in the iron–hydroperoxide intermediate. Acid‐assisted benzene hydroxylation with 1 and a mechanistic probe, 2‐Methyl‐1‐phenyl‐2‐propyl hydroperoxide (MPPH), correlates with O? O bond heterolysis. Independently generated FeIV?O species, which may originate from O? O bond homolysis in FeIII(OOH), proved to be inactive toward aromatic substrates. The reactive oxidant derived from 1 exchanges its oxygen atom with water and electrophilically attacks the aromatic ring (giving rise to an inverse H/D kinetic isotope effect of 0.8). These results have revealed a detailed experimental mechanistic picture of the oxidation reactions catalyzed by 1 , based on direct characterization of the intermediates and products, and kinetic analysis of the individual reaction steps. Our detailed understanding of the mechanism of this reaction revealed both similarities and differences between synthetic and enzymatic aromatic hydroxylation reactions. 相似文献
10.
Dr. Zhiqiang Shen Shaoqiu Zheng Yuanmeng Fang Prof. Dr. Guoying Zhang Prof. Dr. Chen Zhu Prof. Dr. Shiyong Liu Prof. Dr. Jinming Hu 《Angewandte Chemie (International ed. in English)》2023,62(20):e202219153
The peroxynitrite anion (ONOO−) is closely associated with many diseases and the creation of ONOO− donors is an essential means of understanding its pathophysiological functions. However, it is challenging to develop ONOO− donors due to the difficulties in simultaneously producing highly reactive and short-lived nitric oxide (NO) and superoxide anion (O2⋅−). Here, we report a novel strategy for constructing ONOO− donors by combining near-infrared (NIR)-mediated type I photosensitization and photoredox catalysis. The key design using a Nile blue analogue that can serve as both a type I photosensitizer and a metal-free photocatalyst. Intriguingly, the formation of O2⋅− via type I photosensitization avoids oxygen interference and instead activates nitrobenzofurazan-based NO donors via oxygen-tolerant NIR photoredox catalysis. The simultaneous release of O2⋅− and NO leads to ONOO− release, showing both antibacterial and antibiofilm activities. 相似文献
11.
《化学:亚洲杂志》2017,12(15):1909-1914
A dodecavanadate, [V12O32]4−, is an inorganic bowl‐type host with a cavity entrance with a diameter of 4.4 Å in the optimized structure. Linear, bent, and trigonal planar anions are tested as guest anions and the formation of host–guest complexes, [V12O32(X)]5− (X=CN−, OCN−, NO2−, NO3−, HCO2−, and CH3CO2−), were confirmed by X‐ray crystallographic analyses and a 51V NMR spectroscopy study. The degree of distortion of the bowl from a regular to an oval shape depends on the type of guest anion. In 51V NMR spectroscopy, all chemical shifts of the host–guest complexes are clearly shifted after guest incorporation. The incorporation reaction rates for OCN−, NO2−, HCO2−, and CH3CO2− are much larger than those of NO3− and halides. The incorporated nonspherical molecular anions in the dodecavanadate host are easily dissociated or exchanged for other anions, whereas spherical halides in the host are preserved without dissociation, even in the presence of the tested anions. 相似文献
12.
《Tetrahedron》2019,75(48):130693
The efficiency of bicarbonate molecule (HCO3−) as a proton shuttle in the tautomerization and (non)enzymatic CO2 hydration reactions has been investigated with the aid of computational chemistry methods (DFT and ab initio). The results revealed that bicarbonate can decrease the barrier height of tautomerization (keto-enol, azo-hydrazo and imine-amine) more than 70%. This value is around 45% for water molecules. Also, HCO3− can catalyze the CO2 hydration both inside (enzymatic) and outside (nonenzymatic) the active site of human carbonic anhydrases II (HCA II). In the absence of enzyme, bicarbonate molecule can lower the CO2 hydration from ∼50 kcal mol−1 in the gas phase to ∼14 kcal mol−1 in the aqueous media. This reaction maintains its barrier (∼15 kcal mol−1) for bicarbonate-Zn complex in the active site of enzyme; it has been observed that amino acid residues, mainly Thr199 and Glu106, are actively involved in the proton transfer network and facilitate CO2 hydration ability of bicarbonate. 相似文献
13.
Amanda Lyn Robinson Dr. Jean-Noël Rebilly Dr. Régis Guillot Christian Herrero Hélène Maisonneuve Prof. Frédéric Banse 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(28):e202200217
We report two new FeIII complexes [L1FeIII(H2O)](OTf)2 and [L2FeIII(OTf)] , obtained by replacing pyridines by phenolates in a known non-heme aminopyridine iron complex. While the original, starting aminopyridine [(L5 2 )FeII(MeCN)](PF6) complex is stable in air, the potentials of the new FeIII/II couples decrease to the point that [L2FeII] spontaneously reduces O2 to superoxide. We used it as an O2 activator in an electrochemical setup, as its presence allows to generate superoxide at a much more accessible potential (>500 mV gain). Our aim was to achieve substrate oxidation via the reductive activation of O2. While L2FeIII(OTf) proved to be a good O2 activator but a poor oxidation system, its association with another complex (TPEN)FeII(PF6)2 generates a complementary tandem couple for electro-assisted oxidation of substrates, working at a very accessible potential: upon reduction, L2FeIII(OTf) activates O2 to superoxide and transfers it to (TPEN)FeII(PF6)2 leading in fine to the oxidation of thioanisole. 相似文献
14.
Azwana R. Sadique William W. Brennessel Patrick L. Holland 《Acta Crystallographica. Section C, Structural Chemistry》2009,65(5):m174-m176
Reduction of carbon dioxide by a diiron(I) complex gives μ‐carbonato‐κ3O:O′,O′′‐bis{[2,2,6,6‐tetramethyl‐3,5‐bis(2,4,6‐triisopropylphenyl)heptane‐2,5‐diiminate(1−)‐κ2N,N′]iron(II)} toluene disolvate, [Fe2(C41H65N)2(CO3)]·2C7H8, a diiron(II) species with a bridging carbonate ligand. The asymmetric unit contains one diiron complex and two cocrystallized toluene solvent molecules that are distributed over three sites, one with atoms in general positions and two in crystallographic sites. Both FeII atoms are η2‐coordinated to diketiminate ligands, but η1‐ and η2‐coordinated to the bridging carbonate ligand. Thus, one FeII center is three‐coordinate and the other is four‐coordinate. The bridging carbonate ligand is nearly perpendicular to the iron–diketiminate plane of the four‐coordinate FeII center and parallel to the plane of the three‐coordinate FeII center. 相似文献
15.
Dr. Qinhua Zhang Dr. Bo An Dr. Yu Lei Zhixiao Gao Dr. Haonan Zhang Prof. Sheng Xue Prof. Xin Jin Prof. Wengang Xu Zihan Wu Prof. Mingbo Wu Prof. Xin Yang Prof. Wenting Wu 《Angewandte Chemie (International ed. in English)》2023,62(36):e202304699
Developing new reactive pathway to activate inert C(sp3)−H bonds for valuable oxygenated products remains a challenge. We prepared a series of triazine conjugated organic polymers to photoactivate C−H into aldehyde/ketone via O2→H2O2→⋅OH→Cl⋅→Cl2⋅−. Experiment results showed Cl2⋅− could successively activate C(sp3)−H more effectively than Cl⋅ to generate unstable dichlorinated intermediates, increasing the kinetic rate ratio of dichlorination to monochlorination by a factor of 2,000 and thus breaking traditional dichlorination kinetic constraints. These active intermediates were hydrolyzed into aldehydes or ketones easily, when compared with typical stable dichlorinated complexes, avoiding chlorinated by-product generation. Moreover, an integrated two-phase system in an acid solution strengthened the Cl2⋅− mediated process and inhibited product overoxidation, where the conversion rate of toluene reached 16.94 mmol/g/h and the selectivity of benzaldehyde was 99.5 %. This work presents a facile and efficient approach for selective conversion of inert C(sp3)−H bonds using Cl2⋅−. 相似文献
16.
《Journal of mass spectrometry : JMS》2018,53(8):717-724
On‐surface degradation of sildenafil (an adequate substrate as it contains assorted functional groups in its structure) promoted by the Fenton (Fe2+/H2O2) and Fenton‐like (Mn+/H2O2; Mn+ = Fe3+, Co2+, Cu2+, Mn2+) systems was investigated by using paper spray ionization mass spectrometry (PS‐MS). The performance of each system was compared by measuring the ratio between the relative intensities of the ions of m/z 475 (protonated sildenafil) and m/z 235 (protonated lidocaine, used as a convenient internal standard and added to the paper just before the PS‐MS analyzes). The results indicated the following order in the rates of such reactions: Fe2+/H2O2 ≫ H2O2 ≫ Cu2+/H2O2 > Mn+/H2O2 (Mn+ = Fe3+, Co2+, Mn2+) ~ Mn+ (Mn+ = Fe2+, Fe3+, Co2+, Cu2+, Mn2). The superior capability of Fe2+/H2O2 in causing the degradation of sildenafil indicates that Fe2+ efficiently decomposes H2O2 to yield hydroxyl radicals, quite reactive species that cause the substrate oxidation. The results also indicate that H2O2 can spontaneously decompose likely to yield hydroxyl radicals, although in a much smaller extension than the Fenton system. This effect, however, is strongly inhibited by the presence of the other cations, ie, Fe3+, Co2+, Cu2+, and Mn2+. A unique oxidation by‐product was detected in the reaction between Fe2+/H2O2 with sildenafil, and a possible structure for it was proposed based on the MS/MS data. The on‐surface reaction of other substrates (trimethoprim and tamoxifen) with the Fenton system was also investigated. In conclusion, PS‐MS shows to be a convenient platform to promptly monitor on‐surface oxidation reactions. 相似文献
17.
《Journal of photochemistry and photobiology. A, Chemistry》2007,185(2-3):289-294
In this study, we investigated the effects of four inorganic anions (Cl−, SO42−, H2PO4−/HPO42−, and HCO3−/CO32−) on titanium dioxide (TiO2)-based photocatalytic oxidation of aqueous ammonia (NH4+/NH3) at pH ∼ 9 and ∼10 and nitrite (NO2−) over the pH range of 4–11. The initial rates of NH4+/NH3 and NO2− photocatalytic oxidation are dependent on both the pH and the anion species. Our results indicate that, except for CO32−, which decreased the homogeneous oxidation rate of NH4+/NH3 by UV-illuminated hydrogen peroxide, OH scavenging by anions and/or direct oxidation of NH4+/NH3 and NO2− by anion radicals did not affect rates of TiO2 photocatalytic oxidation. While HPO42− enhanced NH4+/NH3 photocatalytic oxidation at pH ∼ 9 and ∼10, H2PO4−/HPO42− inhibited NO2− oxidation at low to neutral pH values. The presence of Cl−, SO42−, and HCO3− had no effect on NH4+/NH3 and NO2− photocatalytic oxidation at pH ∼ 9 and ∼10, whereas CO32− slowed NH4+/NH3 but not NO2− photocatalytic oxidation at pH ∼ 11. Photocatalytic oxidation of NH4+/NH3 to NO2− is the rate-limiting step in the complete oxidation of NH4+/NH3 to NO3− in the presence of common wastewater anions. Therefore, in photocatalytic oxidation treatment, we should choose conditions such as alkaline pH that will maximize the NH4+/NH3 oxidation rate. 相似文献
18.
Dr. Emmanuel Oheix Dr. Christian Herrero Dr. Jules Moutet Dr. Jean-Noël Rebilly Marie Cordier Dr. Régis Guillot Dr. Sophie Bourcier Prof. Frédéric Banse Dr. Katell Sénéchal-David Dr. Audrey Auffrant 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(60):13634-13643
We report on the synthesis and characterization of three iron(III) phosphasalen complexes, [FeIII(Psalen)(X)] differing in the nature of the counter-anion/exogenous ligand (X−=Cl−, NO3−, OTf−), as well as the neutral iron(II) analogue, [FeII(Psalen)] . Phosphasalen (Psalen) differs from salen by the presence of iminophosphorane (P=N) functions in place of the imines. All the complexes were characterized by single-crystal X-ray diffraction, UV/Vis, EPR, and cyclic voltammetry. The [FeII(Psalen)] complex was shown to remain tetracoordinated even in coordinating solvent but surprisingly exhibits a magnetic moment in line with a FeII high-spin ground state. For the FeIII complexes, the higher lability of triflate anion compared to nitrate was demonstrated. As they exhibit lower reduction potentials compared to their salen analogues, these complexes were tested for the coupling of 2-naphthol using O2 from air as oxidant. In order to shed light on this reaction, the interaction between 2-naphthol and the FeIII(Psalen) complexes was studied by cyclic voltammetry as well as UV/Vis spectroscopy. 相似文献
19.
James P. Collman Lei Fu Paul C. Herrmann Zhong Wang Miroslav Rapta Martin Brring Reinhold Schwenninger Bernard Boitrel 《Angewandte Chemie (International ed. in English)》1998,37(24):3397-3400
The environment of the Cu I ion in the distal ligand group decides the fate of the reduction of O2 by the two analogues 1 and 2 of the heme a3 CuB center in cytochrome c oxidase. The fourfold coordination by N in 1 favors the CuII oxidation state and leads to a 4 e−–4 H+ reduction and the formation of H2O under physiological conditions, while with 2 a 2 e−–2 H+ reduction occurs to form the cytotoxic H2O2. 相似文献
20.
Dr. Maxim V. Mikhailenko Dr. Salavat S. Khasanov Prof. Alexader F. Shestakov Dr. Aleksey V. Kuzmin Akihiro Otsuka Hideki Yamochi Hiroshi Kitagawa Dr. Dmitri V. Konarev 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(10):e202104165
Hexaazatrianthracene (HATA) and hexaazatriphenylenehexacarbonitrile {HAT(CN)6} are reduced by metallic iron in the presence of crystal violet (CV+)(Cl−). Anionic ligands are produced, which simultaneously coordinate three FeIICl2 to form (CV+)2{HATA ⋅ (FeIICl2)3}2− ⋅ 3 C6H4Cl2 ( 1 ) and (CV+)3{HAT(CN)6. (FeIICl2)3}3− ⋅ 0.5CVCl ⋅ 2.5 C6H4Cl2 ( 2 ). High-spin (S=2) FeII atoms in both structures are arranged in equilateral triangles at a distance of 7 Å. An antiferromagnetic exchange is observed between FeII in {HATA ⋅ (FeIICl2)3}2− ( 1 ) with a Weiss temperature (Θ) of −80 K, the PHI estimated exchange interaction (J) is −4.7 cm−1. The {HAT(CN)6 ⋅ (FeIICl2)3}3− assembly is obtained in 2 . The formation of HAT(CN)6.3− is supported by the appearance of an intense EPR signal with g=2.0037. The magnetic behavior of 2 is described by a strong antiferromagnetic coupling between the FeII and HAT(CN)6.3− spins with J1=−164 cm−1 (−2 J formalism) and by a weaker antiferromagnetic coupling between the FeII spins with J2=−15.4 cm−1. The stronger coupling results in the spins of the three FeIICl2 units to be aligned parallel to each other in the assembly. As a result, an increase of the χMT values is observed with the decrease of temperature from 9.82 at 300 K up to 15.06 emu ⋅ K/mol at 6 K, and the Weiss temperature is also positive being at +23 K. Thus, a change in the charge and spin state of the HAT-type ligand to ⋅3− results in ferromagnetic alignment of the FeII spins, yielding a high-spin (S=11/2) system. DFT calculations showed that, due to the high symmetry and nearly degenerated LUMO of both HATA and HAT(CN)6, their complexes with FeIICl2 have a variety of closely lying excited high-spin states with multiplicity up to S=15/2. 相似文献