Electronic Structure and Transformation of Dinitrosyl Iron Complexes (DNICs) Regulated by Redox Non-Innocent Imino-Substituted Phenoxide Ligand.

The coupled NO-vibrational peaks [IR ν 1775 s, 1716 vs, 1668 vs cm (THF)] between two adjacent [Fe(NO)] groups implicate the electron delocalization nature of the singly -phenoxide-bridged dinuclear dinitrosyliron complex (DNIC) [Fe(NO)(μ-ON)Fe(NO)] (). Electronic interplay between [Fe(NO)] units and [ON] ligand in DNIC rationalizes that "hard" -phenoxide moiety polarizes iron center(s) of [Fe(NO)] unit(s) to enforce a "constrained" π-conjugation system acting as an electron reservoir to bestow the spin-frustrated {Fe(NO)}-{Fe(NO)}-[ON] electron configuration ( = 1/2). This system plays a crucial role in facilitating the ligand-based redox interconversion, working in harmony to control the storage and redox-triggered transport of the [Fe(NO)] unit, while preserving the {Fe(NO)} core in DNICs {Fe(NO)}-[ON] [K-18-crown-6-ether)][(ON)Fe(NO)] () and {Fe(NO)}-[ON] [(ON)Fe(NO)][PF] ().

Unveiled the Structure-Selectivity Relationship for Carbon Dioxide Reduction Triggered by Bi-Doped Cu-Based Nanocatalysts.

To investigate synergistic effect between geometric and electronic structures on directing CORR selectivity, water phase synthetic protocol and surface architecture engineering strategy are developed to construct monodispersed Bi-doped Cu-based nanocatalysts. The strongly correlated catalytic directionality and Bi dopant can be rationalized by the regulation of [*COOH]/[*CO] adsorption capacities through the appropriate doping of Bi electronic modulator, resulting in volcano relationship between FE/TOF and surface EVBM values. Spectroscopic study reveals that the dual-site binding mode ([Cu─μ─C(═O)O─Bi]) enabled by CuBi motif in single-phase CuBi nanocatalyst drives CO2-to-CO conversion.

One-Pot Photosynthesis of Cubic Fe@FeO Core-Shell Nanoparticle Well-Dispersed in N-Doping Carbonaceous Polymer Using a Molecular Dinitrosyl Iron Precursor.

Nanoscale zerovalent iron (NZVI) features potential application to biomedicine, (electro-/photo)catalysis, and environmental remediation. However, multiple-synthetic steps and limited ZVI content prompt the development of a novel strategy for efficient preparation of NZVI composites. Herein, a dinitrosyl iron complex [(NMDA)Fe(NO)] () was explored as a molecular precursor for one-pot photosynthesis of a cubic Fe@FeO core-shell nanoparticle (ZVI% = 60%) well-dispersed in an N-doping carbonaceous polymer (NZVI@NC).

Insight into chalcogenolate-bound {Fe(NO)} dinitrosyl iron complexes (DNICs): covalent character versus ionic character.

The synthesis, characterization and transformation of the thermally unstable {Fe(NO)2}9 dinitrosyl iron complex (DNIC) [(OMe)2Fe(NO)2]- (2) were investigated. The {Fe(NO)2}9 DNIC 2 characterized by single-crystal X-ray diffraction is exclusively stabilized by the weak intermolecular [Fe(OMe)2(K+)] interactions (O(3)K(1) and O(4)K(1) distances of 2.818(3) and 2.

Electrocatalytic Water Reduction Beginning with a {Fe(NO)}-Reduced Dinitrosyliron Complex: Identification of Nitrogen-Doped FeO (OH) as a Real Heterogeneous Catalyst.

Electron paramagnetic resonance, IR, single-crystal X-ray diffraction, and density functional theory computation reveal that the electronic structure of α-diimine-coordinated {Fe(NO)}-reduced dinitrosyliron complexes (DNICs) may best be described as [{Fe(NO)}-L], with the added electron residing mainly on the α-diimine ligand framework. The combination of electrochemistry, gas chromatography, Fourier transform infrared, X-ray photoelectron spectroscopy, and scanning electron microscopy-energy-dispersive X-ray studies demonstrates that the cathodic potential promotes/triggers the transformation of an α-diimine-coordinated {Fe(NO)}-reduced DNIC into a particulate deposit on the electrode, and electrodeposited-film electrodes, CFeO and CFeNO, are kinetically dominant electrocatalysts responsible for hydrogen evolution reaction (HER) from water with quantitative Faradaic efficiency. In comparison with the CFeO electrode reaching a current density of 10 mA/cm with an overpotential of 333 mV for HER, the nitrogen-doped iron oxide electrode, CFeNO, requires 147 mV of overpotential to achieve a current density of 10 mA/cm in a 1 M NaOH aqueous solution.

In Vitro and in Vivo Imaging of Nitroxyl with Copper Fluorescent Probe in Living Cells and Zebrafish.

Nitroxyl (HNO) plays a critical role in many physiological processes which includes vasorelaxation in heart failure, neuroregulation, and myocardial contractility. Powerful imaging tools are required to obtain information for understanding the mechanisms involved in these in vivo processes. In order to develop a rapid and high sensitive probe for HNO detection in living cells and the zebrafish model organism, 2-((2-(benzothiazole-2yl)benzylidene) amino)benzoic acid (AbTCA) as a ligand, and its corresponding copper(II) complex Cu(II)-AbTCA were synthesized.

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

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.

Environmentally Benign CO2-Based Copolymers: Degradable Polycarbonates Derived from Dihydroxybutyric Acid and Their Platinum-Polymer Conjugates.

(S)-3,4-Dihydroxybutyric acid ((S)-3,4-DHBA), an endogenous straight chain fatty acid, is a normal human urinary metabolite and can be obtained as a valuable chiral biomass for synthesizing statin-class drugs. Hence, its epoxide derivatives should serve as promising monomers for producing biocompatible polymers via alternating copolymerization with carbon dioxide. In this report, we demonstrate the production of poly(tert-butyl 3,4-dihydroxybutanoate carbonate) from racemic-tert-butyl 3,4-epoxybutanoate (rac-(t)Bu 3,4-EB) and CO2 using bifunctional cobalt(III) salen catalysts.

Insight into one-electron oxidation of the {Fe(NO)2}9 dinitrosyl iron complex (DNIC): aminyl radical stabilized by [Fe(NO)2] motif.

A reversible redox reaction ({Fe(NO)(2)}(9) DNIC [(NO)(2)Fe(N(Mes)(TMS))(2)](-) (4) ⇄ oxidized-form DNIC [(NO)(2)Fe(N(Mes)(TMS))(2)] (5) (Mes = mesityl, TMS = trimethylsilane)), characterized by IR, UV-vis, (1)H/(15)N NMR, SQUID, XAS, single-crystal X-ray structure, and DFT calculation, was demonstrated. The electronic structure of the oxidized-form DNIC 5 (S(total) = 0) may be best described as the delocalized aminyl radical [(N(Mes)(TMS))(2)](2)(-•) stabilized by the electron-deficient {Fe(III)(NO(-))(2)}(9) motif, that is, substantial spin is delocalized onto the [(N(Mes)(TMS))(2)](2)(-•) such that the highly covalent dinitrosyl iron core (DNIC) is preserved. In addition to IR, EPR (g ≈ 2.

Nitrate-to-nitrite-to-nitric oxide conversion modulated by nitrate-containing {Fe(NO)2}9 dinitrosyl iron complex (DNIC).

Nitrosylation of high-spin [Fe(κ(2)-O(2)NO)(4)](2-) (1) yields {Fe(NO)}(7) mononitrosyl iron complex (MNIC) [(κ(2)-O(2)NO)(κ(1)-ONO(2))(3)Fe(NO)](2-) (2) displaying an S = 3/2 axial electron paramagnetic resonance (EPR) spectrum (g(⊥) = 3.988 and g(∥) = 2.000).

New members of a class of dinitrosyliron complexes (DNICs): the characteristic EPR signal of the six-coordinate and five-coordinate {Fe(NO)2}9 DNICs.

Compared to the tetrahedral {Fe(NO)(2)}(9) dinitrosyliron complexes (DNICs) [(L)(2)Fe(NO)(2)](-) (L=SR, imidazolate) displaying EPR signal g=2.03, the newly synthesized six-/five-coordinate {Fe(NO)(2)}(9) DNICs [(TPA)Fe(NO)(2)][BF(4)] (1-TPA) (TPA=2-[CH(2)-C(5)H(4)N](3)N), [((iPr)PDI)Fe(NO)(2)][BF(4)] (2-(iPr)PDI) ((iPr)PDI=2,6-[2,6-(i)Pr(2)-C(6)H(3)N=CMe](2)C(5)H(3)N) and [(PyImiS)Fe(NO)(2)] (4-PyImiS) (PyImiS=2-[2-(C(5)H(4)N)CMe=N]C(6)H(4)S) exhibit the distinct EPR signal g=2.015-2.

Roles of the distinct electronic structures of the {Fe(NO)(2)}(9) and {Fe(NO)(2)}(10) dinitrosyliron complexes in modulating nitrite binding modes and nitrite activation pathways.

Nitrosylation of [PPN](2)[(ONO)(2)Fe(eta(2)-ONO)(2)] [1; PPN = bis(triphenylphosphoranylidene)ammonium] yields the nitrite-containing {Fe(NO)}(7) mononitrosyliron complex (MNIC) [PPN](2)[(NO)Fe(ONO)(3)(eta(2)-ONO)] (2). At 4 K, complex 2 exhibits an S = (3)/(2) axial EPR spectrum with principal g values of g( perpendicular) = 3.971 and g( parallel) = 2.

Relative binding affinity of thiolate, imidazolate, phenoxide, and nitrite toward the {Fe(NO)2} motif of dinitrosyl iron complexes (DNICs): the characteristic pre-edge energy of {Fe(NO)2}9 DNICs.

The synthesis, characterization, and transformation of the anionic {Fe(NO)(2)}(9) dinitrosyl iron complexes (DNICs) [(NO)(2)Fe(ONO)(2)](-) (1), [(NO)(2)Fe(OPh)(2)](-) (2), [(NO)(2)Fe(OPh)(C(3)H(3)N(2))](-) (3) (C(3)H(3)N(2) = imidazolate), [(NO)(2)Fe(OPh)(-SC(4)H(3)S)](-) (4), [(NO)(2)Fe(p-OPhF)(2)](-) (5), and [(NO)(2)Fe(SPh)(ONO)](-) (6) were investigated. The binding affinity of ligands ([SPh](-), [-SC(4)H(3)S](-), [C(3)H(3)N(2)](-), [OPh](-), and [NO(2)](-)) toward the {Fe(NO)(2)}(9) motif follows the ligand-displacement series [SPh](-) approximately [-SC(4)H(3)S](-) > [C(3)H(3)N(2)](-) > [OPh](-) > [NO(2)](-). The findings, the pre-edge energy derived from the 1s --> 3d transition in a distorted T(d) environment of the Fe center falling within the range of 7113.

Dinitrosyl iron complexes (DNICs) bearing O-bound nitrito ligand: reversible transformation between the six-coordinate {Fe(NO)2}9 [(1-MeIm)2(eta(2)-ONO)Fe(NO)2] (g = 2.013) and four-coordinate {Fe(NO)2}9 [(1-MeIm)(ONO)Fe(NO)2] (g = 2.03).

In contrast to the four-coordinate tetrahedral {Fe(NO)2}9 DNICs with an EPR g value of 2.03, the newly synthesized nonclassical six-coordinate {Fe(NO)2}9 DNIC [(1-MeIm)2(eta(2)-ONO)Fe(NO)2] (1-MeIm = 1-methylimidazole) (1) displays an EPR signal g = 2.013.

Dinitrosyl iron complexes (DNICs) [L(2)Fe(NO)2]- (L = thiolate): interconversion among {Fe(NO)2}9 DNICs, {Fe(NO)2}10 DNICs, and [2Fe-2S] clusters, and the critical role of the thiolate ligands in regulating NO release of DNICs.

Dinitrosyl iron complex [(-SC(7)H(4)SN)(2)Fe(NO)(2)](-) (1) was prepared by reaction of [S(5)Fe(NO)(2)](-) and bis(2-benzothiozolyl) disulfide. In synthesis of the analogous dinitrosyl iron compounds (DNICs), the stronger electron-donating thiolates [RS](-) (R = C(6)H(4)-o-NHCOCH(3), C(4)H(3)S, C(6)H(4)NH(2), Ph), compared to [-SC(7)H(4)SN](-) of complex 1, trigger thiolate-ligand substitution to yield [(-SC(6)H(4)-o-NHCOCH(3))(2)Fe(NO)(2)](-) (2), [(-SC(4)H(3)S)(2)Fe(NO)(2)](-) (3), and [(SPh)(2)Fe(NO)(2)](-) (4), respectively. At 298 K, complexes 2 and 3 exhibit a well-resolved five-line EPR signal at g = 2.