Search

Your search keyword '"Zhao, Jiyong"' showing total 28 results
Start Over Author "Zhao, Jiyong" Journal inorganic chemistry
28 results on '"Zhao, Jiyong"'

2. Stable Ferrous Mononitroxyl {FeNO}8 Complex with a Hindered Hydrotris(pyrazolyl)borate Coligand: Structure, Spectroscopic Characterization, and Reactivity Toward NO and O2

Author

Fujisawa, Kiyoshi, primary, Soma, Shoko, additional, Kurihara, Haruka, additional, Ohta, Ayuri, additional, Dong, Hai T., additional, Minakawa, Yurika, additional, Zhao, Jiyong, additional, Alp, E. Ercan, additional, Hu, Michael Y., additional, and Lehnert, Nicolai, additional

Published
2019
Full Text
View/download PDF

11. Stable Ferrous Mononitroxyl {FeNO}8Complex with a Hindered Hydrotris(pyrazolyl)borate Coligand: Structure, Spectroscopic Characterization, and Reactivity Toward NO and O2

Author

Fujisawa, Kiyoshi, Soma, Shoko, Kurihara, Haruka, Ohta, Ayuri, Dong, Hai T., Minakawa, Yurika, Zhao, Jiyong, Alp, E. Ercan, Hu, Michael Y., and Lehnert, Nicolai

Abstract

The iron(II)-nitroxyl complex [Fe(NO)(L3)](1) (with L3–= a hindered hydrotris(pyrazolyl)borate ligand), a high-spin (hs)-{FeNO}8complex in the Enemark–Feltham notation, is surprisingly stable and is the first of its kind that could be structurally characterized. We further studied this compound using a variety of spectroscopic methods. These results indicate a hs iron(II) center with a bound 3NO–ligand where the spins are antiferromagnetic coupled (St= 1). Vibrational data show that this complex has a very strong Fe−NO bond. DFT calculations support this result and link it to very strong π-donation from the 3NO–ligand to the iron(II) center. Furthermore, a very unusual equilibrium between the hs-{FeNO}8complex and a dinitrosyl iron complex (DNIC) of {Fe(NO)2}9type is observed. The O2reactivity of the complex is finally reported.

Published
2019
Full Text
View/download PDF

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

Author

Speelman, Amy L., Zhang, Bo, Silakov, Alexey, Skodje, Kelsey M., Alp, E. Ercan, Zhao, Jiyong, Hu, Michael Y., Kim, Eunsuk, Krebs, Carsten, and Lehnert, Nicolai

Abstract

Dinitrosyl iron complexes (DNICs) are among the most abundant NO-derived cellular species. Monomeric DNICs can exist in the {Fe(NO)2}9or {Fe(NO)2}10oxidation 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}9DNIC [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}7complex to yield the {Fe(NO)2}9DNIC 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}9DNICs with neutral N-donor ligands, 1exhibits high solution stability and can be characterized structurally and spectroscopically. Reduction of 1yields the corresponding {Fe(NO)2}10DNIC [Fe(dmp)(NO)2] (2). The Mössbauer isomer shift of 2is 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 1and 2are 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–1in 2in 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)2unit upon reduction of 1to 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}10DNICs in comparison to the corresponding {Fe(NO)2}9complexes, 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.

Published
2016
Full Text
View/download PDF

26. Stable Ferrous Mononitroxyl {FeNO} 8 Complex with a Hindered Hydrotris(pyrazolyl)borate Coligand: Structure, Spectroscopic Characterization, and Reactivity Toward NO and O 2 .

Author

Fujisawa K, Soma S, Kurihara H, Ohta A, Dong HT, Minakawa Y, Zhao J, Alp EE, Hu MY, and Lehnert N

Abstract

The iron(II)-nitroxyl complex [Fe(NO)(L3)] (1) (with L3 - = a hindered hydrotris(pyrazolyl)borate ligand), a high-spin (hs)-{FeNO} 8 complex in the Enemark-Feltham notation, is surprisingly stable and is the first of its kind that could be structurally characterized. We further studied this compound using a variety of spectroscopic methods. These results indicate a hs iron(II) center with a bound 3 NO - ligand where the spins are antiferromagnetic coupled ( S t = 1). Vibrational data show that this complex has a very strong Fe-NO bond. DFT calculations support this result and link it to very strong π-donation from the 3 NO - ligand to the iron(II) center. Furthermore, a very unusual equilibrium between the hs-{FeNO} 8 complex and a dinitrosyl iron complex (DNIC) of {Fe(NO) 2 } 9 type is observed. The O 2 reactivity of the complex is finally reported.

Published
2019
Full Text
View/download PDF

27. Electronic Structures of an [Fe(NNR 2 )] +/0/- Redox Series: Ligand Noninnocence and Implications for Catalytic Nitrogen Fixation.

Author

Thompson NB, Oyala PH, Dong HT, Chalkley MJ, Zhao J, Alp EE, Hu M, Lehnert N, and Peters JC

Abstract

The intermediacy of metal-NNH 2 complexes has been implicated in the catalytic cycles of several examples of transition-metal-mediated nitrogen (N 2 ) fixation. In this context, we have shown that triphosphine-supported Fe(N 2 ) complexes can be reduced and protonated at the distal N atom to yield Fe(NNH 2 ) complexes over an array of charge and oxidation states. Upon exposure to further H + /e - equivalents, these species either continue down a distal-type Chatt pathway to yield a terminal iron(IV) nitride or instead follow a distal-to-alternating pathway resulting in N-H bond formation at the proximal N atom. To understand the origin of this divergent selectivity, herein we synthesize and elucidate the electronic structures of a redox series of Fe(NNMe 2 ) complexes, which serve as spectroscopic models for their reactive protonated congeners. Using a combination of spectroscopies, in concert with density functional theory and correlated ab initio calculations, we evidence one-electron redox noninnocence of the "NNMe 2 " moiety. Specifically, although two closed-shell configurations of the "NNR 2 " ligand have been commonly considered in the literature-isodiazene and hydrazido(2-)-we provide evidence suggesting that, in their reduced forms, the present iron complexes are best viewed in terms of an open-shell [NNR 2 ] •- ligand coupled antiferromagnetically to the Fe center. This one-electron redox noninnocence resembles that of the classically noninnocent ligand NO and may have mechanistic implications for selectivity in N 2 fixation activity.

Published
2019
Full Text
View/download PDF

28. Nuclear resonance vibrational spectroscopy applied to [Fe(OEP)(NO)]: the vibrational assignments of five-coordinate ferrous heme-nitrosyls and implications for electronic structure.

Author

Lehnert N, Galinato MG, Paulat F, Richter-Addo GB, Sturhahn W, Xu N, and Zhao J

Subjects
Computer Simulation, Crystallography, X-Ray, Magnetic Resonance Spectroscopy, Models, Chemical, Models, Molecular, Vibration, Electrons, Heme chemistry, Iron chemistry, Metalloporphyrins chemistry, Nitrogen Oxides chemistry
Abstract

This study presents Nuclear Resonance Vibrational Spectroscopy (NRVS) data on the five-coordinate (5C) ferrous heme-nitrosyl complex [Fe(OEP)(NO)] (1, OEP(2-) = octaethylporphyrinato dianion) and the corresponding (15)N(18)O labeled complex. The obtained spectra identify two isotope sensitive features at 522 and 388 cm(-1), which shift to 508 and 381 cm(-1), respectively, upon isotope labeling. These features are assigned to the Fe-NO stretch nu(Fe-NO) and the in-plane Fe-N-O bending mode delta(ip)(Fe-N-O), the latter has been unambiguously assigned for the first time for 1. The obtained NRVS data were simulated using our quantum chemistry centered normal coordinate analysis (QCC-NCA). Since complex 1 can potentially exist in 12 different conformations involving the FeNO and peripheral ethyl orientations, extended density functional theory (DFT) calculations and QCC-NCA simulations were performed to determine how these conformations affect the NRVS properties of [Fe(OEP)NO]. These results show that the properties and force constants of the FeNO unit are hardly affected by the conformational changes involving the ethyl substituents. On the other hand, the NRVS-active porphyrin-based vibrations around 340-360, 300-320, and 250-270 cm(-1) are sensitive to the conformational changes. The spectroscopic changes observed in these regions are due to selective mechanical couplings of one component of E(u)-type (in ideal D(4h) symmetry) porphyrin-based vibrations with the in-plane Fe-N-O bending mode. This leads to the observed variations in Fe(OEP) core mode energies and NRVS intensities without affecting the properties of the FeNO unit. The QCC-NCA simulated NRVS spectra of 1 show excellent agreement with experiment, and indicate that conformer F is likely present in the samples of this complex investigated here. The observed porphyrin-based vibrations in the NRVS spectra of 1 are also assigned based on the QCC-NCA results. The obtained force constants of the Fe-NO and N-O bonds are 2.83-2.94 (based on the DFT functional applied) and about 12.15 mdyn/A, respectively. The electronic structures of 5C ferrous heme-nitrosyls in different model complexes are then analyzed, and variations in their properties based on different porphyrin substituents are explained. Finally, the shortcomings of different DFT functionals in describing the axial FeNO subunit in heme-nitrosyls are elucidated.

Published
2010
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results