Browsing by Author "Chiou, Tzung-Wen"

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A Dinitrosyliron Complex within the Homoleptic Fe(NO)(4) Anion: NO as Nitroxyl and Nitrosyl Ligands within a Single Structure
(2012-10-01)
Lin, Zong-Sian
;
Chiou, Tzung-Wen
;
Liu, Kuan-Yu
;
Hsieh, Chang-Chih
;
Yu, Jen-Shiang K.
Nitrosylation of the chelate thiolate-containing dinitrosyliron complex (DNIC) [(S(CH2)(3)S)Fe-(NO)(2)](-) triggers nitric oxide (NO) activation to generate the homoleptic nitrosyl {Fe(NO)(2)}(9) DNIC [Fe(NO)(4)](-) (1) made up of two nitroxyls (or two NO anions) attached to a delocalized {Fe(NO)(2)}(9) motif. The significantly longer N3-O3/N4-O4 [1.380(12) and 1.280(12) angstrom] and Fe1-N3/Fe1-N4 [2.008(11) and 2.045(10) angstrom] bond distances reflect that N3-O3 and N4-O4 of complex 1 may act as the nitroxyl-coordinated ligands. That is, the electronic structure of the DNIC 1 is best described as a {Fe(NO)(2)}(9) motif coordinated by two nitroxyl (NO-) ligands.
Dinitrosyliron Complex [(PMDTA)Fe(NO)(2)]: Intermediate for Nitric Oxide Monooxygenation Activity in Nonheme Iron Complex
(2020-06-15)
Lu, Shan
;
Chiou, Tzung-Wen
;
Li, Wei-Liang
;
Wang, Chun-Chieh
;
Wang, Yun-Ming
Despite a comprehensive study on the biosynthesis and function of nitric oxide, biological metabolism of nitric oxide, especially when its concentration exceeds the cytotoxic level, remains elusive. Oxidation of nitric oxide by O-2 in aqueous solution has been known to yield NO2. On the other hand, a biomimetic study on the metal-mediated conversion of NO to NO2/NO3- via O-2 reactivity disclosed a conceivable pathway for aerobic metabolism of NO. During the NO-to-NO2-/NO3- conversion, transient formation of metal-bound peroxynitrite and subsequent release of (NO2)-N-center dot via O-O bond cleavage were evidenced by nitration of tyrosine residue or 2,4-di-tert-butylphenol (DTBP). However, the synthetic/catalytic/enzymatic cycle for conversion of nitric oxide into a nitrite pool is not reported. In this study, sequential reaction of the ferrous complex [(PMDTA)Fe(kappa(2) -O,O'- NO2)(kappa(1) -O-NO2)] (3; PMDTA = pentamethyldiethylenetriamine) with NO(g), KC8, and O-2 established a synthetic cycle, complex 3 -> {Fe(NO)(2)}(9) DNIC [(PMDTA)Fe(NO)(2)][NO2] (4) -> {Fe(NO)(2)}(10) DNIC [(PMDTA)Fe(NO)(2)] (1) -> [(PMDTA)(NO)- Fe(kappa(2)-O,N-ONOO)] (2) -> complex 3, for the transformation of nitric oxide into nitrite. In contrast to the reported reactivity of metal-bound peroxynitrite toward nitration of DTBP, peroxynitrite-bound MNIC 2 lacks phenol nitration reactivity toward DTBP. Presumably, the [(PMDTA)Fe] core in {Fe(NO)}(8) MNIC 2 provides a mononuclear template for intramolecular interaction between Fe-bound peroxynitrite and Fe-bound NO , yielding Fe-bound nitrite stabilized in the form of complex 3. This [(PMDTA)Fe]-core-mediated concerted peroxynitrite homolytic O-O bond cleavage and combination of the O atom with Fe- bound NO - reveals a novel and effective pathway for NO-to-NO2- transformation. Regarding the reported assembly of the dinitrosyliron unit (DNIU) [Fe(NO)(2)] in the biological system, this synthetic cycle highlights DNIU as a potential intermediate for nitric oxide monooxygenation activity in a nonheme iron system.