具nitrite 配位基之雙亞硝基鐵錯合物 (DNICs): 藉由{Fe(NO)x} (x =1, 2) 模組活化nitrite 轉換形成一氧化氮 (NO)

Nitrite-Containing Dinitrosyl Iron Complexes (DNICs): Conversion of nitrite into NO promoted by {Fe(NO)x} (x =1, 2) motif

蔡富淂(Fu-Te Tsai)

指導教授 ： 廖文峯

國立清華大學/理學院/化學系/博士(2009年)

https://doi.org/10.6843/NTHU.2009.00287

摘要

In contrast to the four-coordinate tetrahedral {Fe(NO)2}9 DNICs with EPR g value as 2.03, the newly synthesized non-classical six-coordinate {Fe(NO)2}9 DNIC [(1-MeIm)2(2-ONO)Fe(NO)2] (1-MeIm = 1-methylimidazole) (1-Me) displays an EPR signal g = 2.013. The temperature-dependent reversible transformation occurs between the six-coordinate chelating nitrito {Fe(NO)2}9 DNIC 1-Me and the four-coordinate monodentate nitrito {Fe(NO)2}9 DNIC [(1-MeIm)(ONO)Fe(NO)2] (2-Me). PPh3 promotes oxygen atom transfer of the chelating nitrito under mild condition to generate, describing as nitroxyl (NO—) coordinative addition to the {Fe(NO)x} (x = 1, 2) motif, {Fe(NO)2}9 DNIC [PPN][(ONO)2Fe(NO)2] (6) and {Fe(NO)2}10 DNIC [(1-MeIm)(PPh3)Fe(NO)2] (3). The biomimetic reaction cycle centered on the iron site may be useful for describing a potential mode of nitrite activation involving the dynamic equilibrium, the Fe-NO— (nitrite-to-nitroxyl conversion) step, and the histidine(s) serving as a role in modulating the activation properties of iron center. The result deciphers that the non-classical six-coordinate nitrite-containing {Fe(NO)2}9 DNIC 1-Me and {Fe(NO)}7 MNIC [PPN]2[(ONO)3(2-ONO)Fe(NO)2] (5) may act as an active center to trigger the transformation of nitrite into nitric oxide in biological systems. The dynamic equilibrium between DNIC 1-Me and DNIC 2-Me implicates that the initial nitrite activation may take place via its reversible chelating of a nitrite, which may play a crucial role in subtly tuning NO homeostasis in hypoxia condition.

關鍵字

雙亞硝基鐵錯合物 ； 亞硝基根 ； 一氧化氮

參考文獻

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