雙鐵核{Fe(NO)2}10-{Fe(NO)2}10及單鐵核{Fe(NO)2}10雙亞硝基鐵錯合物之研究與探討：電化學催化產氫之潛能

Insight Into the Dinuclear {Fe(NO)2}10-{Fe(NO)2}10 and Mononuclear {Fe(NO)2}10 Dinitrosyliron Complexes (DNICs): Potential for Electrocatalytic Hydrogen Production

葉士維(Shih-Wey Yeh)

指導教授 ： 廖文峯

國立清華大學/理學院/化學系/博士(2014年)

摘要

The reversible redox transformations [(NO)2Fe(StBu)2]– [Fe(-StBu)(NO)2]22– (2) [Fe(-StBu)(NO)2]2– [Fe(-StBu)(NO)2]2 are demonstrated. The binding preference of ligands [OPh]–/[SR]– toward the {Fe(NO)2}10-{Fe(NO)2}10 motif of dianionic reduced RRE follows the ligand-displacement series [SR]–＞[OPh]–, rationalizing that most of the DNICs and RREs characterized nowadays are bound to protein via cysteinate side chains. Compared to the Fe K-edge pre-edge energy falling within the range of 7113.6-7113.8 eV for the dinuclear {Fe(NO)2}9-{Fe(NO)2}9 DNICs and 7113.4-7113.8 eV for the mononuclear {Fe(NO)2}9 DNICs, the {Fe(NO)2}10 reduced DNICs and the {Fe(NO)2}10-{Fe(NO)2}10 dianionic reduced RREs containing S-/O-/N-ligation modes display the characteristic pre-edge energy 7113.1-7113.3 eV, which may be adopted to probe the formation of the EPR-silent {Fe(NO)2}10-{Fe(NO)2}10 dianionic reduced RREs and {Fe(NO)2}10 dianionic reduced monomeric DNICs in biology. In addition to the characteristic Fe/S K-edge pre-edge energy, the IR νNO spectra may also be adopted to characterize and discriminate [(NO)2Fe(-StBu)]2 (IR νNO 1809 vw, 1778 s, 1753 s cm-1 (KBr)), [Fe(-StBu)(NO)2]2– (IR νNO 1674 s, 1651 s cm-1 (KBr)), and [Fe(-StBu)(NO)2]22– (IR νNO 1637 m, 1613 s, 1578 s, 1567 s cm-1 (KBr)). Additionally, The fluxional terminal and semibridging NO-coordinate ligands of DNIC [Fe4(-S)2(-NO)2(NO)6]2– (3), a precursor of Roussin’s black salt (RBS), are characterized by IR NO), 15N(NO) NMR, single-crystal X-ray diffraction, and DFT calculations. Compared to the {Fe(NO)2}9 and {Fe(NO)2}10 DNICs/RREs displaying 15N (NO) NMR chemical shift (23 ~ 76 ppm) and (-7.8 ~ 25 ppm), respectively, the first semibridging nitroxyl of complex 3 exhibits the distinct 15N (NO) NMR chemical shift (200.8 and 200.1 ppm), suggesting the 15N (NO) NMR technique can serve as an efficient tool to discriminate the binding fashions of NO. In the last part, the stable {Fe(NO)2}10 reduced DNICs [(NO)2Fe(S(CH2)nS)]2– [ n = 3 (4); n = 2 (5) ] containing chelate dithiolate were synthesized. On the basis of the electrochemistry, and DFT calculations of 4 and 5, the bite angle or ring strain inherent in the chelate-dithiolate-bound DNICs will function to tune the Fe-S bonding level, so as to modulate the configurations and electrochemical properties of DNICs (E1/2 = -1.64 V for 4 and E1/2 = -1.33 V for 5). The dithiolate ligands are also introduced to build [(NO)2Fe(-2-SC2H4S)(-NO)Fe(NO)]2– (7) bearing a bridging NO as well as the fluxional isomers of [(NO)2Fe(-2-SC3H6S)(-NO)Fe(NO)]2– (8-a) and [(NO)2Fe(-SC3H6S)Fe(NO)2]2– (8-b). Intriguingly, the electrochemical studies demonstrate that complex 7, resembling to the calculated double-reduced intermediate [(CO)3Fe(-2-edt)(-CO)Fe(CO)2]2– of [FeFe]-H2ase model, act as an active molecular electrocatalyst for proton reduction from weak acid with low overpotential.

關鍵字

一氧化氮 ； 雙亞硝基鐵錯合物 ； 氫化酵素

並列摘要

無資料

並列關鍵字

Nitric oxide ； DNIC ； Hydrogenase

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