748781-52-4Relevant academic research and scientific papers
Photochemistry of the dinitrosyl iron complex [S5Fe(NO) 2]- leading to reversible formation of [S 5Fe(μ-S)2FeS5]2-: Spectroscopic characterization of species relevant to the nitric oxide modification and repair of [2Fe-2S] ferredoxins
Tsai, Ming-Li,Chen, Chiao-Chun,Hsu, I-Jui,Ke, Shyue-Chu,Hsieh, Chung-Hung,Chiang, Kuo-An,Lee, Gene-Hsiang,Wang, Yu,Chen, Jin-Ming,Lee, Jyh-Fu,Liaw, Wen-Feng
, p. 5159 - 5167 (2004)
The reaction of [PPN][Fe(CO)3(NO)] and S8 in a 1:1 molar ratio in THF proceeded to give the dinitrosyl iron complex [PPN][S 5Fe(NO)2] (1) and the known [PPN]2[S 5Fe(μ-S)2FeS5] (2). EPR signals of g values gz = 2.0148, gx = 2.0270, and gy = 2.0485 at 77 K confirmed the existence of the unpaired electron in compound 1. The temperature-dependent magnetic moment of complex 1 indicates that the ground state is one unpaired electron with (St, SL) = (1/2, 1) at very low temperature (St is the total spin quantum number of the system; SL is the sum of the spin quantum numbers of two NO ligands). The O K-edge absorptions of complex 1 and [(NO)Fe(S2CNEt 2)2] at 532.1 and 532.5 eV are assigned to the transition of 1s → π*(NO) and 1S → π*(NO+), respectively. For the electronic structure of the {Fe(NO)2} core, DFT calculations, magnetic susceptibility measurement, EPR, and Fe K-/L-edge XAS spectroscopy of complex 1 lead to a description of {Fe1+(?NO) 2}9. [2Fe-2S] cluster 2 treated with nitric oxide in THF shows that cluster 2 is transformed into the dinitrosyl iron complex 1 identified by IR, UV-vis, and X-ray diffraction analysis. The reaction may be reversed by the photolysis of the THF solution of 1 in the presence of the NO-accepting reagent [(C4H8O)Fe(S,S-C6H 4)2]- to reform 2. This result demonstrates a successful biomimetic reaction cycle of the degradation and reassembly of [2Fe-2S] cluster [S5Fe(μ-S)2FeS5] 2- relevant to the repair of nitric oxide-modified [2Fe-2S] ferredoxin by cysteine desulfurase and L-cysteine in vitro.
Dinitrosyl iron complexes (DNICs) [L2Fe(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
Tsai, Fu-Te,Chiou, Show-Jen,Tsai, Ming-Che,Tsai, Ming-Li,Huang, Hsiao-Wen,Chiang, Ming-Hsi,Liaw, Wen-Feng
, p. 5872 - 5881 (2005)
Dinitrosyl iron complex [(-SC7H4SN) 2Fe(NO)2]- (1) was prepared by reaction of [S5Fe(NO)2]- and bis(2-benzothiozolyl) disulfide. In synthesis of the analogous dinitrosyl iron compounds (DNICs), the stronger electron-donating thiolates [RS]- (R = C6H 4-o-NHCOCH3, C4H3S, C 6H4NH2, Ph), compared to [-SC7H 4SN]- of complex 1, trigger thiolate-ligand substitution to yield [(-SC6H4-o-NHCOCH3) 2Fe(NO)2]- (2), [(-SC4H 3S)2Fe(NO)2]- (3), and [(SPh) 2Fe(NO)2]- (4), respectively. At 298 K, complexes 2 and 3 exhibit a well-resolved five-line EPR signal at g = 2.038 and 2.027, respectively, the characteristic g value of DNICs. The magnetic susceptibility fit indicates that the resonance hybrid of {Fe+( ?NO)2}9 and {Fe-( +NO)2}9 in 2 is dynamic by temperature. The IR νNO stretching frequencies (ranging from (1766, 1716) to (1737, 1693) cm-1 (THF)) of complexes 1-4 signal the entire window of possible electronic configurations for such stable and isolable {Fe(NO) 2}9 [(RS)2Fe(NO)2]-. The NO-releasing ability of {Fe(NO)2}9 [(RS) 2Fe(NO)2]- is finely tuned by the coordinated thiolate ligands. The less electron-donating thiolate ligands coordinated to {Fe(NO)2}9 motif act as better NO-donor DNICs in the presence of NO-trapping agent [Fe(S,S-C6H4) 2]22-. Interconversion between {Fe(NO) 2}9 [(RS)2Fe(NO)2]- and {Fe(NO)2}10 [(Ph3P)2Fe(NO) 2] was verified in the reaction of (a) [(RS)2Fe(NO) 2]-, 10 equiv of PPh3 and sodium-biphenyl, and (b) 2 equiv of thiol, [RS]-, and [(Ph3P) 2Fe(NO)2], respectively. The biomimetic reaction cycle, transformation between {Fe(NO)2}9 [(RS) 2Fe(NO)2]- and {Fe(NO)2}9 [(R′S)2Fe(NO)2]-, reversible interconversion of {Fe(NO)2}9 and {Fe(NO) 2}10 DNICs, and degradation/ reassembly of [2Fe-2S] clusters may decipher and predict the biological cycle of interconversion of {Fe(NO)2}9 DNICs, {Fe(NO)2}10 DNICs, and the [Fe-S] clusters in proteins.
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
Tsai, Fu-Te,Chen, Pei-Lin,Liaw, Wen-Feng
, p. 5290 - 5299 (2010/06/15)
Nitrosylation of [PPN]2[(ONO)2Fe(I2- ONO)2] [1; PPN = bis(triphenylphosphoranylidene)ammonium] yields the nitrite-containing {Fe(NO)}7 mononitrosyliron complex (MNIC) [PPN]2[(NO)Fe(ONO)3(I2-ONO)] (2). At 4 K, complex 2 exhibits an S = 3/2 axial EPR spectrum with principal g values of g⊥ = 3.971 and g∥ = 2.000, suggestive of the {FeIII(NO-)}7 electronic structure. Addition of 1 equiv of PPh3 to complex 2 triggers O-atom transfer of the chelating nitrito ligand under mild conditions to yield the {Fe(NO)2}9 dinitrosyliron complex (DNIC) [PPN][(ONO) 2Fe(NO)2] (3). These results demonstrate that both electronic structure [{FeIII(NO-)}7, S = 3/2] and redox-active ligands ([RS]- for [(RS)3Fe(NO)]- and [NO-] for complex 2) are required for the transformation of {Fe(NO)}7 MNICs into {Fe(NO) 2}9 DNICs. In comparison with the PPh3- triggered O-atom abstraction of the chelating nitrito ligand of the {Fe(NO) 2}9 DNIC [(1-MeIm)2(I2-ONO) Fe(NO)2] (5; 1-MeIm = 1-methylimidazole) to generate the {Fe(NO) 2}10 DNIC [(1-MeIm)(PPh3)Fe(NO)2] (6), glacial acetic acid protonation of the N-bound nitro ligand in the {Fe(NO)2}10 DNIC [PPN][(I1-NO 2)(PPh3)Fe(NO)2] (7) produced the {Fe(NO) 2}9 DNIC [PPN][(OAc)2Fe(NO)2] (8), nitric oxide, and H2O. These results demonstrate that the distinct electronic structures of {Fe(NO)2}9/10 motifs [{Fe(NO)2}9 vs {Fe(NO)2}10] play crucial roles in modulating nitrite binding modes (O-bound chelating/monodentate nitrito for {Fe(NO)2}9 DNICs vs N-bound nitro as a Iε acceptor for {Fe(NO)2}10 DNICs) and regulating nitrite activation pathways (O-atom abstraction by PPh3 leading to the intermediate with a nitroxyl-coordinated ligand vs protonation accompanied by dehydration leading to the intermediate with a nitrosonium-coordinated ligand). That is, the redox shuttling between the {Fe(NO)2}9 and {Fe(NO)2}10 DNICs modulates the nitrite binding modes and then triggers nitrite activation to generate nitric oxide.
