1223627-91-5Relevant academic research and scientific papers
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)
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.
