摘要
In contrast to the four-coordinate tetrahedral {Fe(NO) 2 } 9 DNICs with an EPR g value of 2.03, the newly synthesized nonclassical six-coordinate {Fe(NO) 2 } 9 DNIC [(1-MeIm) 2 (D 2 -ONO)Fe(NO) 2 ] (1-MeIm = 1-methylimidazole) (1) 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 and the four-coordinate monodentate nitrito {Fe(NO) 2 } 9 DNIC [(1-MeIm)(ONO)Fe(NO) 2 ] (2-MeIm). The chelating nitrito of DNIC 1, triggered by PPh3, undergoes O-atom transfer to yield O PPh 3 , accompanied by reductive elimination of NO and the generation of {Fe(NO) 2 } 10 DNIC [(1-MeIm) (PPh 3 )Fe(NO) 2 ] (3), in contrast to the inertness of the nitrite-containing {Fe(NO) 2 } 9 DNIC [(HIm) (ONO)Fe(NO) 2 ] (HIm = imidazole) (2-HIm) toward PPh3. The findings, EPR signals of g = 2.013 for complex 1 and g = 2.03 for complexes 2-MeIm/2-HIm, imply that characterization of DNICs may be possible via their distinctive EPR signal g = 2.03 for the tetrahedral DNICs and EPR signal g = 2.01 for the six-coordinate DNICs. This study also implicates that the six-coordinate nitritecontaining {Fe(NO) 2 } 9 DNICs may act as a transient intermediate (or an active center) to trigger the transformation of nitrite into nitric oxide. Copyright © 2009 American Chemical Society.