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(eta(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=PPh3, accompanied by reductive elimination of NO and the generation of {Fe(NO)2}10 DNIC [(1-MeIm)(PPh3)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 nitrite-containing {Fe(NO)2}9 DNICs may act as a transient intermediate (or an active center) to trigger the transformation of nitrite into nitric oxide.

中文翻译：

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带有 O 键合亚硝基配体的二亚硝基铁配合物 (DNIC)：六配位 {Fe(NO)2}9[(1-MeIm)2(η2-ONO)Fe(NO)2] (g= 2.013) 之间的可逆转化) 和四配位 {Fe(NO)2}9[(1-MeIm)(ONO)Fe(NO)2] (g= 2.03)

与 EPR g 值为 2.03 的四坐标四面体 {Fe(NO)2}9 DNIC 相比，新合成的非经典六坐标 {Fe(NO)2}9 DNIC [(1-MeIm)2(eta (2)-ONO)Fe(NO)2] (1-MeIm = 1-甲基咪唑) (1) 显示 EPR 信号 g = 2.013。温度依赖性可逆转变发生在六配位螯合亚硝基 {Fe(NO)2}9 DNIC 1 和四配位单齿亚硝基 {Fe(NO)2}9 DNIC [(1-MeIm)(ONO)Fe (NO)2](2-MeIm)。DNIC 1 的螯合亚硝基，由 PPh3 触发，经过 O 原子转移产生 O=PPh3，伴随着 NO 的还原消除和 {Fe(NO)2}10 DNIC [(1-MeIm)(PPh3) Fe(NO)2] (3)，与含亚硝酸盐的 {Fe(NO)2}9 DNIC [(HIm)(ONO)Fe(NO)2] (HIm = imidazole) (2- HIm) 朝向 PPh3。结果，g = 2 的 EPR 信号。013 为复合物 1 和 g = 2.03 为复合物 2-MeIm/2-HIm，意味着 DNIC 的表征可能通过其独特的 EPR 信号 g = 2.03 四面体 DNICs 和 EPR 信号 g = 2.01 为六坐标 DNICs . 该研究还表明，含六配位亚硝酸盐的 {Fe(NO)2}9 DNICs 可能作为瞬时中间体（或活性中心）触发亚硝酸盐转化为一氧化氮。