Department of Material and Life Science, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan.
Department of Chemistry, Graduate School of Humanities and Sciences, Nara Women's University, Kitauoyanishi, Nara, 630-8506, Japan.
Angew Chem Int Ed Engl. 2019 Aug 5;58(32):10863-10866. doi: 10.1002/anie.201901608. Epub 2019 Jul 3.
Oxido-iron(IV) porphyrin π-radical cation species are involved in a variety of heme-containing enzymes and have characteristic oxidation states consisting of a high-valent iron center and a π-conjugated macrocyclic ligand. However, the short lifetime of the complex has hampered detailed reactivity studies. Reported herein is a remarkable increase in the lifetime (80 s at 10 °C) of Fe (TMP )(O)(Cl) (2; TMP=5,10,15,20-tetramesitylporphyrin dianion), produced by the oxidation of Fe (TMP)(Cl) (1) by ozone in α,α,α-trifluorotoluene (TFT). The lifetime is 720 times longer compared to that of the currently most stable species reported to date. The increase in the lifetime improves the reaction efficiency of 2 toward inert alkane substrates, and allowed observation of the reaction of 2 with a primary C-H bond (BDE =ca. 100 kcal mol ) directly. Activation parameters for cyclohexane hydroxylation were also obtained.
氧化高铁(IV)卟啉π-自由基阳离子物种参与各种含血红素的酶，并具有特征氧化态，由高价铁中心和π-共轭大环配体组成。然而，该复合物的短寿命妨碍了详细的反应性研究。本文报道了通过臭氧在α,α,α-三氟甲苯（TFT）中氧化 Fe（TMP）（Cl）（1）生成的 Fe（TMP）（O）（Cl）（2）（TMP=5,10,15,20-四甲基卟啉二阴离子）的寿命（10°C 时为 80 s）显著增加。与迄今为止报道的最稳定的物种相比，其寿命延长了 720 倍。寿命的增加提高了 2 对惰性烷烃底物的反应效率，并允许直接观察到 2 与初级 C-H 键（BDE=ca.100 kcal mol）的反应。还获得了环己烷羟化的活化参数。
