State Key Laboratory of Synthetic Chemistry and Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, China.
HKU Shenzhen Institute of Research & Innovation, Shenzhen, China.
Angew Chem Int Ed Engl. 2021 Feb 23;60(9):4796-4803. doi: 10.1002/anie.202014191. Epub 2021 Jan 4.
High-valent iron-nitrido species are nitrogen analogues of iron-oxo species which are versatile reagents for C-H oxidation. Nonetheless, C-H activation by iron-nitrido species has been scarcely explored, as this is often hampered by their instability and short lifetime in solutions. Herein, the hydrogen atom transfer (HAT) reactivity of an Fe porphyrin nitrido species (2 c) toward C-H substrates was studied in solutions at room temperature, which was achieved by nanosecond laser flash photolysis (LFP) of its Fe -azido precursor (1 c) supported by a bulky bis-pocket porphyrin ligand. C-H bonds with bond dissociation enthalpies (BDEs) of up to ≈84 kcal mol could be activated, and the second-order rate constants (k ) are on the order of 10 -10 s m . The Fe-amido product formed after HAT could further release ammonia upon protonation.
高价铁-亚氮物种是铁-氧物种的氮类似物，是 C-H 氧化的多功能试剂。尽管如此，铁-亚氮物种的 C-H 活化作用却很少被探索，因为它们在溶液中的不稳定性和短寿命常常会阻碍这一过程。在此，通过其铁-叠氮前体（1c）在庞大的双口袋卟啉配体的支持下进行纳秒激光闪光光解（LFP），研究了室温下的铁卟啉亚氮物种（2c）对 C-H 底物的氢原子转移（HAT）反应性。可以激活键离解焓（BDE）高达约 84 kcal/mol 的 C-H 键，并且二级速率常数（k ）在 10 -10 至 10 -9 s -1 之间。HAT 后形成的 Fe-酰胺产物在质子化后可进一步释放氨。
