Fast Hydrocarbon Oxidation by a High‐Valent Nickel–Fluoride Complex
Prasenjit Mondal, Marta Lovisari, Brendan Twamley, Aidan R. McDonald
Abstract
Abstract In the search for highly reactive oxidants we have identified high‐valent metal–fluorides as a potential potent oxidant. The high‐valent Ni–F complex [Ni III (F)(L)] ( 2 , L= N , N′ ‐(2,6‐dimethylphenyl)‐2,6‐pyridinedicarboxamidate) was prepared from [Ni II (F)(L)] − ( 1 ) by oxidation with selectfluor. Complexes 1 and 2 were characterized by using 1 H/ 19 F NMR, UV‐vis, and EPR spectroscopies, mass spectrometry, and X‐ray crystallography. Complex 2 was found to be a highly reactive oxidant in the oxidation of hydrocarbons. Kinetic data and products analysis demonstrate a hydrogen atom transfer mechanism of oxidation. The rate constant determined for the oxidation of 9,10‐dihydroanthracene ( k 2 =29 m −1 s −1 ) compared favorably with the most reactive high‐valent metallo‐oxidants. Complex 2 displayed reaction rates 2000–4500‐fold enhanced with respect to [Ni III (Cl)(L)] and also displayed high kinetic isotope effect values. Oxidative hydrocarbon and phosphine fluorination was achieved. Our results provide an interesting direction in designing catalysts for hydrocarbon oxidation and fluorination