Selective Alkane C–H Bond Oxidation Catalyzed by a Non-Heme Iron Complex Featuring a Robust Tetradentate Ligand

Abstract

An iron complex, [FeII(BpyPY2Me)(CH3CN)2](OTf)2 (1-Fe, where BpyPY2Me is 6-(1,1-di(pyridin-2-yl)ethyl)-2,2′-bipyridine and OTf is triflate), supported by an oxidatively rugged tetradentate ligand is reported for the catalytic oxidation of unactivated C–H bonds in cyclohexane and adamantane. With the use of m-chloroperbenzoic acid (mCPBA) as the terminal oxidant, the iron catalyst shows an alcohol-to-ketone (A/K) ratio of 7.5 for cyclohexane oxidation with conversion percentages as high as 90% with respect to oxidant. Moreover, catalysis toward adamantane oxidation shows high regioselectivity (3°/2° = 45) favoring tertiary C–H bonds with yields up to 87%. Results, including electrospray ionization mass spectrometry and UV–vis spectroscopy, indicate that a molecular non-heme iron(IV)-oxo intermediate is the catalytically active species.