Pushing the limits of activity and stability: the effects of Lewis acids on non-heme iron–NHC epoxidation catalysts

Abstract

The catalytic performance of tetradentate iron–NHC complexes in the epoxidation of cis-cyclooctene is considerably improved by addition of strong Lewis acids. Unprecedented TOFs of up to 410 000 h⁻¹ are obtained by applying Sc(OTf)₃, Ce(OTf)₄ or the significantly cheaper Fe(ClO₄)₃·H₂O as supporting additives. Due to reactivation of an oxo-bridged Fe^III–O–Fe^III deactivation species TONs of up to 1200 at 20 °C are achieved.