Oxidation of ethane to ethanol by N2O in a metal-organic framework with coordinatively unsaturated iron(II) sites

Abstract

Enzymic haem and non-haem high-valent iron-oxo species are known to activate strong C-H bonds, yet duplicating this reactivity in a synthetic system remains a formidable challenge. Although instability of the terminal iron-oxo moiety is perhaps the foremost obstacle, steric and electronic factors also limit the activity of previously reported mononuclear iron(IV)-oxo compds. In particular, although nature's non-haem iron(IV)-oxo compds. possess high-spin S = 2 ground states, this electronic configuration has proved difficult to achieve in a mol. species. These challenges may be mitigated within metal-org. frameworks (MOFs) that feature site-isolated iron centers in a constrained, weak-field ligand environment. Here, we show that the metal-org. framework Fe2(dobdc) (dobdc4- = 2,5-dioxido-1,4-benzenedicarboxylate) and its magnesium-dild. analog, Fe0.1Mg1.9(dobdc), are able to activate the C-H bonds of ethane and convert it into ethanol and acetaldehyde using nitrous oxide as the terminal oxidant. Electronic structure calcns. indicate that the active oxidant is likely to be a high-spin S = 2 iron(IV)-oxo species.