Nonheme Iron-Oxo-Catalyzed Methane Formation from Methyl Thioethers: Scope, Mechanism, and Relevance for Natural Systems

Kathrin Benzing; Peter Comba; Bodo Martin; Bianca Pokrandt; Frank Keppler

doi:10.1002/chem.201701986

Nonheme Iron-Oxo-Catalyzed Methane Formation from Methyl Thioethers: Scope, Mechanism, and Relevance for Natural Systems

Chemistry. 2017 Aug 1;23(43):10465-10472. doi: 10.1002/chem.201701986. Epub 2017 Jul 19.

Authors

Kathrin Benzing¹, Peter Comba², Bodo Martin¹, Bianca Pokrandt¹, Frank Keppler³

Affiliations

¹ Institute of Inorganic Chemistry, Heidelberg University, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany.
² Institute of Inorganic Chemistry and Interdisciplinary Center for Scientific Computing (IWR), Heidelberg University, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany.
³ Institute of Earth Sciences and Heidelberg Center for the Environment (HCE), Heidelberg University, Im Neuenheimer Feld 236, 69120, Heidelberg, Germany.

PMID: 28589711
DOI: 10.1002/chem.201701986

Abstract

A range of nonheme oxo-iron(IV) model systems with tetra- or pentadentate ligands is shown to produce methane from methionine and other thioethers. This model reaction for the natural aerobic production of methane is shown to proceed via two sulfoxidation steps involving the oxo-iron(IV) complexes, with a bifurcation in the second step that either produces the sulfone or leads to demethylation with similar probabilities. In the presence of O₂ , the resulting methyl radicals produce methanol and formate or, in an O₂ -depleted environment, lead to formation of methane.

Keywords: aerobic methane formation; demethylation; highvalent iron; methanogenesis; nonheme iron.