Ate Complexes in Iron-Catalyzed Cross-Coupling Reactions

Tobias Parchomyk; Konrad Koszinowski

doi:10.1002/chem.201603574

Ate Complexes in Iron-Catalyzed Cross-Coupling Reactions

Chemistry. 2016 Oct 24;22(44):15609-15613. doi: 10.1002/chem.201603574. Epub 2016 Sep 28.

Authors

Tobias Parchomyk¹, Konrad Koszinowski²

Affiliations

¹ Institut für Organische und Biomolekulare Chemie, Georg-August-Universität Göttingen, Tammannstr. 2, 37077, Göttingen, Germany.
² Institut für Organische und Biomolekulare Chemie, Georg-August-Universität Göttingen, Tammannstr. 2, 37077, Göttingen, Germany. konrad.koszinowski@chemie.uni-goettingen.de.

PMID: 27556569
DOI: 10.1002/chem.201603574

Abstract

Iron-catalyzed cross-coupling reactions have an outstanding potential for sustainable organic synthesis, but remain poorly understood mechanistically. Here, we use electrospray-ionization (ESI) mass spectrometry to identify the ionic species formed in these reactions and characterize their reactivity. Transmetalation of Fe(acac)₃ (acac=acetylacetonato) with PhMgCl in THF (tetrahydrofuran) produces anionic iron ate complexes, whose nuclearity (1 to 4 Fe centers) and oxidation states (ranging from -I to +III) crucially depend on the presence of additives or ligands. Upon addition of iPrCl, formation of the heteroleptic Fe^III complex [Ph₃ Fe(iPr)]^- is observed. Gas-phase fragmentation of this complex results in reductive elimination and release of the cross-coupling product with high selectivity.

Keywords: cross coupling; gas-phase reactions; iron; mass spectrometry; reaction mechanisms.