SYNTHESIS AND CATALYTIC APPLICATIONS OF IRON PINCER COMPLEXES

Abstract

Transition metal complexes bearing pincer ligands have been extensively studied during the past decade. One of the less-explored or perhaps even neglected areas of pincer chemistry is on the reactivity of iron complexes that incorporate these enormously popular ligand sets. Meanwhile, recent emphasis on homogeneous catalysis has been placed on the developments of catalytic reactions promoted by inexpensive and environmentally benign metals, for which iron is particularly attractive. In that regard, investigating the reactivity patterns of well-defined iron pincer complexes can potentially provide valuable guidelines for the rational design of iron catalysis. This review analyzes the challenges and successes of synthesizing iron complexes with different pincer-type ligands, and discusses the established or potential utility of these complexes for catalytic reactions.

Keywords:

• C-H bond activation
• cross-coupling reactions
• first-row transition metals
• homogeneous catalysis
• hydrogenation
• hydrosilylation
• iron
• pincer complexes

Abbreviations:

• acac–acetylacetonate
• DFT–density functional theory
• dmpe–bis(dimethylphosphino)ethane
• MAO–methylaluminoxane
• Mes–2,4,6–trimethylphenyl
• Mes*–2,4,6-tri-tert-butylphenyl
• TMEDA-N, N, N′, N′-tetramethylethylenediamine

ACKNOWLEDGMENTS

We thank the National Science Foundation (CHE-0952083) and the donors of the American Chemical Society Petroleum Research Fund (49646-DNI3) for generous support of our research. P. B. is grateful to the University of Cincinnati University Research Council for a graduate student research fellowship.