Non‐Innocent Ligands: New Opportunities in Iron Catalysis

Abstract

International audienceIntroduced in the late sixties, non-innocent (or redox) ligands have been extensively studied for their unusual and intriguing chemical behavior. Their ability to delocalize and/or provide electrons to the metal center of organometallic complexes confers them undisputable chemical interest and has proved valuable in the development of novel synthetic methodologies. This review will focus on the chemistry and applications of low-valent iron complexes bearing potentially non-innocent ligands. Because of the elusive nature of these ligands, and whenever possible, theoretical calculations and analysis of spectroscopic data will be presented in an effort to provide insights into the catalytic activity of the complexes

Redox-active ligands in catalysis

“…Non-innocence in Fe catalysis has previously been reviewed by Blanchard et al 131 The pyridine-bis-imine ligand framework of Scheme 12 has proved useful in other catalytic reactions and has been the subject of detailed electronic structure studies. 110,112,123,132 DFT and experimental data have thus assigned the rich array of redox states available to the NNN Fe complex (Scheme 12).…”

New Trends in Oxidative Functionalization of Carbon–Hydrogen Bonds: A Review

“…New types of ligands have been proposed in recent decades which form efficient catalysts with transition metal ions. These ligands are: N-heterocyclic carbene (NHC) [202,203], pincer-like [204][205][206][207][208], redox-active ligands [209][210][211][212], and scorpionates [213][214][215][216][217][218].…”

Probing the redox non-innocence of dinuclear, three-coordinate Co(ii) nindigo complexes: not simply β-diketiminate variants

“…3,4 However, these attributes are limited 5 and can be difficult to identify or assess due to an inherent ''hidden non-innocence.'' 3 As the role of redox-active ligands in catalysis (especially with inexpensive base metals) is becoming increasingly important, 6 the limitation in redox capabilities of b-diketiminates can be a major drawback in regard to new catalytic applications that involve multi-electron transformations.…”