# Lewis Base-Enhanced C–H Bond Functionalization Mediated by a Diiron Imido Complex

## TL;DR

This paper explores how ligand design affects the reactivity of diiron complexes in C–H bond functionalization, revealing a bimetallic pathway enhanced by Lewis bases.

## Contribution

The study demonstrates a bimetallic reaction pathway for C–H functionalization using a diiron imido complex enhanced by Lewis bases.

## Key findings

- Toluene amination occurs only in the presence of pyridine, indicating Lewis base enhancement.
- No monometallic species were detected, supporting a bimetallic mechanism for C–H bond functionalization.
- Alkoxide ligands facilitate bimetallic reaction pathways for C–H functionalization.

## Abstract

Herein, we investigate the effects of ligand design on
the nuclearity
and reactivity of metal–ligand multiply bonded (MLMB) complexes
to access an exclusively bimetallic reaction pathway for C–H
bond functionalization. To this end, the diiron alkoxide [Fe2(PhDbf)2] (1) was treated with
3,5-bis(trifluoromethyl)phenyl azide to access the diiron imido complex
[Fe2(PhDbf)2(μ-NC8H3F6)] (2a) that promotes hydrogen
atom abstraction (HAA) from a variety of C–H and O–H
bond containing substrates. A diiron bis(amide) complex [Fe2(PhDbf)2(μ-NHC8H3F6)(NHC8H3F6)] (3) was generated, prompting the isolation of the analogous
bridging amide terminal alkoxide [Fe2(PhDbf)2(μ-NHC8H3F6)(OC19H15)] (4) and the asymmetric pyridine-bound
diiron imido [Fe2(PhDbf)2(μ-NC8H3F6)(NC5H5)]
(6a). We found that 6a is competent for
toluene amination, indicating the effect of Lewis base-enhanced C–H
bond functionalization. Mechanistic investigations suggest that the
bimetallic bridging imido complex is the reactive intermediate as
no monometallic species is detected during the time course of the
reaction.

The effect of ligand design on the nuclearity
and reactivity
of metal–ligand multiply bonded complexes to access an exclusively
bimetallic reaction pathway for C–H bond functionalization
was investigated. Lewis base-enhanced C–H bond functionalization
meditated by a diiron imido complex was observed as toluene amination
only occurred in the presence of pyridine. As no monometallic species
were detected, we propose that alkoxide ligands can facilitate C–H
bond functionalization via bimetallic reaction pathways.