# Access to Heterobimetallic MII/CuI Complexes with a Multichelate Platform and Their Reactivity Studies in CO2RR

## TL;DR

This paper reports the synthesis and reactivity of heterobimetallic complexes containing Fe/Ni and Cu, showing their behavior in CO2 reduction reactions.

## Contribution

The study introduces a new multichelate platform for forming stable heterobimetallic complexes and evaluates their reactivity in CO2 reduction.

## Key findings

- Heterobimetallic complexes were synthesized in high yields and structurally characterized.
- Fe-based complexes showed higher stability and photocatalytic activity in CO2 photoreduction, producing CO with 88% selectivity.
- Complexes were unstable under CO2 electroreduction, forming heterogeneous materials in solution and on electrodes.

## Abstract

We describe the selective formation
of heterobimetallic complexes,
exploiting the coordination trends of the developed bis-terpyridyl trans-1,2-cyclohexadiamine platform (L). Following
a stepwise addition, we first reacted ligand L toward
tetrakisacetonitrile transition metal precursors, [M­(MeCN)4]­[BF4]2 (where M = Fe or Ni), to generate the
monometallic complexes 1 ([FeL]­[BF4]2) and 2 ([NiL]­[BF4]2). These species
were later combined with the tetrakisacetonitrile precursor [Cu­(MeCN)4]­[BF4], generating the corresponding heterobimetallic
complexes 3 ([FeCuL­(MeCN)2]­[BF4]3) and 4 ([NiCuL­(MeCN)2]­[BF4]3). The four species obtained, in high yields,
have been structurally characterized. Their cyclic voltammetry analysis
revealed the impact of the CuI-atom presence on the heterobimetallic
complexes under argon and carbon dioxide (CO2) atmospheres.
Controlled potential electrolysis studies revealed the instability
of complexes 1–4 toward CO2RR, generating
the heterogeneous material in solution and on the electrode surface.
In contrast, CO2 photoreduction studies revealed higher
stability and photocatalytic activity for the FeII-based
complexes (1 and 3), generating CO with
88% selectivity.