# Characterization of Fused Mn and Cu Corroles and Their Potency as ORR Electrocatalysts

## TL;DR

This paper explores the synthesis and performance of bimetallic corrole complexes as efficient oxygen reduction reaction electrocatalysts.

## Contribution

The study introduces binuclear Mn and Cu corrole dimers with distinct structural and electrochemical properties for ORR.

## Key findings

- The bis-copper complex exhibits a nearly perfect square geometry with no axial ligands.
- The binuclear manganese corrole dimer outperforms mononuclear complexes in ORR activity on porous carbon electrodes.

## Abstract

Given the rather poor activity of regular copper and
manganese
corroles as electrocatalysts for the oxygen reduction reaction (ORR),
we now report the synthesis, structural characterization, and catalytic
activity of binuclear manganese and copper complexes coordinated to
β–β dimeric corrole frameworks. X-ray crystallographic
analysis reveals distinct coordination environments and structural
flexibility in these bimetallic systems: an almost perfect square
geometry for the 4-coordinate (no axial ligands) bis-copper complex,
while 5- and 6-coordinate structures were fully characterized for
manganese with varying degrees of corrole planarity and metal displacement.
The conjugation between the corrole subunits differs quite meaningfully
for the copper and manganese complexes, which comes into play by much
shorter near-IR bands in the electronic spectrum of the former, significantly
longer C–C bond lengths in the bridging moiety of the latter,
and differences in their redox potentials relative to the respective
mononuclear complexes. Examination of porous carbon electrodes modified
by these molecular ORR catalysts uncovered the superior performance
of the binuclear manganese corrole dimer.