Issue 42, 2023

Electrocatalytic reduction of CO2 to CO by a series of organometallic Re(i)-tpy complexes

Abstract

A series of organometallic Re(I)(L)(CO)3Br complexes with 4′-substituted terpyridine ligands (L) has been synthesised as electrocatalysts for CO2 reduction. The complexes’ spectroscopic characterisation and computationally optimised geometry demonstrate a facial geometry around Re(I) with three cis COs and the terpyridine ligand coordinating in a bidentate mode. The effect of substitution on the 4′-position of terpyridine (Re1–5) on CO2 electroreduction was investigated and compared with a known Lehn-type catalyst, Re(I)(bpy)(CO)3Br (Re7). All complexes catalyse CO evolution in homogeneous organic media at moderate overpotentials (0.75–0.95 V) with faradaic yields of 62–98%. The electrochemical catalytic activity was further evaluated in the presence of three Brønsted acids to demonstrate the influence of the pKa of the proton sources. The TDDFT and ultrafast transient absorption spectroscopy (TAS) studies showed combined charge transfer bands of ILCT and MLCT. Amongst the series, the Re-complex containing a ferrocenyl-substituted terpyridine ligand (Re5) shows an additional intra-ligand charge transfer band and was probed using UV-Vis spectroelectrochemistry.

Graphical abstract: Electrocatalytic reduction of CO2 to CO by a series of organometallic Re(i)-tpy complexes

Supplementary files

Article information

Article type
Paper
Submitted
11 feb. 2023
Accepted
27 apr. 2023
First published
03 maí 2023

Dalton Trans., 2023,52, 15394-15411

Electrocatalytic reduction of CO2 to CO by a series of organometallic Re(I)-tpy complexes

S. Saha, T. Doughty, D. Banerjee, S. K. Patel, D. Mallick, E. S. S. Iyer, S. Roy and R. Mitra, Dalton Trans., 2023, 52, 15394 DOI: 10.1039/D3DT00441D

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