Mechanism of the formation of a Mn-based CO2 reduction catalyst revealed by pulse radiolysis with time-resolved infrared detection

David Grills, Jaime A. Farrington, Bobby H. Layne, Sergei V. Lymar, Barbara A. Mello, Jack M. Preses, James F. Wishart

Research output: Contribution to journalArticle

55 Citations (Scopus)

Abstract

Using a new technique, which combines pulse radiolysis with nanosecond time-resolved infrared (TRIR) spectroscopy in the condensed phase, we have conducted a detailed kinetic and mechanistic investigation of the formation of a Mn-based CO2 reduction electrocatalyst, [Mn(tBu 2-bpy)(CO)3]2 (tBu2-bpy = 4,4′-tBu2-2,2′-bipyridine), in acetonitrile. The use of TRIR allowed, for the first time, direct observation of all the intermediates involved in this process. Addition of excess [nBu 4N][HCO2] to an acetonitrile solution of fac-MnBr( tBu2-bpy)(CO)3 results in its quantitative conversion to the Mn-formate complex, fac-Mn(OCHO)(tBu 2-bpy)(CO)3, which is a precatalyst for the electrocatalytic reduction of CO2. Formation of the catalyst is initiated by one-electron reduction of the Mn-formate precatalyst, which produces the bpy ligand-based radical. This radical undergoes extremely rapid (τ = 77 ns) formate dissociation accompanied by a free valence shift to yield the five-coordinate Mn-based radical, Mn( tBu2-bpy)(CO)3. TRIR data also provide evidence that the Mn-centered radical does not bind acetonitrile prior to its dimerization. This reaction occurs with a characteristically high radical-radical recombination rate (2kdim = (1.3 ± 0.1) × 109 M-1 s-1), generating the catalytically active Mn-Mn bound dimer.

Original languageEnglish
Pages (from-to)5563-5566
Number of pages4
JournalJournal of the American Chemical Society
Volume136
Issue number15
DOIs
Publication statusPublished - Apr 16 2014

Fingerprint

formic acid
Pulse Radiolysis
Radiolysis
Carbon Monoxide
Acetonitrile
Infrared radiation
Catalysts
Dimerization
Electrocatalysts
Dimers
Infrared spectroscopy
Ligands
Genetic Recombination
Spectrum Analysis
Kinetics
Electrons
Observation
acetonitrile

ASJC Scopus subject areas

  • Chemistry(all)
  • Catalysis
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

Mechanism of the formation of a Mn-based CO2 reduction catalyst revealed by pulse radiolysis with time-resolved infrared detection. / Grills, David; Farrington, Jaime A.; Layne, Bobby H.; Lymar, Sergei V.; Mello, Barbara A.; Preses, Jack M.; Wishart, James F.

In: Journal of the American Chemical Society, Vol. 136, No. 15, 16.04.2014, p. 5563-5566.

Research output: Contribution to journalArticle

Grills, David ; Farrington, Jaime A. ; Layne, Bobby H. ; Lymar, Sergei V. ; Mello, Barbara A. ; Preses, Jack M. ; Wishart, James F. / Mechanism of the formation of a Mn-based CO2 reduction catalyst revealed by pulse radiolysis with time-resolved infrared detection. In: Journal of the American Chemical Society. 2014 ; Vol. 136, No. 15. pp. 5563-5566.
@article{01c3357c0408404e91e68b609f48682d,
title = "Mechanism of the formation of a Mn-based CO2 reduction catalyst revealed by pulse radiolysis with time-resolved infrared detection",
abstract = "Using a new technique, which combines pulse radiolysis with nanosecond time-resolved infrared (TRIR) spectroscopy in the condensed phase, we have conducted a detailed kinetic and mechanistic investigation of the formation of a Mn-based CO2 reduction electrocatalyst, [Mn(tBu 2-bpy)(CO)3]2 (tBu2-bpy = 4,4′-tBu2-2,2′-bipyridine), in acetonitrile. The use of TRIR allowed, for the first time, direct observation of all the intermediates involved in this process. Addition of excess [nBu 4N][HCO2] to an acetonitrile solution of fac-MnBr( tBu2-bpy)(CO)3 results in its quantitative conversion to the Mn-formate complex, fac-Mn(OCHO)(tBu 2-bpy)(CO)3, which is a precatalyst for the electrocatalytic reduction of CO2. Formation of the catalyst is initiated by one-electron reduction of the Mn-formate precatalyst, which produces the bpy ligand-based radical. This radical undergoes extremely rapid (τ = 77 ns) formate dissociation accompanied by a free valence shift to yield the five-coordinate Mn-based radical, Mn•( tBu2-bpy)(CO)3. TRIR data also provide evidence that the Mn-centered radical does not bind acetonitrile prior to its dimerization. This reaction occurs with a characteristically high radical-radical recombination rate (2kdim = (1.3 ± 0.1) × 109 M-1 s-1), generating the catalytically active Mn-Mn bound dimer.",
author = "David Grills and Farrington, {Jaime A.} and Layne, {Bobby H.} and Lymar, {Sergei V.} and Mello, {Barbara A.} and Preses, {Jack M.} and Wishart, {James F.}",
year = "2014",
month = "4",
day = "16",
doi = "10.1021/ja501051s",
language = "English",
volume = "136",
pages = "5563--5566",
journal = "Journal of the American Chemical Society",
issn = "0002-7863",
publisher = "American Chemical Society",
number = "15",

}

TY - JOUR

T1 - Mechanism of the formation of a Mn-based CO2 reduction catalyst revealed by pulse radiolysis with time-resolved infrared detection

AU - Grills, David

AU - Farrington, Jaime A.

AU - Layne, Bobby H.

AU - Lymar, Sergei V.

AU - Mello, Barbara A.

AU - Preses, Jack M.

AU - Wishart, James F.

PY - 2014/4/16

Y1 - 2014/4/16

N2 - Using a new technique, which combines pulse radiolysis with nanosecond time-resolved infrared (TRIR) spectroscopy in the condensed phase, we have conducted a detailed kinetic and mechanistic investigation of the formation of a Mn-based CO2 reduction electrocatalyst, [Mn(tBu 2-bpy)(CO)3]2 (tBu2-bpy = 4,4′-tBu2-2,2′-bipyridine), in acetonitrile. The use of TRIR allowed, for the first time, direct observation of all the intermediates involved in this process. Addition of excess [nBu 4N][HCO2] to an acetonitrile solution of fac-MnBr( tBu2-bpy)(CO)3 results in its quantitative conversion to the Mn-formate complex, fac-Mn(OCHO)(tBu 2-bpy)(CO)3, which is a precatalyst for the electrocatalytic reduction of CO2. Formation of the catalyst is initiated by one-electron reduction of the Mn-formate precatalyst, which produces the bpy ligand-based radical. This radical undergoes extremely rapid (τ = 77 ns) formate dissociation accompanied by a free valence shift to yield the five-coordinate Mn-based radical, Mn•( tBu2-bpy)(CO)3. TRIR data also provide evidence that the Mn-centered radical does not bind acetonitrile prior to its dimerization. This reaction occurs with a characteristically high radical-radical recombination rate (2kdim = (1.3 ± 0.1) × 109 M-1 s-1), generating the catalytically active Mn-Mn bound dimer.

AB - Using a new technique, which combines pulse radiolysis with nanosecond time-resolved infrared (TRIR) spectroscopy in the condensed phase, we have conducted a detailed kinetic and mechanistic investigation of the formation of a Mn-based CO2 reduction electrocatalyst, [Mn(tBu 2-bpy)(CO)3]2 (tBu2-bpy = 4,4′-tBu2-2,2′-bipyridine), in acetonitrile. The use of TRIR allowed, for the first time, direct observation of all the intermediates involved in this process. Addition of excess [nBu 4N][HCO2] to an acetonitrile solution of fac-MnBr( tBu2-bpy)(CO)3 results in its quantitative conversion to the Mn-formate complex, fac-Mn(OCHO)(tBu 2-bpy)(CO)3, which is a precatalyst for the electrocatalytic reduction of CO2. Formation of the catalyst is initiated by one-electron reduction of the Mn-formate precatalyst, which produces the bpy ligand-based radical. This radical undergoes extremely rapid (τ = 77 ns) formate dissociation accompanied by a free valence shift to yield the five-coordinate Mn-based radical, Mn•( tBu2-bpy)(CO)3. TRIR data also provide evidence that the Mn-centered radical does not bind acetonitrile prior to its dimerization. This reaction occurs with a characteristically high radical-radical recombination rate (2kdim = (1.3 ± 0.1) × 109 M-1 s-1), generating the catalytically active Mn-Mn bound dimer.

UR - http://www.scopus.com/inward/record.url?scp=84898978305&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84898978305&partnerID=8YFLogxK

U2 - 10.1021/ja501051s

DO - 10.1021/ja501051s

M3 - Article

VL - 136

SP - 5563

EP - 5566

JO - Journal of the American Chemical Society

JF - Journal of the American Chemical Society

SN - 0002-7863

IS - 15

ER -