[CoII(BPyPy2COH)(OH2)2]2+: A Catalytic Pourbaix Diagram and AIMD Simulations on Four Key Intermediates

Authors

  • Roger Alberto Department of Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich
  • Marcella Iannuzzi Department of Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich
  • Yeliz Gurdal Department of Bioengineering, Adana Alparslan Turkes Science and Technology University, Catalan Caddesi 201, Saricam, Adana, Turkey;, Email: ygurdal@atu.edu.tr
  • Benjamin Probst Department of Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich;, Email: benjamin.probst@uzh.ch

DOI:

https://doi.org/10.2533/chimia.2019.906

Keywords:

Ab initio molecular dynamics, Cobalt polypyridyl, Density functional theory, Pourbaix diagram, Proton coupled electron transfer

Abstract

Proton reduction by [CoII(BPyPy2COH)(OH2)2]2+ (BPyPy2COH = [2,2'-bipyridin]-6-yl-di[pyridin-2-yl]methanol) proceeds through two distinct, pH-dependent pathways involving proton-coupled electron transfer (PCET), reduction and protonation steps. In this account we give an overview of the key mechanistic aspects in aqueous solution from pH 3 to 10, based on electrochemical data, time-resolved spectroscopy and ab initio molecular dynamics simulations of the key catalytic intermediates. In the acidic pH branch, a PCET to give a CoIII hydride is followed by a reduction and a protonation step, to close the catalytic cycle. At elevated pH, a reduction to CoI is observed, followed by a PCET to a CoII hydride, and the catalytic cycle is closed by a slow protonation step. In our simulation, both CoI and CoII–H feature a strong interaction with the surrounding solvent via hydrogen bonding, which is expected to foster the following catalytic step.

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Published

2019-11-01

How to Cite

[1]
R. Alberto, M. Iannuzzi, Y. Gurdal, B. Probst, Chimia 2019, 73, 906, DOI: 10.2533/chimia.2019.906.