Electronic Structure of a Formal Iron(0) Porphyrin Complex Relevant to CO2 Reduction

Christina Römelt; Jinshuai Song; Maxime Tarrago; Julian A Rees; Maurice van Gastel; Thomas Weyhermüller; Serena DeBeer; Eckhard Bill; Frank Neese; Shengfa Ye

doi:10.1021/acs.inorgchem.7b00401

Electronic Structure of a Formal Iron(0) Porphyrin Complex Relevant to CO₂ Reduction

Inorg Chem. 2017 Apr 17;56(8):4746-4751. doi: 10.1021/acs.inorgchem.7b00401. Epub 2017 Apr 5.

Authors

Christina Römelt¹, Jinshuai Song^{1

2}, Maxime Tarrago¹, Julian A Rees^{1

3}, Maurice van Gastel¹, Thomas Weyhermüller¹, Serena DeBeer^{1

4}, Eckhard Bill¹, Frank Neese¹, Shengfa Ye¹

Affiliations

¹ Max Planck Institute for Chemical Energy Conversion , Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany.
² Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences , Fuzhou, Fujian 350002, P. R. China.
³ Department of Chemistry, University of Washington , Box 351700, Seattle, Washington 98195-1700, United States.
⁴ Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States.

PMID: 28379689
DOI: 10.1021/acs.inorgchem.7b00401

Abstract

Iron porphyrins can act as potent electrocatalysts for CO₂ functionalization. The catalytically active species has been proposed to be a formal Fe(0) porphyrin complex, [Fe(TPP)]^2- (TPP = tetraphenylporphyrin), generated by two-electron reduction of [Fe^II(TPP)]. Our combined spectroscopic and computational investigations reveal that the reduction is ligand-centered and that [Fe(TPP)]^2- is best formulated as an intermediate-spin Fe(II) center that is antiferromagnetically coupled to a porphyrin diradical anion, yielding an overall singlet ground state. As such, [Fe(TPP)]^2- contains two readily accessible electrons, setting the stage for CO₂ reduction.