Editing Molecular Catalysis of the Electrochemical and Photochemical Reduction of CO2 with Earth-Abundant Metal Complexes. Selective Production of CO vs HCOOH by Switching of the Metal Center

{{DOI|doi=10.1021/jacs.5b06535}}
[[Category:Photocatalytic CO2 conversion to HCOOH]]
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===Abstract===
==== Summary====
A photochemical reduction of CO<sub>2</sub> to CO or formic acid was shown using the iron complex {{#moleculelink:|link=XTLBRFNUSVMBAM-DQIPMIPLSA-K|image=false|width=300|height=200}} or the cobalt complex {{#moleculelink:|link=UEQRGEGBADTDNK-YBRXSBAKSA-L|image=false|width=300|height=200}} as catalysts in combination with the iridium-based photosensitizer {{#moleculelink:|link=NSABRUJKERBGOU-UHFFFAOYSA-N|image=false|width=300|height=200}}. Turnover numbers (TONs) of 270 for CO with the cobalt complex and 5 for formic acid with the iron complex were reached in acetonitrile. The experiments were conducted under visible-light irradiation (λ > 460 nm) using TEA as sacrificial electron donor (see section SEDs below). 
====Advances and special progress====
The authors could demonstrate that switching the metal center has a major influence on the outcome of CO<sub>2</sub> reduction, enabling the generation of either CO or formic acid depending on the employed metal. For the cobalt complex, CO<sub>2</sub> reduction was possible both under electrochemical conditions and photochemically with a photosensitizer under visible light.

====Additional remarks====
In electrocatalytic experiments with E = -1.5 V vs SCE, CO formation with high faradaic yields of 82% was possible employing the cobalt catalyst.

===Content of the published article in detail===
The article contains results for the reduction of CO<sub>2</sub> to CO and formic acid under visible-light catalysis using iron or cobalt complexes as catalysts. The catalytic system performs best (referring to the TON of CO production) in acetonitrile with the cobalt catalyst.
====Catalyst====
<chemform smiles="C1C2C(C)=N3[Fe+3]([Cl-])([Cl-])456N(CCN4CCN5CC3)=C(C)C(N=26)=CC=1.Cl([O-])(=O)(=O)=O" inchi="1S/C15H23N5.ClHO4.2ClH.Fe/c1-12-14-4-3-5-15(20-14)13(2)19-11-9-17-7-6-16-8-10-18-12;2-1(3,4)5;;;/h3-5,16-17H,6-11H2,1-2H3;(H,2,3,4,5);2*1H;/q;;;;+3/p-3/b18-12+,19-13+;;;;" inchikey="XTLBRFNUSVMBAM-DQIPMIPLSA-K" height="200px" width="300px" float="none">
  -INDIGO-05172314152D

  0  0  0  0  0  0  0  0  0  0  0 V3000
M  V30 BEGIN CTAB
M  V30 COUNTS 28 32 0 0 0
M  V30 BEGIN ATOM
M  V30 1 C 7.50985 -3.90007 0.0 0
M  V30 2 C 9.24015 -3.89959 0.0 0
M  V30 3 C 8.37664 -3.39997 0.0 0
M  V30 4 C 9.24015 -4.90053 0.0 0
M  V30 5 C 7.50985 -4.90502 0.0 0
M  V30 6 N 8.37882 -5.40003 0.0 0
M  V30 7 C 6.64382 -5.40502 0.0 0
M  V30 8 N 6.64382 -6.40502 0.0 0
M  V30 9 C 5.7778 -4.90502 0.0 0
M  V30 10 C 10.1062 -5.40053 0.0 0
M  V30 11 N 10.1062 -6.40053 0.0 0
M  V30 12 C 10.9722 -4.90053 0.0 0
M  V30 13 N 7.375 -7.625 0.0 0
M  V30 14 N 9.275 -7.6 0.0 0
M  V30 15 C 6.1028 -7.18002 0.0 0
M  V30 16 C 6.45907 -7.70882 0.0 0
M  V30 17 C 7.875 -8.49102 0.0 0
M  V30 18 C 8.775 -8.46603 0.0 0
M  V30 19 C 10.2409 -7.70882 0.0 0
M  V30 20 C 10.5312 -7.21656 0.0 0
M  V30 21 Fe 8.35 -6.5 0.0 0 CHG=3
M  V30 22 Cl 7.64289 -5.79289 0.0 0 CHG=-1
M  V30 23 Cl 9.05711 -5.79289 0.0 0 CHG=-1
M  V30 24 Cl 12.6 -2.85 0.0 0
M  V30 25 O 12.6 -3.85 0.0 0
M  V30 26 O 13.6 -2.85 0.0 0
M  V30 27 O 11.6 -2.85 0.0 0
M  V30 28 O 12.6 -1.85 0.0 0 CHG=-1
M  V30 END ATOM
M  V30 BEGIN BOND
M  V30 1 2 3 1
M  V30 2 2 4 2
M  V30 3 1 1 5
M  V30 4 1 2 3
M  V30 5 2 5 6
M  V30 6 1 6 4
M  V30 7 1 5 7
M  V30 8 2 7 8
M  V30 9 1 7 9
M  V30 10 1 4 10
M  V30 11 2 10 11
M  V30 12 1 10 12
M  V30 13 1 8 15
M  V30 14 1 13 16
M  V30 15 1 16 15
M  V30 16 1 13 17
M  V30 17 1 14 18
M  V30 18 1 17 18
M  V30 19 1 14 19
M  V30 20 1 11 20
M  V30 21 1 20 19
M  V30 22 10 6 21
M  V30 23 10 13 21
M  V30 24 10 14 21
M  V30 25 10 11 21
M  V30 26 10 8 21
M  V30 27 10 21 22
M  V30 28 10 21 23
M  V30 29 2 24 25
M  V30 30 2 24 26
M  V30 31 2 24 27
M  V30 32 1 24 28
M  V30 END BOND
M  V30 END CTAB
M  END
</chemform><chemform smiles="C1C2C(C)=N3[Co+2]456N(CCN4CCN5=C(C)C(N=26)=CC=1)CC3.Cl([O-])(=O)(=O)=O.Cl(=O)(=O)(=O)[O-]" inchi="1S/C15H23N5.2ClHO4.Co/c1-12-14-4-3-5-15(20-14)13(2)19-11-9-17-7-6-16-8-10-18-12;2*2-1(3,4)5;/h3-5,16-17H,6-11H2,1-2H3;2*(H,2,3,4,5);/q;;;+2/p-2/b18-12+,19-13+;;;" inchikey="UEQRGEGBADTDNK-YBRXSBAKSA-L" height="200px" width="300px" float="none">
  -INDIGO-05192309532D

  0  0  0  0  0  0  0  0  0  0  0 V3000
M  V30 BEGIN CTAB
M  V30 COUNTS 31 34 0 0 0
M  V30 BEGIN ATOM
M  V30 1 C 7.28485 -4.85007 0.0 0
M  V30 2 C 9.01515 -4.84959 0.0 0
M  V30 3 C 8.15164 -4.34997 0.0 0
M  V30 4 C 9.01515 -5.85053 0.0 0
M  V30 5 C 7.28485 -5.85502 0.0 0
M  V30 6 N 8.15382 -6.35003 0.0 0
M  V30 7 C 6.41882 -6.35502 0.0 0
M  V30 8 N 6.41882 -7.35502 0.0 0
M  V30 9 C 9.88118 -6.35053 0.0 0
M  V30 10 N 9.88118 -7.35053 0.0 0
M  V30 11 C 5.5528 -5.85502 0.0 0
M  V30 12 C 10.7472 -5.85053 0.0 0
M  V30 13 N 7.15 -8.625 0.0 0
M  V30 14 N 8.925 -8.625 0.0 0
M  V30 15 C 5.71172 -8.06213 0.0 0
M  V30 16 C 6.21172 -8.92815 0.0 0
M  V30 17 C 9.86602 -8.95 0.0 0
M  V30 18 C 10.3812 -8.21656 0.0 0
M  V30 19 C 7.40882 -9.59093 0.0 0
M  V30 20 C 8.66618 -9.59093 0.0 0
M  V30 21 Co 8.125 -7.45 0.0 0 CHG=2
M  V30 22 Cl 12.975 -3.075 0.0 0
M  V30 23 O 12.975 -4.075 0.0 0
M  V30 24 O 13.975 -3.075 0.0 0
M  V30 25 O 11.975 -3.075 0.0 0
M  V30 26 O 12.975 -2.075 0.0 0 CHG=-1
M  V30 27 Cl 13.925 -5.1 0.0 0
M  V30 28 O 13.925 -4.1 0.0 0 CHG=-1
M  V30 29 O 14.925 -5.1 0.0 0
M  V30 30 O 13.925 -6.1 0.0 0
M  V30 31 O 12.925 -5.1 0.0 0
M  V30 END ATOM
M  V30 BEGIN BOND
M  V30 1 2 3 1
M  V30 2 2 4 2
M  V30 3 1 1 5
M  V30 4 1 2 3
M  V30 5 2 5 6
M  V30 6 1 6 4
M  V30 7 1 5 7
M  V30 8 2 7 8
M  V30 9 1 4 9
M  V30 10 2 9 10
M  V30 11 1 7 11
M  V30 12 1 9 12
M  V30 13 1 8 15
M  V30 14 1 15 16
M  V30 15 1 16 13
M  V30 16 1 14 17
M  V30 17 1 10 18
M  V30 18 1 17 18
M  V30 19 1 13 19
M  V30 20 1 14 20
M  V30 21 1 20 19
M  V30 22 10 6 21
M  V30 23 10 8 21
M  V30 24 10 10 21
M  V30 25 10 14 21
M  V30 26 10 13 21
M  V30 27 2 22 23
M  V30 28 2 22 24
M  V30 29 2 22 25
M  V30 30 1 22 26
M  V30 31 1 27 28
M  V30 32 2 27 29
M  V30 33 2 27 30
M  V30 34 2 27 31
M  V30 END BOND
M  V30 END CTAB
M  END
</chemform>

====Photosensitizer====
{{#moleculelink: |link=NSABRUJKERBGOU-UHFFFAOYSA-N|image=true}}

====Investigation====
{{#experimentlist:|form=Photocatalytic_CO2_conversion_experiments|name=Table 1}}
====Sacrificial electron donor====
In this study, the experiments were done with the sacrificial electron donor TEA ([[Molecule:100505|100505]]).
====Additives====
In this study, no additives were tested.