Catalytic hydrogen evolution by Fe(II) carbonyls featuring a dithiolate and a chelating phosphine

Souvik Roy, Shobeir K S Mazinani, Thomas L. Groy, Lu Gan, Pilarisetty Tarakeshwar, Vladimiro Mujica, Anne Katherine Jones

Research output: Contribution to journalArticle

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Abstract

Two pentacoordinate mononuclear iron carbonyls of the form (bdt)Fe(CO)P2 [bdt = benzene-1,2-dithiolate; P2 = 1,1′-diphenylphosphinoferrocene (1) or methyl-2- {bis(diphenylphosphinomethyl)amino}acetate (2)] were prepared as functional, biomimetic models for the distal iron (Fed) of the active site of [FeFe]-hydrogenase. X-ray crystal structures of the complexes reveal that, despite similar ν(CO) stretching band frequencies, the two complexes have different coordination geometries. In X-ray crystal structures, the iron center of 1 is in a distorted trigonal bipyramidal arrangement, and that of 2 is in a distorted square pyramidal geometry. Electrochemical investigation shows that both complexes catalyze electrochemical proton reduction from acetic acid at mild overpotential, 0.17 and 0.38 V for 1 and 2, respectively. Although coordinatively unsaturated, the complexes display only weak, reversible binding affinity toward CO (1 bar). However, ligand centered protonation by the strong acid, HBF4·OEt2, triggers quantitative CO uptake by 1 to form a dicarbonyl analogue [1(H)-CO]+ that can be reversibly converted back to 1 by deprotonation using NEt3. Both crystallographically determined distances within the bdt ligand and density functional theory calculations suggest that the iron centers in both 1 and 2 are partially reduced at the expense of partial oxidation of the bdt ligand. Ligand protonation interrupts this extensive electronic delocalization between the Fe and bdt making 1(H)+ susceptible to external CO binding.

Original languageEnglish
Pages (from-to)8919-8929
Number of pages11
JournalInorganic Chemistry
Volume53
Issue number17
DOIs
Publication statusPublished - Sep 2 2014

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phosphine
Carbon Monoxide
Chelation
phosphines
Hydrogen
iron
ligands
hydrogen
Iron
Ligands
Protonation
crystal structure
biomimetics
geometry
Crystal structure
acetic acid
X-Rays
affinity
Hydrogenase
acetates

ASJC Scopus subject areas

  • Inorganic Chemistry
  • Physical and Theoretical Chemistry
  • Medicine(all)

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Catalytic hydrogen evolution by Fe(II) carbonyls featuring a dithiolate and a chelating phosphine. / Roy, Souvik; Mazinani, Shobeir K S; Groy, Thomas L.; Gan, Lu; Tarakeshwar, Pilarisetty; Mujica, Vladimiro; Jones, Anne Katherine.

In: Inorganic Chemistry, Vol. 53, No. 17, 02.09.2014, p. 8919-8929.

Research output: Contribution to journalArticle

Roy, Souvik ; Mazinani, Shobeir K S ; Groy, Thomas L. ; Gan, Lu ; Tarakeshwar, Pilarisetty ; Mujica, Vladimiro ; Jones, Anne Katherine. / Catalytic hydrogen evolution by Fe(II) carbonyls featuring a dithiolate and a chelating phosphine. In: Inorganic Chemistry. 2014 ; Vol. 53, No. 17. pp. 8919-8929.
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