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Diferrate [Fe 2 (CO) 6 (μ‐CO){μ‐P(aryl) 2 }] − as Self‐Assembling Iron/Phosphor‐Based Catalyst for the Hydrogen Evolution Reaction in Photocatalytic Proton Reduction—Spectroscopic Insights
Author(s) -
Fischer Steffen,
Rösel Arend,
Kammer Anja,
Barsch Enrico,
Schoch Roland,
Junge Henrik,
Bauer Matthias,
Beller Matthias,
Ludwig Ralf
Publication year - 2018
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201802694
Subject(s) - catalysis , chemistry , photochemistry , photocatalysis , aryl , reagent , inorganic chemistry , organic chemistry , alkyl
This work is focused on the identification and investigation of the catalytically relevant key iron species in a photocatalytic proton reduction system described by Beller and co‐workers. The system is driven by visible light and consists of the low‐cost [Fe 3 (CO) 12 ] as catalyst precursor, electron‐poor phosphines P(R) 3 as co‐catalysts, and a standard iridium‐based photosensitizer dissolved in a mixture of THF, water, and the sacrificial reagent triethylamine. The catalytic reaction system was investigated by operando continuous‐flow FTIR spectroscopy coupled with H 2 gas volumetry, as well as by X‐ray absorption spectroscopy, NMR spectroscopy, DFT calculations, and cyclic voltammetry. Several iron carbonyl species were identified, all of which emerge throughout the catalytic process. Depending on the applied P(R) 3 , the iron carbonyl species were finally converted into [Fe 2 (CO) 6 (μ‐CO){μ‐P(R) 2 }] − . This involves a P−C cleavage reaction. The requirements of P(R) 3 and the necessary reaction conditions are specified. [Fe 2 (CO) 6 (μ‐CO){μ‐P(R) 2 }] − represents a self‐assembling, sulfur‐free [FeFe]‐hydrogenase active‐site mimic and shows good catalytic activity if the substituent R is electron poor. Deactivation mechanisms have also been investigated, for example, the decomposition of the photosensitizer or processes observed in the case of excessive amounts of P(R) 3 . [Fe 2 (CO) 6 (μ‐CO){μ‐P(R) 2 }] − has potential for future applications.