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Photodissociation of ironpentacarbonyl acts as a carbonmonoxide geyser

Transition metal complexes are efficiently acting as catalysts and are used for energy conversion in photochemical processes because of easily accessible close-lying electronic states. Computer simulations are essential to resolve mechanistic details determining the reaction pathway.

In theoretical simulation, we have followed the non-adiabatic dynamics in the photodissociation of ironpentacarbonyl, in the sub-picosecond regime, which is challenging to access experimentally.

We can resolve the initial events and find that the bright metal-to-ligand charge-transfer transition induces synchronous Fe-C oscillations, followed by transitions for dissociative metal-centered excited states. This leads to periodically reoccurring release of carbonmonoxide and creation of a catalytically active irontetracarbonyl fragment

Potential energy surfaces of electronic states of interest displayed along selected Fe-C coordinates
Potential energy surfaces of electronic states of interest displayed along selected Fe-C coordinates.Photoexcitation of the ironpentacarbonyl complex from the electronic ground state (GS) into a metal-to-ligand charge-transfer (MLCT) state triggers Fe-CO oscillations, which after electronic rearrangement into a metal-centered state (MC) lead to periodic bursts of carbonmonooxide (CO).

Significance for photocatalysis

The work was lead by Ambar Banerjee and Michael Odelius at Fysikum, Stockholm University.

- This detailed mechanistic insight will have to be explored experimentally, and might be an essential ingredient in understanding the photophysics and photochemistry of transition metal carbonyls and give a handle on improved design of photocatalysts, says the lead author Ambar Banerjee.

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The study is also part of the thesis work of Michael Coates, who is a PhD student at the division of Chemical Physics and will give a licentiate seminar on the 18th of March 2022. Link to the seminar

The results are published in a recent issue of Nature Communication
Photoinduced bond oscillations in ironpentacarbonyl give delayed synchronous bursts of carbonmonoxide release
Ambar Banerjee,  Michael R. Coates, Markus Kowalewski, Hampus Wikmark, Raphael M. Jay, Philippe Wernet, and Michael Odelius  DOI:10.1038/s41467-022-28997-z

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