Photoinduced bond oscillations in ironpentacarbonylFe(CO)5 give delayed, synchronous bursts of carbonmonoxide(CO) release

12 July 2021, Version 2
This content is a preprint and has not undergone peer review at the time of posting.


The early excited state dynamics in the photodissociation of transition metal carbonyls determines the chemical nature of short-lived catalytically active reaction intermediates. However, time-resolved experiments have not yet revealed the mechanistic details in the sub-picosecond regime. Hence in this study, the photoexcitation of ironpentacarbonyl Fe(CO)5 has been simulated by semi-classical surface-hopping excited state molecular dynamics based on time-dependent density functional theory. We find that the bright metal-to-ligand charge-transfer (MLCT) transition induces Fe-C oscillations in the trigonal bipyramidal complex leading to periodically reoccurring release of predominantly axial CO. Metaphorically the photoactivated Fe(CO)5 acts as a CO geyser, which we explain in terms of dynamics in the potential energy landscape of the axial Fe-C distances and non-adiabatic transitions between manifolds of bound MLCT and dissociative metal-centered(MC) excited states. The predominant release of axial CO ligands and a delayed release of equatorial CO ligands are explained in an unified mechanism based on the (sigma*)(Fe-C) anti-bonding character of the receiving orbital in the dissociative MC states both in the Franck-Condon region and at distorted geometries.


Excited state dynamics
Transition metal photochemisty
Iron pentacarbonyl
Ultrafast Dynamics

Supplementary materials

Supplementary Information for Photoinduced bond oscillations in ironpentacarbonyl give delayed, synchronous bursts of carbonmonoxide release
PDF file Contains Supplementary Figures, Table and Text.


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