Issue 17, 2025

Ultrafast competition between CO release and spin crossover upon photoexcitation of a cyclopropenone-bipyridyl FeII complex

Abstract

The photo-triggered release of carbon monoxide (CO) from a cyclopropenone-bipyridyl ligand and its iron(II) complex was investigated using a combination of stationary and ultrafast time-resolved spectroscopies. Upon continuous irradiation, the complex undergoes CO release and forms the corresponding acetylene photoproduct, albeit at a ∼ 3 times lower rate than the free cyclopropenone ligand, indicating a drastic reduction in quantum yield. We attribute this to the ultrafast dynamics revealed by femtosecond time-resolved electronic absorption spectroscopy, where photoexcitation of ligand-centered states of the complex is predominantely followed by energy-transfer, leading to spin-crossover of the FeII ion rather than CO release. This ultrafast response stands out as highly remarkable as it virtually outcompetes the photo-decarbonylation, which in the free ligand occurs in only ∼130 fs.

Graphical abstract: Ultrafast competition between CO release and spin crossover upon photoexcitation of a cyclopropenone-bipyridyl FeII complex

Supplementary files

Article information

Article type
Paper
Submitted
02 Jan 2025
Accepted
07 Apr 2025
First published
08 Apr 2025
This article is Open Access
Creative Commons BY license

Phys. Chem. Chem. Phys., 2025,27, 9152-9158

Ultrafast competition between CO release and spin crossover upon photoexcitation of a cyclopropenone-bipyridyl FeII complex

S. Megow, A. Prax, T. Neumann, M. Lehr, A. J. McConnell and F. Temps, Phys. Chem. Chem. Phys., 2025, 27, 9152 DOI: 10.1039/D5CP00019J

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