Issue 6, 2021

Ultrafast structural dynamics of in-cage isomerization of diiodomethane in solution

Abstract

Despite extensive studies on the isomer species formed by photodissociation of haloalkanes in solution, the molecular structure of the precursor of the isomer, which is often assumed to be a vibrationally hot isomer formed from the radical pair, and its in-cage isomerization mechanism remain elusive. Here, the structural dynamics of CH2I2 upon 267 nm photoexcitation in methanol were probed with femtosecond X-ray solution scattering at an X-ray free-electron laser. The determined molecular structure of the transiently formed species that converts to the CH2I–I isomer has the I–I distance of 4.17 Å, which is longer than that of the isomer (3.15 Å) by more than 1.0 Å and the mean-squared displacement of 0.45 Å2, which is about 100 times larger than those of typical regular chemical bonds. These unusual structural characteristics are consistent with either a vibrationally hot form of the CH2I–I isomer or the loosely-bound radical pair (CH2I˙⋯I˙).

Graphical abstract: Ultrafast structural dynamics of in-cage isomerization of diiodomethane in solution

Supplementary files

Article information

Article type
Edge Article
Submitted
15 Sep 2020
Accepted
04 Dec 2020
First published
07 Dec 2020
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY-NC license

Chem. Sci., 2021,12, 2114-2120

Ultrafast structural dynamics of in-cage isomerization of diiodomethane in solution

H. Kim, J. G. Kim, T. W. Kim, S. J. Lee, S. Nozawa, S. Adachi, K. Yoon, J. Kim and H. Ihee, Chem. Sci., 2021, 12, 2114 DOI: 10.1039/D0SC05108J

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