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

被引：8

作者：

Kim, Hanui ^{[1
,2
,3
]}

Kim, Jong Goo ^{[3
]}

Kim, Tae Wu ^{[3
]}

Lee, Sang Jin ^{[1
,2
,3
]}

Nozawa, Shunsuke ^{[4
,5
]}

Adachi, Shin-ichi ^{[4
,5
]}

Yoon, Kihwan ^{[6
]}

Kim, Joonghan ^{[6
]}

Ihee, Hyotcherl ^{[1
,2
,3
]}

机构：

[1] Korea Adv Inst Sci & Technol KAIST, Dept Chem, Daejeon 34141, South Korea

[2] Korea Adv Inst Sci & Technol KAIST, KI BioCentwy, Daejeon 34141, South Korea

[3] Ctr Nanomat & Chem React, Inst Basic Sci IBS, Daejeon 34141, South Korea

[4] High Energy Accelerator Res Org KEK, Inst Mat Struct Sci, Photon Factory, Tsukuba, Ibaraki 3050801, Japan

[5] Grad Univ Adv Studies, Sch High Energy Accelerator Sci, Dept Mat Struct Sci, Tsukuba, Ibaraki 3050801, Japan

[6] Catholic Univ Korea, Dept Chem, Bucheon 14662, South Korea

来源：

CHEMICAL SCIENCE | 2021年 / 12卷 / 06期

关键词：

Diiodomethane - Femtoseconds - Haloalkanes - Mean squared displacement - Radical pair - Solution scatterings - Structural characteristics - X-ray free electron lasers;

D O I：

10.1039/d0sc05108j

中图分类号：

O6 [化学];

学科分类号：

0703 ;

摘要：

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 angstrom, which is longer than that of the isomer (3.15 angstrom) by more than 1.0 angstrom and the mean-squared displacement of 0.45 angstrom(2), 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 (CH2IMIDLINE HORIZONTAL ELLIPSISI).

引用

页码：2114 / 2120

页数：7

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