Campus Units

Chemistry

Document Type

Article

Publication Version

Published Version

Publication Date

2014

Journal or Book Title

Journal of the American Chemical Society

Volume

136

Issue

25

First Page

8933

Last Page

8940

DOI

10.1021/ja501777r

Abstract

Heterolytic bond scission is a staple of chemical reactions. While qualitative and quantitative models exist for understanding the thermal heterolysis of carbon–leaving group (C–LG) bonds, no general models connect structure to reactivity for heterolysis in the excited state. CASSCF conical intersection searches were performed to investigate representative systems that undergo photoheterolysis to generate carbocations. Certain classes of unstabilized cations are found to have structurally nearby, low-energy conical intersections, whereas stabilized cations are found to have high-energy, unfavorable conical intersections. The former systems are often favored from photochemical heterolysis, whereas the latter are favored from thermal heterolysis. These results suggest that the frequent inversion of the substrate preferences for nonadiabatic photoheterolysis reactions arises from switching from transition-state control in thermal heterolysis reactions to conical intersection control for photochemical heterolysis reactions. The elevated ground-state surfaces resulting from generating unstabilized or destabilized cations, in conjunction with stabilized excited-state surfaces, can lead to productive conical intersections along the heterolysis reaction coordinate.

Comments

Reprinted (adapted) with permission from J. Am. Chem. Soc., 2014, 136 (25), pp 8933–8940. Copyright 2014 American Chemical Society.

Copyright Owner

American Chemical Society

Language

en

File Format

application/pdf

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