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Title: Taming the Chlorine Radical: Enforcing Steric Control over Chlorine-Radical-Mediated C-H Activation
Chlorine radicals readily activate C-H bonds, but the high reactivity of these intermediates precludes their use in regioselective C-H functionalization reactions. We demonstrate that the secondary coordination sphere of a metal complex can confine photoeliminated chlorine radicals and afford steric control over their reactivity. Specifically, a series of iron(III) chloride pyridinediimine complexes exhibit activity for photochemical C(sp(3))-H chlorination and bromination with selectivity for primary and secondary C-H bonds, overriding thermodynamic preference for weaker tertiary C-H bonds. Transient absorption spectroscopy reveals that Cl center dot remains confined through formation of a Cl center dot larene complex with aromatic groups on the pyridinediimine ligand. Furthermore, photocrystallography confirms that this selectivity arises from the generation of Cl center dot within the steric environment defined by the iron secondary coordination sphere.  more » « less
Award ID(s):
1855531
PAR ID:
10352272
Author(s) / Creator(s):
; ; ; ; ; ;
Date Published:
Journal Name:
Journal of the American Chemical Society
Volume:
144
Issue:
3
ISSN:
0002-7863
Page Range / eLocation ID:
1464–1472
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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