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Title: The mechanism of directed Ni( ii )-catalyzed C–H iodination with molecular iodine
The density functional theory method is used to elucidate the elementary steps of Ni( ii )-catalyzed C(sp 2 )–H iodination with I 2 and substrates bearing N , N ′-bidentate directing centers, amide-oxazoline (AO) and 8-aminoquinoline (AQ). The relative stability of the lowest energy high- and low-spin electronic states of the catalyst and intermediates is found to be an important factor for all of the steps in the reaction. As a result, two-state reactivity for these systems is reported, where the reaction is initiated on the triplet surface and generates a high energy singlet nickelacycle. It is shown that the addition of Na 2 CO 3 base to the reaction mixture facilitates C–H activation. The presence of I 2 in the reaction provides the much needed driving force for the C–H activation and nickelacycle formation and ultimately reacts to form a new C–I bond through either a redox neutral electrophilic cleavage (EC) pathway or a one-electron reductive cleavage (REC) pathway. The previously proposed Ni( ii )/Ni( iv ) and homolytic cleavage pathways are found to be higher in energy. The nature of the substrate is found to have a large impact on the relative stability of the lowest electronic states more » and on the stability of the nickelacycle resulting from C–H activation. « less
Authors:
; ;
Award ID(s):
1700982
Publication Date:
NSF-PAR ID:
10057944
Journal Name:
Chemical Science
Volume:
9
Issue:
5
Page Range or eLocation-ID:
1144 to 1154
ISSN:
2041-6520
Sponsoring Org:
National Science Foundation
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