Research & Teaching Faculty

Default Header Image

Understanding Ni(II)-Mediated C(sp(3))-H Activation: Tertiary Ureas as Model Substrates

TitleUnderstanding Ni(II)-Mediated C(sp(3))-H Activation: Tertiary Ureas as Model Substrates
Publication TypeJournal Article
Year of Publication2018
AuthorsD. Beattie, D, Grunwald, AC, Perse, T, Schafer, LL, Love, JA
JournalJOURNAL OF THE AMERICAN CHEMICAL SOCIETY
Volume140
Pagination12602-12610
Date PublishedOCT 3
ISSN0002-7863
Abstract

We report a mechanistic study of C(sp(3))-H bond activation mediated by nickel. Cyclometalated Ni(II) ureate {[}(PEt3)Ni(kappa(3)-C,N,N-((C) under barH(2))N(Cy)(CO)(N) under bar(((N) under bar)-quinolin-8-y1))] was synthesized and isolated from the urea precursor, (Me)(Cy)N(CO)N(H)(quinolin-8-yl), via C(sp(3))-H activation. We investigated the effects of solvents and base additives on the rate of C-H activation. Kinetic isotope effect experiments showed that C-H activation is rate determining. Through deuterium labeling and protonation studies, we also showed that C-H activation can be reversible. We extended this reaction to a range of ureas with primary and secondary C(sp(3))-H bonds, which activate readily to form analogous nickelated products. Finally, we showed that carboxylate additives assist with both ligand dissociation and initial N-H bond activation, consistent with a concerted metalation-deprotonation mechanism.

DOI10.1021/jacs.8b07708