The Webster and Hollis Groups report the extreme π-loading (CCC-NHC) pincer Ta(V) bis(imido) complex that catalyzes the cyclization of α,ω-aminoalkene (2,2-diphenylpent-4-en-1-amine) to produce three different products in varying proportions: cyclic imine from oxidative amination (OA), reduction product (RP) from hydrogenated substrate, and hydroamination (HA). Various plausible pathways for the reactions were evaluated using density functional theory computations. The overall turnover-limiting step of the proposed catalytic cycle of the conversions of α,ω-aminoalkene substrate is the regeneration of the Ta(V) bis(imido) intermediate from Ta(V)-hydride amido intermediate. An amido hydride Ta intermediate is the computed resting state of the proposed catalytic cycle. The computational results are consistent with the experimentally observed product ratios and selectivity.
G. Liang, T. K. Hollis, C. E. Webster. "Computational Analysis of the Intramolecular Oxidative Amination of an Alkene Catalyzed by the Extreme π-loading N-Heterocyclic Carbene Pincer Tantalum(V) Bis(imido) Complex" Organometallics, 2018, 37, 1671-1681.
T. R. Helgert, X. Zhang, H. K. Box, J. A. Denny, H. U. Valle, A. G. Oliver, G. Akurathi, C. E. Webster, T. K. Hollis. "Extreme π-Loading as a Design Element for Accessing Imido Ligand Reactivity. A CCC-NHC Pincer Tantalum Bis(imido) Complex: Synthesis, Characterization, and Catalytic Oxidative Amination of Alkenes" Organometallics, 2016, 35, 3452-3460.
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