ic7b02097_si_001.pdf (1.77 MB)
Computational Insight Into the Hydroamination of an Activated Olefin, As Catalyzed by a 1,2,4-Triazole-Derived Nickel(II) N‑Heterocyclic Carbene Complex
journal contribution
posted on 2017-12-07, 20:35 authored by Ravi Kumar, Madanakrishna Katari, Ajay Choudhary, Gopalan Rajaraman, Prasenjit GhoshA density
functional theory (DFT) investigation performed at the
B3LYP/TZVP//B3LYP/6-31G(d)-LANL2DZ level of theory on the hydroamination
of dimethylamine (Me2NH) on an activated olefin (namely,
acrylonitrile (CH2CHCN)), as catalyzed by a 1,2,4-triazol
based nickel(II) N-heterocyclic carbene complex (namely, [1,4-dimethyl-1,2,4-triazole-5-ylidene]2 nickel dichloride) revealed that the olefin coordination
pathway is favorable over the amine coordination pathway, although
the initial olefin coordination step is higher in energy than the
initial amine coordination step. Significantly enough, the reaction
involved a crucial 1,3-proton transfer step between the resonance
intermediates, i.e., the C-bound [(NHC)2Ni(CH(CN)CH2NHMe2)]+ (D) species or
N-bound [(NHC)2Ni(NCCHCH2NHMe2)]+ (E) species and the intermediate [(NHC)2Ni(NCCH2CH2NMe2)]+ (F), depicting the cleavage of a N–H bond and
the formation of a C–H bond facilitated by a water-assisted/amine-assisted
proton shuttle. Overall, among the various pathways explored, the
lowest energy pathway involved alkene coordination, followed by an
amine-assisted 1,3-proton transfer step.