cs9b02184_si_001.pdf (2.02 MB)
Mechanistic Study of Hydroamination of Alkyne through Tantalum-Based Silica-Supported Surface Species
journal contribution
posted on 2019-08-23, 15:04 authored by Maha A. Aljuhani, Ziyun Zhang, Samir Barman, Mohamad El Eter, Laura Failvene, Samy Ould-Chikh, Erjia Guan, Edy Abou-Hamad, Abdul-Hamid Emwas, Jérémie
D. A. Pelletier, Bruce C. Gates, Luigi Cavallo, Jean-Marie BassetSelective
hydroamination of terminal alkynes with primary aryl
amines is catalyzed by an unprecedented well-defined silica-supported
tantalum complex [(≡Si–O−)Ta(η1σ-NEtMe)2(=NtBu)]. A molecular-level
characterization of the surface organometallic Ta species was done
with the help of characterization techniques including in situ infrared, 1H and 13C solid-state NMR (including double and
triple quanta sequencing), and X-ray absorption spectroscopies. These
were complemented by the state-of-the-art DNP-SENS 15N
characterization. Several catalytic intermediates have been isolated,
in particular the 4-membered metallacycle ring intermediate resulting
from the anti-Markovnikov addition of the alkyne to the surface tantalum
imido. A mechanism is proposed that is on the isolation of all intermediates.
A density functional theory (DFT) calculation has confirmed all the
elementary steps and intermediates that were fully characterized.
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Keywords
surface organometallic Ta speciesTantalum-Based Silica-Supported Surface Species4- membered metallacycle ringterminal alkynesmolecular-level characterizationanti-Markovnikov additionaryl aminesMechanistic StudyX-ray absorption spectroscopiessilica-supported tantalumcharacterization techniques1 HintermediateDNP-SENS 15 N characterizationDFTNMRsurface tantalum imido13 C
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