Ionic Pd/NHC Catalytic System Enables Recoverable Homogeneous Catalysis: Mechanistic Study and Application in the Mizoroki-Heck Reaction

N-Heterocyclic carbene (NHC) ligands are ubiquitously utilized in catalysis. A common catalyst design model assumes strong M-NHC binding in this metal-ligand framework. In contrast to this common assumption, we demonstrate here that lability and controlled cleavage of the M-NHC bond (rather than its stabilization) could be more important for high-performance catalysis at low catalyst concentrations. The present study reveals a dynamic stabilization mechanism with labile metal-NHC binding and [PdX3](-)[NHC-R](+) ion pair formation. Access to reactive anionic palladium intermediates formed by dissociation of the NHC ligands and plausible stabilization of the molecular catalyst in solution by interaction with the [NHC-R](+) azolium ion is of particular importance for an efficient and recyclable catalyst. These ionic Pd/NHC complexes allowed for the first time the recycling of the complex in a well-defined form with isolation at each cycle. Computational investigation of the reaction mechanism confirms a facile formation of NHC-free anionic Pd in polar media through either Ph-NHC coupling or reversible H-NHC coupling. The present study formulates novel ideas for M/NHC catalyst design.

Авторы
Eremin D.B.1 , Denisova E.A.1 , Kostyukovich A.Y.1 , Martens J.2 , Berden G.2 , Oomens J.2 , Khrustalev V.N. 3, 4 , Chernyshev V.M. 1, 5 , Ananikov V.P. 1
Издательство
Wiley-VCH Verlag
Номер выпуска
72
Язык
Английский
Страницы
16564-16572
Статус
Опубликовано
Том
25
Год
2019
Организации
  • 1 Russian Acad Sci, Zelinsky Inst Organ Chem, Leninsky Pr 47, Moscow 119991, Russia
  • 2 Radboud Univ Nijmegen, FELIX Lab, Inst Mol & Mat, Toernooiveld 7c, NL-6525 ED Nijmegen, Netherlands
  • 3 Natl Res Ctr, Kurchatov Inst, Acad Kurchatov Sq 1, Moscow 123182, Russia
  • 4 RUDN Univ, Peoples Friendship Univ Russia, Miklukho Maklay St 6, Moscow 117198, Russia
  • 5 Platov South Russian State Polytech Univ NPI, Prosveschenya 132, Novocherkassk 346428, Russia
Дата создания
02.11.2020
Дата изменения
02.11.2020
Постоянная ссылка
https://repository.rudn.ru/ru/records/article/record/66155/