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Cooperative Catalysis of Combined Systems of Transition‐Metal Complexes with Lewis Acids: Theoretical Understanding
Author(s) -
Guan Wei,
Zeng Guixiang,
Kameo Hajime,
Nakao Yoshiaki,
Sakaki Shigeyoshi
Publication year - 2016
Publication title -
the chemical record
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.61
H-Index - 78
eISSN - 1528-0691
pISSN - 1527-8999
DOI - 10.1002/tcr.201600086
Subject(s) - chemistry , lewis acids and bases , borane , moiety , catalysis , frustrated lewis pair , alkylation , molecule , transition metal , stereochemistry , medicinal chemistry , photochemistry , organic chemistry
The combination of transition‐metal complexes and Lewis acids has been recently applied to several catalytic reactions, in which the Lewis acid plays a crucial role as a non‐innocent additive to accelerate the reaction. In this review article, the reasons for the acceleration by the Lewis acid are discussed based on our recent theoretical studies. In the H–H σ‐bond activation of a dihydrogen molecule by a nickel(0)–borane complex, the empty p orbital of the borane moiety interacts with the H–H σ bonding MO to form charge transfer (CT) from the dihydrogen molecule to the borane moiety to accelerate the reaction. In the B–F σ‐bond activation of BF 3 by a platinum(0)–bisphosphine complex, the second BF 3 molecule interacts with the F atom that is dissociating from the B atom to stabilize the transition state and product by the CT from the F atom to the second BF 3 . In this reaction, the substrate BF 3 plays a crucial role as the Lewis acid to accelerate the activation of the B–F σ bond. In the nickel‐catalyzed decyanative coupling of arylcarboxybenzonitriles with acetylenes, two molecules of the aluminum Lewis acid interact with the cyano N atom and the carbonyl O atom of the substrate to stabilize the transition state and intermediate. In the nickel‐catalyzed alkylation of aromatic amides with alkenes, the Lewis acid enhances the para regioselectivity of alkylation by interacting with the carbonyl O atom. In the nickel‐catalyzed carboxylation of sp 3 carbon and sp carbon atoms with carbon dioxide, not the σ‐bond activation but the insertion reaction of carbon dioxide into the metal–carbon bond is accelerated by the Lewis acid by interacting with the O atom of carbon dioxide, because the CT from the metal–carbon bond to carbon dioxide is enhanced by the interaction. This theoretical knowledge suggests that the combination of transition‐metal complex and Lewis acid can broaden the application range of transition‐metal complex as catalyst.