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Metal Cation‐Driven Dynamic Covalent Formation of Imine and Hydrazone Ligands Displaying Synergistic Co‐catalysis and Auxiliary Amine Effects
Author(s) -
He Meixia,
Lehn JeanMarie
Publication year - 2021
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202100662
Subject(s) - imine , hydrazone , chemistry , covalent bond , catalysis , hydrazine (antidepressant) , aldehyde , amine gas treating , dynamic covalent chemistry , metal , combinatorial chemistry , organic chemistry , polymer chemistry , medicinal chemistry , molecule , supramolecular chemistry , chromatography
Optimizing C=N bond formation and C/N component exchange has major significance in Dynamic Covalent Chemistry (DCC). Imine and hydrazone generation from their aldehyde, amine and hydrazine components showed large accelerations in presence of AgOTf or Zn(OTf) 2 , up to 10 4 for the Zn(II)‐( p ‐anisidine)imine complex. Zn(OTf) 2 and auxiliary p ‐anisidine together accelerated 630 times the formation of the Zn(II)‐hydrazone complex, revealing a strong synergistic effect, traced to very fast initial formation of the reactive Zn(II)‐imine complex presenting a C=N bond metallo‐activated towards reaction with the hydrazine component. Reactions involving more entities showed kinetically faster and thermodynamically simpler outputs due to dynamic competition within a mixture of higher complexity. Catalytic amounts of metal salts and auxiliary amine gave similar marked rate accelerations and turnover, indicating true catalysis. The synergistic effect achieved by combining metallo‐ and organo‐catalysis points to a powerful co‐catalysis strategy of bond‐formation in DCC through interconnected chemical transformations.