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Ruthenium(II) Complexes Containing Lutidine‐Derived Pincer CNC Ligands: Synthesis, Structure, and Catalytic Hydrogenation of CN bonds
Author(s) -
HernándezJuárez Martín,
LópezSerrano Joaquín,
Lara Patricia,
MoralesCerón Judith P.,
Vaquero Mónica,
Álvarez Eleuterio,
Salazar Verónica,
Suárez Andrés
Publication year - 2015
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.201406040
Subject(s) - deprotonation , chemistry , carbene , pincer movement , ligand (biochemistry) , transmetalation , ruthenium , hydrogen bond , catalysis , pincer ligand , yield (engineering) , coordination sphere , medicinal chemistry , photochemistry , stereochemistry , molecule , polymer chemistry , organic chemistry , materials science , receptor , metallurgy , ion , biochemistry
A series of Ru complexes containing lutidine‐derived pincer CNC ligands have been prepared by transmetalation with the corresponding silver‐carbene derivatives. Characterization of these derivatives shows both mer and fac coordination of the CNC ligands depending on the wingtips of the N‐heterocyclic carbene fragments. In the presence of t BuOK, the Ru‐CNC complexes are active in the hydrogenation of a series of imines. In addition, these complexes catalyze the reversible hydrogenation of phenantridine. Detailed NMR spectroscopic studies have shown the capability of the CNC ligand to be deprotonated and get involved in ligand‐assisted activation of dihydrogen. More interestingly, upon deprotonation, the Ru‐CNC complex 5 e (BF 4 ) is able to add aldimines to the metal–ligand framework to yield an amido complex. Finally, investigation of the mechanism of the hydrogenation of imines has been carried out by means of DFT calculations. The calculated mechanism involves outer‐sphere stepwise hydrogen transfer to the CN bond assisted either by the pincer ligand or a second coordinated H 2 molecule.