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Synthetic, Structural, and Catalytic Studies of Well‐Defined Allyl 1,2,3‐Triazol‐5‐ylidene ( tz NHC) Palladium Complexes
Author(s) -
Terashima Takahiro,
Inomata Sayuri,
Ogata Kenichi,
Fukuzawa Shinichi
Publication year - 2012
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201101383
Subject(s) - chemistry , carbene , steric effects , palladium , imidazole , catalysis , aryl , medicinal chemistry , coupling reaction , stereochemistry , organic chemistry , alkyl
A series of allyl 1,2,3‐triazol‐5‐ylidene ( tz NHC) palladium complexes was prepared, and the structures of the complexes were fully characterized by NMR and X‐ray diffraction analyses. The donor properties of these ligands were evaluated by studying the vibrational spectra of their carbonyliridium complexes and their X‐ray photoelectron spectra. These evaluations showed that the structures of the tz NHC palladium complexes are almost identical to those of the corresponding imidazole carbene palladium complexes, and that the tz NHC ligands have stronger donor properties than the imidazole carbene ligands. The relationship between catalytic activity and structure was examined by carrying out a room‐temperature Suzuki–Miyaura coupling reaction, and the cinnamylpalladium complex bearing 1,4‐bis(2,6‐diisopropylphenyl)‐3‐methyl‐1,2,3‐triazol‐5‐ylidene (TPr) was found to be the most active catalyst. (cinnamyl)(TPr)PdCl showed high activity in the room‐temperature reaction performed with aryl chlorides regardless of the electronic and steric properties of the substituents, and was effective in reactions with sterically crowded arylboronic acids.