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Rhodium(I)‐NHC Complexes Bearing Bidentate Bis‐Heteroatomic Acidato Ligands as gem ‐Selective Catalysts for Alkyne Dimerization
Author(s) -
GalianaCameo María,
Borraz Marina,
Zelenkova Yaroslava,
Passarelli Vincenzo,
Lahoz Fernando J.,
PérezTorrente Jesús J.,
Oro Luis A.,
Di Giuseppe Andrea,
Castarlenas Ricardo
Publication year - 2020
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.202001584
Subject(s) - denticity , alkyne , rhodium , catalysis , chemistry , bearing (navigation) , medicinal chemistry , combinatorial chemistry , organic chemistry , physics , metal , astronomy
A series of Rh( κ 2 ‐BHetA)( η 2 ‐coe)(IPr) complexes bearing 1,3‐bis‐hetereoatomic acidato ligands (BHetA) including carboxylato (O,O), thioacetato (O,S), amidato (O,N), thioamidato (N,S), and amidinato (N,N), have been prepared by reaction of the dinuclear precursor [Rh( μ ‐Cl)(IPr)( η 2 ‐coe)] 2 with the corresponding anionic BHetA species. The Rh I ‐NHC‐BHetA compounds catalyze the dimerization of aryl alkynes, showing excellent selectivity for the head‐to‐tail enynes. Among them, the acetanilidato‐based catalyst has shown an outstanding catalytic performance reaching unprecedented TOF levels of 2500 h −1 with complete selectivity for the gem‐ isomer. Investigation of the reaction mechanism supports a non‐oxidative pathway in which the BHetA ligand behaves as proton shuttle through intermediate κ 1 ‐HBHetA species. However, in the presence of pyridine as additive, the identification of the common Rh III H(C≡CPh) 2 (IPr)(py) 2 intermediate gives support for an alternative oxidative route.