Rhodium(I)‐NHC Complexes Bearing Bidentate Bis‐Heteroatomic Acidato Ligands as gem‐Selective Catalysts for Alkyne Dimerization. Issue 43 (7th July 2020)

• Record Type: Journal Article
• Authors: Galiana‐Cameo, María; Borraz, Marina; Zelenkova, Yaroslava; Passarelli, Vincenzo; Lahoz, Fernando J.; Pérez‐Torrente, Jesús J.; Oro, Luis A.; Di Giuseppe, Andrea; Castarlenas, Ricardo
• Is Part Of: Chemistry. Volume 26:Issue 43(2020)
• Page Start: 9598
• Page End: 9608
• Publication Date: 2020-07-07
• Subjects: alkyne dimerization -- amidato -- carboxylato -- N-heterocyclic carbenes -- rhodium; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.202001584
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: 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. Abstract : Flash Catalyst : Several rhodium‐NHC‐BHetA complexes has been prepared and compared as alkyne dimerization catalysts. The N, O framework of acetanilidato ligand is essential for a very high activity.