title: Peptide-tethered monodentate and chelating histidylidene metal complexes: synthesis and application in catalytic hydrosilylation.
abstract: The Nδ,Nε-dimethylated histidinium salt (His*) was tethered to oligopeptides and metallated to form Ir(III) and Rh(I) NHC complexes. Peptide-based histidylidene complexes containing only alanine, Ala-Ala-His*-[M] and Ala-Ala-Ala-His*-[M] were synthesised ([M] = Rh(cod)Cl, Ir(Cp*)Cl2), as well as oligopeptide complexes featuring a potentially chelating methionine and tyrosine residue, Met-Ala-Ala-His*-Rh(cod)Cl and Tyr-Ala-Ala-His*-Rh(cod)Cl. Chelation of the methionine-containing histidylidene ligand was induced by halide abstraction from the rhodium centre, while tyrosine remained non-coordinating under identical conditions. High catalytic activities in hydrosilylation were achieved with all peptide-based rhodium complexes. The cationic S(Met),C(His*)-bidentate peptide rhodium catalyst outperformed the monodentate neutral peptide complexes and constitutes one of the most efficient rhodium carbene catalysts for hydrosilylation, providing new opportunities for the use of peptides as N-heterocyclic carbene ligands in catalysis.
authors: School of Chemistry and Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland.
authors: Angèle
authors: A
authors: Monney
authors: Flavia
authors: F
authors: Nastri
authors: Martin
authors: M
authors: Albrecht
mesh_terms: D000595:Amino Acid Sequence; D002384:Catalysis; D002614:Chelating Agents / Q000737:chemistry; D056831:Coordination Complexes / Q000138:chemical synthesis / Q000737:chemistry*; D006571:Heterocyclic Compounds / Q000737:chemistry; D006639:Histidine / Q000737:chemistry*; D007495:Iridium / Q000737:chemistry*; D008697:Methane / Q000031:analogs & derivatives / Q000737:chemistry; D009842:Oligopeptides; D012238:Rhodium / Q000737:chemistry*; D012825:Silicon / Q000737:chemistry*
chemical_list: D002614:Chelating Agents; D056831:Coordination Complexes; D006571:Heterocyclic Compounds; D009842:Oligopeptides; C030011:carbene; D007495:Iridium; D006639:Histidine; D012238:Rhodium; D008697:Methane; D012825:Silicon