title: Expanded ring and functionalised expanded ring N-heterocyclic carbenes as ligands in catalysis.
abstract: The synthesis of new functionalised 6- and 7-membered NHC (N-heterocyclic carbene) precursors bearing anisidyl or pyridine N-substituents, both symmetrically and non-symmetrically substituted is reported. Their corresponding rhodium(i) and iridium(i) complexes, M(COD)(NHC)Cl, were also prepared and characterised. The unusual Rh(iii)/Rh(i) salt, [Rh(eta(2)-NHC-py)(2)Cl(2)][Rh(COD)Cl(2)], was obtained with one of the pyridyl-functionalised NHC ligands. Single-crystal X-ray analyses have been obtained for the majority of the complexes and NHC salts. The activity of these complexes was tested in the hydrogenation of a range of substrates with molecular hydrogen, including 1-cyclooctadiene and 2-methyl styrene, where they show enhanced activity and stability in comparison to non-functionalised NHC analogues, operating under exceptionally mild conditions (ambient temperature and atmospheric pressure).
authors.affiliation: School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff, UKCF10 3AT.
authors.forename: Abeer
authors.initials: A
authors.lastname: Binobaid
authors.forename: Manuel
authors.initials: M
authors.lastname: Iglesias
authors.forename: Dirk J
authors.initials: DJ
authors.lastname: Beetstra
authors.forename: Benson
authors.initials: B
authors.lastname: Kariuki
authors.forename: Athanasia
authors.initials: A
authors.lastname: Dervisi
authors.forename: Ian A
authors.initials: IA
authors.lastname: Fallis
authors.forename: Kingsley J
authors.initials: KJ
authors.lastname: Cavell
mesh_terms: D002384:Catalysis; D018360:Crystallography, X-Ray; D006571:Heterocyclic Compounds / Q000737:chemistry*; D007495:Iridium / Q000737:chemistry; D008024:Ligands; D008697:Methane / Q000031:analogs & derivatives* / Q000737:chemistry; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D012238:Rhodium / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D006571:Heterocyclic Compounds; D008024:Ligands; D009942:Organometallic Compounds; C030011:carbene; D007495:Iridium; D012238:Rhodium; D008697:Methane