Expanded ring and functionalised expanded ring N-heterocyclic carbenes as ligands in catalysis.
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).
Binobaid
Abeer
A
School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff, UKCF10 3AT.
Iglesias
Manuel
M
Beetstra
Dirk J
DJ
Kariuki
Benson
B
Dervisi
Athanasia
A
Fallis
Ian A
IA
Cavell
Kingsley J
KJ
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
D006571:Heterocyclic Compounds; D008024:Ligands; D009942:Organometallic Compounds; C030011:carbene; D007495:Iridium; D012238:Rhodium; D008697:Methane