title: Heterobimetallic N-Heterocyclic Carbene Complexes: A Synthetic, Spectroscopic, and Theoretical Study.
abstract: A new synthetic methodology has been developed for the preparation of heterobimetallic group 11 and group 12 complexes of a symmetrical bis-NHC "pincer" ligand. The synthetic route involved the initial preparation of a mononuclear [Au(NHC)2](+) complex with pendent imidazole moieties on the NHC ligands. Subsequent alkylation of the imidazole groups with Et3OBF4 and metalation with a second metal ion (Ag(I) or Hg(II)) provided two heterobimetallic complexes. Four homobimetallic (Cu(I)2, Ag(I)2, Au(I)2, and Hg(II)2) complexes of the same bis-NHC "pincer" ligand were also prepared. The homobimetallic Cu(I)2, Au(I)2, and Hg(II)2 complexes and heterobimetallic Au(I)-Ag(I) and Au(I)-Hg(II) complexes and the synthetic intermediates for the heterobimetallic complexes were characterized by X-ray crystallography. These X-ray structures show that the bimetallic complexes adopt "twisted" conformations in the solid state, supporting short M···M interactions. Crystalline samples of the homobimetallic Ag(I)2 and Au(I)2 and heterobimetallic Au(I)-Ag(I) and Au(I)-Hg(II) complexes were emissive at room temperature and at 77 K. The geometries of the synthesized complexes were optimized at the M06-L/def2-SVP level of theory, and the electronic nature of the M···M interactions for all synthesized complexes was investigated using natural bond orbital (NBO) calculations.
authors.affiliation: Department of Chemistry and Physics, La Trobe Institute of Molecular Science, La Trobe University , Melbourne, Victoria 3086, Australia.
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Pell
authors.affiliation: Department of Chemistry and Physics, La Trobe Institute of Molecular Science, La Trobe University , Melbourne, Victoria 3086, Australia.
authors.forename: David J D
authors.initials: DJ
authors.lastname: Wilson
authors.affiliation: Centre for Microscopy, Characterization and Analysis, The University of Western Australia , 35 Stirling Highway, Crawley, Western Australia 6009, Australia.
authors.forename: Brian W
authors.initials: BW
authors.lastname: Skelton
authors.affiliation: Department of Chemistry and Physics, La Trobe Institute of Molecular Science, La Trobe University , Melbourne, Victoria 3086, Australia.
authors.forename: Jason L
authors.initials: JL
authors.lastname: Dutton
authors.affiliation: Department of Chemistry and Physics, La Trobe Institute of Molecular Science, La Trobe University , Melbourne, Victoria 3086, Australia.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Barnard