title: Exploring Coordination Modes: Late Transition Metal Complexes with a Methylene-bridged Macrocyclic Tetra-NHC Ligand.
abstract: A tetranuclear silver(I) N-heterocyclic carbene (NHC) complex bearing a macrocyclic, exclusively methylene-bridged, tetracarbene ligand was synthesized and employed as transmetalation agent for the synthesis of nickel(II), palladium(II), platinum(II), and gold(I) derivatives. The transition metal complexes exhibit different coordination geometries, the coinage metals being bound in a linear fashion forming molecular box-type complexes, whereas the group 10 metals adapt an almost ideal square planar coordination geometry within the ligand's cavity, resulting in saddle-shaped complexes. Both the Ag(I) and the Au(I) complexes show ligand-induced metal-metal contacts, causing photoluminescence in the blue region for the gold complex. Distinct metal-dependent differences of the coordination behavior between the group 10 transition metals were elucidated by low-temperature NMR spectroscopy and DFT calculations.
authors.affiliation: Department of Chemistry and Catalysis Research Center, Molecular Catalysis, Technische Universität München, Lichtenbergstraße 4, 85747, Garching bei München, Germany.
authors.forename: Philipp J
authors.initials: PJ
authors.lastname: Altmann
authors.affiliation: Department of Chemistry and Catalysis Research Center, Molecular Catalysis, Technische Universität München, Lichtenbergstraße 4, 85747, Garching bei München, Germany.
authors.forename: Daniel T
authors.initials: DT
authors.lastname: Weiss
authors.affiliation: Single Crystal XRD Laboratory of the Catalysis Research Center, Technische Universität München, Ernst-Otto-Fischer-Straße 1, 85747, Garching bei München, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Jandl
authors.affiliation: Department of Chemistry and Catalysis Research Center, Molecular Catalysis, Technische Universität München, Lichtenbergstraße 4, 85747, Garching bei München, Germany. fritz.kuehn@ch.tum.de.
authors.forename: Fritz E
authors.initials: FE
authors.lastname: Kühn
keywords: N-heterocyclic carbenes; late transition metals; macrocyclic ligands; photoluminescence; transmetalation