Binuclear C

Binuclear C^C* cyclometalated NHC platinum(II) compounds with bridging amidinate ligands were synthesized to evaluate their photophysical properties. Their three-dimensional structures were determined by a combination of 2D NMR experiments, mass spectrometry, DFT calculations, and solid-state structure analysis. The bridging amidinate ligands enforce short distances between the platinum centers of the two cyclometalated structures, which gives rise to extraordinary photophysical properties.

Phosphorescent Platinum(II) Complexes with Mesoionic 1H-1,2,3-Triazolylidene Ligands.

The synthesis and characterization of eight unprecedented phosphorescent C^C* cyclometalated mesoionic aryl-1,2,3-triazolylidene platinum(II) complexes with different ß-diketonate ligands are reported. All compounds proved to be strongly emissive at room temperature in poly(methyl methacrylate) films with an emitter concentration of 2 wt %. The observed photoluminescence properties were strongly dependent on the substitution on the aryl system and the ß-diketonate ligand. Compared to acetylacetonate, the ß-diketonates with aromatic substituents (mesityl and duryl) were found to significantly enhance the quantum yield while simultaneously reducing the emission lifetimes. Characterization was carried out by standard techniques, as well as solid-state structure determination, which confirmed the binding mode of the carbene ligand. DFT calculations, carried out to predict the emission wavelength with maximum intensity, were in excellent agreement with the (later) obtained experimental data.

Palladium(ii) complexes with electron-poor, 4,5-disubstituted diimidazol-2-ylidene ligands: synthesis, characterization and catalytic activity.

Diimidazolium salts featuring different bridges between the imidazolium groups, as well as electron-withdrawing groups (chloride, cyanide) at the 4- and 5-position of the heterocyclic rings, have been successfully prepared. The diimidazolium salts serve as convenient precursors of di(N-heterocyclic carbene) ligands, which coordinate in a chelating fashion to palladium(ii) centres. The effect of the newly introduced electron-withdrawing groups on the spectroscopic and structural characteristics of the resulting complexes as well as on their reactivity as catalysts in a model alkyne hydroarylation reaction has been investigated and is discussed herein.

(Acetylacetonato-κ2O,O')[1-(4-bromophenyl-κC2)-3-methylimidazol-2-ylidene-κC2]platinum(II).

The title platinum(II) complex, [Pt(C(10)H(8)BrN(2))(C(5)H(7)O(2))], has a bidentate cyclometallated phenylimidazolylidene ligand and an acetylacetonate spectator ligand, which form a distorted square-planar coordination environment around the Pt(II) centre. In the solid state, the molecules are oriented in a parallel fashion by intermolecular hydrogen bonding and π-π and C-H···π interactions, while close Pt···Pt contacts are not observed. The structure is only the second example for this new class of compounds.