We studied the catalytic activity of palladium(II) complexes with chelating imidazolium and benzimidazolium ligands in the Suzuki–Miyaura cross‐coupling reaction. The methylene‐bridged systems with aryl substituents carrying sterically and electronically different groups (F, NO2, OMe, H, Me, iPr) show good to excellent catalytic activities in the Suzuki–Miyaura cross‐coupling reaction of aryl bromides. The p‐methoxyphenyl‐substituted bis(NHC)–palladium complex was the most active one under our reaction conditions, also in the context of a wide substrate scope. Several ortho‐ as well as para‐substituted aryl bromides were coupled in excellent yields under mild reaction conditions.

We present the syntheses of 12 cyclometalated palladium C ∧ N 2-phenylimidazole carbene complexes with different N-1 groups as well as different substituents at the C-2 phenyl group of the cyclometalating imidazole. We investigated the influence of these substituents by comparing the catalytic performance of the complexes in the Suzuki−Miyaura cross-coupling reaction of aryl chlorides. We can show a strong dependence between the steric demand of the N-1 substituent of the cyclometalating imidazole and the catalytic activity in the cross-coupling reaction. The most active complex shows a wide substrate scope, where several aryl as well as benzyl chlorides could be coupled with different boronic acids in excellent yields using very low catalyst concentrations of 0.05 mol %.

Substituted imidazolium ionic liquids (ILs) were investigated for their reactivity towards Na12Ge17 as a model system containing redox‐sensitive Zintl cluster anions. The ILs proved widely inert for imidazolium cations with a 1,2,3‐trisubstitution at least by alkyl groups, and for the anion bis(trifluoromethylsulfonyl)azanide (TFSI). A minute conversion of Na12Ge17 observed on long‐time contact with such ILs was not caused by dissolution of the salt‐like compound, and did thus not provide dissolved Ge clusters. Rather, a cation exchange led to the transfer of Na+ ions into solution. In contrast, by using benzophenone as an oxidizer, heterogeneous redox reactions of Na12Ge17 were initiated, transferring a considerable part of Na+ into solution. At optimized conditions, an X‐ray amorphous product NaGe6.25 was obtained, which was thermally convertible to the crystalline type‐II clathrate Na24–δGe136 with almost completely Na‐filled polyhedral cages, and α‐Ge. The presented method thus provides unexpected access to Na24–δGe136 in bulk quantities.

1,2‐Diarylimidazoles are an important class of compounds. They are frequently used as ligands for photophysically active metal complexes and also display physiological activity. We developed a new, high‐yielding procedure for the synthesis of 1,2‐diaryl‐substituted imidazoles with sterically demanding substituents at the respective ortho positions by starting from commercially available anilines and benzoic acids through the corresponding acid chlorides. The metal‐free method provides access to a variety of different substituents on the phenyl rings at N‐1 and C‐2 as well as at the 4,5‐positions of the imidazole backbone. Our new method is also suitable for the preparation of 1‐aryl‐2‐alkylimidazoles.

We describe the synthesis, characterization, and photophysical properties of 12 neutral cyclometalated platinum(II) complexes with sterically demanding 1,2-diarylimidazole ligands and β-diketonate ancillary ligands. All complexes are photophysically active emitting in the blue-green to red region (490–590 nm) of the spectrum with quantum yields up to 58%, measured in poly(methyl methacrylate) (PMMA) at room temperature. The steric demand of the imidazole ligand as well as of the β-diketonate ligand shows a significant effect on the quantum yield but not on the emission wavelength. These can be tuned by changing the substituents at the C-2 phenyl group of the imidazole ligand.