Synthesis, characterization and crystal structures of silver(I)– and gold(I)–N-heterocyclic carbene complexes having benzimidazol-2-ylidene ligands

•New allyl and nitrile substituted benzimidazolium salts were prepared.•Ag– and Au–N-heterocyclic carbene complexes were prepared.•All complexes are almost linearly coordinated by two NHC ligands.•Both, salts and carbene complexes were successfully characterized.

A series of N,N′-disubstituted benzimidazolium salts (1–3) were prepared via the successive N-alkylation method. Cationic, linearly coordinated silver(I)–NHC complexes (4–6) were synthesized in good yield by the reaction of Ag2O with salts 1–3. The corresponding cationic gold(I)–NHC complexes (7–9) of silver(I)–NHC derivatives were prepared by the technique of transmetallation at mild reaction condition. The new azolium salts and their carbene complexes were characterized by 1H and 13C NMR and FTIR spectroscopy, and elemental analysis. Additionally, benzimidazolium salts 2 and 3, silver(I)–carbene complexes 4a and 6a, and gold(I)–carbene complex 8 were structurally characterized by single crystal X-ray diffraction technique.

Graphical abstractA series of N,N′-disubstituted benzimidazolium salts and their silver(I)– and gold(I)–carbene complexes are reported. The new azolium salts and their carbene complexes were characterized by spectroscopic and analytical techniques.Figure optionsDownload full-size imageDownload as PowerPoint slide