Bimetallic Ru(II)–Ir(III) complexes with bridging 2,2′‐bipyrimidine: Synthesis, structures and characterization

In this work, four bimetallic Ru(II)–Ir(III) complexes with the general formula [(bpy) 2 Ru(bpm)Ir(C^N) 2 ](PF 6 ) 3 (bpy = 2,2‐bipyridine, bpm = 2,2′‐bipyrimidine, C^N = 2‐phenylpyridinato ( 2 ), (2‐ p ‐tolyl)pyridinato ( 3 ), 2‐(2,4‐difluorophenyl)pyridinato ( 4 ), and 2‐thienylpyridinato ( 5 )) were synthesized. Complexes 2 – 5 were characterized by NMR spectroscopy, high‐resolution mass spectrometry, and elemental analysis. The structures of the complexes 2 and 4 were further confirmed by single‐crystal X‐ray diffraction analysis. All the complexes display strong absorption in the high‐energy UV region assigned to intraligand (IL) transitions, and the lower energy bands are ascribed to metal‐to‐ligand charge transfer (MLCT) transitions. The reduction and oxidation behavior of the complexes 2 – 5 were examined by cyclic voltammetry. Variation of the ligands on Ir(III) center resulted in significant changes in electrochemical properties.