Synthesis, Structure, and Redox Properties of Dinuclear Ruthenium Complexes Connected by Bis(ethynyl)thiophene and Bis(ethynyl)benzene

Two binuclear ruthenium complexes featuring σ‑acetylide bridged [{Ru(bpy)(PPh3)2(MeCN)}2(μ‑C≡C–R–C≡C)] with R = 2,5‑thiophenediyl (I) or 1,4‑benzenediyl (II) were synthesized by reacting [Ru(bpy)(PPh3)2(MeCN)2]2+ with the corresponding silyl‑protected dialkynes Me3Si–C≡C–R–C≡C–SiMe3 in the presence of K2CO3. In each complex, the ruthenium center is chelated by a 2,2'‑bipyridyl (bpy) ligand and connected through π‑conjugated 2,5‑thiophene or 1,4‑phenylene spacers. Both compounds were fully characterized by microanalysis, 1H and 31P{1H} NMR spectroscopy, and ESI‑mass spectrometry. The solid‑state structure of complex I was unambiguously determined by single‑crystal X‑ray diffraction. Furthermore, the electrochemical and photophysical properties of these complexes have been investigated.