Synthesis, structure and electrochemistry properties of [Ru2(CO)4]2+ complexes with di(pyridyl)pyrrolide ligands

Treatment of [Ru3(CO)12] with 2,5-di(2-pyridyl)pyrrole (HL1) and 2,5-di(2-(5-bromopyridyl)pyrrole (HL2) in refluxing toluene afforded the dinuclear Ru(I) carbonyl complexes [Ru2(CO)4(L)] (L = L1 (1), L2 (3), respectively). Alternatively, 1 along with a minor mononuclear product [Ru(CO)2(L1)2] (2) was synthesized from reaction of [Ru(CO)2Cl2]n with HL1 in methanol in the presence of triethylamine. Complexes 1–3 have been fully characterized by NMR, IR, UV–vis, ESI-MS, and elementary analysis. Single-crystal X-ray diffraction indicates that both 1 and 3 feature a Ru–Ru single bond and the di(pyridyl)pyrrolide ligands bind to the two Ru(I) centers in a μ-κ2N,N’:κ1N” chelating-bridging mode. Complex 2 is mononuclear Ru(II) complex with two κ2N,N’ di(pyridyl)pyrrolide ligand. The spectroscopic and electrochemical properties of 1 and 3 were also explored.