Ruthenium complexes containing pyridine-2,6-dicarboxylato ligands

• Seven mono- and binuclear ruthenium complexes were synthesized.
• The synthesized complexes were characterized by different spectroscopic techniques and X-ray crystallography.
• Different coordination modes of pyridine-2,6-dicarboxylate were observed.

Treatment of RuCl3·3H2O, [Et4N][RuCl4(CH3CN)2] or [Ru(DMSO)4Cl2] with the ligand pyridine-2,6-dicarboxylic acid (dipicH2) in the presence of Et3N afforded the mononuclear complex [Et3NH]2[Ru(κ3-dipic)Cl3] (1), [Et4N][Ru(κ3-dipic)(MeCN)Cl2] (2) or [Et3NH][Ru(κ3-dipic)-(DMSO)2Cl] (4), respectively, with a κ3-dipic coordination mode. Reaction of [Ru(CO)2Cl2]x or [Ru(NO)(PPh3)2Cl3] with dipicH2 in the presence of Et3N gave the mononuclear complex [Et3NH]2[Ru(κ2-dipic)(CO)2Cl2] (3) or [Et3NH][Ru(κ2-dipic)(NO)(PPh3)Cl2] (5), respectively, with a κ2-dipic coordination mode. Reaction of [Et4N][RuCl4(CH3CN)2] with dipicH2 in the presence of AgNO3 in EtOH/MeCN resulted in a dianionic Ru(III) complex, [Et4N]3[Ru(κ3-dipic)2][Ru(κ3-dipic)(κ2-dipic)Cl] (6), with the mixed κ3-dipic and κ2-dipic coordination modes. Interaction of RuCl3·3H2O with dipicH2 and Et3N gave the dinuclear Ru(III) complex [Et3NH]2[Ru(κ3-dipic)(μ2-κ1,κ2-dipic)]2 (7) with a bridging μ-κ1,κ2-dipic coordination mode. All complexes have been spectroscopically characterized along with the electrochemical analyses. The structures of 1, 2, 3·H2O, 4, 5·½Et2O, 6·CH2Cl2·C6H14, 7·CH2Cl2 have been also determined by single-crystal X-ray diffraction.

Treatment of the ruthenium starting complexes with pyridine-2,6-dicarboxylic acid (dipicH2) in the presence of Et3N gave a series of Ru(II)/Ru(III) complexes with a κ3-dipic, κ2-dipic and/or μ2-κ1,κ2-dipic coordination mode ligands. A new dinuclear ruthenium(III) complex [Et3NH]2[Ru(κ3-dipic)(μ2-κ1,κ2-dipic)]2 features a bridging μ2-κ1,κ2-dipic coordination mode is found for the dipic2− ligand.Figure optionsDownload as PowerPoint slide