Synthesis, characterization and behavior in water/DMSO solution of Ru(II) arene complexes with bioactive carboxylates

The reactions of [RuCl(mu-Cl)(eta(6)-p-cymene)](2) with sodium carboxylates, in methanol or acetonitrile solution, afforded the complexes [RuCl(kappa O-2-RCO2)(eta(6)-p-cymene)] (RCO2 = valproate, 1; aspirinate, 2; diclofenate, 3), in 79-96% yields. Analogously, [RuCl(kappa O-2-dfCO(2))(eta(6)-benzene)], 4, was obtained in admixture with minor by-products from [RuCl(mu-Cl)(eta(6)-benzene)](2) and sodium/silver diclofenate. The sequential reaction of [RuCl(mu-Cl)(eta(6)-p-cymene)](2) with sodium salicylate and PPh3 gave [Ru(kappa O-2,O'-salCO(2))(PPh3)(eta(6)-p-cymene)], 5, in 70% yield. The hydride complex [Ru2Cl2(mu-Cl)(mu-H)(eta(6)-p-cymene)(2)], 6, was produced in 36% yield from [RuCl(mu-Cl)(eta(6)-p-cymene)](2) and sodium formate. An optimization of the experimental work-up allowed to isolate [RuCl(mu-Cl)(eta(6)-p-cymene)](2) with an improved yield respect to the literature (98% vs. 65%). The bidentate coordination mode of the carboxylato ligands in 1-5 was unambiguously ascertained by IR and NMR spectroscopy, moreover the solid state structure of 1 was elucidated by single crystal X-ray diffraction. Complexes 1-3 experience rapid and quantitative dissociation of the carboxylato anion in DMSO/water/NaCl mixtures, mainly converting into [RuCl2(DMSO)(eta(6)-p-cymene)], 7. (C) 2018 Elsevier B.V. All rights reserved.