Synthesis of mer-[RuCl3(DMSO)(bpy)], reactivity and electrochemistry of mer-[RuCl3(DMSO)(bpy)] and mer-[RuCl3(TMSO)(bpy)] complexes

[H(DMSO)2][trans-RuCl4(DMSO)2] (1) reacts with 2,2′-bipyridine in ethanol at room temperature resulting in the formation of a major compound, mer-[RuCl3(DMSO)(bpy)] (bpy = 2,2′-bipyridine) 3 and a known minor compound, cis-[RuCl2(DMSO)4] (4). The compounds 3 and 4 are formed via an anticipated intermediate mer-[RuCl3(DMSO)3] (2). The reaction of 3 and mer-[RuCl3(TMSO)(bpy)] (5) with small molecules like imidazole, carbon monoxide and KSCN yield, mer-[RuCl3(bpy)(im)] · 2DMSO (im = imidazole) (6) and cis-[RuCl2(TMSO)(CO)(bpy)] (7), cis-[RuCl2(DMSO)(CO)(bpy)] (8) and K[RuCl3(bpy)(SCN)] (9), respectively. The formations of 3, 6 and 7 have been authenticated by single crystal structure determinations. Compound 6 is formed by the substitution of DMSO or TMSO from 3 and 5, respectively, whereas 7 and 8 are formed by unprecedented one-electron reductions of 5 and 3. The reactions of 3 and 5 with KSCN resulted in the same compound, K[RuCl3(NCS)(bpy)] (9). DFT calculations were performed to distinguish whether the thiocyanate ligand is bound to ruthenium through S or N. In the ruthenium bipyridine systems, the HOMO contains ruthenium d-orbitals and the LUMO is typically π∗-orbitals of the bipyridine ring. Complexes 3, 6 and 7 are redox active in acetone and DMSO solvent showing prominent a reduction peak and corresponding oxidation peak.

The reaction of 1 with 2,2′-bipyridine in ethanol at room temperature resulted in the formation of a major compound, mer-[RuCl3(DMSO)(bpy)] (bpy = 2,2′-bipyridine) 3. The reaction of mer-RuCl3(TMSO)(bpy)] 5 with imidazole, carbon monoxide and KSCN yield mer-[RuCl3(bpy)(im)] · 2DMSO (im = imidazole) 6 and cis-RuCl2(TMSO)(CO)(bpy)] 7 and K[RuCl3(bpy)(SCN)] 9, respectively. Ru-DMSO analogues are synthesized analogously. The compounds 3, 6 and 7 are characterized by X-ray diffraction. The Compound 6 is formed by the substitution of TMSO or DMSO frommer-RuCl3(TMSO)(bpy)] and 3, respectively, whereas 7 and 8 are formed by unprecedented one-electron reductions of 5 and 3. The reactions of 3 and 5 with KSCN resulted in the same compound, K[RuCl3(NCS)(bpy)] 9. Replacing S-bonded TMSO or DMSO from 5 and 3, respectively forms the N-bonded thiocyanate complex 9.Figure optionsDownload as PowerPoint slide