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 KRuCl₃(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, KRuCl₃(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.