Unexpected formation and structure elucidation of mer-[RuCl3(TMSO)(bpy)] derived from [H(TMSO)][trans-RuCl4(TMSO)2] under mild condition

Treatment of [H(TMSO)][trans-RuCl4(TMSO)2] (1) with 2,2′-bipyridine (bpy) in ethanol at room temperature resulted an unknown mer-[RuCl3(TMSO)(bpy)] (3) and a known cis-[RuCl2(TMSO)4] (4) (TMSO = tetramethylene sulfoxide) complexes. The 3 was obtained by the substitution with bpy in mer-[RuCl3(TMSO)3] (2), whereas 4 was obtained by one-electron reduction of 2, suggesting that 2 is a precursor for both 3 and 4. The structure of 3 was determined by single crystal X-ray diffraction. The reaction is a new synthetic procedure for 3 and/or 3 and 4 in mild reaction conditions from the anionic complex 1. It involves simultaneous substitution and redox reaction. This is the first known example of precisely characterized Ru(III)-chloride–TMSO–bpy-complex derived from anionic [H(TMSO)][trans-RuCl4(TMSO)2] at room temperature.