Arene ruthenium bis-saccharinato complexes: Synthesis, molecular structure and catalytic oxidation properties in aqueous solution

Arene ruthenium complexes [(η6-arene)Ru(sacc)2(OH2)] (arene = para-cymeme, benzene) containing an aqua and two saccharinato ligands have been synthesized from [(η6-arene)RuCl2]2 and sodium saccharinate in a water-ethanol mixture (1:1). The aqua complex [(η6-MeC6H4Pri)Ru(sacc)2(OH2)] reacts with acetonitrile to give the acetonitrile complex [(η6-MeC6H4Pri)Ru(sacc)2(NCMe)]. The corresponding benzene derivative [(η6-C6H6)Ru(sacc)2(NCMe)] was obtained from [(η6-C6H6)RuCl2]2 and saccNa in an acetonitrile-methanol mixture (1:1). All new complexes show a piano-stool geometry with two mono-hapto nitrogen-bonded saccharinato ligands in addition to a H2O or MeCN ligand. All complexes of the type [(η6-arene)Ru(sacc)2(OH2)] and [(η6-arene)Ru(sacc)2(NCMe)] were found to catalyze the oxidation of secondary alcohols with tert-butyl hydroperoxide (ButOOH) to give the corresponding ketones in aqueous solution.

The new arene ruthenium bis-saccharinato complexes of the type [(η6-arene)Ru(sacc)2(OH2)] and [(η6-arene)Ru(sacc)2(NCMe)] catalyze the oxidation of secondary alcohols to give the corresponding ketones in aqueous solution with turnover frequencies up to 33000 h−1.Figure optionsDownload as PowerPoint slideHighlights
► Two series of arene ruthenium bis-saccharinato complexes have been prepared.
► X-ray analysis reveals an aqua ligand hydrogen-bridged by the saccharinato ligands.
► All complexes catalyze the oxidation of secondary alcohols in aqueous solution.