Organometallic ionic liquids from half-sandwich Ru(II) complexes with various chelating ligands

• Organometallic ionic liquids from half-sandwich Ru(II) complexes were prepared.
• The salts exhibited high Tm and Tg values owing to the bulkiness of the ligands.
• The salts exhibited catalytic activity for the oxidation of cyclohexanol.

Salts comprising of cationic half-sandwich Ru(II) complexes with various chelating ligands and the bis(trifluoromethanesulfonyl)amide anion (Tf2N−) were prepared. These salts can be represented as [(arene)RuCl(L–L)][Tf2N] (arene = C6Me5Bu, C6Me6, p-cymene, C6H6; L–L = 2-Py-CH2NHCMe2Et, 2-Py-CHNC6H13, H13C6NHCH2CH2NHC6H13, Me2NCH2CH2SC4H9, Me2CNCHCHNCMe2). Two of the eight salts are liquids at room temperature (∼20 °C), while the other salts are solids with melting points of 60–130 °C. Upon cooling from the melt, most salts exhibited glass transitions between −30 °C and −5 °C. The salts were found to catalyze the oxidation of cyclohexanol although decomposition occurred during the reaction. Crystal structures of related salts were also determined.

Salts represented as [(arene)RuCl(L–L)]Tf2N were prepared, which contain bulky cationic half-sandwich Ru(II) complexes with various chelating ligands (L–L). Two of the eight salts are liquids at room temperature (∼20 °C), while the other salts are solids with melting points of 60–130 °C. These salts exhibited catalytic activity for the oxidation of cyclohexanol although decomposition occurred during the reaction.Figure optionsDownload as PowerPoint slide