Selective Extraction of Lithium with a Macrocyclic Trinuclear Complex of (1,3,5-Trimethylbenzene)ruthenium(II) Bridged by 2,3-Dioxopyridine

A macrocyclic trinuclear complex of (1,3,5-trimethylbenzene)ruthenium(II) bridged by 2,3-dioxopyridine was synthesized, and the extraction properties for lithium and sodium picrates were investigated in a dichloromethane/water system at 25°C. The complex was found to have extremely high extractability and selectivity for lithium picrate; the logarithmic values of the extraction constants are 5.86 and 2.63 for Li+ and Na+, respectively. By using this complex as an extractant, nearly quantitative extraction and separation of Li+ from Na+ could be achieved by a single extraction.