Extraction properties for alkali metal picrates of macrocyclic trinuclear (p-cymene)ruthenium(II) and (pentamethylcyclopentadienyl)rhodium(III) complexes

The extraction equilibria of [(p-cymene)Ru(2,3-dioxopyridine)]3 and [Cp∗Rh(2,3-dioxopyridine)]3 for Li+, Na+, and K+ picrates have been investigated in a dichloromethane-water system at 25 °C. These macrocyclic organometallic compounds extract the alkali metal picrates with unusually slow rate; however, their extractability and selectivity for Li+ are very high compared to 6,6-dibenzyl-14-crown-4 which is one of the best Li+-selective crown ethers.