Complexation of crown ethers and heteroanalogs of 18-crown-6 with alkali and alkaline earth metal cations in dichloroethane

Data on the complexing ability of a series of crown ethers and heteroanalogs of 18-crown-6, containing S-, SO-, SO₂- and SONH fragments at the 1- and 10-positions of the macrocyclic ring, with Li, Na, K, Mg and Ba picrates in dichloroethane were obtained from the solubility of the salts in the presence of the crown compounds. It was found that 18-crown-6 is the best but the least selective ligand of all the picrates, while polyethers with SO- and SONH fragments show an appreciable selectivity toward Li⁺, and to a lesser extent, toward Mg⁺. The complexing ability of the disulfone ligand is inappreciable under the conditions studied. A 11 stoichiometry of the complexes has been found for the individual crown-picrate pairs.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 24, No. 2, pp. 191–196, March–April, 1988.