THE CRYSTAL-STRUCTURES AND SPECTRAL BEHAVIOR OF BENZO-15-CROWN-5 ADDUCTS WITH HYDRATED LANTHANIDE PICRATES

A new series of benzo-15-crown-5 adducts with hydrated lanthanide (La, Pr, Nd, Sm, Eu, Gd, Er) picrates has been obtained. Elemental analyse s indicated that their stoichiometry is 1:2:3 (metal:benzo-15-crown-5: picrate) except for the lanthanum adduct. X-ray structural analysis of the Nd, Sm and Er adducts revealed that Nd, Sm or Er ions coordinate directly with water molecules and the picrate anion. The benzo-15-crow n-5 acts as a second-sphere ligand which associates with the Nd, Sm or Er ion through hydrogen bonding by coordinating water molecules. From investigation of the IR and UV-vis spectra of the adducts, it can be deduced that the adducts, except lanthanum, exhibit a similar molecula r structure to that of the Nd, Sm and Er adducts. These new adducts ma y also be classified as supermolecules because each is an associate of two chemical species of hydrated lanthanide picrate and benzo-15-crow n-5 held together by coordination water molecules. Copyright (C) 1996 Elsevier Science Ltd