Fluorite topology in lanthanoid coordination polymers with Di- and trimetallic building blocks

摘要

Reaction of the pseudotetrahedral tetracarboxylic acid proligand tetrakis(4-carboxyphenyl)silane (H _4L) with salts of various lanthanoid metals has afforded three new lanthanoid coordination polymers: {[H _3O] _2[Ce _2(L) _2(H _2O) _2]?2DMF?2H _2O} _∞ (1), {[Eu _3L _2(NO _3)(DMF) _4(H _2O)] ?0.5DMF?6H _2O} _∞ (2), and {Eu(HL)(DMF) _2(H _2O)]?DMF?2.5H _2O} _∞ (3) (DMF = N,N′-dimethylformamide), which have been structurally characterized by single-crystal X-ray diffraction. Compounds 1 and 2 are both noninterpenetrated three-dimensional networks that display the rare fluorite (CaF _2) topology. In compound 1, the fully deprotonated L ~(4-) ligands act as pseudotetrahedral 4-connecting nodes and dinuclear cerium-carboxylate building blocks act as 8-connecting nodes, while in compound 2 the L ~(4-) ligands and trinuclear europium-carboxylate units are 4- and 8-connecting, respectively. In contrast, compound 3 exhibits a two-dimensional layered structure with triply deprotonated HL ~(3-) ligands acting as 3-connecting units, linking single europium centers within each layer. Gas sorption studies of 2 show a high affinity of the pretreated microcrystalline solid for carbon dioxide gas.