Lanthanoid Heteroleptic Complexes with Cucurbit[5]uril and Dicarboxylate Ligands: From Discrete Structures to One-Dimensional and Two-Dimensional Polymers.

Abstract

Lanthanoid heteroleptic complexes with cucurbit[5]uril {Q[5]} and two dicarboxylate ligands, e.g., diglycolic acid (H2DGC) and glutaric acid (H2GT), have been investigated with six new compounds featuring a tetrametallic and dimetallic discrete structures, a one-dimensional (1D) polymer, and three two-dimensional (2D) polymers with a unique honeycomb-type topology being synthesized and structurally characterized. [La4(Q[5])3(DGC)2(NO3)2(H2O)12][La(DGC)(H2O)6]·7NO3· nH2O (1) has a tetrametallic structure constructed with three bis-bidentate Q[5] ligands linking two [La(DGC)(H2O)2]+ species in the middle and two [La(H2O)4(NO3)]2+ species at both ends. [Ce2(Q[5])(DGC)(NO3)(H2O)10]·3NO3·4H2O (2) has a dimetallic structure built up with a bis-bidentate Q[5] ligand linking [Ce(DGC)(H2O)3(NO3)] and [Ce(H2O)7]3+ on each side of the Q[5] portals. [Ce3(Q[5])3(DGC)2(H2O)9][Ce(DGC)(H2O)6]2·7NO3· nH2O (3) has a 1D polymeric structure built up with bis-bidentate Q[5] ligands in-turn linking one [Ce(H2O)6]3+ and two [Ce(DGC)(H2O)6]1+ cationic species. [Ln2(Q[5])2(GT)(H2O)6]·4NO3· nH2O [Ln = La (4), Ce (5) and Nd (6)] have similar 2D polymeric structures built up with two types of 9-fold coordinated Ln polyhedra linked by Q[5] via bis-bidentate carbonyl groups on both sides forming 1D chains which are further connected by bridging GT2- ligands to form 2D polymers with a unique honeycomb-type topology. Their vibrational modes and electronic structures have also been investigated.