LiBF4-Induced Rearrangement and Desymmetrization of a Palladium-Ligand Assembly

Thirteen palladium-ligand assemblies with different structures and topologies were investigated for the ability to bind lithium ions. In one case, the addition of LiBF4 resulted in a profound structural rearrangement, converting a dincluclear [Pd2L4](4+) complex into a low-symmetry [Pd4L8](8+) assembly with two binding pockets for solvated LiBF4 ion pairs. The rearrangement could only be induced by Li+, indicating highly specific host-guest interactions. A structural analysis of the [Pd4L8](8+) receptor revealed a compact structure with multiple intramolecular interactions, reminiscent of what is seen for natural and synthetic foldamers.