Fluorinated Twists: A Pathway to a Stable Pd ₈ L ₁₆ Square Antiprism

Within the extensive family of Pd_<i>n</i>L_2<i>n</i> metal-organic cages, some structures are much easier to access than others. Ligands are generally constructed from planar aromatic linkers. While small structures (Pd₂L₄ to Pd₆L₁₂) and large pseudospherical structures (≥Pd₁₂L₂₄) can be readily obtained from these flat aryl-based ligands, strategies to intermediate-sized structures have remained elusive as the required angle between metal-ligand coordination vectors (90-120°) is hard to construct from the common toolkit of organic molecules. Herein, we report the Pd₈L₁₆ square antiprism as a new addition to the Pd_<i>n</i>L_2<i>n</i> family, a structure shown as thermodynamically stable in both solution and the solid state, for the first time. The ligand achieves close to the ideal angle of 105.1° needed for the square antiprism through the incorporation of a perfluorobiphenyl backbone. The substantial dihedral twist induced by the fluorines diverges the coordination vectors compared to nonfluorous examples while crucially maintaining ligand rigidity to avoid the formation of mixtures of structures─a strategy we believe will have widespread applications in (metallo)supramolecular chemistry.