Crystal supramolecular motifs. Ladders, layers and labyrinths of Ph4P+ cations engaged in fourfold phenyl embraces

Abstract

Tetraphenylphosphonium cations in crystals associate with attractive fourfold phenyl embraces (4PE), in which two phenyl rings from each cation engage in concerted edge-to-face and offset-face-to-face local interactions. The names of the orthogonal (O4PE) and parallel (P4PE) subclasses refer to the relationship between the relevant C–P–C planes in the two cations. One-dimensional ladder networks with O4PE along the sides and P4PE as rungs, and two-dimensional networks with O4PE in both directions, P4PE in both directions, or O4PE in one direction and P4PE in the other have been explored. The layers can be planar or corrugated. Crystalline [Ph₄P⁺][Cl₃Te(OCH₂CH₂O)]^– contains a zeolite-like network of cations involved in 4PE, with the anions in channels. Most of the crystals included in this survey contain mono-negative anions, ranging from Cl₃^– to metal complexes with chelate ligands, and include structurally non-molecular anions such as [{Cu₄I₅ReS₄}^2–]_∞. The crystalline compound [Ph₄P⁺]₂[C₆₀]^–[I^–]_x contains a high symmetry two-dimensional network of cations in P4PE, which functions as an effective host lattice completely encapsulating the [C₆₀]^–, with phenyl· · ·fullerene interactions which are both face-to-face and edge-to-face.