High symmetry crystal supramolecularity: –XPh3 molecules in cubic lattices

Abstract

The majority of molecular crystals in the Cambridge Structural Database involve relatively low symmetry molecules, engaged by intermolecular interactions with restricted symmetry, resulting in the preponderant occurrence of a small number of relatively low symmetry crystallographic space groups as expounded by Brock and Dunitz. We are examining some contrasting crystal structure types that contain higher symmetry molecules involved in high symmetry intermolecular motifs and generating high symmetry space groups. This paper considers molecules containing XPh₃ groups, engaged in multiple phenyl embraces with local S₆ () symmetry, generating crystal lattices with cubic symmetry. The conceptual framework for these analyses also involves the presence, symmetry, and occupancy of cavities in high symmetry lattices, with extensions to crystal trapping of unusual species such as [Cu₂Br₅]²⁻ and [Cu₈Br₁₅]⁶⁻. The compounds included in the analyses of crystal packing and symmetry in this paper are (MePh₃P⁺)₂[Cu₂Br₅]²⁻, Ph₃POGaCl₃ , Ph₃AsI₂ , N(Ph-2-OMe)₃ , Ph₃SnCl, Ph₃PAuCCAuPPh₃·(C₆H₆)₂ , Ph₃PAu(B₆H₆)AuPPh₃ , (Ph₃PH⁺)₂[SnCl₆]²⁻, and (Ph₃MeP⁺)₆ [Cu₈Br₁₅]⁶⁻. Concerts of edge-to-face (EF) and offset-face-to-face (OFF) local interactions between phenyl groups generate bimolecular (EF)₆ = 6PE with symmetry S₆ , hexamolecular (EF)₆ with symmetry S₆ , trimolecular (EF)₃ , hexamolecular (OFF)₆ , and two-dimensional {(OFF)₆}_∞ . Crystal supramolecular analysis includes description of the asymmetric segments of intermolecular motifs, as well as the conventional asymmetric sector of the molecule.