Mixed halobenzenes also prefer face?face approaches of aromatic rings, revealing a new inversion symthon?

CrystEngComm Pub Date: 2023-05-01 DOI: 10.1039/D3CE00276D

Abstract

Analysis of known crystal structures of halobenzenes reveals that the 176 closest intermolecular interactions contain either edge?face or face?face approaches between aromatic rings. Most of these close approaches possess the specific geometry and symmetry of π–π stacking defined as “symthon I”. A further 20 face?face approaches have similar geometry but exhibit only inversion symmetry, yielding a geometric definition for the new “symthon III”. There are 17 examples of edge?face approaches that meet the previously defined symmetry and geometric requirements for “symthon II”. The other close interactions are simple variants of these three symthons. Only symthon I accommodates halogen disorder and solid solutions – in this dataset exclusively in space group no. 14. The number (N) and disposition of halogen substituents influence the preferred symthons; for example edge?face interactions are confined to N ≤ 3. The inclusion here of halobenzenes containing more than one type of halogen completes an earlier study of unmixed halobenzenes.

Graphical abstract: Mixed halobenzenes also prefer face?face approaches of aromatic rings, revealing a new inversion symthon
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