Chalcogen Bond versus Halogen Bond: Changing Contributions in Determining the Crystal Packing of Dihalobenzochalcogenadiazoles

In the crystals of 4,7-dihalobenzo[c][1,2,5]chalcogenadiazoles, the molecules are connected by two competing secondary bonding interactions: chalcogen bond (ChB) and halogen bond (HaB). Because the strengths of ChB and HaB change according to the kind of chalcogen (E: S, Se, Te) and halogen (X: Cl, Br, l), their relative contributions in determining the crystal packing can also change. Six newly determined crystal structures as well as 3 previously reported structures can be categorized into two groups: ChB-dominant and HaB-dominant structures. HaB in which X = I is strong enough to dictate the crystal packing of compounds with E = S and Se, but not where E = Te, whereas HaB in which X = Cl or Br has little effect on ChB-dominant molecular networks in crystals. The observed changing contributions of ChB and HaB may be useful for designing new supramolecular synthons for crystal engineering.

Automated summary

In the crystals of 4,7-dihalobenzo[c][1,2,5]chalcogenadiazoles, the molecules are connected by competing chalcogen bond (ChB) and halogen bond (HaB). The relative contributions of ChB and HaB in determining the crystal packing can change depending on the type of chalcogen and halogen. This observation may be useful for designing new supramolecular synthons for crystal engineering.