Crystal structures of 5-bromo-1-arylpyrazoles and their halogen bonding features

Single crystal X-ray diffraction analysis was employed to investigate the supramolecular properties of five 5-brominated pyrazoles in order to evaluate the role of the Br atom in the formation of halogen bonding duly recognizing that the Br atom is less polarizable than the iodine atom. Hirshfeld analysis was employed to conceive a more descriptive image of the halogen bond propensity of 5-bromopyrazoles. The compounds display Br center dot center dot center dot O contacts or Br center dot center dot center dot Br as type I or type II halogen contacts. The structural analyses revealed the isostructurality of compounds 2 and 3 while compound 5 was found to be isostructural with its iodo-analogue, suggesting the importance of the halogen contacts even if they are considered weak in nature.

Automated summary

Single crystal X-ray diffraction analysis and Hirshfeld analysis were used in this study to investigate the supramolecular properties of five 5-brominated pyrazoles. The results revealed the formation of Br·O or Br·Br type halogen contacts in these compounds. Structural analysis showed the isostructurality of compounds 2 and 3, while compound 5 was found to be isostructural with its iodo-analogue, indicating the importance of halogen contacts in these compounds.