Hydrogen vs. halogen bonding in crystals of 2,5-dibromothiophene-3-carboxylic acid derivatives

The competition between hydrogen (HB) and halogen (HaB) bonding in crystal structures of 2,5-dibromothiophene-3-carboxylic acid derivatives such as amides, esters, hydrazide and hydroxamic acid was studied by the analysis of both literature and newly obtained X-ray structures. It was found that the oxygen atom of carbonyl group either is involved in Br center dot center dot center dot O HaB or form NH center dot center dot center dot O HB with acidic protons of amide moieties and the latter interaction is more preferably. Theoretical calculations including topological analyses of the electron density distribution (QTAIM) and noncovalent interactions (NCI) approach were performed to prove the existence of these interactions and clarify their noncovalent nature. (c) 2022 Elsevier B.V. All rights reserved.

Automated summary

The competition between hydrogen bonding and halogen bonding in crystal structures of 2,5-dibromothiophene-3-carboxylic acid derivatives was studied. It was found that the oxygen atom of the carbonyl group forms preferential interaction with the acidic protons of the amide moieties. Theoretical calculations confirmed the presence of these interactions and clarified their noncovalent nature.