Work

Unique halogen–π association detected in single crystals of C–N atropisomeric N -(2-halophenyl)quinolin-2-one derivatives and the thione analogue

Year: 2025

Type: article

Abstract: In single crystals of C–N atropisomeric N -(2-halophenyl)quinolin-2-one and the thione analogue, a unique association based on a halogen–π interaction was detected. In racemic and optically pure N -(2-bromo- or 2-chlorophenyl)quinolin-2-ones, homochiral layered polymers, which consist of ( P )- or ( M )-atropisomers, were formed through intermolecular halogen–π association. The halogen–π association in the racemates is due to a halogen bond (C–X···π) between a σ-hole on the halogen atom and a π-electron on the quinolinone benzene ring, while that in optically pure forms is caused by an n–π* interaction between a lone electron pair on the halogen atom and a π* orbital of the quinolinone. In contrast to the formation of the homochiral layered polymer in quinolinones, in racemic N -(2-bromophenyl)quinoline-2-thione, heterochiral layered polymers, in which ( P )- and ( M )-atropisomers were alternately connected, were formed through an n–π* interaction between a lone electron pair on the bromine atom and a π* orbital of the quinoline-2-thione.

Source: Beilstein Journal of Organic Chemistry

DOI: 10.3762/bjoc.21.138