Crystal Structure of Halogenated N-Methylquinoline-2-Ones: Preparation and Study of Intermolecular Interactions in Crystals

A series of novel N-methylquinoline-2-ones with a fluorinated benzene ring (with and without Br atoms) is prepared by the interaction of halogenated quinoline-2-ones with CH₃I in methanol in the presence of KOH. The molecular and crystal structures of these compounds are determined by XRD. It is shown that the main structure-forming interaction in the crystals of these compounds is π-staking, while the main supramolecular motif is formed by the π-stacks of molecules resulting from the expected π–π-interaction between the electron-deficient haloarene species and a more electron-donating pyridinone ring (fluoroarene–fluoroarene interactions are also present). In all cases, the intra-stack molecular packing changes noticeably upon the transition from fluorinated N-methylfluoroquinoline-2-ones to their bromine-containing derivatives: the lateral shift increases, the Br…π interactions appear. The Br atoms form Br…F or Br…Br intermolecular interactions.