Evaluation of 6‐Halogenated 2‐Pyridone Moieties as Halogen Bond Donors.

6‐Halo‐2‐pyridones and their pyridol tautomers show different grades of polarization on their halogen substituents in DFT calculations. This and the fact that the tautomeric equilibrium is affected by the surrounding medium make them interesting candidates for a new platform of halogen bond donors. We therefore probed four simple halopyridones for their halogen bonding properties both in the solid state and in solution. Concurring with hydrogen bonding, halogen bonding indeed is found to be an interaction governing the packing motif in pyridone crystals, which is more pronounced in N‐methylated congeners. Solution studies using a halide abstraction reaction, and NMR titrations against bromide salts, however, showed no clear evidence for halogen bonding in solution. [ABSTRACT FROM AUTHOR]