Influence of Deuteration and Fluorination on the Supramolecular Architecture of Pyridine N-Oxide Crystals

To understand how deuterium and fluorine substituents influence the supramolecular architecture of pyridine N‐oxide crystals, the crystal structure of 3‐fluoropyridine N‐oxide (PNO‐3F) was determined and the crystal packing motives of non‐deuterated pyridine‐N‐oxide (PNO), partial‐deuterated pyridine‐N‐oxide (PNO‐D) and PNO‐3F were analyzed based on ab initio quantum‐chemical calculations of the intermolecular interaction energy, using the MP2/6‐311G(d,p) method. The appearance of the weak‐directing substituents deuterium and fluorine leads to significant changes in the crystal organization of the isotropic packing of PNO molecules. Weak but strong: The weak directing substituents deuterium and fluorine lead to significant changes in the crystal organization of the isotropic packing of pyridine‐N‐oxide molecules.