Charge density studies on 2,3,5,6-tetrafluoro- and pentafluoropyridine

Crystals of 2,3,5,6-tetrafluoropyridine and pentafluoropyridine have been grown by in situ methods in capillaries. The crystal structures of these compounds have been determined by X-ray diffraction up to high diffraction angles of 2θ = 100°. The charge density distributions of the crystals have been derived by multipole refinements. The charge densities of the title compounds as well as of pyridine have been calculated at the MP2(full)/cc-pVTZ level of theory. The structures are discussed with respect to differences to the non-substituted pyridine. The crystal structures are discussed with the focus on intermolecular interactions of the F⋯F, F⋯C and F⋯H type. The charge density topologies and parameters are discussed concerning atomic charges, bonding within the molecules and the nature of the intermolecular interactions. On the molecular level they are compared with those of pyridine.