CRYSTAL-STRUCTURE OF 9(10-METHYL)-ACRIDINIMINE HYDRIODIDE - LATTICE ENERGETICS OF THE COMPOUND AND HALIDE SALTS OF NITROGEN ORGANIC-BASES

The crystal structure of hydriodide of 9(10-methyl)-acridinimine, the cation of which originates from the imino tautomeric form of 9-acridin amine, was determined by X-ray analysis (monoclinic; space group P2(1) /c; Z=4; R=0.0368 for 1651 observed reflections). The bond between the egzocyclic N atom and the acridine moiety retains a length typical fo r double bonds, while lengths of adjacent C-C bonds are contained betw een those characteristic for single and aromatic bonds. The central ri ng system is strongly conjugated with the side rings through bonds at the endocyclic N atom which results in the acridine skeleton being alm ost planar. For this molecule and fifteen halide salts of simple nitro gen organic bases, the electrostatic, dispersive and repulsive contrib utions to the lattice energy were evaluated, boiling down the problem of intermolecular interactions to atom - atom interactions. Coulombic energies arising from charges fitted to the molecular electrostatic po tential on the DFT level, compare well with experimental values of the crystal lattice energy and show a decreasing tendency with growth of dimensions (volume of a stoichiometric unit) of interacting ions.