The title compound, C15H11N2+.HN2O6-, crystallizes in the monoclinic space group C2/c with four molecules in the unit cell. The planar 9-cyano-10-methylacridinium cations lie on crystallographic twofold axes and are arranged in layers, almost perpendicular to the ac plane, in such a way that neighbouring molecules are positioned in a 'head-to-tail' manner. These cations and the hydrogen dinitrate anions are linked through C-H...O interactions involving four of the six O atoms of the anion and the H atoms attached to the C atoms of the acridine moiety in ring positions 2 and 4. The H atom of the hydrogen dinitrate anion appears to be located on the centre of inversion relating two of the four O atoms engaged in the above-mentioned C-H...O interactions. In this way, columns of either anions or cations running along the c axis are held in place by the network of C-H...O interactions, forming a relatively compact crystal lattice.
The deprotonation of the cationradical of 9-cyanomethylacridane by a series of normal bases is investigated and its pKa and homolytic bond dissociation energy determined experimentally. The latter parameter has the largest value in the NADHanalogue series, thanks to the strong destabilization of the corresponding cation by the cyano group. It thus allows a significant extension of the attempted correlation
Compounds of the formula I ##STR1## in which the general symbols are as defined in claim 1, as stabilizers for organic materials against thermal, oxidative or light-induced degradation are described.
Es werden Verbindungen der Formel I,
worin die allgemeinen Symbole wie in Anspruch 1 definiert sind, als Stabilisatoren für organische Materialien gegen thermischen, oxidativen oder lichtinduzierten Abbau beschrieben.