Theoretical analysis of the crystal packing of nitronyl nitroxide radicals: the packing of the α-2-hydro nitronyl nitroxide radical

The crystal packing of the simplest member of the nitronyl nitroxide familyof compounds, the 2-hydro nitronyl nitroxide radical in its α phase, is analyzed by means of a combination of distance analysis and accurate ab initio computations using correlated methods and extended basis sets. The packing is found to be driven by two types of intermolecular interactions, the C(sp2)H ··· ON and C(sp3)H ··· ON interactions, both of them found to be stable by ab initio computations (by −3.71 and −0.40 kcal/mol, respectively). The packing can be rationalized as planes kept together by C(sp2H ··· ON interactions. The planes are then linked by C(sp3)H ··· ON interactions.