Mechanochemical synthesis and X‐ray structural characterization of three 3‐nitrophenol cocrystals with three aminal cage azaadamantanes: the role of the stereoelectronic effect on intermolecular hydrogen‐bonding patterns

The structures of the cocrystalline adducts of 3‐nitrophenol (3‐NP) with 1,3,5,7‐tetraazatricyclo[3.3.1.1^3,7]decane [HMTA, ( 1 )] as the 2:1:1 hydrate, 2C₆H₅NO₃·C₆H₁₂N₄·H₂O, ( 1a ), with 1,3,6,8‐tetraazatricyclo[4.3.1.1^3,8]undecane [TATU ( 2 )] as the 2:1 cocrystal, 2C₆H₅NO₃·C₇H₁₄N₄, ( 2a ), and with 1,3,6,8‐tetraazatricyclo[4.4.1.1^3,8]dodecane [TATD, ( 3 )] as the 2:1 cocrystal, 2C₆H₅NO₃·C₈H₁₆N₄, ( 3a ), are reported. In the binary crystals ( 2a ) and ( 3a ), the 3‐nitrophenol molecules are linked via O—H…N hydrogen bonds into aminal cage azaadamantanes. In ( 1a ), the structure is stabilized by O—H…N and O—H…O hydrogen bonds, and generates ternary cocrystals. There are C—H…O hydrogen bonds present in all three cocrystals, and in ( 1a ), there are also C—H…O and C—H…π interactions present. The presence of an ethylene bridge in the structures of ( 2 ) and ( 3 ) defines the formation of a hydrogen‐bonded motif in the supramolecular architectures of ( 2a ) and ( 3a ). The differences in the C—N bond lengths of the aminal cage structures, as a result of hyperconjugative interactions and electron delocalization, were analysed. These three cocrystals were obtained by the solvent‐free assisted grinding method. Crystals suitable for single‐crystal X‐ray diffraction were grown by slow evaporation from a mixture of hexanes.