The Amine Group as Halogen Bond Acceptor in Cocrystals of Aromatic Diamines and Perfluorinated Iodobenzenes

In order to study the proclivity of primary amine groups act as halogen bond acceptors, three aromatic diamines (p-phenylenediamine (pphda), benzidine (bnzd) and o-tolidine (otol)) were cocrystallised with perfluorinated iodobenzenes (1,4-tetrafluorodiiodobenzene (14tfib), 1,3-tetrafluorodiiodobenzene (13tfib) 1,3,5-trifluorotriiodobenzene (135tfib)) donors. Five cocrystals obtained: (pphda)(14tfib), (bnzd)(13tfib)2, (bnzd)(135tfib)4, (otol)(14tfib) (otol)(135tfib)2. spite variability both stoichiometries structures cocrystals, in all prepared form exclusively I···N bonds, while hydrogen atoms participate mostly N–H⋯F contacts. The preference nitrogen atom toward bond, opposed (with a donor), is rationalised by means computed energies, indicating that energy between simple (methylamine) iodobenzene (pentafluoroiodobenze ne) ca. 15 kJ mol−1 higher than (H)NH∙∙∙NH2 two molecules.