Single crystal X-ray diffraction and PIXEL calculation of intermolecular pair energies, with partitioning into coulombic and dispersive factors, have been performed on the title crystals with the aim of testing the relative efficiency of molecular recognition synthons. X-Ray diffraction reveals that the crystals contain extended hydrogen-bonded layers, with various degrees of aromatic ring overlap between the layers. The calculation of molecular pair energies quantitatively reveals that the primary binding force in these crystals is hydrogen bonding, and that the areneperfluoroarene stacking mode becomes less important, or almost optional. The various degrees of offset between overlapping aromatic rings found in the present crystals, also in comparison with some non-hydrogen bonding analogs, suggest a transition from perfect, highly stabilizing ArHArF overlap, to the less favourable, but still energetically stabilizing, ArFArF and ArHArH overlaps. The selectivity towards ArHArF stacking is not overwhelming.
Competition between hydrogen bonding and arene--perfluoroarene stacking. X-Ray diffraction and molecular simulation on 5,6,7,8-tetrafluoro-2-naphthoic acid and 5,6,7,8-tetrafluoro-2-naphthamide crystals
Filippini G;Pilati T;
2009
Abstract
Single crystal X-ray diffraction and PIXEL calculation of intermolecular pair energies, with partitioning into coulombic and dispersive factors, have been performed on the title crystals with the aim of testing the relative efficiency of molecular recognition synthons. X-Ray diffraction reveals that the crystals contain extended hydrogen-bonded layers, with various degrees of aromatic ring overlap between the layers. The calculation of molecular pair energies quantitatively reveals that the primary binding force in these crystals is hydrogen bonding, and that the areneperfluoroarene stacking mode becomes less important, or almost optional. The various degrees of offset between overlapping aromatic rings found in the present crystals, also in comparison with some non-hydrogen bonding analogs, suggest a transition from perfect, highly stabilizing ArHArF overlap, to the less favourable, but still energetically stabilizing, ArFArF and ArHArH overlaps. The selectivity towards ArHArF stacking is not overwhelming.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.