Crystal structures of secondary arenedicarboxamides. An investigation of arene-hydrogen bonding relationships in the solid state

The crystal structures of a family of six secondary arenedicarboxamides have been determined. Four rodlike arenedicarboxamides pack in one-dimensional tapes in which the hydrogen-bonded scaffold holds adjacent arenes at a fixed separation of 5 Angstrom. The dihedral angles between the planes of adjacent arenes range from 0 degrees (face to-face) to 68 degrees (edge-to-face). Two naphthalenedicarboxamides pack in two-dimensional sheets. The 2,6-naphthalenedicarboxamide packs in a highly puckered single-layer sheet with no arene-arene close contacts. The 1,4-naphthalenedicarboxamide packs in an unusual bilayer sheet with partial face-to-face overlap of naphthalenes from adjacent sheets. Force field calculations indicate that electrostatic interactions are dominated by hydrogen bonding within a single tape or sheet and that the energetics of crystal packing in tapes or sheets are very similar. Thus, the nonbonded interactions between neighboring tapes or sheets play an important role in the determination of the packing motif. In the case of the tape structures, adjacent tapes have close-packed edge-to-face or herringbone arene-arene interactions, whereas the sheet structures display pi-stacking and C=O...H-C hydrogen bonding.