CRYSTAL-STRUCTURE OF AN UNCOMPLEXED 25-CROWN-7 COMPRISING ONE 2,6-PYRIDINO AND 2 1,4-BENZO CONDENSATIONS

Single crystal X-ray analysis of the uncomplexed crown macroring 1 is reported. Crystals are triclinic, P $($) over bar$$ 1, with a = 10.809 (1), b = 10.945(1), c = 10.256(1) Angstrom, alpha = 107.85(1), beta = 104.15(1), gamma = 87.27(1)degrees, D-c = 1.318 g cm(-3), Z = 2. Three torsion angles in the macrocycle take up gauche conformations in cont rast to the usual anti conformation. The crystal structure is stabiliz ed by intramolecular van der Waals forces and weak C-H...O and C-H...N hydrogen bond attractions. Stacking of pyridine rings is a noticeable packing feature in the crystal lattice.