CRYSTAL STRUCTURE OF ALPHA -CYCLODEXTRIN-ACETONITRILE-HEXAHYDRATE

: Crystals of the ternary alpha-cyclodextrin-acetonitrile hexahydrate inclusion complex belong to the orthorhombic space group P212121 with unit cell dimensions a = 9.479(2), b = 14.323(4), c = 37.397(9) A. Refinement against 4202 X-ray diffraction data converged at R=0.059. The alpha-cyclodextrin macrocycle forms a regular torus which is stabilized by intramolecular O-3-O-2 hydrogen bonds between neighboring glucose units. Within the cavity, one acetonitrile and one water molecule are located with occupancy factors of 0.8 and 0.7. respectively. They are hydrogen bonded to disordered O65B, and acetonitrile is stabilized in position by C-5-H...N interactions. The remaining five water molecules link symmetry related cyclodextrin molecules.