THE LOCATION OF P-DICHLOROBENZENE IN A SINGLE-CRYSTAL OF ZEOLITE H-ZSM-5 AT HIGH SORBATE LOADING

The crystal structure of a high-loaded complex of H-ZSM-5 with eight m olecules of p-dichlorobenzene per unit cell has been solved by single- crystal X-ray diffraction. The orthorhombic space group P2(1)2(1)2(1) with a = 20.102 (6), b = 19.797 (9), c = 13.436 (3) Angstrom and V = 5 347 (3) Angstrom(3) has four Si23.92Al0.08O48.2C(6)H(4)Cl(2) units per unit cell. D-x = 2.164 Mg m(-3), lambda(MoK alpha) = 0.71073 Angstrom and mu(MoK alpha) = 0.876 mm(-1). The final R(wR) = 0.046 (0.039), w = 1/sigma(2)(F), for 6090 observed reflections with I > 1.0 sigma(I) m easured at 293 K. The straight channel parallel to [010] is slightly c orrugated. The elliptical cross sections have limiting apertures of 6. 0 x 4.9 Angstrom (r(oxygen) = 1.35 Angstrom). The sinusoidal channel p arallel to [100] is elliptical with major and minor axes of 6.1 x 4.8 Angstrom, respectively. One of the two independent p-dichlorobenzene m olecule lies at the intersection of the straight and sinusoidal channe ls with its long molecular axis almost parallel to (100) and deviating similar to 8 degrees from [010]. The second p-dichlorobenzene molecul e is in the sinusoidal channel. Its long molecular axis deviates almos t 7 degrees from [100] and is practically parallel to (010). The struc tural aspects are in all details comparable to those in the high-loade d H-ZSM-5/p-xylene complex [van Koningsveld, Tuinstra, van Bekkum & Ja nsen (1989). Acta Cryst. B45, 423-431], except for the main interactio n forces between the p-dichlorobenzene molecules at the channel inters ection.