Single-Crystal Structures of the o-, m-, and p-Xylene Sorption Complexes of Fully Dehydrated, Fully Mn2+-Exchanged Zeolite Y (FAU)

Abstract

Three single crystals of zeolite Y, each 0.3 mm in diameter, fully exchanged with Mn2+ and fully dehydrated, were treated with zeolitically dry o-, m-, and p-xylene, respectively, at 297(1) K, followed by evacuation. Their crystal structures were determined by synchrotron X-ray diffraction techniques in the space group Fd3m at 100(1) K and were refined using all intensities to the final error indices R1/wR2 = 0.056/0.160, 0.080/0.217, and 0.066/0.177, respectively. In each structure, Mn2+ ions occupy sites I, I′, II′, and II. In each structure, 18 Mn2+ ions per unit cell at site II (on the 3-fold axes of the single 6-rings) each extend 0.63, 0.68, and 0.67 A into the supercage to coordinate facially to an o-, m-, and p-xylene molecule, respectively. The corresponding distances from Mn2+ to the centers of the xylene rings are 2.67, 2.65, and 2.63 A. The methyl groups are all somewhat off the planes of their rings, indicative of a net repulsive interaction with oxygen atoms of the zeolite framework. The h...