Structure of a cyclopropane sorption complex of dehydrated fully Mn2+-exchanged zeolite X

The structure of a cyclopropane sorption complex of dehydrated fully Mn2+-exchanged zeolite X, Mn46Si100Al92O384.30C(3)H(6) (a = 24.690(4) Angstrom), has been determined by single-crystal X-ray diffraction techniques in the cubic space group Fd3 at 21(1)degreesC. The crystal was prepared by ion exchange in a flowing stream of 0.05 M aqueous Mn(NO3)(2) for three days, followed by dehydration at 460 degreesC and 2 x 10(-6) Torr for two days, and exposure to 100 Torr of cyclopropane gas at 21(1)degreesC. The structure was determined in this atmosphere and was refined to the final error indices R-1 = 0.065 and R-2 = 0.071 with 509 reflections for which I > 3 sigma (I). In this structure, Mn2+ ions are located at two crystallographic sites. Sixteen Mn2+ ions fill the octahedral site I at the centers of the hexagonal prisms (Mn-O = 2.290(9) Angstrom. The remaining 30 Mn2+ ions are at site II; each extends 0.41 Angstrom into the supercage tan increase of 0.27 Angstrom upon C3H6 sorption as compared to fully dehydrated Mn46Si100Al92O384) where it coordinates to three trigonally arranged framework oxygens at 2.148(8) Angstrom and complexes weakly and facially to a cyclopropane molecule by a primarily quadrupolar interaction. The carbon atoms of each cyclopropane molecule are equivalent and equidistant from its Mn2+ ion (Mn-C = 2.95(9) Angstrom). Because of high thermal motion, the C-C bond length is inaccurately determined; the value found, 1.21(8) Angstrom, is too small. (C) 2000 Elsevier Science B.V. All rights.