CRYSTAL-STRUCTURES OF CYCLOPROPANE COMPLEXES OF COBALT(II) AND MANGANESE(II) IN PARTIALLY EXCHANGED ZEOLITE-A

被引:72
作者
CRUZ, WV [1 ]
LEUNG, PCW [1 ]
SEFF, K [1 ]
机构
[1] UNIV HAWAII,DEPT CHEM,HONOLULU,HI 96822
关键词
D O I
10.1021/ja00490a036
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
The crystal structures of the cyclopropane sorption complexes of partially Co(ll)-exchanged and partially Mn(ll)-exchanged zeolite A have been determined using X-ray diffraction data collected by counter methods. Both structures were solved and refined in the cubic space group Pm3m; at 26 (1)°, the unit cell constants are 12.147 (2) Å for CO4Na4Si12Al12O484C3H6 (unit cell stoichiometry) and 12.146 (4) Å for Mn4Na4Si12Al12O48-4C3H6. Both complexes were prepared by dehydration at 350 °C and 1 × 10-5 Torr for 48 h, followed by exposure to cyclopropane gas at approximately atmospheric pressure. In each structure, the transition metal cations are located on threefold axes inside the large cavity, close to three trigonally arranged framework oxide ions on alternate 6-oxygen rings. The metal to oxygen distances are Co(ll)-O=2.174 (7) A and Mn(ll)-O=2.122 (8) Å. Each of the four cyclopropane molecules in each structure is found to complex to a transition metal ion with Co(II)-C=2.81 (7) Å and Mn(II)-C=3.09 (6) Å. The threefold axes of the zeolite and of the sorbed molecules coincide, so that all carbon atoms in each cyclopropane molecule are equivalent and equidistant from the transition metal cation with which they are associated. In both cases, the cyclopropane molecules are loosely bound to the metal ions by a π ion to induced dipole interaction, a conclusion based on the long metal to carbon approach distances and the large anisotropic carbon thermal parameters. No interaction between Na+ ions and cyclopropane molecules is observed. Full-matrix least-squares refinement converged to weighted R indices of 0.065 for the Co(II) complex and 0.083 for the Mn(II) complex, using the 373 and 331 reflections, respectively, for which Io > 3a(lo). © 1978, American Chemical Society. All rights reserved.
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页码:6997 / 7003
页数:7
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