CRYSTAL STRUCTURE OF CERIC AMMONIUM NITRATE

The crystal structure of ceric ammonium nitrate, (NH4)2Ce(NO3)6, has been determined from three-dimensional single¬crystal X-ray diffraction data collected by counter methods. The crystals are monoclinic, space group P21/n with unit cell parameters a = 13.061 ± 0.007, b = 6.842 ± 0.004, c = 8.183 ± 0.004 Å, β = 91.34 ± 0.02°, ρ0 = 2.49, ρ0 = 2.490 g/cm3 for 2=2. Block-diagonal anisotropic least-squares refinement led to a conventional R of 0.036 for 625 observed reflections. The structure is composed of ammonium cations and hexanitratocerate anions. The hexanitratocerate anions result from the bidentate coordination of six nitrate groups about each cerium atdm. The approximate symmetry is Th. The average Ce-O distance is 2.508 ± 0.007 A, the average N-O distance involving a coordinated oxygen is 1.282 ± 0.011 Å, and the average N-O distance involving a noncoordinated oxygen is 1.235 ± 0.011 Å. © 1968, American Chemical Society. All rights reserved.