Crystal structure of ceric ammonium nitrate

The crystal structure of ceric ammonium nitrate, (NH^^Ce^O^)^, has been determined from three dimensional single-crystal X-ray dif fraction data collected by counter methods.The crystals are monoclinic, space group P2^/n with unit cell parameters a = 13.061± 0. 007, b = 6.842 ± 0. 004, c = 8. 183 ± 0. 004A, B = 91.34± 0. 02°, p = 2. 49, --'o _3 Pc = 2.490 g/cm for Z = Z.Block-diagonal anisotropic least-squares refinement led to a conventional R of 0. 036 for 625 observed re flections.The structure is composed of ammonium cations and hexanitratocerate dianions.The hexanitratocerate anions result from the bidentate coordination of six nitrate groups about each cerium atom.The approximate symmetry is T^.The average Ce-O distance is 2. 508 ± 0. 007; the average N-O distance involving a coordinated oxygen, 1. 282 ± 0. 011; the average N-O distance involving a non-coordinated oxygen, 1.235 ± 0.011A.