3-LAYERED CLOSE PACKING IN THE CRYSTAL-STRUCTURE OF TRIS(ETHYLENEDIAMINE)COBALT(III) HEXANITRORHODATE(III) HYDRATE, [CO(EN)(3)][RH(NO2)(6)]CENTER-DOT-3H(2)O, EN=C2H8N2

In the structure of cubic tris(ethylenediamine)cobalt(III) hexanitrorh odate(III) hydrate, [Co(en)(3)][Rh(NO2)(6)]. 3H(2)O, en = C2H8N2, with a = 16.540(5) Angstrom, space group Pa3 (nonstandard, reduced to orth orhombic Pcab), the complex cations, anions, and water molecules are a rranged by the law of three-layered (fcc) close packing of ''quasisphe rical'' species according to two structural types, NaCl And CaF2. The packing is formed of [Rh(NO2)(6)](3-) anions, which also fill the octa hedral voids. The tetrahedral voids are occupied by the central atoms of the [Co(en)(3)](3+) cations, and the H2O molecules lie between the cations, performing the packing function: the Ow...N-en contacts of 3. 04 Angstrom and the Ow..O-NO2 contacts of 3.01 Angstrom characterize w eak van der Waals interactions. The values of the interatomic distance s Co-N, Rh-N, N-O, N-C, and C-C are in good agreement with the known d ata.