CRYSTAL STRUCTURE OF MU-AMIDO-MU-SUPEROXO-BIS[TETRAAMMINECOBALT(3)] TETRANITRATE [(NH3)4CO(NH2)(O2)CO(NH3)4](NO3)4

The crystal and molecular structure of μ-amido-μ-superoxo-bis[tetraamminecobalt(III)] tetranitrate, (NH3)4Co(NH2)- (O2)Co(NH3)44+.4NO3-, has been determined by X-ray crystallographic analysis. The green-black salt crystallizes in the monoclinic space group P21/c with unit cell dimensions a = 8.451 ± 0.003 Å,b = 13.196 ± 0.006 Å, c = 17.304 ± 0.003 Å, β = 103.90 ± 0.03°, and Z = 4. The measured density is 1.95 ± 0.01 g/cm8; the calculated density is 1.947 =b 0.001 g/ cm3. Intensity data were collected with a Datex-automated General Electric diffractometer using Fe Kα radiation. The structure was determined by Patterson methods and refined by three-dimensional Fourier and least-squares techniques. Refinement of all positional and thermal parameters (hydrogen atoms isotropic) yielded a final R index of 0.051 for 1888 reflections. The coordinating ligands form nearly regular octahedra about the cobalt atoms, with Co-N and Co-O distances of about 1.96 and 1.87 Å. The five-membered ring Co-N-Co-O-O- is very nearly planar; the O-O distance is 1.32 Å, and the Co-N-Co and Co-O-O angles are 115 and 120°, respectively. This geometry indicates that the O2 bridge is a superoxo rather than a peroxo group. © 1969, American Chemical Society. All rights reserved.