The Crystal Structure of Octammine µ-Amido µ-Peroxo Dicobalt Tetranitrate

Octammine µ-amido µ-peroxo dicobalt tetranitrate, See PDF abstract for formula. forms green-black plate-like crystals with space group P21/c and unit cell dimensions a = 8.451, b = 13.196, c = 17.304 Å, β = 103.90° There are four molecules per unit cell. The crystal structure was determined and refined using three dimensional Fourier and least-squares techniques. The coordinating ligands form nearly regular octahedra about the cobalt atoms with Co-N and Co-O distances of 1.96 and 1.87 Å. The five-membered ring formed by the two cobalt atoms and the peroxo and amido bridges is very nearly planar. The Co-Co distance is 3.24 Å, the O-O distance is 1.32 Å, and the Co-N-Co and Co-O-O angles are 115° and 120° respectively. The extensive system of hydrogen bonds in the crystal appears to involve nearly all of the ammine hydrogens and all of the oxygen acceptors with the exception of the oxygen atoms in the peroxo bridge. The present value of the residual R index is 0.053 for all 2078 observed reflections.