— The structure of [Co(NH3)5CO3]NO3•H2O is determined ab initio from conventional X-ray powder diffractometry by the direct methods. The cell is monoclinic, space group P21, Z = 2, a = 7.6733(4) Å, b = 9.6398(5) Å, c = 7.0852(3) Å and β = 106.195(3)°. Refinements by the Rietveld method, lead to RB = 0.053, RP = 0.100, and RWP = 0.119. Hydrogen atoms could not be located. Nevertheless a bonding ...