The Structure of Tris(ethylenediamine)chromium(III) Hexacyanocobaltate(III) Hexahydrate, [Cr(C₂H₈N₂)₃] [Co(CN)₆]•6H₂O

The structure of tris(ethylenediamine)chromium(III) hexacyanocobaltate(III) hexahydrate, [Cr(C₂H₈N₂)₃ [Co(CN)₆] • 6H₂O, has been determined from three-dimensional X-ray data collected by counter methods. The final R factor on F for the 1035 F² values above σ(F²) is 9.4%, and for the 735 reflections above 3σ(F²) it is 6.1%. The material crystallizes with four molecules in space group C_2h⁶-12/a of the monoclinic system in a cell of dimensions a = 16.745 (20), b = 10.546 (15), c = 14.331 (20) Å, β = 96.9 (1)°. The measured and calculated densities are both 1.46 g/cm³. The site symmetry at Co is 1; that at Cr is 2. The structure consists of discrete Cr(C₂H₈N2)₃³⁺ cations and Co(CN)₆³⁻ anions. Hydrogen bonding connects the anions, cations, and water molecules. The Cr(C₂H₈N₂)₃³⁺ cation has its expected coordination geometry. For a Λ configuration of the cation the conformation of the complex is Λλλλ. The average Cr-N, N-C, and C-C distances are 2.081 (5), 1.481 (12), and 1.489 (9) Å. The Co(CN)₆³⁻ anion has its expected octahedral geometry. The average Co-C distance is 1.869 Å, although the three independent Co-C distances appear to differ slightly. The average C-N distance is 1.155 (8) Å.