The Crystal Structure of fac(N)-Δ-Tris(L-asparaginato)cobalt(III) Trihydrate

The crystal structure of tris(L-asparaginato)cobalt(III) trihydrate, [Co(L-H2NCOCH2CHNH2COO)3]·3H2O, has been determined by the X-ray diffraction method, and refined by a block-diagonal least-squares method to give R=0.055 for 1302 non-zero reflections. The crystals are orthorhombic with a space group P212121, a=39.082(4), b=7.523(2), c=6.643(2) A, and Z=4. The complex molecule has a slightly distorted octahedral coordination with fac(N)-Δ geometry. The three bidentate ligand ions form five-membered planar chelate rings with coordination through amino nitrogen and carboxyl oxygen atoms. The amide groups of the two side-chains approach the central atom, and the oxygen atoms are connected through intramolecular hydrogen bonds. Another amide group is, however, far from the central atom. The complex molecules are hydrogen-bonded to one another to form layers parallel to the (100) plane. These layers are piled up through hydrogen bonds to complete a threedimensional network.