Molecular structure of sym-fac-[(1,5,9-triazanonane)-(R,S)-aspartato]cobalt(III) perchlorate monohydrate and its relationship to the optically active [Co(dtp)(S)-Asp]+ isomers
The crystal and molecular structure of the title compound was determined by X-ray diffraction. The structure was solved by the heavy-atom method and refined to an R value of 0.118 for 997 observed reflections. The unit cell is monoclinic with a = 11.980(1), b = 12.130(1), c = 12.641(1) Å, β = 108.18(1)°, Z = 4. The space group is P21/c. The crystals are composed of sym-fac-[Co(dtp)(R,S)-Asp]+, ClO4-, and H2O held together probably in a network of hydrogen bonds. The structural data obtained allow an explanation for the sym-fac-[Co(dtp)(S)-Asp]+ isomer optical activity contributions which can arise from the distorted chair conformation of one of the two dpt fused chelate rings, the donor atom distortions from the defined plane, and the (S)-aspartic acid vicinal chirality.