Stereochemistry from X-Ray Diffraction Studies of Three Palladium(II) Complexes with Terdentate Chelating Amines

X-ray crystal structure analysis of three Pd(II) complexes with cis-3,5-diaminopiperidine (DAPI) shows that the metal ion has a square planar coordination. The DAPI groups are trans in the protonated and mixed complexes. Most surprisingly, the unprotonated complex has a basket-like structure with the DAPI groups cis.