Highly selective crystallization of metal(II) ions with 1,3-pdta ligand: Syntheses and crystal structures of the [Mg(H2O)6][Cd(1,3-pdta)(H2O)] · 2H2O and two isomorphic [Zn(1,3-pdta)]2− complexes

X-ray crystallography has been applied to investigate 1,3-pdta complexes of Zn2+ and Cd2+ ions. The [Zn(1,3-pdta)]2− (a) and [Cd(1,3-pdta)(H2O)]2− (b) complexes are different in coordination number and geometry, as (b) constitutes the first example of transition metal complex with 1,3-pdta ligand that possesses CN equal to 7.