Metal complexes of macrocyclic ligands. Part XXIII. Synthesis, properties, and structures of mononuclear complexes with 12‐ and 14‐membered tetraazamacrocycle‐N,N′,N″,N‴‐tetraacetic Acids

The two tetraazamacrocycle‐N,N′,N″,N‴‐tetraacetic acids H4dota and H4teta form with Ni2+, Cu2+, and Zn2+ (M2+) mononuclear complexes MLH2 and M′[ML], M′ being an alkaline earth ion. The structures of Ni(H2dota) and Cu(H2dota) have been solved by X‐ray structure analysis. The metal ions are in a distorted octahedral geometry coordinated by four amino N‐atoms and two carboxylates. In the case of Cu2+, the distortions are more pronounced than for Ni2+ indicating that the Jahn‐Teller effect is operating. Starting from these two structures, the coordination geometry of the other complexes is discussed using VIS and IR spectra.