Synthesis and structure of cyclen hydroxylamine ligands and their zinc(II) complexes

The synthesis of two new zinc(II) complexes with 1,4,7,10-tetraazacyclododecan-1-ol and 1,4,7,10-tetraazacyclododecan-1,7-diol as ligands is described. One of these complexes is characterized by X-ray structure analysis. By coordination to the metal cation the acidity of the hydroxylamine groups of the ligands is significantly increased as confirmed by potentiometric pH titrations.