Willi Steinmann1, Thomas A. Kaden1
1Institut für Anorganische Chemie, Spitalstr. 51, CH–4056 Basel
Tóm tắt
Abstract12,12‐Dimethyl‐1,4,7,10‐tetraazacyclotridecane (I), 11,13‐dimethyl‐1,4,7,10‐tetraazacyclotridecane (II), 11,11,13‐trimethyl‐1,4,7,10‐tetraazacyclotridecane (III) and 1,4,7,10,12,12‐hexamethyl‐1,4,7,10‐tetraazacyclotridecane (IV) have been synthesized and their properties are described.While the Ni2+ and Cu2+ complexes of I–III have square planar geometries, those of IV are pentacoordinate according to their absorption spectra. Similarly, while the Co2+ complex of I is octahedral and readily oxygenated, the analogous complex with IV is pentacoordinate and not sensitive to oxygen.The rate of complexation of these ligands with Cu2+ and Ni2+ decreases in the order I > II > III ≫ IV, indicating that the number as well as the position of the methyl groups are important. Finally for Cu2+ the formation of the thermodynamic stable end product is slown down by methyl substitution in α‐position to the coordinating nitrogen atoms (ligand II and III) so that an intermediate can be observed, whereas with I Cu2+ directly forms the end product.
