| Abstract
| - New face-to-face homodinuclear copper(II) and nickel(II) complexes in identical tetraazamacrocyclic environments exhibit interactions between the metal centers. For the heteronuclear nickel/copper complex, the interactions are found intermediary compared to the homonuclear cases. The increase of intermetallic interactions leads to the increased stability of the intermediate mixed-valence states.
- New face-to-face heterodinuclear complexes containing copper(II) and nickel(II) in identical tetraazamacrocyclicenvironments have been synthesized and characterized using ESI mass-spectrometry, X-ray diffraction, spectroscopicmethods, and elemental analysis. These new bismacrocyclic systems were compared with the respective mono-and bismacrocyclic and [2]catenane homonuclear complexes. Interactions between the metal centers were monitoredby magnetic and electrochemical measurements. Magnetic data indicate that all copper compounds studied behaveas weakly interacting magnets. In the case of copper [2]catenane, the extent of magnetic interactions decreasedwhen a benzocrown moiety was introduced between the macrocyclic units. On the basis of electrochemical data,the interactions between the metal centers were found to be substantially larger for the nickel complexes than forthe corresponding copper ones. Interlocking of a benzocrown ether to form [2]catenane led to a nonequivalenceof the metal centers and to the increase of donor abilities of the catenane compared to the respective bismacrocycliccomplex. This is reflected by the shift of the first formal potential to less positive values. Intermetallic interactionsfor the heteronuclear nickel/copper complexes were found intermediary compared to the homonuclear ones. Theywere strengthened by shortening the spacer between the two tetraazamacrocyclic subunits which is a convenientway of fine-tuning the interactions. The increase of intermetallic interactions led to the increased stability of theintermediate mixed-valence states indicated by the higher values of comproportionation constants.
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