Tetraazacyclophanes by palladium-catalyzed aromatic amination. Geometrically defined, stable, high-spin diradicals

[GRAPHICS] Neutral tetraazacyclophanes were prepared in a one-step palladium-catalyzed amination reaction, Simple oxidation of these materials creates dication d iradicals that are stable at room temperature and that are geometrically we ll defined. The electronic and magnetic properties of the dications were in vestigated by CV, UV-vis, and EPR spectroscopy. These spectral data and sol ution phase magnetic susceptibility measurements indicate high spin ground states in certain media. EPR zero field splitting parameters for the diradi cal suggest that the distance between the two radical sites can be approxim ated simply by the distance between alternating nitrogens in the macrocycle .