Abstract Starting from ready available compounds, a stable diradical of imino-nitroxide type has been synthesized in a multistep process. Structural characterization of the intermediates and final product included 1 H-and 13 C-NMR, elemental analysis, IR, UV-Vis and EPR spectroscopy. The stable diradical contains also a betaine structure with extended conjugation, which is responsible for its intense colour. Reduction of the stable betaine ...