Fig. 1: Multi-step synthesis of 1*.

The initial chloride complex is converted to the corresponding azide by salt elimination. Reduction releases N2 to produce a bridging nitride dimer, which can be cleaved into a separated ion pair by treatment with the appropriate crown ether. Oxidation of the separated ion pair gives neutral, 50% 15N-labelled 1* for the NMR investigations described in this study. B15C5 = benzo-15-crown-5 ether.