Mechanistic reactivity studies of 1 using 1 H and 51 V NMR spectroscopy were carried out as follows: solutions containing 10.0 mg (5.0 µmol) {V12} in water-free, de-aerated acetonitrile-d3 (500 µL) were prepared as references. The reactivity of these solutions with Mg 2+ were studied by addition of 2.0 mg (21.0 µmol) anhydrous MgCl2 to these solutions. The solutions were studied under the conditions described (i.e., after storage in the dark, after irradiation, etc.). All solutions were prepared in an argonfilled glovebox.