During the charging process (sequential addition of electrons to the neutral (NH4)2[V V 6O13{(OCH2)3CR}2] and Mg[V V 6O13{(OCH2)3CR}2]), the charge tends to leak quickly from the POV6 core (Fig. ). This process is rather independent of the considered ligands and cation type and suggests that the POV6, as an intrinsic property, can accommodate only two additional charges.