In the first part of calculations, we performed the geometry optimization of [V V 6O13{(OCH2)3CR}2] 2-in the presence of Mg 2+ and NH4 + counterions, so that the total system is closed shell and charge neutral (charge 𝑞𝑞 = 0, and multiplicity 𝑀𝑀 = 1). The obtained configuration is used as the initial one for geometry optimization of a system with the same number of cations and with one additional electron (𝑞𝑞 = -1, 𝑀𝑀 = 2). We repeated this procedure for up to six additional electrons (𝑛𝑛 = 6, 𝑞𝑞 = -6), and found the energy minimum always at 𝑀𝑀 = 𝑛𝑛 + 1.