We used charge and spin densities to monitor the electronic state of the POV6 core. Each additional electron reduces the V V centres to V IV , and each reduced V atom carries a spin 1/2. This approach monitors simultaneously both cases that limit charge transfer to/from the bisligated POV6 complex: (i) (partial) discharge of the cations and (ii) electron leakage from the POV6 core to the ligands. We also used atomic charges (Mulliken scheme ) to monitor charge and spin transfer.