The lowest six states are the components of the ground state sextet, with a strong ZFS between the ± 5 2 and ± 3 2 components. The first excited quartet state, with a relatively small positive ZFS, is found at around 400 cm -1 . At around 600 cm -1 a doublet follows. The ground state sextet splitting is mainly governed by the spin-orbit coupling at the cobalt centers, whereas the splitting between the different multiplets is mainly dictated by the exchange coupling.