  The Li-centered "ferric wheel" molecules with six oxo-bridged iron atoms form
molecular crystals. We probed their electronic structure by X-ray photoelectron
(XPS) and soft X-ray emission spectroscopy (XES), having calculated in parallel
the electronic structure of a single "ferric wheel" molecule from
first-principles by tools of the density-functional theory, using,
specifically, the Siesta method. The Fe local moments were found to be 4 mu_B,
irrespective of their mutual orientation. Neighbouring atoms, primarily oxygen,
exhibit a noticeable magnetic polarization, yielding effective spin S=5/2 per
iron atom, that can get inverted as a "rigid" one in magnetic transitions.
Corresponding energy preferences can be mapped onto the Heisenberg model with
effective exchange parameter J of about -80 K.
