  Inelastic neutron scattering (INS) experiments under applied magnetic field
at low temperatures show detailed low lying magnetic excitations in the so
called tridiminshed iron icosahedron magnetic molecule. The magnetic molecule
consists of nine iron Fe$^{3+}$ ($s = 5/2$) and three phosphorous atoms that
are situated on the twelve vertices of a nearly perfect icosahedron. The three
phosphorous atoms form a plane that separates the iron cluster into two weakly
coupled three- and six-ion fragments, \{Fe$_3$\} and \{Fe$_6$\}, respectively.
The magnetic field INS results exhibit an $S=1/2$ ground state expected from a
perfect equilateral triangle of the \{Fe$_3$\} triad with a powder averaged
$g$-value $=2.00$. Two sets of triplet excitations whose temperature and
magnetic field dependence indicate an $S=0$ ground state with two
non-degenerate $S=1$ states are attributed to the \{Fe$_6$\} fragment. The
splitting may result from a finite coupling between the two fragments,
single-ion anisotropy, antisymmetric exchange couplings, or from magnetic
frustration of its triangular building blocks.
