Complex Fe(bpy(B))(3) (1, bpy(B) = 5,5'-bis(dimesitylboranyl)-2,2'-bipyridine) and its reduced species [(18-c-6)K(THF)(2)]center dot[Fe(bpy(B))(3)] (2) were synthesized. Their solid state and electronic structures were investigated by single crystal X-ray crystallography, electron paramagnetic resonance and UV-vis spectroscopy, and SQUID measurements. In 1 two bpy(B) radical anions are fused by a diamagnetic Fe-II ion, whereas in 2 all three bpy(B) ligands are in the radical state. Complex 1 possesses an open-shell singlet ground state with a singlet-triplet gap of 0.18 kcal mol(-1) and 2 features an open-shell doublet ground state with a doublet-quartet gap of 1.4 kcal mol(-1), as determined by SQUID measurements. The unpaired electrons in 1 and 2 mainly delocalize over the boron atoms and the bipyrdine moieties with negligible spin density at the iron center. Complex 2 represents the first isolable example of boron-based triradicals.