Pseudo-octahedral Fe(II) complexes have a wide variety of
potential applications due to their magnetic and photophysical
properties. As a first-row transition metal, Fe provides for weak
ligand field strength if used as a central metal in a coordination
complex. Therefore, Fe compounds are characterized by the
presence of a large number of electronic states with different
multiplicities close to each other in energy. Depending on the
ligand set utilized, energy ordering of the various electronic
states can change and Fe(II) complexes with either a low-spin
or a high-spin ground state can be prepared. This tunability
makes iron compounds interesting as candidates for molecular
memory,1 pigments in display devices,2 photosensitizers,3 and
other functional materials.4 Fe(II) polypyridines are of
particular interest for dye-sensitized solar cells3,5 (DSSCs)
and spin-crossover (SCO) materials.4