Probing the photophysical capability of mono and bis(cyclometallated) Fe(II) polypyridine complexes using inexpensive ground state DFT

The abundance and low toxicity of iron with respect to ruthenium would certainly make it valuable for photophysical applications if one could circumvent its tendency to make high-spin compounds and the kinetic lability of its polypyridine complexes, both related to the presence of low-lying quintet metal-centered excited states. The aim of this study was to probe the photophysical potential of six cyclometallated Fe(ii) polypyridine complexes by means of ground state DFT and TDDFT calculations. Quantitative and qualitative indicators were extracted from such calculations and bring us to the conclusion that two complexes should display promising photophysical properties: Fe(NCN)(NNC) and Fe(NNC)(2).