Orange-glowing iron at room temperature: Many photoactive coordination compounds contain precious metals. Replacing ruthenium with more–earth-abundant iron has been a long-sought goal, but iron compounds generally relax too rapidly after light absorption to channel the energy productively. Kjær et al. prepared an iron compound with an excited state stable enough to emit light for nanoseconds, or that could engage in bimolecular electron transfer (see the Perspective by Young and Oldacre). Targeting a ligand-to-metal rather than metal-to-ligand charge-transfer state was key to the achievement, as was the octahedral coordination environment rigidly enforced by two tridentate carbene ligands. Science , this issue p. 249 ; see also p. 225

A 9 ps ³MLCT lifetime was achieved by a Fe^II complex based on C(NHC)⁁N(py)⁁C(NHC) pincer ligands. This is the longest known so far for any kind of complexes of this abundant metal, and increased by almost two orders of magnitude compared to the reference Fe^II bis-terpyridine complex.