Resolving ultrafast excited-state dynamics in molecules is an ultimate goal in modern physics and chemistry. In addition to its fundamental importance in natural sciences, such knowledge can also be exploited in various technological areas such as molecular data storage and the production of green energy based on solar energy conversion and photocatalysis. Photoactive transition metal complexes are among the most-investigated molecules owing to their favorable properties, both in terms of applications (e.g., strong absorption in the visible region, long-lived excited states) and implementation of time-resolved X-ray scattering and spectroscopic experiments. Fe complexes are particularly appealing as they are cheap, environment friendly, and several of them possess advantageous excited-state profiles. Such properties are, e.g., the photoswitchable lowspin (LS) and high-spin (HS) states of Fe(II) polypyridines , making them promising candidates as molecular data storage devices , and the long-lived metal-to-ligand charge transfer (MLCT) states of Fe-N-heterocyclic carbenes, which could be potentially exploited in solar cells and photoctalysts.