Selective activation of carbon-hydrogen (C–H) bonds in organic molecules without excessive energy input remains a key challenge in chemistry. Transition metal complexes of the type CpM(CO)₂ (Cp = cyclopentadienyl; M = Rh, Ir) have long served as model systems for investigating mechanisms of photochemical C–H bond activation in saturated hydrocarbons. Upon UV photolysis, these complexes lose one CO ligand, generating a coordinatively unsaturated, highly reactive metal center. In this transient state, the metal can bind an alkane from solution and subsequently activate it via oxidative addition into the C–H bond. However, replacing the 4d or 5d metal centers with their 3d analogue dramatically reduces the system’s reactivity toward photochemical C–H bond activation. Similar to its heavier congeners, CpCo(CO)₂ undergoes CO dissociation upon UV excitation, forming an undercoordinated CpCo(CO) species. Yet, unlike Rh or Ir complexes, this intermediate does not engage in alkane binding. Instead, it forms a triplet state, which is the electronic ground state of CpCo(CO). Although triplet CpCo(CO) can coordinate solvent molecules and catalyze reactions such as cyclotrimerization, cyclo-oligomerization of alkynes and alkenes, and Si–H bond activation, it shows no reactivity toward alkane C–H bonds. Therefore, CpCo(CO)₂ serves as a critical model system for understanding how the use of earth-abundant 3d transition metals can introduce limitations in catalytic C–H activation. The early excited-state dynamics governing the photodissociation of transition metal carbonyls are key to defining the chemical nature of short-lived, catalytically active intermediates. Yet, mechanistic insights on the sub-picosecond timescale remain elusive. In this project, we will first investigate the photoexcitation of CpCo(CO)₂ using excited-state molecular dynamics at the multiconfigurational theory level. Subsequently, transient X-ray spectroscopy will be simulated for selected key intermediate states.