Photoelimination of Ligands in Transition Metal Complexes

Photoelimination of ligands in transition metal complexes can create reactive species that can act as catalysts and reagents for several useful reactions. To better understand the dynamics of this process, the photoelimination of the ligands in the tricarbonylnitrosylcobalt complex was studied as a model for the elimination of nitrosyl ligands from mixed-ligand species. To do this, the cobalt complex can be ionized using resonance-enhanced multi-photon ionization (REMPI) to eliminate one or more ligands, and the resulting velocities and spectra can be analyzed to obtain pathways for the photoelimination. The elimination of the nitrosyl group can be achieved with visible light, and its mechanism is known to be due to a metal-to-ligand charge transfer. The photoelimination of a carbonyl group is only achievable with ultraviolet light, and is reported in this paper to also be due to a metal-to-ligand charge transfer. The characteristics of the secondary photodissociation are also reported with a notable difference in kinetic energy of the nitrosyl fragment that depends on whether the nitrosyl was eliminated before any carbonyls or after. These results help to further deepen the understanding of photodissociation in mixed-ligand nitrosyl complexes which is a field of active study.