Transition metal complexes have received throughout the past decades grand attention due to their fascinating functionalities. Among the variety of functional transition-metal containing molecules, the class of light-harvesting complexes is especially intriguing, being a key component of technologies based on clean and green energy, such as solar energy conversion and photocatalysis . In both transition-metal based solar cells and photocatalytic assemblies, the process is initiated by a light-induced electron transfer from the metal to the ligand in a photosensitiser, leading to a metal-to-ligand charge transfer (MLCT) excited state.