Mononuclear and Heterotrinuclear Ruthenium Complexes: Synthesis and Water Oxidation Activity

Artificial photosynthesis constitutes an intriguing alternative to fossil fuels, and the water oxidation reaction is considered a bottleneck for the achievement of an efficient device to perform it. Extensive research has been carried out, and is still ongoing, to identify the properties and mechanisms that define a good water oxidation catalyst. Ruthenium complexes have shown to be valid candidates for this task.

This work presents the synthesis and characterization of multiple mononuclear and heterotrinuclear ruthenium complexes based on two different ligands. Their properties were investigated through spectroscopic and electrochemical methods, and related to the structures obtained by X-ray diffraction. Isomerization reactions were examined and rationalized through spectroscopy, electrochemistry and DFT simulations. Possible reactivity towards chemical or photochemical water oxidation was tested and rationalized in light of the structure and electronic properties of the compounds. Selected catalytic reactions underwent mechanistic, kinetic or thermodynamic studies, by means of spectroscopic, isotopic labelling or electrochemical experiments. Finally, two complexes were supported on metal oxide surfaces and tested for heterogeneous water oxidation.