Systematic influence of electronic modification of ligand on the catalytic rate of water oxidation by a single-site Ru-based catalyst

• Published in: ChemSusChem 2022-01, Vol.15 (4), p.e202101657-e202101657
• Main Authors: Patel, Jully, Bury, Gabriel, Ravari, Alireza K., Ezhov, Roman, Pushkar, Yulia
• Format: Article
• Language: English
• ISSN: 1864-5631; 1864-564X
• DOI: 10.1002/cssc.202101657

Catalytic water oxidation is an important process for the development of future clean energy solutions and energy storage. Despite the significant number of reports on active catalysts, systematic control of the catalytic activity remains elusive. Here, we continue to explore descriptors which can be correlated with catalytic activity. [Ru(tpy)(pic) 2 (H 2 O)](NO 3 ) 2 , 1 , and [Ru(EtO-tpy)(pic) 2 (H 2 O)](NO 3 ) 2 , 2 , (where tpy = 2,2′:6′,2″-terpyridine, EtO-tpy = 4′-(ethoxy)-2,2′:6′,2″-terpyridine, pic = 4-picoline) have been synthesized and characterized by NMR, UV-vis, electrochemical analysis, EPR, resonance Raman, and X-ray absorption spectroscopy. Addition of the ethoxy group increases catalytic activity in chemically driven and photocatalytic water oxidation. Thus, the effect of the electron-donating group known for the [Ru(tpy)(bpy)(H 2 O)] 2+ family is transferable to architectures with tpy ligand trans to the Ru-oxo unit. Under catalytic conditions, 2 displays new spectroscopic signals tentatively assigned to a peroxo intermediate. Reaction pathways were analyzed using DFT. Currently 2 is one of the most active catalysts functioning via a water nucleophilic attack mechanism.