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Synthesis, Structure, and Water Oxidation Activity of Ruthenium(II) Complexes: Influence of Intramolecular Redox Process on O 2 Evolution
Author(s) -
Dhiman Rekha,
Nagaraja C. M.
Publication year - 2018
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201800105
Subject(s) - chemistry , intramolecular force , redox , ruthenium , catalysis , pyrazine , bipyridine , terpyridine , photochemistry , intermolecular force , crystallography , crystal structure , stereochemistry , inorganic chemistry , metal , molecule , organic chemistry
The synthesis and characterization of two new Ru II complexes, a mononuclear complex [Ru II (MeMPTP)(bpp)Cl]PF 6 ( 1 ) and a dinuclear complex [Ru II (MeMPTP)(bpp)Ru II (bpy) 2 Cl](PF 6 ) 3 ( 2 ), [where MeMPTP = 4′‐(4‐methylmercaptophenyl)‐2,2′:6′2′′‐terpyridine, bpp = 2,3‐bis(2‐pyridyl)pyrazine, bpy = 2,2′‐bipyridine] is reported. Single‐crystal X‐ray structural determination of the compounds unambiguously confirms the formation of the complexes 1 and 2 . Catalytic investigations of the complexes for the chemical oxidation of water in the presence of Ce 4+ as a sacrificial oxidant reveals a higher rate of O 2 evolution by the dinuclear complex 2 over the physical mixture of complex 1 and a redox mediator, [Ru(bpy) 3 ] 2+ ( med ), followed by the mononuclear complex 1 . The enhancement in the catalytic rate of O 2 evolution by 2 is ascribed to being due to the intramolecular redox process, which facilitates the facile formation of a high‐valent ruthenium–oxo species that is required for water oxidation through a cooperative effect. The present study highlights the importance of the intramolecular redox process over the intermolecular redox process.