Design, Identification and Evolution of Surface Ruthenium (II/III) Single‐Site for CO Activation

Ru(II) compounds are widely used in catalysis, photocatalysis and medical applications. They are usually obtained in reductive environment as molecular O 2 can oxidize Ru(II) to Ru(III) and Ru(IV). Here we report the design, identification and evolution of an air-stable surface -[bipy-Ru(II)(CO) 2 Cl 2 ] site that is covalently mounted onto a polyphenylene framework. Such Ru(II) site was obtained by reduction of -[bipy-Ru(III)Cl 4 ] - with simultaneous ligand exchange from Cl - to CO. This structural evolution was witnessed by a combination of in situ X-ray and infrared spectroscopy studies. The -[bipy-Ru(II)(CO) 2 Cl 2 ] site enables oxidation of CO with a turnover frequency of 0.73 × 10 -2 s -1 at 462 K, while the Ru(III) site is completely inert. This work contributes to the studies of structure-activity relationship by demonstrating a practical control over both geometric and electronic structures of single-site catalysts at molecular level, which can be further applied in other single site catalyst researches.