Novel 2-Mercaptopyridine−Ruthenium Complex Exhibiting Electrochemically Induced Linkage Isomerization Switched On/Off by Protolysis
datasetposted on 10.12.2007, 00:00 by Tomohiko Hamaguchi, Kikujiro Ujimoto, Isao Ando
A ruthenium complex [ruthenium bis(2,2‘-bipyridine)(2-mercaptopyridine)(pyridine)](PF6)2 was crystallographically characterized from its deprotonated form and was electrochemically investigated. In the deprotonated complex, the 2-mercaptopyridine ligand coordinates to the Ru atom only by the S atom; therefore, the N atom of the 2-mercaptopyridine ligand can be protonated. In a CH3CN solution, the complex shows a reversible redox couple attributed to RuIII/II−S. The addition of a base to the CH3CN solution of the complex gives irreversible voltammograms, implying electrochemically induced linkage isomerization between RuII−S and RuIII−N. Analysis of the observed cyclic voltammograms gave the equilibrium and rate constants for linkage isomerization: KIINS = 1.2 × 1018, KIIINS = 0.64, kIINS = 5 × 10 s-1, kIISN = 4 × 10-17 s-1, kIIINS = 0.26 s-1, and kIIISN = 0.40 s-1.