Effect of ligand basicity on electrochemically induced linkage isomerization in 2-mercaptopyridine–ruthenium complexes

[Ru(2,2′-bipyridine)2(L)(2-mercaptopyridine)](PF6)2 (L: 4-aminopyridine or isonicotinamide) was synthesized and characterized by 1H NMR spectroscopy, electrospray ionization-mass spectrometry, and elemental analysis. Cyclic voltammograms revealed that the complex involving isonicotinamide as an ancillary ligand displayed electrochemically induced linkage isomerization between RuII–(2-pyS-κS) and RuIII–(2-pyS-κN) (2-pyS: 2-mercaptopyridinato) during the redox reaction of RuIII/II, but that the 4-aminopyridine complex did not. The difference in electrochemical behavior is discussed on the basis of basicity of the ancillary ligand L.

Graphical abstractSynthesis, spectroscopic and electrochemical studies of [Ru(2,2′-bipyridine)2(L)(2-mercaptopyridine)](PF6)2 (L: 4-aminopyridine or isonicotinamide) are reported. The isonicotinamide complex displayed electrochemically induced linkage isomerization during the redox reaction of RuIII/II, but that the 4-aminopyridine complex did not. The difference is discussed on the basis of basicity of the ancillary ligand L.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► 2-Mercaptopyridine Ru complexes with various ancillary ligand were synthesized. ► Electrochemically induced linkage isomerization was investigated. ► The basicity of the ancillary ligand influences the isomerization.