Synthesis, spectral characterisation, redox studies of isomeric dichloro-bis-[1-alkyl-2-(naphthyl-(α/β)-azo)imidazole]ruthenium(II). Single crystal X-ray structure of blue-green dichloro-bis-[1-ethyl-2-(naphthyl-α-azo)imidazole] ruthenium(II)

• Published in: Polyhedron 2001-04, Vol.20 (9), p.905-913
• Main Authors: Byabartta, Prithwiraj, Santra, Prasanta K., Misra, Tarun K., Sinha, Chittaranjan, Kennard, Colin H.L.
• Format: Article
• Language: English
• Subjects: Electrochemistry; Isomers; Naphthylazoimidazoles; Ruthenium(II) complexes; X-ray structure
• ISSN: 0277-5387
• DOI: 10.1016/S0277-5387(01)00740-9

Ruthenium(II) complexes with 1-alkyl-2-(naphthyl-(α/β)-azo)imidazoles (α/β-NaiR), where R=Me, Et and Bz have been synthesised. Two isomers, blue-green, trans–cis–cis and blue, cis–trans–cis of the composition Ru(NaiR) 2Cl 2, are chromatographically separated. With reference to the pairs Cl, N(imidazole) and N(azo), the blue-green isomer is assigned to a trans–cis–cis configuration and the blue, isomer is assigned to a cis–trans–cis configuration. They are characterized by IR and 1H NMR data. The structure of the blue-green complex, Ru(α-NaiEt) 2Cl 2 has been determined by X-ray crystallography and the trans–cis–cis configuration has been confirmed. The complexes exhibit t 2(Ru)→π * (ligand) MLCT transitions in the visible region. Cyclic voltammetry shows a Ru(III)/Ru(II) couple for the blue-green isomer at 0.4–0.5 V and the blue complexes at 0.5–0.6 V versus SCE, as well as multiple azo reductions.