Synthesis, spectroscopy and electrochemistry of 2-(mercapto/hydroxyl)pyridine-bis-{1-(alkyl)-2-(arylazo) imidazole}ruthenium(II)

Ruthenium–pyridine complexes incorporating azoimidazole ligands, L, of the type [RuII(RaaiR´)2-(X-pyridine)] 1–6 [RaaiR/ = p-R-C6H4-N=N-C3H2-NN-1-R/, (1-6), abbreviated as N,N/-chelator, where N(imidazole) and N(azo) represent N and N/, respectively; R=H (a), Me (b), Cl (c) and R/ = Me (1,4), CH2CH3 (2,5), Bz(3,6), X=S, 2-mercaptopyridine(1-3), X=O, 2-hydroxy-pyridine(4-6)] have been synthesized and their spectroelectrochemical aspects investigated. The complexes show intense charge-transfer bands in the UV-visible region which have been found to be reasonably blue shifted. The complexes systematically exhibit two oxidation processes and two successive one-electron reductions.   Key words: Ruthenium (II), arylazoimidazole, Infrared spectroscopy (IR), Nuclear magnetic resonance (NMR), Electrospray Ionization Mass Spectrometry (ESIMS), Cyclic Voltammetry  (CV).