Synthesis, spectra and electrochemistry of ruthenium(III) complexes with cage-like schiff-base ligands

Abstract

A series of non-electrolytic low-spin ruthenium(III) complexes [μ_eff (in dichloromethane solution): 1.79-1.93 μ_B at 298 K] have been synthesized using closely-related encapsulating Schiff-base ligands having an aliphatic nitrogen and a phenolate oxygen as donor sites. The structural behaviour of the complexes in CDCl₃ solution has been examined by ¹H NMR spectroscopy utilizing paramagnetically-shifted ligand proton resonances. Cyclic voltammetric studies in dichloromethane solution at a platinum working electrode reveal the presence of a reversible-to-quasi-reversible Ru^III-R^II couple (E^f = -0.62 to -0.74 V) and an Ru^IV-Ru^III couple (E_f = 0.53-0.70 V) vs S.C.E. (saturated calomel electrode). Additionally, an Ru^V-Ru^IV couple (E_f/E_pa = 1.02-1.18 V) is also observed.