Benzotriazolate-bridged ruthenium dinuclear and trinuclear complexes

摘要

A new series of mononuclear, dinuclear and trinuclear benzotriazolato-complexes (namely trans-[Ru(NH3)(4)(bta)(2)](x+), trans[(NH3)(4)(bta)Ru(bta)Ru(edta)](y-), and trans-[(NH3)(4)Ru{(bta)Ru(edta)}(2)](z-); where bta = benzotriazolate, edta = ethylenediamine-N,N,N',N'-tetraacetate, x = 0 or 1, y = 0, 1 or 2, z = 1, 2 or 4) has been prepared and investigated in aqueous solutions by means of electrochemical and UV-Vis-NIR spectroelectrochemical methods. Particular emphasis is given to the mixed-valence properties of the dinuclear (Ru-II-Ru-III) and trinuclear (Ru-III-Ru-II-Ru-III) species, which display a large degree of metal-metal electronic coupling with localized oxidation states, as deduced from their intervalence charge transfer bands and electrochemical parameters. Analysis of the results within the context of Mulliken-Hush perturbational theory reveals that the intermetallic electronic communication increases slightly with the nuclearity of the system, leading to the conclusion that the symmetrical (nonlinear) trinuclear complex acts as a model/precursor for extended molecular chains of the type 'molecular wires'. A comparison with a set of analogues studied previously is also reported, reinforcing the quite interesting properties of benzotriazole derivatives as molecular bridges. (C) 2002 Elsevier Science Ltd. All rights reserved. [References: 40]