Ruthenium Complexes of Non-Innocent Ligands: Aspects of Charge Transfer Spectroscopy

Abstract

The chapter presents in some detail how the electronic structure of a series of ruthenium complexes of non-innocent, i.e. redox active, ligands can be assessed through a combination of optical spectroscopy and INDO/S computation. Complexes of the type [Ru(NH₃)₄(LL)]ⁿ⁺ and [Ru(bpy)₂(LL)]ⁿ⁺ are analyzed where LL is o-phenylenediamine or its series of congeners where the nitrogen atom is replaced by oxygen or sulfur. The complexes obtained by one- or two-electron oxidation of these species to their semiquinone and quinone oxidation state analogs, are discussed in detail in a comparative and pedagogical fashion. The consequences of the very strong covalent interaction which occurs between ruthenium and most of these ligands are probed in depth and the methodology for dealing with such systems is presented.