Substituent Effects and Bonding Characteristics in o-Benzoquinonediiminebis(bipyrdine) Ruthenium(II) Complexes

摘要

The effect of substituents on the electrochemistry and electronic spectroscopy ofRuII(bpy)2LL complexes is reported, where bpy = 2,2'-bipyridine and LL = 4,5-disubstituted o-benzoquinonediimines, o-semiquinonediimines, o-phenylenediamides and o-phenylenediamines. These data are used to create a map of the orbital energies as a function of the Hammett parameter of the substituents, giving insight into the electronic behavior of these complexes. Electronic spectra are characterized with respect to energy, intensity and bandwidth, and bands are assigned with support from resonance Raman (rR) and FTIR data. The solvatochromism Of the o-benzoquinonediimine species is discussed. The data are interpreted in the context of metal-ligand orbital mixing and electronic structure. An ab initio study of the uncomplexed ligand in its quinonediimine oxidation state, is also included.