Intervalence charge transfer in a 'chain-like' ruthenium trinuclear assembly based on the bridging ligand 4,7-phenanthrolino-5,6 : 5 ',6 '-pyrazine (ppz)

摘要

The IVCT characteristics of the mixed valence forms of the trinuclear complex [{Delta-Ru(bpy)(2)}(2){Delta(t)-Ru(bpy)(mu-ppz)(2)}]n(+) (n = 7, 8; t = trans), and the diastereoisomers (meso and rac) of the dinuclear complex [{Ru(bpy)(2)}(2)(mu-ppz)](5+), display a marked dependence on the nuclearity and extent of oxidation of the assemblies. The dinuclear species are classified as borderline localised-delocalised mixed valence species while the two mixed valence states of the trinuclear complex exhibit localised behaviour. One-electron oxidation of a terminal Ru centre in the trinuclear case gives rise to a broad, low intensity IVCT band for the +7 mixed valence species which is composed of two underlying Gaussian-shaped bands. The transitions are identified as adjacent and remote IVCT transitions, with the former dominating the intensity of the IVCT manifold. The +8 mixed valence species exhibits a single dominant IVCT band arising from the equivalent IVCT transitions from the central Ru-II to peripheral Ru centres.