Exploring the Localized to Delocalized Transition in Non-Symmetric Bimetallic Ruthenium Polypyridines

In this work, we report the evolution of the properties of the inter-valence charge transfer (IVCT) transition in a family of cyanide-bridged ruthenium polypyridines of general formula [RuII(tpy)(bpy)(μ-CN)RuIII(bpy)2(L)]3/4+ (tpy = 2,2',6',2''-terpyridine; bpy = 2,2'-bipyridine; L = Cl-, NCS-, 4-dimethylaminopyridine or acetonitrile). In these complexes, the redox potential difference between both ruthenium centers (ΔE) is systematically modified. A decrease in ΔE causes a red shift of the energy and an intensity enhancement of the observed IVCT transitions. For L = acetonitrile, the IVCT band becomes narrower and asymmetrical, and shows very little dependence on the nature of the solvent, suggesting a delocalized configuration, although a non-symmetrical one. Also, additional electronic transitions of low energy are clearly resolved in this complex. The observed variation in the properties of the IVCT transitions can be understood on the basis of DFT calculations, that point to increasing mixing between the dπ orbitals of both Ru ions.


ELECTRONIC SUPPLEMENTARY INFORMATION
Exploring the Localized to Delocalized Transition in Non-Symmetric Bimetallic Ruthenium Polypyridines Paola S. Oviedo, German E. Pieslinger, Alejandro Cadranel, and Luis M. Baraldo.
MLCT Table S5.Selected electronic transitions of the doublet 1 3+ ion calculated in MeCN.

Figure S11 .
Figure S11.Comparison of the IR spectra of 1 2+ (top) to 4 3+ (bottom) in acetonitrile/0.1 M [TBA]PF6 and the energy of the vibrations predicted by the DFT calculations (bars).

Figure S12 .
Figure S12.Comparison of the IR spectra of 1 4+ (top) to 4 5+ (bottom) in acetonitrile/0.1 M [TBA]PF6 and the energy of the vibrations predicted by the DFT calculations (bars).

Figure S14 .
Figure S14.Electron Density Difference Maps for the selected electronic transitions of the doublet 1 3+ ion calculated in MeCN.

Figure S18 .
Figure S18.Electron Density Difference Maps for the selected electronic transitions of the doublet 3 4+ ion calculated in MeCN.

Figure S20 .
Figure S20.Electron Density Difference Maps for the selected electronic transitions of the doublet 4 4+ ion calculated in MeCN.

Table S4 .
Experimental and calculated IR frequencies for complexes 1 to 4 in their [II,II], [II,III] and [III,III] oxidation states.Experimental measures were done in acetonitrile/0.1 M [TBA]PF6

Table S6 .
Selected electronic transitions of the doublet 2 3+ ion calculated in MeCN.Electron Density Difference Maps for the selected electronic transitions of the doublet 2 3+ ion calculated in MeCN.

Table S7 .
Selected electronic transitions of the doublet 3 4+ ion calculated in MeCN.