Driving the Localized-to-Delocalized Transition in Unsymmetrical Dinuclear Ruthenium Mixed-Valence Complexes

Deanna M. D’Alessandro; F. Richard Keene

doi:10.1071/CH05246

RESEARCH ARTICLE

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Driving the Localized-to-Delocalized Transition in Unsymmetrical Dinuclear Ruthenium Mixed-Valence Complexes

Deanna M. D’Alessandro ^A and F. Richard Keene ^A ^B

+ Author Affiliations

- Author Affiliations

^A School of Pharmacy and Molecular Sciences, James Cook University, Townsville QLD 4811, Australia.

^B Corresponding author. Email: richard.keene@jcu.edu.au

Australian Journal of Chemistry 58(11) 767-777 https://doi.org/10.1071/CH05246
Submitted: 3 September 2005 Accepted: 8 November 2005 Published: 9 December 2005

Abstract

The degree of delocalization in the symmetrical complexes [{Ru(bpy)₂}₂(μ-dpb′)]⁵⁺ and [{Ru(bpy)₂}₂(μ-dpb)]⁵⁺ (dpb = 2,3-bis(2-pyridyl)-1,4-benzoquinoxaline; dpb′ = dipyrido(2,3-a;3′,2′-c)benzophenazine; bpy = 2,2′-bipyridine) is diminished by the substitution of the terminal bpy ligands at one end of the complex. The results of a classical analysis for the diastereoisomeric forms of the series of complexes [{Ru(bpy)₂}(μ-BL){Ru(pp)₂}]⁵⁺ (pp = bpy, Me₂bpy (4,4′-dimethyl-2,2′-bipyridine), Me₄bpy (4,4′,5,5′-tetramethyl-2,2′-bipyridine)) indicate that a greater degree of ground-state delocalization exists in the complexes incorporating the bridging ligand dpb′ compared with the dpb analogue. A two-state analysis in which ΔE ₀ (the redox asymmetry) is varied at constant H _ab (the electronic coupling) and λ (the reorganizational energy) does not adequately describe the properties of the systems due to the importance of a third electronic state corresponding to the bridging ligand.

Acknowledgements

We gratefully acknowledge Professor Joe Hupp (North-Western University, Chicago) for inspiring these experiments, and Dr Jeff Reimers and Professor Noel Hush (University of Sydney) for helpful discussions on their analysis. This work was supported by the Australian Research Council.

References

Driving the Localized-to-Delocalized Transition in Unsymmetrical Dinuclear Ruthenium Mixed-Valence Complexes

Abstract

Acknowledgements

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