Ruthenium complexes with non-innocent ligands: Electron distribution and implications for catalysis

Julie L. Boyer, Jonathan Rochford, Ming Kang Tsai, James T. Muckerman, Etsuko Fujita*

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review

156 Citations (Scopus)


Ruthenium complexes with the non-innocent ligands (NILs) benzoquinone, iminobenzoquinone and benzoquinonediimine and their redox derivatives exhibit intriguing electronic properties. With the proper ligand set the NIL π* orbitals mix extensively with the ruthenium dπ orbitals resulting in delocalized electron distributions and non-integer oxidation states, and in most of these systems a particular ruthenium oxidation state dominates. This review critically examines the electronic structure of Ru-NIL systems from both an experimental and computational (DFT) perspective. The electron distribution within these complexes can be modulated by altering both the ancillary ligands and the NIL, and in a few cases the resultant electron distributions are exploited for catalysis. The Ru-NIL systems that perform alcohol oxidation and water oxidation catalysis are discussed in detail. The Tanaka catalyst, an anthracene-bridged dinuclear Ru complex, is an intriguing example of a Ru-NIL framework in catalysis. Unlike other known ruthenium water oxidation catalysts, the two Ru atoms remain low valent during the catalytic cycle according to DFT calculations, some experimental evidence, and predictions based on the behavior of the related mononuclear species.

Original languageEnglish
Pages (from-to)309-330
Number of pages22
JournalCoordination Chemistry Reviews
Issue number3-4
Publication statusPublished - 2010 Feb
Externally publishedYes


  • Catalysis
  • Non-innocent ligands
  • Oxidation
  • Quinone
  • Redox-active ligands
  • Ruthenium complexes

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry
  • Materials Chemistry


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