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Structural Origins of Noninnocent Coordination Chemistry

  1. Robert K. Szilagyi

Published Online: 15 SEP 2009

DOI: 10.1002/0470862106.ia630

Encyclopedia of Inorganic Chemistry

Encyclopedia of Inorganic Chemistry

How to Cite

Szilagyi, R. K. 2009. Structural Origins of Noninnocent Coordination Chemistry. Encyclopedia of Inorganic Chemistry. .

Author Information

  1. Montana State University, Bozeman, MT, USA

Publication History

  1. Published Online: 15 SEP 2009


A concise synthesis is provided for key electronic and geometric structural features, leading to noninnocent coordination chemistry as manifested by unprecedented reactivity, unusual coordination chemistry, and ligand-based redox chemistry. These include ligand–ligand repulsion arising from steric rigidity, reduced effective nuclear charge of the ligand-donor atoms, and increased effective nuclear charge of the metal centers in addition to suitable metal–ligand overlap for efficient intramolecular electron transfer. These features can contribute to considerable deviations from formal oxidation states by leading to effectively low-valent, reduced metal centers and oxidized ligands that can have very different electronic and geometric structures from their uncoordinated forms. To demonstrate the influence of these structural factors, classical examples of dithiolene complexes are discussed, followed by pincer-type ligands with late transition metals that show unexpected noninnocent behavior. Combined calibrated density functional theory and multi-edge X-ray absorption spectroscopy (XAS) has the potential for uncovering new families of noninnocent ligands that have importance in involving generally redox silent metals in electron-transfer processes or inducing nucleophilic character for metals due to extreme ligand-to-metal electron donation.


  • noninnocent coordination compounds;
  • nickel dithiolenes;
  • pincer-type complexes;
  • multi-edge X-ray absorption spectroscopy;
  • electronic structure calculations