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Mixed Valence Compounds

  1. John P. Fackler Jr

Published Online: 15 DEC 2011

DOI: 10.1002/9781119951438.eibc0133

Encyclopedia of Inorganic and Bioinorganic Chemistry

Encyclopedia of Inorganic and Bioinorganic Chemistry

How to Cite

Fackler, J. P. 2011. Mixed Valence Compounds. Encyclopedia of Inorganic and Bioinorganic Chemistry. .

Author Information

  1. Texas A&M University, College Station, TX, USA

Publication History

  1. Published Online: 15 DEC 2011


The concept of mixed valence has referred to compounds in which a given element exists for an appropriate time in what can be described as more that one formal oxidation number. Clearly it is a formalism that has limited meaning when electron delocalization occurs on a timescale at or near the frequency of vibrations. The formalism that historically has been valuable, the Robin and Day classification, classifies such substances into three types depending upon an ability of experiment to identify well defined oxidation states. When electron transfer occurs readily between these mixed valence species, the concept of mixed valence may lose its meaning. These types of compounds are of considerable interest today since the nature of the bonding connecting the components influences significantly the electronic properties of the material. Understanding these factors is needed to help us develop and understand organic and ionic high-Tc superconductors.


  • valence;
  • delocalized;
  • superconductivity;
  • optical electron;
  • vibronic