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Valence Tautomerism: New Challenges for Electroactive Ligands
Author(s) -
Evangelio Emilia,
RuizMolina Daniel
Publication year - 2005
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200500323
Subject(s) - tautomer , chemistry , valence (chemistry) , intramolecular force , redox , tetraphenylporphyrin , photochemistry , electron transfer , quinone , radical , electronic structure , crystallography , computational chemistry , stereochemistry , porphyrin , inorganic chemistry , organic chemistry
Valence tautomeric complexes combine redox‐active ligands and transition metal ions with two or more accessible oxidation states, exhibiting two nearly degenerated electronic states with localized electronic structures. Charge distribution in such electronic isomers has an appreciable sensitivity to the environment so an external perturbation, like photons, temperature and/or pressure, may lead to an intramolecular electron transfer between both redox active units and therefore to a reversible interconversion between the two degenerated electronic states. Moreover, since each electronic isomer exhibits different optical, electronic and/or magnetic properties, these complexes are being proposed as candidates for future use in molecular electronic devices and switches. Most of the valence tautomeric complexes reported thus far are based on quinone or quinone‐type ligands with a series of transition metal ions such as Co, Cu, Ni and Mn. Nevertheless, in the last few years, the number of electroactive ligands identified to be active in valence tautomeric complexes is being expanded by including new radical ligands such as polychlorotriphenylmethyl, phenoxyl or tetraphenylporphyrin radicals. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)