Electromerism is a type of
isomerism
In chemistry, isomers are molecules or polyatomic ions with identical molecular formulae – that is, same number of atoms of each element – but distinct arrangements of atoms in space. Isomerism is existence or possibility of isomers.
Iso ...
between a pair of
molecules (electromers, electro-isomers) differing in the way
electrons are distributed among the atoms and the connecting chemical bonds. In some literature electromerism is equated to
valence tautomerism, a term usually reserved for tautomerism involving reconnecting chemical bonds.
One group of electromers are excited electronic states but isomerism is usually limited to ground state molecules. Another group of electromers are also called redox isomers: metal ions that can exchange their
oxidation state with their ligands (see
non-innocent ligand). One of the first instances was a cobalt bis(quinone) complex described by Buchanan and Pierpont in 1980 with a cobalt(II) complex in
chemical equilibrium with the cobalt(III) complex. Ligands commonly found are based on
dioxolenes,
phenoxyl radicals and
polychlorotriphenylmethyl radicals.
Metalloporphyrins have also been studied. A set of electromers not requiring redox-active ligands have been described as well as a set without a metal. A new group of electromers has also been described recently.
References
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Isomerism