Tautomeria de Valência – dos Conceitos aos Recentes Compostos de Cobalto

Resumo

The development of molecular systems that switch between two states when exposed to external stimuli
is a possible alternative in the construction of electronic devices that can eventually be applied in
sensors, signal processors, or information storage devices. Coordination compounds that exhibit valence
tautomerism have gained considerable importance due to changes in magnetic and optical properties
that occur in these compounds. The changes are caused by metal-ligand electron transfer which is
accompanied by a change in the spin state of the metal ion, creating two electronic states. Cobalt and
o-dioxolene coordination compounds, with nitrogenous auxiliary ligands, represent a large part of the
compounds presenting valence tautomerism. This article’s main purpose is to present the characteristics
of compounds that exhibit this property and to report the most recent advances in studies of mono- and
dinuclear coordination compounds of this class.