Diradicals in the Origin of Chemical Reactions.

Abstract

Diradicals in the Origin of Chemical Reactions S. Medina Rivero1, 2, J. Casado Cordón1 1 Univeristy of Málaga, Department of Physical Chemistry, Málaga, Spain 2 University of Sheffield, Department of Physics and Astronomy, Sheffield, United Kingdom π-Conjugated organic diradicals are appealing systems for organic electronic materials due to the possibility of tailoring their chemical and physical properties by controlling the interaction between the radical centers in their ground electronic state. The spin-spin interaction can be tuned by the extension of the π-electron delocalization, e.g. increasing the spin-spin distance or including alternative π-conjugated frameworks, hence providing a direct chemical control through organic synthesis over the magnitude and sign of this interaction. Unfortunately, bearing two unpaired electron spins in the ground electronic state is both a blessing and a curse, as it also makes these species highly reactive. Increasing the diradical character usually entails the loss of chemical stability, making the handling and characterization of these materials very challenging. In this contribution we show how to smartly exploit this high reactivity to obtain new architectures based on a dicyanomethylene substituted diazaacene and a bisindenedione compound. Using electronic and vibrational spectroscopy we demonstrate that diradical species are the cornerstone of the mechanism of the chemical reactions described in both cases.