Pancake bonds: π-Stacked dimers of organic and light-atom radicals

The nature of the chemical bond is fundamental to the modern concept of chemistry. Species that exhibit unusual interactions provide a valuable challenge to current theoretical models and computational techniques. One of the areas that has garnered significant interest in the past decade is the computational analysis of so-called “pancake bonds” between planar organic or light-atoms radicals. The present review provides a timely survey of the more common organic and light-atom neutral radicals, radical cations and radical anions that are known to form π-dimers in the solid state.