The pancake bond: on the border of covalent and intermolecular

Abstract

The two-electron multicentre (2e/mc) bond or pancake bond, a weak π-bond occurring between planar π-based organic radicals, is described and discussed. Its importance in chemistry (nature of the chemical bond) and materials science (its application in design of radical-based functional materials) is emphasized: the latest developments, concepts, and new directions of research; challenges and possible pitfalls are discussed.