Is π-Single Bonding (C–π–C) Possible? A Challenge in Organic Chemistry

Abstract

Chemical bonding systems determine the nature of molecules. In organic chemistry, there are two bonding types for carbon–carbon connections: σ-bonding and π-bonding. In this Highlight Review, several aspects of studies in the last two decades addressing a naive question “Is π-single bonding (C–π–C) possible?” were reviewed: (1) features of π-single bonded species; (2) molecular design for π-single bonding; (3) generation and detection of singlet diradicaloids with a π-single bonding character; (4) future prospects of π-single bonded species. In this Highlight Review, several aspects of studies addressing a naive question “Is π-single bonding (C–π–C) possible?” were reviewed: (1) features of π-single bonded species; (2) molecular design for π-single bonding; (3) generation and detection of singlet diradicaloids with a π-single bonding character; (4) future prospects of π-single bonded species.