Abstract:

In chemistry, covalent bonds are divided into two categories: σ and π bonds. A σ bond can exist independently or concurrently with π bonds, as found in multiple bonds. In contrast, textbooks indicate that all π bonds are accompanied by a σ bond. Is it possible for π single bonds to exist independently? Although there are few references, recent studies have shown that compounds that contain a π single bond do exist. Herein, we review the research progress and characteristics of independent π single bonds.

Key words: Covalent bonds, σ bond, π bond, π single bond