Abstract: The concept of covalent bonds was initially introduced by the American chemist Lewis, with the σ bond being one of its fundamental types. A classical σ bond is formed through the sharing of an electron pair between two atoms. A distinctive variant, the one-electron σ bond, involves two atoms sharing a single electron, a possibility first theorized by the American chemist Pauling in 1931. Due to its inherent instability, the synthesis of organic compounds featuring such bonds remained elusive for many years. This review highlights the advancements in the study of the formation and characteristics of one-electron σ bonds in various organic compounds, including organometallic compounds, over the past two decades. Key focus areas include phosphorus-phosphorus, boron-boron, and carbon-carbon one-electron σ bonds, as well as polar one-electron σ bonds between boron/aluminum/gallium and copper atoms.

Key words: Chemical bond, One-electron σ-bond, Organic compound, Research progress