Radical revelations: the pnictogen effect in linear acetylenes

• Published in: Physical chemistry chemical physics : PCCP 2024-02, Vol.26 (9), p.7718-773
• Main Authors: Gallegos, Miguel, del Amo, Vicente, Guevara-Vela, José Manuel, Moreno-Alcántar, Guillermo, Martín Pendás, Ángel
• Format: Article
• Language: English
• Subjects: Chemical bonds; Modularity
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/d3cp06324k

Acetylenes are essential building blocks in modern chemistry due to their remarkable modularity. The introduction of heteroatoms, such as pnictogens (X), is one of the simplest approaches to altering the C≡C bond. However, the chemistry of the resultant dipnictogenoacetylenes (DXAs) is strongly dependent on the nature of X. In this work, rigorous theoretical chemistry tools are employed to shed light on the origin of these differences, providing a detailed evaluation of the impact of X on the geometrical and electronic features of DXAs. Special emphasis is made on the study of the carbene character of the systems through the analysis of the interconversion mechanism between the linear and zigzag isomers. Our results show that second-period atoms behave drastically differently to the remaining X: down the group, a zwitterionic resonance form emerges at the expense of decreasing the carbenoid role, eventually resulting in an electrostatically driven ring closure. Furthermore, our findings pave the way to potentially unveiling novel routes for the promotion of free-radical chemistry. Acetylenes are crucial in chemistry. Adding heteroatoms like pnictogens changes their properties. This study explores how these changes affect dipnictogenoacetylenes (DXAs), offering insights into potential new routes for free-radical chemistry.