Free Radical Chemistry of Phosphasilenes. Issue 37 (9th July 2020)

• Record Type: Journal Article
• Authors: Samedov, Kerim; Heider, Yannic; Cai, Yuanjing; Willmes, Philipp; Mühlhausen, Daniel; Huch, Volker; West, Robert; Scheschkewitz, David; Percival, Paul W.
• Is Part Of: Angewandte Chemie international edition. Volume 59:Issue 37(2020)
• Page Start: 16007
• Page End: 16012
• Publication Date: 2020-07-09
• Subjects: conformational analysis -- muon spin spectroscopy -- phosphasilenes -- radicals; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.202006289
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: Understanding the characteristics of radicals formed from silicon‐containing heavy analogues of alkenes is of great importance for their application in radical polymerization. Steric and electronic substituent effects in compounds such as phosphasilenes not only stabilize the Si=P double bond, but also influence the structure and species of the formed radicals. Herein we report our first investigations of radicals derived from phosphasilenes with Mes, Tip, Dur, and NMe2 substituents on the P atom, using muon spin spectroscopy and DFT calculations. Adding muonium (a light isotope of hydrogen) to phosphasilenes reveals that: a) the electron‐donor NMe2 and the bulkiest Tip‐substituted phosphasilenes form several muoniated radicals with different rotamer conformations; b) bulky Dur‐substituted phosphasilene forms two radicals (Si‐ and P‐centred); and c) Mes‐substituted phosphasilene mainly forms one species of radical, at the P centre. These significant differences result from intramolecular substituent effects. Abstract : Radical rotations about Si–P bonds : Muonium, a light isotope of H, reacts with phosphasilenes to form P‐centred and/or Si‐centred radicals. In some cases, multiple rotamer conformations of the same radical can be detected, depending on the nature of the substituents on the parent phosphasilene.