Free Radical Reactivity of a Phosphaalkene Explored Through Studies of Radical Isotopologues

Abstract

Abstract Muonium (Mu), an H atom analogue, is employed to probe the addition of free radicals to the P=C bond of a phosphaalkene. Specifically, two unprecedented muoniated free radicals, MesP . −CMu(Me) 2 ( 1 a , minor product) and MesPMu−C . Me 2 ( 1 b , major product), were detected by muon spin spectroscopy (μSR) when a solution of MesP=CMe 2 ( 1 : Mes=2,4,6‐trimethylphenyl) was exposed to a beam of positive muons (μ + ). The μ + serves as a source of Mu (that is, Mu=μ + +e − ). To confirm the identity of the major product 1 b , its spectral features were compared to its isotopologue, MesPH‐C . (Me)CH 2 Mu ( 2 a ). Conveniently, 2 a is the sole product of the reaction of MesPH(CMe=CH 2 ) ( 2 ) with Mu. For all observed radicals, muon, proton, and phosphorus hyperfine coupling constants were determined by μSR and compared to DFT‐calculated values.