Radicals containing β-muonium and α or β substituents:

A range of radicals, CH₂(Mu) HX (1) and XCH(Mu)CR₂ (2), where X is a second-row substituent, have been studied by transverse-fieldμ ⁺SR spectroscopy. The reduced muon—electron hyperfine coupling constants (A′_Mu) for class (1) were all close to 37.3 G, the value for the parent radical CH₂(Mu)CH₂. However, for class (2)A′ _Mu values are greatly reduced, as is the case for the corresponding hydrogen derivatives, XCH₂CR₂, relative to CH₃CH₂. Nevertheless, the reduction in coupling for Mu in (2] is appreciably less that that for¹H in XCH₂CR₂ radicals, suggesting significant competition between Mu and X for the out-of-plane site. In addition to theμ ⁺ SR studies, the ESR spectra for the radicals (MeO)₃SiCHCH₃ and (MeO)₃SiCH₂CH₂ have been measured for comparative purposes.