Unstable intermediates. Part CXLVII. Electron spin resonance spectra of radicals in irradiated organotin compounds: the radicals R3Sn, R4Sn–, R5Sn, R3SnCl–, Ph6Sn2–, H2ĊSn(Me)2SnMe3, and H2ĊSn(Me)2Cl

Abstract

Exposure of the following compounds or their solutions to ⁶⁰Co γ-rays at 77 K gave e.s.r. spectra which are interpreted in terms of the radicals in parentheses: Me₄Sn (Me₃Sṅ, Me₄Sṅ–, Me₅Sn, H₂ĊSnMe₃); Et₄Sn (Et₃Sṅ, MeĊHSnEt₃, H₂ĊCH₂SnEt₃); Bu₄Sn (Bu₃Sṅ, EtĊHCH₂SnBu₃, RĊHSnBu₃); Me₃SṅCl (Me₃SṅSCl–, Me₃SṅH₂ĊSnMe₂Cl); Bu₃SnCl (Bu₃Sṅ, EtĊHCH₂SnBu₂Cl, PrĊHSnBu₂Cl); Me₆Sn₂(Me₂SṅSnMe₃, H₂CSnMe₂-SnMe₃); Ph₆Sn₂(Ph₆Sn₂^–); and Ph₃SnH (Ph₃Sn·). Interesting aspects of these result include the pyramidal character of R₃Sṅ radicals and the low spin density on tin for Me₅Sṅ, which is through to have D_3h symmetry with major spin density on the axial methyl groups. The absence of hyperfine interaction from the β-Cl or β-SnMe₃ groups for H₂ĊSn(Me)₂Cl and H₂ĊSn(Me)₂SnMe₃ suggest that these groups lie near the nodal plan of the half-occupied 2p(carbon) orbital, In complete contrast with the preferred conformation for the corresponding carbon radicals, H₂ĊCR₂Cl and H₂ĊCR₂SnMe₃.