Muonium adducts of benzaldehyde: Structural correlation with nitroxides

We have formed adduct radicals (ArCHOMubullet) by muonium addition to the carbonyl group of benzaldehyde and its derivatives. The muon coupling is found to be highly sensitive to the nature of substituents in the benzene ring, being increased by electron releasing groups. Similarly, the ¹⁴N coupling in a series of nitroxides [ArN(Obullet)OSiEt₃], measured using ESR spectroscopy, is increased by electron releasing substituents and a linear correlation is found between the two; their connected nature is discussed. For the radical derived from benzaldehyde itself, a strong dependence is also found on the solvent in which it is solved. We suggest that this may be used in the study of solvent effects, particularly H‐bonding, pertinent to organic and bioorganic media. This revised version was published online in August 2006 with corrections to the Cover Date.