Download full text in PDF Opens in a new window. Article suggestions will be shown in a dialog on return to ScienceDirect. ... Please enable JavaScript to use all the features on this page. ... The paramagnetic heterocyclic aldonitrone, 2,2,5,5-tetra-methyl-3-imidazoline-3-oxide-1-oxyl , reacts with C=C and C=N containing dipolarophiles to yield cycloadducts with radical centres. ... A detailed discussion of the spectra will be presented elsewhere.