Novel cation-bound bi-radicals are generated in a chemical ionization source from either the stable free radical, 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO), or the phenoxyl radical and cations including carbonyl isocyanate, ( [ OCNCO' ] ), and, in one case, the proton. The dimeric cluster ions, mildly activated under collision-S'~, CS'Δ© nduced dissociation (CID) conditions, dissociate to yield the cationized monomer (e.g. the [ OCNCO ] '-bound TEMPO radical, [ OCNCO ] '-bound phenoxyl radical, TEMPO radical or TEMPO S'~-bound CS'~-bound radical). Such facile dissociation suggests a loosely bound structure comparable to that of a proton-bound dimer. Binding of this sort, radical-cation-radical, suggests the possible formation of an "interrupted sigma bondΓ (electron-electron interactions mediated by the cation). The cluster ion comprised of Cl' and two TEMPO radicals behaves di β erently and gives a complex set of lower abundance products under similar activation conditions. This indicates that in this case the dissociating cluster has a conventional covalently bound structure. Analogous behavior is observed in the cases of proton-bound bis-TEMPO clusters and the corresponding mixed phenoxyl-TEMPO species, the Cl'-bound bis-phenoxyl cluster and the Cl'-bound cluster with mixed TEMPO-phenoxyl cluster, as well as the bis-phenoxyl and bis-phenoxyl complexes. The CID of the putative S'~-bound CS'~-bound proton-bound bis-phenoxyl cluster also suggests a conventional structure and its dissociation shows a strong dependence on collision energy, possibly because of facile rearrangement from the desired weakly bound bi-radical cluster ion.