Heteroatom-Incorporated Trimethylenemethane: Synthesis and Properties of Triphenylphenylnitroxide–(Nitronyl Nitroxide) Dyad

We designed and synthesized a triphenylphenylnitroxide-(nitronyl nitroxide) dyad with a structure isoelectronic with trimethylenemethane. Crystal structure analysis demonstrated that the dihedral angle between the nitroxide and nitronyl nitroxide moieties was excessively small due to the steric effects of the triphenylphenyl moiety. The coplanarity of the two radical systems induced an excessively strong ferromagnetic intramolecular interaction (2J/k(B) >= +2000K; H = -2JS(1/2)center dot S-1/2).