Synthesis and Magnetic Properties of (Pyrrolidin-1-oxyl)-(Nitronyl Nitroxide)/(Iminonitroxide)-Dyads.

Unlike extensively studied diradicals linked by π-conjugated systems, only a few studies have investigated weakly coupled diradicals linked by an sp carbon atom. Herein, we prepared pyrrolidin-1-oxyl-(nitronyl nitroxide)-dyad 5 and pyrrolidin-1-oxyl-iminonitroxide-dyad 6. From the observed temperature dependence of the magnetic susceptibility, 5 and 6 were determined to be in singlet ground states with 2J /k =-35.