Stable (BIII -Subporphyrin-5-yl)dicyanomethyl Radicals

Stable BIII -subporphyrin-substituted dicyanomethyl radicals were synthesized by SN Ar reaction of meso-bromo- or meso-chlorosubporphyrins with malononitrile followed by oxidation with PbO2 . Different from previously reported dicyanomethyl radicals that underwent σ- or π-dimer formation both in the solid state and in solutions, subporphyrin-stabilized dicyanomethyl radicals exist as monomers in solutions even at low temperature. DFT calculations revealed efficient spin delocalization over the entire subporphyrin. In the solid state, these radicals form weak π-dimers with antiferromagnetic interactions depending on the crystal packing structures.