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

Stable B-III-subporphyrin-substituted dicyanomethyl radicals were synthesized by SNAr reaction of meso-bromo- or meso-chlorosubporphyrins with malononitrile followed by oxidation with PbO2. Different from previously reported dicyanomethyl radicals that underwent sigma- or pi-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 pi-dimers with antiferromagnetic interactions depending on the crystal packing structures.