Molecular recognition for stable organic radicals - 2-(6-uradinyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-1oxyl

Stable radical 2-(6-uradinyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-1-oxyl shows antiferromagnetic spin pairing with 2J/k=–14 K, attributable to a close contact between unpaired spin density on the imidazole-type nitrogen atoms; hydrogen bonds aid dimer formation, but do not appear to play an eletronic role in the magnetic behaviour.