Chain versus dimer contacts in crystalline 5-(4-[N-tert-butyl-N-aminoxyl]phenyl)pyrimidine radicals: Choices among competing intermolecular exchange mechanisms

The title compound forms both alternating chains, in-plane dimer, and π-stack dimer contacts between sites of delocalized spin density. Magnetic measurements show that the 50% of molecules that form π-stacked dimers (Ja-a′) dominate the exchange behavior at lower temperatures, with the rest of molecules showing essentially paramagnetic behavior.