Low temperature insights into the crystal and magnetic structure of a neutral radical ferromagnet.

The crystal structure of the radical ferromagnet 1a at 2 K reveals a contraction in the unit cell constant which, at the molecular level, translates into a decrease in slippage of the radical π-stacks and an increase in ferromagnetic exchange interactions along the stacking axis. The results of BS-DFT calculations using long-range corrected functionals are consistent with an overall ferromagnetic topology.