Redetermination of para ‐aminopyridine (fampridine, EL‐970) at 150 K

The structure of fampridine (EL‐970) or 4‐aminopyridine, C 5 H 6 N 2 , has been redetermined at 150 K. The room‐temperature structure has been reported previously [Chao & Schempp (1977). Acta Cryst. B 33 , 1557–1564]. Pyramidalization at the amine N atom occurs in fampridine, with the N atom 0.133 (11) Å from the plane of the three C/H/H atoms to which it is bonded; the interplanar angle between the pyridyl ring and NH 2 group is 21 (2)°. Aggregation in the solid state occurs by N—H⋯N and N—H⋯π(pyridine) interactions with N⋯N and N⋯π(centroid) distances of 2.9829 (18) and 3.3954 (15) Å, respectively; a C—H⋯π(pyridine) contact completes the intermolecular interactions [C⋯π(centroid) = 3.6360 (16) Å].