A long symmetric N...H...N hydrogen bond in bis(4-aminopyridinium)(1+) azide(1−): redetermination from the original data

The structure of the title molecular salt, C10H13N4+·N3−, has been redetermined from the data published by Qian & Huang [Acta Cryst.(2010), E66, o3086; refcode WACMIY (Groomet al., 2016)]. The improvement of the present redetermination consists in a correction of the site-occupancy parameter of the bridging H atom between the pyridine rings, as well as of its position. The present study has shown that the bridging H atom (site symmetry 2) is involved in a symmetric N...H...N hydrogen bond, which is one of the longest ever observed [N...N = 2.678 (3) Å]. In addition, there are also present weaker Nam—H...Nazhydrogen bonds (am = amine and az = azide) of moderate strength and π-electron pyridine...π-electron interactions in the structure. All the azide N atoms also lie on a twofold axis.