4-Hydrazinopyridinium chloride

In the title compound, C5H8N3 +·Cl−, the cation and the anion lie on a mirror plane and are hydrogen bonded in a three-dimensional network via the H atoms of the two hydrazine N atoms. The pyridine N atom is protonated and hydrogen bonded to the terminal hydrazine N atom.

In the title compound, C 5 H 8 N 3 + ÁCl À , the cation and the anion lie on a mirror plane and are hydrogen bonded in a threedimensional network via the H atoms of the two hydrazine N atoms. The pyridine N atom is protonated and hydrogen bonded to the terminal hydrazine N atom.

Structure Reports Online
In summary, the structure of (I) has a higher symmetry than (II) and (III) and is tightly packed due to a network of strong H bonds.
After refluxing for 48 h, the mixture was cooled to 273 K and washed with cold 1-propanol. Recrystallization from methanol yielded 3.6 g of the title compound (I) as colorless needles in 65% yield. The compound (I) has a melting point of 516-517 K, which was in agreement with published values (Mann et al. 1959).

Refinement
Space group determination was ambiguous between P2 1 and P2 1 /m because of poor E-statistics. However, the structure was successfully solved using the SHELXD procedure (Sheldrick, 2008) and refined in P2 1 /m. The origin of the ambiguous E-statistics became obvious after structure solution, as every atom except for the two N8 hydrogen atoms are found on a crystallographic mirror plane. All H atoms were located in a difference map. N-bound H atoms were freely refined with the constraint U iso (H) = 1.2U eq (N). The C-bound H atoms were placed in calculated positions (C-H = 0.95 Å) and refined as riding with U iso (H) = 1.2U eq (C).
supplementary materials sup-2 Figures   Fig. 1. A view of (I) plotted with displacement ellipsoids at 50% probability level.

4-Hydrazinopyridinium chloride
Crystal data Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating Rfactors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.