Redetermination of phenylhydrazinium chloride

In the redetermined structure [Koo (1965 ▶). Bull. Chem. Soc. Jpn, 38, 286] of the title compound, C6H9N2 +·Cl−, the H atoms have been located and the hydrogen-bonding scheme established. A series of N—H⋯Cl and N—H⋯N hydrogen bonds leads to a layered network parallel to the (010) plane.

In the redetermined structure [Koo (1965). Bull. Chem. Soc. Jpn, 38, 286] of the title compound, C 6 H 9 N 2 + ÁCl À , the H atoms have been located and the hydrogen-bonding scheme established. A series of N-HÁ Á ÁCl and N-HÁ Á ÁN hydrogen bonds leads to a layered network parallel to the (010) plane.

Comment
The structure of the title compound, (I), was established by Koo (1965), but no hydrogen atoms were located. The hydrogen bonding pattern in the crystal of (I) cannot be established based on geometrical placement of the H atoms because roatation of the terminal -NH 3 + group leads to different plausible arrangements for the hydrogen bonds. Here, the redetermined structure of (I), including the H atom positions is presented (Fig. 1), and the hydrogen bonding scheme is definitively established.
The crystal packing for (I) is influenced by cation-to-cation N-H···N and cation-to-anion N-H···Cl hydrogen bonds (Table 1). The former of these leads to [100] chains in the crystal. One of the H···Cl separations is unusually short, with H···Cl = 2.04 (6) Å, which possibly correlates with the its long N-H separation of 1.04 (6) Å. Together, the hydrogen bonds lead to sheets parallel to the (010) plane (Fig. 2).
Only one other crystal structure containing the phenylhydrazinium cation has been determined (Hammerl et al., 2001), which has similar geometrical paramaters to those in (I).

Experimental
The title compound was prepared by dropwise addition of concentrated hydrochloric acid (1 equivalent) to an ethanolic solution of phenylhydrazine. The product, which appreared on standing, was collected and colourless blades of (I) were recrystallized from EtOH, m.p 525-528 K (decomp).