(Methoxycarbonyl)hydrazinium chloride monohydrate

In the title compound, C2H7N2O2 +·Cl−·H2O, the non-H atoms of the cation are approximately coplanar. The organic cations, chloride ions and water molecules are linked into a two-dimensional network parallel to the bc plane by N—H⋯O, N—H⋯Cl and O—H⋯Cl hydrogen bonds.

In the title compound, C 2 H 7 N 2 O 2 + ÁCl À ÁH 2 O, the non-H atoms of the cation are approximately coplanar. The organic cations, chloride ions and water molecules are linked into a twodimensional network parallel to the bc plane by N-HÁ Á ÁO, N-HÁ Á ÁCl and O-HÁ Á ÁCl hydrogen bonds.

Comment
Benzaldehydehydrazone derivatives have received considerable attention for a long time due to their pharmacological activity (Parashar et al., 1988) and their photochromic properties (Hadjoudis et al., 1987). The title compound is an important intermediate in the synthesis of benzaldehydehydrazone derivatives. We report here the crystal structure of the title compound ( Fig. 1).
The molecules are linked into a two-dimensional network parallel to the bc plane by N-H···O, N-H···Cl and O-H···Cl hydrogen bonds involving the water molecule and chloride ions (Table 1 and Fig.2).

Experimental
Methyl hydrazinecarboxylate (0.90 g, 0.01 mol) was dissolved in ethanol-dilute HCl and single crystals suitable for X-ray analysis were obtained by slow evaporation at room temperature (m.p. 463-465 K).

Refinement
O-and N-bound H atoms were located in a difference map and were refined with O-H and N2-H2 distances restrained to 0.85 (2) Å and 0.87 (1) Å, respectively. The methyl H atoms were disordered over two orientations and their occupancies were initially refined and later fixed at 0.75 and 0.25, with C-H = 0.96 å and U iso (H) = 1.5U eq (C). Fig. 1. The molecular structure of the title compound, showing 30% probability displacement ellipsoids and the atomic numbering. Hydrogen bonds are shown as dashed lines.

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.
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.
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )