Redetermination of hydrogen­hydrazinium dichloride

The crystal structure of the title compound, N₂H₆²⁺·2Cl⁻, previously determined by photographic methods [Wyckoff (1923). Am. J. Sci. 5, 15–22; Donohue & Lipscomb (1947). J. Chem. Phys. 15, 115–119], has been redetermined from single-crystal data. The N and Cl atoms are located on threefold rotation axes, whereas the H atom lies in a general position. The [H₆N₂]²⁺ cations and the Cl⁻ anions are connected via N—H...Cl hydrogen bonds forming a three-dimensional net, whereby R₆³(14) rings are generated.

Key indicators

• Single-crystal X-ray study
• T = 291 K
• Mean [sigma](N-N) = 0.001 Å
• R factor = 0.017
• wR factor = 0.044
• Data-to-parameter ratio = 12.2

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT042_ALERT_1_C Calc. and Rep. MoietyFormula Strings Differ ....          ?
PLAT127_ALERT_1_C Implicit Hall Symbol  Inconsistent with Explicit    -P 2ac 2ab
PLAT180_ALERT_3_C Check Cell Rounding: # of Values Ending with 0 =          3
PLAT737_ALERT_1_C D...A   Calc   3.0943(7), Rep   3.0944(3) ......       2.33 su-Ra
              N1   -CL1     1.555   1.555

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   4 ALERT level C = Check and explain
   0 ALERT level G = General alerts; check

   3 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

Hydrogenhydrazinium dichloride, or commonly hydrazine dihydrochloride, is the most excellent source of dry hydrazine for organic syntheses. It is commonly used as a reducing agent for the recovery of precious metals or in soldering fluxes for aluminium and magnesium alloys. It is also used as a polymerization catalyst and a chain extender, and is a source of a large number of derivatives, for example used in agrochemicals, pharmaceuticals, photographics, heat stabilizers, polymerization catalysts, flame-retardants, blowing agents for plastics, explosives, and dyes.

The crystal structure of the title compound has been previously determined by photographic methods (Wyckoff, 1923; Donohue & Lipscomb, 1947). The results of the present re-determination show a much higher precision and accuracy. The nitrogen and chlorine atoms are located on threefold rotation axis, whereas the hydrogen atom lies in a general position. The [H₆N₂]²⁺ cations and Cl^- anions are connected via N—H···Cl hydrogen bonds (Table) to a 3-D net, generating R₆³(14) rings (Bernstein et al., 1995). The bond lengths in the title compound (Table) are comparable to those observed for hydrazinium chloride (Sakurai & Tomiie, 1952; Chekhlov & Martynov, 1988) and hydrazine (Collin & Lipscomb, 1951), respectively.

Related literature

For previously reported determinations of the title compound, see: Wyckoff (1923); Donohue & Lipscomb (1947). For the crystal structures of hydrazinium chloride, see: Sakurai & Tomiie (1952); Chekhlov & Martynov (1988). For the crystal structure of hydrazine, see: Collin & Lipscomb (1951). For patterns in hydrogen bonding, see: Bernstein et al. (1995).

S2. Experimental

Commercially available hydrogenhydrazinium dichloride (pure, Merck, CAS 5341–61-7) was recrystallized from a saturated solution of 0.2 mol/dm³ hydrochloric acid (about 2.7 g of the title compound in 1 cm³ of acid).

S3. Refinement

The H atom was found from a difference Fourier synthesis after four cycles of anisotropic refinement for the N and Cl atoms, and was refined freely.

Computing details

Data collection: CrysAlis CCD (UNIL IC & Kuma, 2000); cell refinement: CrysAlis RED (UNIL IC & Kuma, 2000); data reduction: CrysAlis RED (UNIL IC & Kuma, 2000); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: XP in SHELXTL (Sheldrick, 1990) and ORTEP-3 (Farrugia 1997); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997) and PLATON (Spek, 2003).

Figures

	Fig. 1. The molecular structure of the title compound. Displacement ellipsoids are drawn at the 50% probability level. [Symmetry code: (i) -x + 1, -y + 1, -z.]
	Fig. 2. The packing of the structure units in a view approximately along [111]. Hydrogen bonds are indicated by dashed lines.

Hydrogenhydrazinium dichloride

Crystal data

N2H6^2+·2Cl^−	Dx = 1.429 Mg m^−3 Dm = 1.43 Mg m^−3 Dm measured by Berman density torsion balance
Mr = 104.97	Mo Kα radiation, λ = 0.71073 Å
Cubic, Pa3	Cell parameters from 1003 reflections
Hall symbol: -P 2ac 2ab	θ = 4.0–25.0°
a = 7.8731 (1) Å	µ = 1.15 mm^−1
V = 488.02 (1) Å^3	T = 291 K
Z = 4	Needle, colourless
F(000) = 216	0.37 × 0.11 × 0.11 mm

Data collection

Kuma KM4 CCD diffractometer	146 independent reflections
Radiation source: fine-focus sealed tube	146 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.015
Detector resolution: 1048576 pixels mm^-1	θmax = 25.1°, θmin = 4.5°
ω scans	h = −9→9
Absorption correction: numerical (X-RED; Stoe & Cie, 1999)	k = −9→9
Tmin = 0.837, Tmax = 0.880	l = −9→9
4076 measured reflections

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.017	All H-atom parameters refined
wR(F^2) = 0.044	w = 1/[σ^2(Fo^2) + (0.0276P)^2 + 0.0263P] where P = (Fo^2 + 2Fc^2)/3
S = 1.34	(Δ/σ)max < 0.001
146 reflections	Δρmax = 0.16 e Å^−3
12 parameters	Δρmin = −0.42 e Å^−3
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 1997), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.46 (3)

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 F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² 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 (Ų)

	x	y	z	Uiso*/Ueq
Cl1	0.77910 (3)	0.27910 (3)	0.22090 (3)	0.0283 (4)
N1	0.55244 (9)	0.44756 (9)	−0.05244 (9)	0.0254 (4)
H1	0.6227 (17)	0.3953 (15)	0.0133 (16)	0.042 (3)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cl1	0.0283 (4)	0.0283 (4)	0.0283 (4)	0.00117 (8)	−0.00117 (8)	−0.00117 (8)
N1	0.0254 (4)	0.0254 (4)	0.0254 (4)	0.0005 (3)	0.0005 (3)	−0.0005 (3)

Geometric parameters (Å, º)

N1—N1^i	1.4302 (10)	N1—H1	0.862 (13)
N1^i—N1—H1	107.5 (9)

Symmetry code: (i) −x+1, −y+1, −z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···Cl1	0.862 (13)	2.242 (13)	3.0944 (3)	170.0 (12)