1-Amino-2-nitraminoethane

The mol­ecule of title compound, C₂H₇N₃O₂, has a zwitterionic structure. All non-H atoms, apart from the terminal N atom of the NH₃ group, lie in the same plane, with a maximum deviation of 0.056 (1) Å for the amine N atom of the nitr­amine group, whereas the deviation of the terminal N atom of the NH₃ group from the same plane is 1.222 (2) Å. Intermolecular hydrogen bonds within the crystal form a three-dimensional network.

S1. Comment

Aminonitramines are of interest as biologically active non-protein amino acids (Alston et al., 1981; Nilsson et al., 1983) and as a new class of energetic compounds (Astachov et al., 2000a). The zwitterionic nature of aminonitramines was established on the basis of indirect physical and chemical investigations (McKay et al., 1954). Here, we present an X-ray structure determination of 1-amino-2-nitraminoethane, (I), which belongs to the same class of compounds. \sch

The present study unambiguously confirms the zwitterionic structure of (I). Fig. 1 provides a view of the crystal packing with the numbering scheme; selected molecular bond lengths and angles are given in Table 1. The C2—N3 bond length is in accord with that of various salts of organic amines (1.474–1.480 Å; Allen & Kennard, 1993; Georg et al., 1991; Burgess et al., 1991). The N—N bond length of the molecular nitramine part is shorter, and N—O bond lengths are longer, than the corresponding values in primary nitramines (N—N 1.301, and N—O 1.236 and 1.240 Å in 1,2-dinitraminoethane; Turley, 1968). As a whole, the nitramine fragment and bond lengths in (I) are close to the values characteristic of onium salts of primary nitramines (N—N 1.273 and N—O 1.283 Å in the dihydrazinium salt of 1,2-dinitraminoethane; Allen & Kennard, 1993; Bircher et al., 1996).

In the structure of (I), atom O1 forms two short hydrogen bonds with atoms H6 and H7 of two neighbouring molecules. The second oxygen, O2, is not involved in any hydrogen-bonding contacts. As a consequence, there is a significant difference in N—O bond lengths in (I) compared with both 1,2-dinitraminoethane (Turley, 1968) and its dihydrazine salt (Bircher et al., 1996). An intermolecular N3—H5···N2 hydrogen bond (Table 2) completes the picture of molecular packing.

From the established bond length values, it is difficult to fix the negative charge unambiguously on any atom of the nitramine part of the molecule. By analogy with salts of primary nitramines (Avakyan, 1971), the anion charge is rather delocalized over the whole nitramine fragment, but the electron density is distributed unevenly: the negative charge on atom O1 exceeds that on atoms N2 and O2.

In conclusion, the zwitterionic structure of aminonitramines, and of (I) in particular, leads to an increase in intermolecular interaction (crystal lattice energy) and, as a consequence, to an increase in thermal stability and the density of the compounds in comparison with the primary nitramines (Astachov et al., 2000a; Astachov, 1999).

S2. Experimental

Compound (I) was synthesized as described by Astachov et al. (2000b).

S3. Refinement

H atoms were located on a difference Fourier map and refined as riding, with a common isotropic displacement parameter of 0.032 Ų for CH₂ groups and 0.039 Ų for the NH₃ group. C—H distances were constrained to 0.97 Å and N—H distances to 0.935 Å.

Computing details

Data collection: KM-4 Software (Kuma, 1991); cell refinement: KM-4 Software; data reduction: DATARED in KM-4 Software; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Sheldrick, 1995); software used to prepare material for publication: SHELXL97.

Figures

Fig. 1. The molecular arrangement of (I) in the crystal, with the atomic numbering scheme and 50% probability displacement ellipsoids. H atoms are shown as small spheres of arbitrary radii and dashed lines indicate intermolecular hydrogen bonds.

1-Amino-2-nitraminoethane

Crystal data

C2H7N3O2	Z = 2
Mr = 105.11	F(000) = 112
Triclinic, P1	Dx = 1.563 Mg m^−3
a = 4.3449 (2) Å	Cu Kα radiation, λ = 1.5418 Å
b = 6.2955 (3) Å	Cell parameters from 25 reflections
c = 8.5432 (5) Å	θ = 27–35°
α = 105.240 (5)°	µ = 1.17 mm^−1
β = 92.743 (4)°	T = 293 K
γ = 96.356 (4)°	Lump, colourless
V = 223.36 (2) Å^3	0.36 × 0.32 × 0.27 mm

Data collection

Kuma KM-4 diffractometer	Rint = 0.029
Radiation source: fine-focus sealed tube	θmax = 64.8°, θmin = 5.4°
Graphite monochromator	h = −5→5
θ/2θ scans	k = −7→7
814 measured reflections	l = 0→9
756 independent reflections	2 standard reflections every 40 reflections
685 reflections with I > 2σ(I)	intensity decay: no decay, variation 0.4%

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.029	H-atom parameters constrained
wR(F^2) = 0.082	w = 1/[σ^2(Fo^2) + (0.0534P)^2 + 0.0467P] where P = (Fo^2 + 2Fc^2)/3
S = 1.02	(Δ/σ)max = 0.002
756 reflections	Δρmax = 0.21 e Å^−3
67 parameters	Δρmin = −0.14 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: 0.135 (10)

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
N1	0.0237 (2)	0.32208 (17)	0.21151 (12)	0.0220 (3)
O1	−0.1902 (2)	0.21586 (15)	0.09892 (11)	0.0333 (3)
O2	0.0966 (2)	0.23165 (16)	0.32042 (12)	0.0359 (3)
N2	0.1460 (2)	0.51362 (17)	0.20486 (12)	0.0240 (3)
C1	0.3897 (3)	0.6137 (2)	0.33447 (15)	0.0250 (3)
H1	0.5417	0.5121	0.3352	0.032*
H2	0.3015	0.6457	0.4391	0.032*
C2	0.5438 (3)	0.8261 (2)	0.30539 (16)	0.0264 (4)
H3	0.3949	0.9320	0.3161	0.032*
H4	0.7145	0.8897	0.3877	0.032*
N3	0.6629 (2)	0.78806 (17)	0.14224 (13)	0.0241 (3)
H5	0.8118	0.6899	0.1328	0.039*
H6	0.7533	0.9230	0.1282	0.039*
H7	0.4989	0.7272	0.0625	0.039*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0224 (6)	0.0211 (5)	0.0250 (6)	0.0040 (4)	0.0037 (4)	0.0100 (4)
O1	0.0337 (6)	0.0291 (5)	0.0350 (6)	−0.0072 (4)	−0.0085 (4)	0.0116 (4)
O2	0.0423 (6)	0.0316 (6)	0.0395 (6)	−0.0009 (4)	−0.0047 (4)	0.0235 (5)
N2	0.0259 (6)	0.0210 (6)	0.0272 (6)	0.0011 (4)	0.0012 (4)	0.0109 (4)
C1	0.0272 (7)	0.0264 (7)	0.0226 (7)	0.0030 (5)	0.0018 (5)	0.0089 (5)
C2	0.0292 (7)	0.0220 (6)	0.0254 (7)	0.0005 (5)	0.0029 (5)	0.0031 (5)
N3	0.0248 (6)	0.0210 (6)	0.0270 (6)	−0.0003 (4)	0.0012 (4)	0.0088 (4)

Geometric parameters (Å, º)

N1—O2	1.2571 (14)	C2—N3	1.4794 (16)
N1—N2	1.2794 (15)	C2—H3	0.9700
N1—O1	1.2942 (14)	C2—H4	0.9700
N2—C1	1.4551 (16)	N3—H5	0.9350
C1—C2	1.5136 (17)	N3—H6	0.9350
C1—H1	0.9700	N3—H7	0.9350
C1—H2	0.9700
O2—N1—N2	124.29 (10)	N3—C2—H3	109.2
O2—N1—O1	118.17 (10)	C1—C2—H3	109.2
N2—N1—O1	117.53 (10)	N3—C2—H4	109.2
N1—N2—C1	112.56 (10)	C1—C2—H4	109.2
N2—C1—C2	108.58 (10)	H3—C2—H4	107.9
N2—C1—H1	110.0	C2—N3—H5	109.5
C2—C1—H1	110.0	C2—N3—H6	109.5
N2—C1—H2	110.0	H5—N3—H6	109.5
C2—C1—H2	110.0	C2—N3—H7	109.5
H1—C1—H2	108.4	H5—N3—H7	109.5
N3—C2—C1	112.00 (10)	H6—N3—H7	109.5
O2—N1—N2—C1	2.25 (16)	N1—N2—C1—C2	173.66 (10)
O1—N1—N2—C1	−178.19 (9)	N2—C1—C2—N3	−55.64 (13)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N3—H5···N2^i	0.94	2.09	2.976 (2)	159
N3—H6···O1^ii	0.94	1.92	2.822 (2)	163
N3—H7···O1^iii	0.94	2.00	2.832 (2)	147

Symmetry codes: (i) x+1, y, z; (ii) x+1, y+1, z; (iii) −x, −y+1, −z.