Buy article online - an online subscription or single-article purchase is required to access this article.
The title compound (Z)-2-nitroethenamine, C2H4N2O2, is a small energetic compound composed of only C, H, N and O, with a density of 1.513 g cm-3. The molecules of this crystal structure have bond lengths and angles that are characteristic of a type of push-pull ethylenes. The overall molecular organization in stacks of almost planar parallel layers is a result of intermolecular amine-to-nitro hydrogen bonding.
Supporting information
CCDC reference: 175365
Key indicators
- Single-crystal X-ray study
- T = 293 K
- Mean (C-C) = 0.002 Å
- R factor = 0.044
- wR factor = 0.119
- Data-to-parameter ratio = 9.6
checkCIF results
No syntax errors found
ADDSYM reports no extra symmetry
Alert Level C:
REFLT_03
From the CIF: _diffrn_reflns_theta_max 66.68
From the CIF: _reflns_number_total 650
TEST2: Reflns within _diffrn_reflns_theta_max
Count of symmetry unique reflns 691
Completeness (_total/calc) 94.07%
Alert C: < 95% complete
0 Alert Level A = Potentially serious problem
0 Alert Level B = Potential problem
1 Alert Level C = Please check
Dr Mao-Xi Zhang of the University of Chicago Chemistry Department supplied
crystals of the title compound.
Data collection: SMART (Bruker, 2001); cell refinement: SAINT (Bruker, 2001); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Sheldrick, 1997); software used to prepare material for publication: SHELXTL.
(
Z)-2-nitroethenamine
top
Crystal data top
C2H4N2O2 | F(000) = 184 |
Mr = 88.07 | Dx = 1.513 Mg m−3 |
Monoclinic, P21/c | Cu Kα radiation, λ = 1.54178 Å |
a = 5.5459 (2) Å | Cell parameters from 1596 reflections |
b = 10.3058 (3) Å | θ = 7.8–66.8° |
c = 6.8702 (3) Å | µ = 1.18 mm−1 |
β = 100.131 (2)° | T = 293 K |
V = 386.54 (2) Å3 | Plate, pale yellow |
Z = 4 | 0.39 × 0.27 × 0.03 mm |
Data collection top
CCD area-detector diffractometer | 650 independent reflections |
Radiation source: fine-focus sealed tube | 593 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.029 |
ϕ and ω scans | θmax = 66.7°, θmin = 7.8° |
Absorption correction: multi-scan (SADABS; Bruker, 2001) | h = −6→6 |
Tmin = 0.75, Tmax = 0.97 | k = −11→11 |
1860 measured reflections | l = −8→7 |
Refinement top
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.044 | Only H-atom coordinates refined |
wR(F2) = 0.119 | w = 1/[σ2(Fo2) + (0.0824P)2 + 0.0213P] where P = (Fo2 + 2Fc2)/3 |
S = 1.09 | (Δ/σ)max < 0.001 |
650 reflections | Δρmax = 0.18 e Å−3 |
68 parameters | Δρmin = −0.24 e Å−3 |
0 restraints | Extinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.144 (15) |
Crystal data top
C2H4N2O2 | V = 386.54 (2) Å3 |
Mr = 88.07 | Z = 4 |
Monoclinic, P21/c | Cu Kα radiation |
a = 5.5459 (2) Å | µ = 1.18 mm−1 |
b = 10.3058 (3) Å | T = 293 K |
c = 6.8702 (3) Å | 0.39 × 0.27 × 0.03 mm |
β = 100.131 (2)° | |
Data collection top
CCD area-detector diffractometer | 650 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2001) | 593 reflections with I > 2σ(I) |
Tmin = 0.75, Tmax = 0.97 | Rint = 0.029 |
1860 measured reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.044 | 0 restraints |
wR(F2) = 0.119 | Only H-atom coordinates refined |
S = 1.09 | Δρmax = 0.18 e Å−3 |
650 reflections | Δρmin = −0.24 e Å−3 |
68 parameters | |
Special details top
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 (Å2) top | x | y | z | Uiso*/Ueq | |
N1 | 0.8749 (2) | 0.79870 (13) | 0.40604 (19) | 0.0630 (5) | |
H1A | 1.011 (4) | 0.8389 (14) | 0.466 (3) | 0.076* | |
H1B | 0.754 (3) | 0.850 (2) | 0.354 (3) | 0.076* | |
C1 | 0.8617 (2) | 0.67328 (15) | 0.4003 (2) | 0.0613 (5) | |
H1 | 0.998 (3) | 0.6280 (15) | 0.461 (2) | 0.074* | |
C2 | 0.6720 (2) | 0.59581 (14) | 0.3149 (2) | 0.0609 (5) | |
H2 | 0.688 (3) | 0.509 (2) | 0.317 (2) | 0.073* | |
N2 | 0.45367 (18) | 0.64422 (12) | 0.21808 (15) | 0.0569 (5) | |
O2A | 0.28745 (17) | 0.56588 (11) | 0.14658 (18) | 0.0782 (5) | |
O2B | 0.41900 (18) | 0.76326 (10) | 0.20014 (16) | 0.0665 (5) | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
N1 | 0.0529 (8) | 0.0575 (9) | 0.0717 (9) | −0.0015 (5) | −0.0081 (6) | −0.0036 (5) |
C1 | 0.0517 (8) | 0.0577 (9) | 0.0678 (9) | 0.0071 (6) | −0.0076 (6) | 0.0008 (6) |
C2 | 0.0555 (8) | 0.0462 (8) | 0.0741 (10) | 0.0070 (6) | −0.0077 (6) | 0.0025 (6) |
N2 | 0.0502 (7) | 0.0500 (8) | 0.0659 (8) | −0.0007 (5) | −0.0029 (5) | −0.0004 (4) |
O2A | 0.0570 (7) | 0.0570 (8) | 0.1083 (10) | −0.0059 (4) | −0.0192 (6) | −0.0020 (5) |
O2B | 0.0565 (7) | 0.0469 (8) | 0.0881 (9) | 0.0058 (4) | −0.0093 (5) | 0.0031 (4) |
Geometric parameters (Å, º) top
N1—C1 | 1.295 (2) | N1—H1A | 0.90 (2) |
C1—C2 | 1.368 (2) | N1—H1B | 0.88 (2) |
C2—N2 | 1.3688 (16) | C1—H1 | 0.925 (18) |
N2—O2B | 1.2445 (15) | C2—H2 | 0.90 (2) |
N2—O2A | 1.2584 (14) | | |
| | | |
N1—C1—C2 | 129.10 (13) | C1—N1—H1B | 123.4 (13) |
C1—C2—N2 | 122.92 (14) | H1A—N1—H1B | 115.7 (17) |
O2B—N2—O2A | 120.26 (11) | N1—C1—H1 | 116.9 (11) |
O2B—N2—C2 | 121.03 (12) | C2—C1—H1 | 114.0 (11) |
O2A—N2—C2 | 118.71 (12) | C1—C2—H2 | 120.6 (10) |
C1—N1—H1A | 120.9 (11) | N2—C2—H2 | 116.5 (10) |
| | | |
N1—C1—C2—N2 | −0.5 (2) | C1—C2—N2—O2A | −178.87 (13) |
C1—C2—N2—O2B | 1.26 (19) | | |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1B···O2B | 0.88 (2) | 2.161 (19) | 2.6959 (16) | 118.8 (16) |
N1—H1A···O2Ai | 0.90 (2) | 2.04 (2) | 2.9299 (16) | 169.0 (14) |
N1—H1B···O2Aii | 0.88 (2) | 2.24 (2) | 2.8997 (19) | 131.9 (16) |
Symmetry codes: (i) x+1, −y+3/2, z+1/2; (ii) −x+1, y+1/2, −z+1/2. |
Experimental details
Crystal data |
Chemical formula | C2H4N2O2 |
Mr | 88.07 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 293 |
a, b, c (Å) | 5.5459 (2), 10.3058 (3), 6.8702 (3) |
β (°) | 100.131 (2) |
V (Å3) | 386.54 (2) |
Z | 4 |
Radiation type | Cu Kα |
µ (mm−1) | 1.18 |
Crystal size (mm) | 0.39 × 0.27 × 0.03 |
|
Data collection |
Diffractometer | CCD area-detector diffractometer |
Absorption correction | Multi-scan (SADABS; Bruker, 2001) |
Tmin, Tmax | 0.75, 0.97 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 1860, 650, 593 |
Rint | 0.029 |
(sin θ/λ)max (Å−1) | 0.596 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.044, 0.119, 1.09 |
No. of reflections | 650 |
No. of parameters | 68 |
H-atom treatment | Only H-atom coordinates refined |
Δρmax, Δρmin (e Å−3) | 0.18, −0.24 |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1B···O2B | 0.88 (2) | 2.161 (19) | 2.6959 (16) | 118.8 (16) |
N1—H1A···O2Ai | 0.90 (2) | 2.04 (2) | 2.9299 (16) | 169.0 (14) |
N1—H1B···O2Aii | 0.88 (2) | 2.24 (2) | 2.8997 (19) | 131.9 (16) |
Symmetry codes: (i) x+1, −y+3/2, z+1/2; (ii) −x+1, y+1/2, −z+1/2. |
Subscribe to Acta Crystallographica Section E: Crystallographic Communications
The full text of this article is available to subscribers to the journal.
If you have already registered and are using a computer listed in your registration details, please email
support@iucr.org for assistance.
Several olefins with nitro and amino substituents have been studied by X-ray crystal structure analysis (Gate et al., 1985; Hazell et al., 1980; Bemm & Östmark, 1998), spectroscopy and theoretical chemistry (Karafiloglou & Marcos, 1992) because of their importance in synthetic chemistry and their biological activity (Gate et al., 1992). The X-ray crystal structure of the simplest member of the nitroethenamine family, (Z)-2-nitroethenamine, (1), has not been reported yet and is the subject of this article. This type of ethylene is commonly referred to as a push–pull ethylene because of the effects of the nitro and amino substituents on the π-electron distribution, as illustrated by the resonance structures of (1a), (1 b), and (1c). In common with other members of this group, the combined effects of the electron-withdrawing nitro group and the electron-donating amino group serve to lengthen the central olefin bond of the title compound from a `normal' value of 1.317 Å (Allen et al., 1987) to the observed value of 1.363 Å. In a similar molecule (1,1-diaminodinitroethylene), the central bond is lengthened to 1.456 Å (Bemm & Östmark, 1998). This is substantially longer than the distance in the title compound, due to the stronger push–pull effect and increased steric crowding. In addition to the lengthening of the central bond, the terminal bonds to the amino and the nitro substituents in these compounds are shortened. In the title compound, the amino C—N distance is 1.311 Å and the nitro C—N distance is 1.372 Å. These values are similar to those observed in the Cambridge Structural Database (CSD; Allen et al., 1987) for three RNH-C═C—NO2 molecules; the reported CSD amino C—N distances range from 1.303 to 1.335 Å (Gate et al., 1985; Hazell & Mukhopadhyay, 1980; Dianez et al., 1985; Schlueter & Cook, 1989) and the nitro C—N distances range from 1.378 to 1.395 Å. Thus, the observed terminal distances are always shorter than the expected (Allen et al., 1987) Csp2-amino and Csp2-nitro distances of 1.336 and 1.468 Å, respectively. The push–pull effect also plays a role in reducing the barrier to rotation of the olefin bond. This barrier, which is normally very high, is lowered, permitting large distortions from `olefinic' planarity when bulky groups are substituted on the amine (e.g., see Baum et al., 1992). The title molecule, (Z)-2-nitroethenamine, is almost entirely planar. (The mean deviation from the plane through the molecule is 0.01 Å with a range of 0.00–0.02 Å.) The cis arrangement of amino and nitro in this molecule also enables an intramolecular hydrogen bond. In addition, there are two unique intermolecular NH—-NO2 hydrogen bonds which tie the molecules into sheets that are almost flat; the mean deviation of the atoms in each sheet from a plane is 0.133 Å. These slightly wavy sheets (see Fig. 2) extend throughout the crystal in two dimensions and form a parallel stack. This packing is similar to that seen in the crystals of the 1,1-diaminodinitroethylene (Bemm & Östmark, 1998).