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The electron density and related properties of the quasi-stable β form of 5-nitro-2,4-dihydro-3H-1,2,4-triazol-3-one (NTO; space group P21/c) have been determined from a low-temperature [100 (1) K] X-ray diffraction experiment. Intensities were measured with a 2K CCD Bruker diffractometer using Ag Kα radiation. Two detector settings, several φ settings, 0.3° ω scans and 160 s exposure time per frame gave Rint = 0.0215 for 68 989 (4080 unique) reflections and (sin θ/λ)max = 1.23 Å−1. The Hansen–Coppens [Acta Cryst. (1978), A34, 909–921] multipole model as implemented in the XD program gave R = 0.0333 (all reflections), which allowed calculation of the electron density, Laplacian and electrostatic potential distributions. The bonding (3,−1) critical points and the molecular dipole moment of 3.2 (1) D were also obtained. Chemical bonding in the molecule is discussed.
Supporting information
 | Crystallographic Information File (CIF) https://doi.org/10.1107/S0108768100020048/br0102sup1.cif |
 | Portable Document Format (PDF) file https://doi.org/10.1107/S0108768100020048/br0102sup2.pdf |
 | Structure factor file (CIF format) https://doi.org/10.1107/S0108768100020048/br0102sup3.hkl |
CCDC reference: 166510
Computing details top
Data collection: SMART5.054, Siemens (1996a); cell refinement: SMART5.054, Siemens (1996a); data reduction: SAINT7.08, Siemens (1996b); program(s) used to solve structure: SHELXTL, 'Sheldrick (1997); program(s) used to refine structure: XD, Koritsanszky et al., (1995); molecular graphics: XD, Koritsanszky et al., (1995); software used to prepare material for publication: XD, Koritsanszky et al., (1995).
![[Figure 1]](http://journals.iucr.org/b/issues/2001/03/00/br0102/br0102fig1thm.gif)
![[Figure 2]](http://journals.iucr.org/b/issues/2001/03/00/br0102/br0102fig2thm.gif)
![[Figure 3]](http://journals.iucr.org/b/issues/2001/03/00/br0102/br0102fig3thm.gif)
![[Figure 4]](http://journals.iucr.org/b/issues/2001/03/00/br0102/br0102fig4thm.gif)
![[Figure 5]](http://journals.iucr.org/b/issues/2001/03/00/br0102/br0102fig5thm.gif)
![[Figure 6]](http://journals.iucr.org/b/issues/2001/03/00/br0102/br0102fig6thm.gif)
(NTO) top
Crystal data top
| C2H2N4O3 | Dx = 1.919 Mg m−3 |
| Mr = 130.08 | Ag Kα radiation, λ = 0.56085 Å |
| Monoclinic, P21/c | Cell parameters from 8330 reflections |
| a = 9.3255 (1) Å | θ = 0–27° |
| b = 5.4503 (1) Å | µ = 0.10 mm−1 |
| c = 9.0400 (1) Å | T = 100 K |
| β = 101.474 (1)° | Plate, colorless |
| V = 450.29 Å3 | 0.40 × 0.12 × 0.12 mm |
| Z = 4 |
Data collection top
| Bruker platform diffractometer | Rint = 0.022 |
| w scans | θmax = 43.7° |
| 68989 measured reflections | h = −22→22 |
| 6909 independent reflections | k = −13→13 |
| 4080 reflections with I > 2σ for sintl<1.0, I > 6σ for sintl > 1.0 | l = −22→22 |
Refinement top
| Refinement on F | w = 1/[σ2(F) + 0.0001F2] |
| R[F2 > 2σ(F2)] = 0.033 | (Δ/σ)max < 0.001 |
| wR(F2) = 0.043 | Δρmax = 0.1 e Å−3 |
| S = 1.13 | Δρmin = −0.3 e Å−3 |
| 4080 reflections | Extinction correction: isotropic Becker-Coppens, type 1 |
| 308 parameters | Extinction coefficient: 0.2195 |
| All H-atom parameters refined |
Crystal data top
| C2H2N4O3 | V = 450.29 Å3 |
| Mr = 130.08 | Z = 4 |
| Monoclinic, P21/c | Ag Kα radiation, λ = 0.56085 Å |
| a = 9.3255 (1) Å | µ = 0.10 mm−1 |
| b = 5.4503 (1) Å | T = 100 K |
| c = 9.0400 (1) Å | 0.40 × 0.12 × 0.12 mm |
| β = 101.474 (1)° |
Data collection top
| Bruker platform diffractometer | 4080 reflections with I > 2σ for sintl<1.0, I > 6σ for sintl > 1.0 |
| 68989 measured reflections | Rint = 0.022 |
| 6909 independent reflections |
Refinement top
| R[F2 > 2σ(F2)] = 0.033 | 308 parameters |
| wR(F2) = 0.043 | All H-atom parameters refined |
| S = 1.13 | Δρmax = 0.1 e Å−3 |
| 4080 reflections | Δρmin = −0.3 e Å−3 |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
| x | y | z | Uiso*/Ueq | ||
| N(2) | 0.65343 (3) | 0.73475 (4) | 0.23553 (3) | 0.010 | |
| H(2) | 0.57735 | 0.61089 | 0.18887 | 0.008 | |
| O(3) | 0.86295 (2) | 0.58983 (4) | 0.15996 (3) | 0.011 | |
| N(1) | 0.61566 (3) | 0.92544 (4) | 0.31807 (3) | 0.010 | |
| N(4) | 0.85229 (2) | 0.94632 (4) | 0.30610 (3) | 0.008 | |
| H(4) | 0.95523 | 1.01280 | 0.32263 | 0.009 | |
| C(3) | 0.79842 (3) | 0.74010 (5) | 0.22532 (3) | 0.008 | |
| O(5B) | 0.86967 (3) | 1.36316 (4) | 0.47666 (3) | 0.014 | |
| O(5A) | 0.64118 (3) | 1.32520 (5) | 0.49799 (3) | 0.017 | |
| N(5) | 0.75032 (3) | 1.26075 (5) | 0.45135 (3) | 0.010 | |
| C(5) | 0.73793 (3) | 1.04447 (5) | 0.35760 (3) | 0.008 |
Atomic displacement parameters (Å2) top
| U11 | U22 | U33 | U12 | U13 | U23 | |
| N(2) | 0.0054 (1) | 0.0094 (1) | 0.0132 (1) | −0.0009 (1) | 0.0017 (1) | −0.0018 (1) |
| O(3) | 0.0078 (1) | 0.0123 (1) | 0.0124 (1) | 0.0016 (1) | 0.0019 (1) | −0.0033 (1) |
| N(1) | 0.0057 (1) | 0.0104 (1) | 0.0125 (1) | 0.0002 (1) | 0.0023 (1) | −0.0011 (1) |
| N(4) | 0.0053 (1) | 0.0095 (1) | 0.0098 (1) | −0.0010 (1) | 0.0017 (1) | −0.0014 (1) |
| C(3) | 0.0056 (1) | 0.0086 (1) | 0.0092 (1) | 0.0003 (1) | 0.0014 (1) | −0.0008 (1) |
| O(5B) | 0.0142 (1) | 0.0125 (1) | 0.0156 (2) | −0.0047 (1) | 0.0035 (1) | −0.0031 (1) |
| O(5A) | 0.0127 (1) | 0.0178 (2) | 0.0187 (2) | 0.0029 (1) | 0.0043 (1) | −0.0067 (1) |
| N(5) | 0.0096 (1) | 0.0092 (1) | 0.0100 (1) | 0.0004 (1) | 0.0019 (1) | −0.0011 (1) |
| C(5) | 0.0067 (1) | 0.0086 (1) | 0.0091 (1) | 0.0000 (1) | 0.0017 (1) | −0.0009 (1) |
Geometric parameters (Å, º) top
| N(2)—H(2) | 1.0090 | N(4)—C(3) | 1.3795 (3) |
| N(2)—N(1) | 1.3658 (3) | N(4)—C(5) | 1.3556 (4) |
| N(2)—C(3) | 1.3737 (3) | O(5B)—N(5) | 1.2253 (3) |
| O(3)—C(3) | 1.2343 (3) | O(5A)—N(5) | 1.2279 (3) |
| N(1)—C(5) | 1.2987 (4) | N(5)—C(5) | 1.4430 (4) |
| N(4)—H(4) | 1.0090 | ||
| H(2)—N(2)—N(1) | 120.1 (1) | N(2)—C(3)—N(4) | 104.0 (1) |
| H(2)—N(2)—C(3) | 127.3 (1) | O(3)—C(3)—N(4) | 129.3 (1) |
| N(1)—N(2)—C(3) | 112.6 (1) | O(5B)—N(5)—O(5A) | 126.1 (1) |
| N(2)—N(1)—C(5) | 102.9 (1) | O(5B)—N(5)—C(5) | 116.4 (1) |
| H(4)—N(4)—C(3) | 127.3 (1) | O(5A)—N(5)—C(5) | 117.4 (1) |
| H(4)—N(4)—C(5) | 126.7 (1) | N(1)—C(5)—N(4) | 114.6 (1) |
| C(3)—N(4)—C(5) | 105.9 (1) | N(1)—C(5)—N(5) | 122.2 (1) |
| N(2)—C(3)—O(3) | 126.7 (1) | N(4)—C(5)—N(5) | 123.2 (1) |
Experimental details
| Crystal data | |
| Chemical formula | C2H2N4O3 |
| Mr | 130.08 |
| Crystal system, space group | Monoclinic, P21/c |
| Temperature (K) | 100 |
| a, b, c (Å) | 9.3255 (1), 5.4503 (1), 9.0400 (1) |
| β (°) | 101.474 (1) |
| V (Å3) | 450.29 |
| Z | 4 |
| Radiation type | Ag Kα, λ = 0.56085 Å |
| µ (mm−1) | 0.10 |
| Crystal size (mm) | 0.40 × 0.12 × 0.12 |
| Data collection | |
| Diffractometer | Bruker platform diffractometer |
| Absorption correction | – |
| No. of measured, independent and observed (I > 2σ for sintl<1.0, I > 6σ for sintl > 1.0) reflections | 68989, 6909, 4080 |
| Rint | 0.022 |
| (sin θ/λ)max (Å−1) | 1.232 |
| Refinement | |
| R[F2 > 2σ(F2)], wR(F2), S | 0.033, 0.043, 1.13 |
| No. of reflections | 4080 |
| No. of parameters | 308 |
| No. of restraints | ? |
| H-atom treatment | All H-atom parameters refined |
| Δρmax, Δρmin (e Å−3) | 0.1, −0.3 |
Computer programs: SMART5.054, Siemens (1996a), SAINT7.08, Siemens (1996b), SHELXTL, 'Sheldrick (1997), XD, Koritsanszky et al., (1995).
Selected geometric parameters (Å, º) top
| N(2)—H(2) | 1.0090 | N(4)—C(3) | 1.3795 (3) |
| N(2)—N(1) | 1.3658 (3) | N(4)—C(5) | 1.3556 (4) |
| N(2)—C(3) | 1.3737 (3) | O(5B)—N(5) | 1.2253 (3) |
| O(3)—C(3) | 1.2343 (3) | O(5A)—N(5) | 1.2279 (3) |
| N(1)—C(5) | 1.2987 (4) | N(5)—C(5) | 1.4430 (4) |
| N(4)—H(4) | 1.0090 | ||
| H(2)—N(2)—N(1) | 120.1 (1) | N(2)—C(3)—N(4) | 104.0 (1) |
| H(2)—N(2)—C(3) | 127.3 (1) | O(3)—C(3)—N(4) | 129.3 (1) |
| N(1)—N(2)—C(3) | 112.6 (1) | O(5B)—N(5)—O(5A) | 126.1 (1) |
| N(2)—N(1)—C(5) | 102.9 (1) | O(5B)—N(5)—C(5) | 116.4 (1) |
| H(4)—N(4)—C(3) | 127.3 (1) | O(5A)—N(5)—C(5) | 117.4 (1) |
| H(4)—N(4)—C(5) | 126.7 (1) | N(1)—C(5)—N(4) | 114.6 (1) |
| C(3)—N(4)—C(5) | 105.9 (1) | N(1)—C(5)—N(5) | 122.2 (1) |
| N(2)—C(3)—O(3) | 126.7 (1) | N(4)—C(5)—N(5) | 123.2 (1) |
