organic compounds
3,5-Dimethyl-4-nitroso-1H-pyrazole
aDepartment of Chemistry, Kiev National Taras Shevchenko University, Volodymyrska Str. 64, 01601 Kiev, Ukraine, and bDepartment of Chemistry, University of Joensuu, PO Box, 111, FI-80101 Joensuu, Finland
*Correspondence e-mail: safyanova_inna@mail.ru
In the 5H7N3O, there are two conformers (A and B) which differ in the position of the oxime group with respect to the protonated pyrazole nitrogen (trans in the A conformer and cis in the B conformer) and in the geometric parameters. The oxime group exists in the nitroso form in both conformers. In the crystal, molecules are linked by intermolecular N—H⋯O and N—H⋯N hydrogen bonds into zigzag-like chains along the b axis.
of the title compound, CRelated literature
For the use of pyrazole-based ligands, see: Mullins & Pecoraro (2008); Mukhopadhyay et al. (2004). For the magnetic properties of pyrazolate complexes, see: Aromi & Brechin (2006); Gatteschi et al. (2006). For the use of oxime substituents in the synthesis of polynuclear ligands, see: Petrusenko et al. (1997); Kanderal et al. (2005); Sachse et al. (2008); Moroz et al. (2010). For the use of 4-nitropyrazoles as ligands, see: Halcrow (2005). For related structures, see: Fletcher et al. (1997); Kovbasyuk et al. (2004); Mokhir et al. (2002); Sliva et al. (1997); Wörl, Fritsky et al. (2005); Wörl, Pritzkow et al. (2005). For the synthesis of the title compound, see: Cameron et al. (1996).
Experimental
Crystal data
|
Refinement
|
Data collection: COLLECT (Nonius, 2000); cell DENZO/SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO/SCALEPACK; program(s) used to solve structure: SIR2004 (Burla et al., 2005); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2008); software used to prepare material for publication: SHELXL97.
Supporting information
10.1107/S1600536811033794/jh2317sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536811033794/jh2317Isup2.hkl
Supporting information file. DOI: 10.1107/S1600536811033794/jh2317Isup3.cml
3,5-dimethyl-4-nitrozo-1H-pyrazole was synthesized by using a literature procedure (Cameron et al., 1996) from acetylacetone, sodium nitrite and hydrazine hydrate in aqueous hydrochloric acid. The crude product was collected by filtration and purified by recrystallization from benzene. Colorless crystals suitable for the X-ray diffraction were obtained after several hours (yield 78%).
The aromatic NH H atoms were located from the difference Fourier map and refined isotropically. Other H atoms were positioned geometrically and allowed to ride on their parent atoms, with C—H = 0.98 Å, and Uiso = 1.5 Ueq (parent atom).
Data collection: COLLECT (Nonius, 2000); cell
DENZO/SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO/SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: SIR2004 (Burla et al., 2005); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2008); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).C5H7N3O | F(000) = 528 |
Mr = 125.14 | Dx = 1.370 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 4238 reflections |
a = 4.0268 (2) Å | θ = 1.0–27.5° |
b = 15.3793 (7) Å | µ = 0.10 mm−1 |
c = 19.6627 (9) Å | T = 120 K |
β = 94.613 (3)° | Plate, blue |
V = 1213.75 (10) Å3 | 0.46 × 0.33 × 0.13 mm |
Z = 8 |
Nonius KappaCCD diffractometer | 2747 independent reflections |
Radiation source: fine-focus sealed tube | 1866 reflections with I > 2σ(I) |
Horizontally mounted graphite crystal monochromator | Rint = 0.040 |
Detector resolution: 9 pixels mm-1 | θmax = 27.4°, θmin = 2.5° |
ϕ scans and ω scans with κ offset | h = −4→5 |
Absorption correction: multi-scan (DENZO/SCALEPACK; Otwinowski & Minor, 1997) | k = −18→19 |
Tmin = 0.955, Tmax = 0.987 | l = −25→25 |
9003 measured reflections |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.041 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.109 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.03 | w = 1/[σ2(Fo2) + (0.0516P)2 + 0.0988P] where P = (Fo2 + 2Fc2)/3 |
2747 reflections | (Δ/σ)max < 0.001 |
175 parameters | Δρmax = 0.23 e Å−3 |
0 restraints | Δρmin = −0.25 e Å−3 |
C5H7N3O | V = 1213.75 (10) Å3 |
Mr = 125.14 | Z = 8 |
Monoclinic, P21/c | Mo Kα radiation |
a = 4.0268 (2) Å | µ = 0.10 mm−1 |
b = 15.3793 (7) Å | T = 120 K |
c = 19.6627 (9) Å | 0.46 × 0.33 × 0.13 mm |
β = 94.613 (3)° |
Nonius KappaCCD diffractometer | 2747 independent reflections |
Absorption correction: multi-scan (DENZO/SCALEPACK; Otwinowski & Minor, 1997) | 1866 reflections with I > 2σ(I) |
Tmin = 0.955, Tmax = 0.987 | Rint = 0.040 |
9003 measured reflections |
R[F2 > 2σ(F2)] = 0.041 | 0 restraints |
wR(F2) = 0.109 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.03 | Δρmax = 0.23 e Å−3 |
2747 reflections | Δρmin = −0.25 e Å−3 |
175 parameters |
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. |
x | y | z | Uiso*/Ueq | ||
O1A | −0.1796 (3) | 0.16615 (7) | 0.22546 (5) | 0.0279 (3) | |
N1A | 0.3665 (3) | −0.05073 (9) | 0.32527 (7) | 0.0241 (3) | |
N2A | 0.4403 (3) | 0.02548 (8) | 0.36162 (6) | 0.0243 (3) | |
N3A | −0.1316 (3) | 0.08489 (8) | 0.22016 (7) | 0.0240 (3) | |
C1A | 0.2710 (3) | 0.08712 (10) | 0.32773 (8) | 0.0210 (4) | |
C2A | 0.2872 (4) | 0.17879 (10) | 0.35059 (8) | 0.0258 (4) | |
H2A | 0.4408 | 0.1837 | 0.3917 | 0.039* | |
H2B | 0.0648 | 0.1981 | 0.3609 | 0.039* | |
H2C | 0.3667 | 0.2152 | 0.3144 | 0.039* | |
C3A | 0.0867 (4) | 0.05016 (9) | 0.26876 (8) | 0.0202 (4) | |
C4A | 0.1598 (4) | −0.03950 (10) | 0.27044 (8) | 0.0225 (4) | |
C5A | 0.0466 (4) | −0.11093 (10) | 0.22306 (9) | 0.0308 (4) | |
H5A | 0.1902 | −0.1133 | 0.1852 | 0.046* | |
H5B | −0.1839 | −0.1001 | 0.2052 | 0.046* | |
H5C | 0.0589 | −0.1664 | 0.2476 | 0.046* | |
O1B | −0.2132 (3) | 0.13230 (7) | −0.04852 (6) | 0.0356 (3) | |
N1B | 0.3699 (3) | 0.21423 (8) | 0.11942 (7) | 0.0216 (3) | |
N2B | 0.3158 (3) | 0.30207 (8) | 0.10938 (7) | 0.0226 (3) | |
N3B | −0.1646 (3) | 0.20960 (9) | −0.03253 (7) | 0.0275 (3) | |
C1B | 0.1150 (4) | 0.30759 (10) | 0.05258 (8) | 0.0214 (4) | |
C2B | 0.0044 (4) | 0.39331 (10) | 0.02337 (8) | 0.0267 (4) | |
H2B1 | 0.0884 | 0.4400 | 0.0540 | 0.040* | |
H2B2 | −0.2395 | 0.3953 | 0.0182 | 0.040* | |
H2B3 | 0.0918 | 0.4009 | −0.0213 | 0.040* | |
C3B | 0.0397 (4) | 0.22318 (10) | 0.02693 (7) | 0.0201 (3) | |
C4B | 0.2123 (4) | 0.16456 (10) | 0.07173 (8) | 0.0208 (4) | |
C5B | 0.2411 (4) | 0.06867 (10) | 0.07173 (8) | 0.0264 (4) | |
H5B1 | 0.3957 | 0.0502 | 0.1100 | 0.040* | |
H5B2 | 0.3250 | 0.0494 | 0.0288 | 0.040* | |
H5B3 | 0.0216 | 0.0428 | 0.0763 | 0.040* | |
H1A | 0.453 (4) | −0.1013 (13) | 0.3437 (9) | 0.040 (5)* | |
H1B | 0.515 (4) | 0.1949 (11) | 0.1572 (9) | 0.035 (5)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1A | 0.0312 (6) | 0.0231 (6) | 0.0288 (7) | 0.0049 (5) | −0.0017 (5) | 0.0031 (5) |
N1A | 0.0283 (7) | 0.0183 (7) | 0.0252 (8) | 0.0026 (6) | −0.0006 (6) | 0.0023 (6) |
N2A | 0.0268 (7) | 0.0221 (8) | 0.0236 (7) | 0.0000 (6) | 0.0000 (6) | 0.0000 (6) |
N3A | 0.0240 (7) | 0.0244 (8) | 0.0236 (7) | 0.0010 (6) | 0.0024 (6) | 0.0034 (6) |
C1A | 0.0187 (8) | 0.0230 (9) | 0.0216 (8) | 0.0002 (6) | 0.0028 (6) | 0.0019 (6) |
C2A | 0.0259 (8) | 0.0246 (9) | 0.0261 (9) | 0.0004 (7) | −0.0024 (7) | −0.0031 (7) |
C3A | 0.0198 (8) | 0.0204 (8) | 0.0205 (8) | −0.0002 (6) | 0.0023 (6) | 0.0010 (6) |
C4A | 0.0224 (8) | 0.0218 (9) | 0.0235 (9) | −0.0005 (7) | 0.0039 (7) | 0.0021 (6) |
C5A | 0.0352 (9) | 0.0228 (9) | 0.0337 (10) | −0.0011 (7) | −0.0005 (8) | −0.0046 (7) |
O1B | 0.0459 (7) | 0.0269 (7) | 0.0328 (7) | −0.0057 (6) | −0.0044 (6) | −0.0041 (5) |
N1B | 0.0249 (7) | 0.0172 (7) | 0.0222 (7) | 0.0014 (6) | −0.0014 (6) | 0.0019 (5) |
N2B | 0.0270 (7) | 0.0153 (7) | 0.0250 (7) | 0.0008 (5) | −0.0008 (6) | 0.0011 (5) |
N3B | 0.0295 (7) | 0.0247 (8) | 0.0280 (8) | −0.0038 (6) | 0.0007 (6) | −0.0014 (6) |
C1B | 0.0220 (8) | 0.0203 (8) | 0.0223 (8) | 0.0005 (6) | 0.0037 (7) | 0.0001 (6) |
C2B | 0.0308 (9) | 0.0205 (8) | 0.0282 (9) | 0.0013 (7) | −0.0010 (7) | 0.0030 (7) |
C3B | 0.0212 (8) | 0.0194 (8) | 0.0198 (8) | −0.0005 (6) | 0.0020 (6) | 0.0002 (6) |
C4B | 0.0204 (8) | 0.0211 (8) | 0.0214 (8) | −0.0018 (6) | 0.0041 (7) | −0.0013 (6) |
C5B | 0.0313 (9) | 0.0184 (8) | 0.0294 (9) | 0.0012 (7) | 0.0017 (7) | −0.0003 (7) |
O1A—N3A | 1.2701 (16) | O1B—N3B | 1.2412 (16) |
N1A—C4A | 1.319 (2) | N1B—C4B | 1.330 (2) |
N1A—N2A | 1.3922 (18) | N1B—N2B | 1.3801 (17) |
N1A—H1A | 0.915 (19) | N1B—H1B | 0.954 (18) |
N2A—C1A | 1.3170 (19) | N2B—C1B | 1.3279 (19) |
N3A—C3A | 1.3553 (19) | N3B—C3B | 1.3902 (19) |
C1A—C3A | 1.442 (2) | C1B—C3B | 1.417 (2) |
C1A—C2A | 1.479 (2) | C1B—C2B | 1.492 (2) |
C2A—H2A | 0.9800 | C2B—H2B1 | 0.9800 |
C2A—H2B | 0.9800 | C2B—H2B2 | 0.9800 |
C2A—H2C | 0.9800 | C2B—H2B3 | 0.9800 |
C3A—C4A | 1.410 (2) | C3B—C4B | 1.405 (2) |
C4A—C5A | 1.488 (2) | C4B—C5B | 1.479 (2) |
C5A—H5A | 0.9800 | C5B—H5B1 | 0.9800 |
C5A—H5B | 0.9800 | C5B—H5B2 | 0.9800 |
C5A—H5C | 0.9800 | C5B—H5B3 | 0.9800 |
C4A—N1A—N2A | 113.82 (13) | C4B—N1B—N2B | 113.61 (12) |
C4A—N1A—H1A | 129.1 (11) | C4B—N1B—H1B | 126.7 (10) |
N2A—N1A—H1A | 116.9 (11) | N2B—N1B—H1B | 119.7 (10) |
C1A—N2A—N1A | 105.42 (12) | C1B—N2B—N1B | 105.14 (12) |
O1A—N3A—C3A | 115.11 (12) | O1B—N3B—C3B | 115.32 (13) |
N2A—C1A—C3A | 109.56 (13) | N2B—C1B—C3B | 109.83 (13) |
N2A—C1A—C2A | 121.60 (13) | N2B—C1B—C2B | 121.54 (13) |
C3A—C1A—C2A | 128.84 (13) | C3B—C1B—C2B | 128.62 (14) |
C1A—C2A—H2A | 109.5 | C1B—C2B—H2B1 | 109.5 |
C1A—C2A—H2B | 109.5 | C1B—C2B—H2B2 | 109.5 |
H2A—C2A—H2B | 109.5 | H2B1—C2B—H2B2 | 109.5 |
C1A—C2A—H2C | 109.5 | C1B—C2B—H2B3 | 109.5 |
H2A—C2A—H2C | 109.5 | H2B1—C2B—H2B3 | 109.5 |
H2B—C2A—H2C | 109.5 | H2B2—C2B—H2B3 | 109.5 |
N3A—C3A—C4A | 121.63 (13) | N3B—C3B—C4B | 131.33 (14) |
N3A—C3A—C1A | 132.39 (14) | N3B—C3B—C1B | 122.16 (14) |
C4A—C3A—C1A | 105.89 (13) | C4B—C3B—C1B | 106.50 (13) |
N1A—C4A—C3A | 105.30 (13) | N1B—C4B—C3B | 104.92 (13) |
N1A—C4A—C5A | 123.80 (14) | N1B—C4B—C5B | 122.65 (14) |
C3A—C4A—C5A | 130.89 (14) | C3B—C4B—C5B | 132.42 (14) |
C4A—C5A—H5A | 109.5 | C4B—C5B—H5B1 | 109.5 |
C4A—C5A—H5B | 109.5 | C4B—C5B—H5B2 | 109.5 |
H5A—C5A—H5B | 109.5 | H5B1—C5B—H5B2 | 109.5 |
C4A—C5A—H5C | 109.5 | C4B—C5B—H5B3 | 109.5 |
H5A—C5A—H5C | 109.5 | H5B1—C5B—H5B3 | 109.5 |
H5B—C5A—H5C | 109.5 | H5B2—C5B—H5B3 | 109.5 |
C4A—N1A—N2A—C1A | 0.03 (17) | C4B—N1B—N2B—C1B | −0.10 (17) |
N1A—N2A—C1A—C3A | −0.15 (16) | N1B—N2B—C1B—C3B | 0.46 (17) |
N1A—N2A—C1A—C2A | −179.56 (13) | N1B—N2B—C1B—C2B | −178.40 (13) |
O1A—N3A—C3A—C4A | 178.61 (13) | O1B—N3B—C3B—C4B | 2.4 (2) |
O1A—N3A—C3A—C1A | 2.4 (2) | O1B—N3B—C3B—C1B | −179.01 (14) |
N2A—C1A—C3A—N3A | 176.84 (15) | N2B—C1B—C3B—N3B | −179.59 (13) |
C2A—C1A—C3A—N3A | −3.8 (3) | C2B—C1B—C3B—N3B | −0.8 (2) |
N2A—C1A—C3A—C4A | 0.22 (16) | N2B—C1B—C3B—C4B | −0.65 (17) |
C2A—C1A—C3A—C4A | 179.57 (15) | C2B—C1B—C3B—C4B | 178.11 (15) |
N2A—N1A—C4A—C3A | 0.11 (17) | N2B—N1B—C4B—C3B | −0.30 (16) |
N2A—N1A—C4A—C5A | 179.38 (14) | N2B—N1B—C4B—C5B | 178.69 (13) |
N3A—C3A—C4A—N1A | −177.26 (14) | N3B—C3B—C4B—N1B | 179.36 (15) |
C1A—C3A—C4A—N1A | −0.19 (16) | C1B—C3B—C4B—N1B | 0.56 (16) |
N3A—C3A—C4A—C5A | 3.5 (3) | N3B—C3B—C4B—C5B | 0.5 (3) |
C1A—C3A—C4A—C5A | −179.39 (16) | C1B—C3B—C4B—C5B | −178.29 (15) |
D—H···A | D—H | H···A | D···A | D—H···A |
N1B—H1B···O1Ai | 0.954 (18) | 1.802 (18) | 2.7526 (16) | 174.0 (15) |
N1A—H1A···N2Bii | 0.915 (19) | 1.95 (2) | 2.8544 (18) | 171.5 (16) |
Symmetry codes: (i) x+1, y, z; (ii) −x+1, y−1/2, −z+1/2. |
Experimental details
Crystal data | |
Chemical formula | C5H7N3O |
Mr | 125.14 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 120 |
a, b, c (Å) | 4.0268 (2), 15.3793 (7), 19.6627 (9) |
β (°) | 94.613 (3) |
V (Å3) | 1213.75 (10) |
Z | 8 |
Radiation type | Mo Kα |
µ (mm−1) | 0.10 |
Crystal size (mm) | 0.46 × 0.33 × 0.13 |
Data collection | |
Diffractometer | Nonius KappaCCD diffractometer |
Absorption correction | Multi-scan (DENZO/SCALEPACK; Otwinowski & Minor, 1997) |
Tmin, Tmax | 0.955, 0.987 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 9003, 2747, 1866 |
Rint | 0.040 |
(sin θ/λ)max (Å−1) | 0.647 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.041, 0.109, 1.03 |
No. of reflections | 2747 |
No. of parameters | 175 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.23, −0.25 |
Computer programs: COLLECT (Nonius, 2000), DENZO/SCALEPACK (Otwinowski & Minor, 1997), SIR2004 (Burla et al., 2005), SHELXL97 (Sheldrick, 2008), DIAMOND (Brandenburg, 2008).
D—H···A | D—H | H···A | D···A | D—H···A |
N1B—H1B···O1Ai | 0.954 (18) | 1.802 (18) | 2.7526 (16) | 174.0 (15) |
N1A—H1A···N2Bii | 0.915 (19) | 1.95 (2) | 2.8544 (18) | 171.5 (16) |
Symmetry codes: (i) x+1, y, z; (ii) −x+1, y−1/2, −z+1/2. |
Acknowledgements
Financial support from the State Fund for Fundamental Research of Ukraine (grant No. F40.3/041) and the Swedish Institute (Visby Program) is gratefully acknowledged.
References
Aromi, G. & Brechin, E. K. (2006). Struct. Bonding (Berlin), 122, 1–67. CAS Google Scholar
Brandenburg, K. (2008). DIAMOND. Crystal Impact GbR, Bonn, Germany. Google Scholar
Burla, M. C., Caliandro, R., Camalli, M., Carrozzini, B., Cascarano, G. L., De Caro, L., Giacovazzo, C., Polidori, G. & Spagna, R. (2005). J. Appl. Cryst. 38, 381–388. Web of Science CrossRef CAS IUCr Journals Google Scholar
Cameron, M., Gowenlock, B. G. & Boyd, A. S. F. (1996). J. Chem. Soc. Perkin Trans. 2, pp. 2271–2274. Google Scholar
Fletcher, D. A., Gowenlock, B. G., Orrell, K. G., Šik, V., Hibbs, D. E., Hursthouse, M. B. & Abdul Malik, K. M. (1997). J. Chem. Soc. Perkin Trans. 2, pp. 721–728. Google Scholar
Gatteschi, D., Sessoli, R. & Villain, J. (2006). Molecular Nanomagnets. Oxford University Press. Google Scholar
Halcrow, M. A. (2005). Coord. Chem. Rev. 249, 2880–2908. Web of Science CSD CrossRef CAS Google Scholar
Kanderal, O. M., Kozłowski, H., Dobosz, A., Świątek-Kozłowska, J., Meyer, F. & Fritsky, I. O. (2005). Dalton Trans. pp. 1428–1437. Web of Science CrossRef PubMed Google Scholar
Kovbasyuk, L., Pritzkow, H., Krämer, R. & Fritsky, I. O. (2004). Chem. Commun. pp. 880–881. Web of Science CrossRef Google Scholar
Mokhir, A. A., Gumienna-Kontecka, E. S., Świątek-Kozłowska, J., Petkova, E. G., Fritsky, I. O., Jerzykiewicz, L., Kapshuk, A. A. & Sliva, T. Yu. (2002). Inorg. Chim. Acta, 329, 113–121. Web of Science CSD CrossRef CAS Google Scholar
Moroz, Y. S., Szyrweil, L., Demeshko, S., Kozłowski, H., Meyer, F. & Fritsky, I. O. (2010). Inorg. Chem. 49, 4750–4752. Web of Science CSD CrossRef CAS PubMed Google Scholar
Mukhopadhyay, S., Mandal, S. K., Bhaduri, S. & Armstrong, W. H. (2004). Chem. Rev. 104, 3981–4026. Web of Science CrossRef PubMed CAS Google Scholar
Mullins, C. S. & Pecoraro, V. L. (2008). Coord. Chem. Rev. 252, 416–443. Google Scholar
Nonius (2000). COLLECT. Nonius BV, Delft, The Netherlands. Google Scholar
Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M. Sweet, pp. 307–326. New York: Academic Press. Google Scholar
Petrusenko, S. R., Kokozay, V. N. & Fritsky, I. O. (1997). Polyhedron, 16, 267–274. CSD CrossRef CAS Web of Science Google Scholar
Sachse, A., Penkova, L., Noel, G., Dechert, S., Varzatskii, O. A., Fritsky, I. O. & Meyer, F. (2008). Synthesis, pp. 800–806. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Sliva, T. Yu., Kowalik-Jankowska, T., Amirkhanov, V. M., Głowiak, T., Onindo, C. O., Fritsky, I. O. & Kozłowski, H. (1997). J. Inorg. Biochem. 65, 287–294. CSD CrossRef CAS Web of Science Google Scholar
Wörl, S., Fritsky, I. O., Hellwinkel, D., Pritzkow, H. & Krämer, R. (2005). Eur. J. Inorg. Chem. pp. 759–765. Google Scholar
Wörl, S., Pritzkow, H., Fritsky, I. O. & Krämer, R. (2005). Dalton Trans. pp. 27–29. Google Scholar
This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
Pyrazole-based ligands are widely used in bioinorganic chemistry, molecular magnetism and supramolecular chemistry, as they are able to form different architectures, ranging from polynuclear clusters to metallocycles (Mullins, et al., 2008; Mukhopadhyay, et al., 2004). In addition to the ability to bridge two or more metal ions, pyrazole ligands also provide an effective magnetic exchange pathway between them (Aromi et al. 2006; Gatteschi, et al., 2006). The incorporation of other coordinating groups to the pyrazole ring can increase the variety of polynuclear compounds that can be formed. For example, introduction of the potentially bridging oxime group in the molecules of the ligands already having bridging moieties (such as pyrazolates) can lead to increase of nuclearity and complexity of the metal complexes on their basis (Petrusenko et al., 1997; Kanderal et al., 2005; Sachse et al., 2008; Moroz et al., 2010). In this work, we report the crystal structure of the title compound which contains the oxime group in the 4-position of the pyrazole ring. Unlike 4-nitropyrazoles which have been widely used for preparation of oligonuclear metal complexes (Halcrow et al., 2005), 4-nitrosopyrazoles have never been studied as ligands, and no metal complexes based on this type of ligands have been reported up to date. Crystal and molecular structures of only two 4-nitrosopyrazoles have been reported before (Cameron et al., 1996; Fletcher et al., 1997).
In the unit cell there are two types of conformers (A and B) of the title compound which differs significantly by the geometrical parameters and by the position of the oxime group with respect to the protonated pyrazole nitrogen (Fig. 1). In the conformer A, the oxime group is trans- with respect to the pyrazole hydrogen, while in the conformer B the oxime-group is cis-situated. In the conformers A and B the bond lengths markedly differs, first of all it is noticeable upon comparing the interatomic distances within the oxime groups. In the conformer B, the difference in bond lengths between C—N (1.3902 (19) Å) and N=O (1.2412 (16) Å) bonds of the oxime groups is quite large (ca 0.15 Å) while in the conformer A (C—N 1.3553 (19) Å and N=O 1.2701 (16) Å) it is much less pronounced (less than 0.08 Å). This clearly indicates that the CNO moiety in both conformers exists in the nitroso-form (Sliva et al. (1997); Mokhir et al., 2002), however, in the conformer A there is a noticeable contribution of the isonitroso-form. Such a difference can be a consequence of the involvement of the oxime oxygen O1A in formation of the intermolecular H-bond, while O1B does not participate in any H-bond (Table 1).
The differences in geometrical and electronic structure of the oxime groups significantly influence on the C—C, C—N, N—N bond lengths within the pyrazole rings which are deviated from normal values (Kovbasyuk et al., 2004; Wörl, Fritsky et al., 2005; Wörl, Pritzkow et al., 2005). Thus, there are signs of conjugation of the C(3B)—C(4B) bond with the O(1B)—N(3B) bond which results in noticeable shortening of the former (1.405 (2) Å) as compare to that observed in the conformer A, C(3)—C(4) = 1.442 (2) Å.
In the crystal, the molecules are linked by intermolecular N—H···O and N—H···N hydrogen bonds building zigzag chains along the b axis (Fig.2, Table 1). The translational along a axis chains form walls which are united into the crystal by van der Waals interactions.