organic compounds
3,5-Di-tert-butyl-1H-pyrazole-4-carbonitrile
aDepartment of Chemistry, Jacksonville University, Jacksonville, FL 32211, USA
*Correspondence e-mail: pzhao@ju.edu
In the title compound, C12H19N3, the cyano group lies in the plane of the pyrazole ring, and has a linear C—C N bond angle of 179.2 (1)°. The NH H atom of the pyrazole ring is disordered equally over the two ring N atoms. In the crystal, molecules are linked via N—H⋯N hydrogen bonds, forming inversion dimers with an R22(6) ring motif.
Keywords: crystal structure; cyanopyrazole; carbonitrile; symmetrically substituted; N—H⋯N hydrogen bonds; inversion dimers.
CCDC reference: 1475402
Structure description
The title compound, represents the first symmetrically substituted 4-carbonitrile pyrazole, and was prepared as a precursor for the preparation of scorpionate ligands. In the title compound, Fig. 1, the NH H atom is disordered across the two N atoms (N2 and N3) of the pyrazole ring. The carbonitrile unit, C2—C1 N1, lies in the plane of the pyrazole ring and deviates only slightly from linearity with a bond angle of 179.2 (1)°.
In the crystal, molecules are linked by pairs of N—H⋯N hydrogen bonds, forming inversion dimers with an (6) ring motif (Fig. 2 and Table 1). There are no other significant intermolecular interactions present.
Synthesis and crystallization
Sodium hydride (0.69 g, 17.24 mmol, 60% dispersion in mineral oil) was added to 100 ml of dry toluene in an ice bath forming a suspension. Trimethylacetylacetonitrile (2.16 g, 17.24 mmol) was added to this suspension, resulting in the immediate appearance of bubbles. The mixture was stirred for 18 h before trimethylacetyl chloride (2.08 g, 17.24 mmol) was added. The reaction mixture was stirred overnight followed by three extractions using 100 ml of 0.2 M NaOH solution each time. The aqueous layers were combined and acidified with an HCl/H2O (50/50) solution to pH1. A white precipitate appeared immediately and was extracted with three portions of 100 ml of ethyl acetate. Removal of the solvent under reduced pressure yielded 2.15 g (10.29 mmol, yield 59.67%) of the crude product, which was recrystallized from ethanol to give 4-cyano-2,2,6,6-tetramethyl-3,5-heptanedione (1.07 g, 5.12 mmol, 29.70%). This diketone compound was then reacted with hydrazine monohydrate (0.26 g, 5.12 mmol) in 100 ml of methanol and stirred overnight. The solvent was removed under reduced pressure to yield the crude product of the title compound as a white solid (0.93 g, 4.54 mmol, 26.31%). X-ray quality crystals were obtained by slow evaporation of a solution in ethanol at room temperature (0.66 g, 3.22 mmol, 18.67%).
Refinement
Crystal data, data collection and structure . The NH H atom was located in a difference Fourier map and found to be disordered equally across the two N atoms (N2 and N3) of the pyrazole ring. These two H atoms (H2 and H3) were freely refined with an occupancy of 0.5 each.
details are summarized in Table 2Structural data
CCDC reference: 1475402
10.1107/S2414314616006738/su4036sup1.cif
contains datablocks Global, I. DOI:Structure factors: contains datablock I. DOI: 10.1107/S2414314616006738/su4036Isup2.hkl
Supporting information file. DOI: 10.1107/S2414314616006738/su4036Isup3.cml
Sodium hydride (0.69 g, 17.24 mmol, 60% dispersion in mineral oil) was added to 100 ml of dry toluene in an ice bath forming a suspension. Trimethylacetylacetonitrile (2.16 g, 17.24 mmol) was added to this suspension, resulting in the immediate appearance of bubbles. The mixture was stirred for 18 h before trimethylacetyl chloride (2.08 g, 17.24 mmol) was added. The reaction mixture was stirred overnight followed by three extractions using 100 ml of 0.2 M NaOH solution each time. The aqueous layers were combined and acidified with an HCl/H2O (50/50) solution to pH~1. A white precipitate appeared immediately and was extracted with three portions of 100 ml of ethyl acetate. Removal of the solvent under reduced pressure yielded 2.15 g (10.29 mmol, yield 59.67%) of the crude product, which was recrystallized from ethanol to give 4-cyano-2,2,6,6-tetramethyl-3,5-heptanedione (1.07 g, 5.12 mmol, 29.70%). This diketone compound was then reacted with hydrazine monohydrate (0.26 g, 5.12 mmol) in 100 ml of methanol and stirred overnight. The solvent was removed under reduced pressure to yield the crude product of the title compound as a white solid (0.93 g, 4.54 mmol, 26.31%). X-ray quality crystals were obtained by slow evaporation of a solution in ethanol at room temperature (0.66 g, 3.22 mmol, 18.67%).
Crystal data, data collection and structure
details are summarized in Table 2. The NH H atom was located in a difference Fourier map and found to be disordered across the two N atoms (N2 and N3) of the pyrazole ring. These two H atoms (H2 and H3) were freely refined with an occupancy of 0.5 each.The title compound, represents the first symmetrically substituted 4-carbonitrile pyrazole, and was prepared as a precursor for the preparation of scorpionate ligands. In the title compound, Fig. 1, the NH H atom is disordered across the two N atoms (N2 and N3) of the pyrazole ring. The carbonitrile unit, C2—C1≡N1, lies in the plane of the pyrazole ring and deviates only slightly from linearity with a bond angle of 179.2 (1)°.
In the crystal, molecules are linked by pairs of N—H···N hydrogen bonds, forming inversion dimers with an R22(6) ring motif (Fig. 2 and Table 1). There are no other significant intermolecular interactions present.
Data collection: APEX3 (Bruker, 2016); cell
SAINT (Bruker, 2016); data reduction: SAINT (Bruker, 2016); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015b); molecular graphics: Mercury (Macrae et al., 2008); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).Fig. 1. A view of the molecular structure of the title compound, showing the atom labeling. Displacement ellipsoids are drawn at the 50% probability level. The two positions of the disordered NH H atoms are shown, with hashed bonds. | |
Fig. 2. A view along the b axis of the crystal packing of the title compound. The N—H···N hydrogen bonds are shown as dashed lines. Only one disordered NH H atom is shown and all C-bound H atoms have been omitted for clarity. |
C12H19N3 | F(000) = 448 |
Mr = 205.30 | Dx = 1.120 Mg m−3 |
Monoclinic, P21/c | Cu Kα radiation, λ = 1.54178 Å |
a = 10.5993 (3) Å | Cell parameters from 7895 reflections |
b = 9.7641 (3) Å | θ = 4.4–68.3° |
c = 12.4435 (4) Å | µ = 0.53 mm−1 |
β = 109.065 (1)° | T = 100 K |
V = 1217.17 (6) Å3 | Block, colourless |
Z = 4 | 0.15 × 0.10 × 0.09 mm |
Bruker D8 Platinum135 diffractometer | 2183 independent reflections |
Radiation source: Micro Focus Rotating Anode, Bruker FR-591 | 2037 reflections with I > 2σ(I) |
Multilayer Mirrors monochromator | Rint = 0.040 |
Detector resolution: 7.9 pixels mm-1 | θmax = 68.2°, θmin = 4.4° |
ω and φ scans | h = −10→12 |
Absorption correction: multi-scan (SADABS; Bruker, 2016) | k = −11→11 |
Tmin = 0.211, Tmax = 0.320 | l = −14→13 |
11126 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)] = 0.037 | Hydrogen site location: mixed |
wR(F2) = 0.096 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.05 | w = 1/[σ2(Fo2) + (0.0453P)2 + 0.4223P] where P = (Fo2 + 2Fc2)/3 |
2183 reflections | (Δ/σ)max < 0.001 |
150 parameters | Δρmax = 0.21 e Å−3 |
0 restraints | Δρmin = −0.19 e Å−3 |
C12H19N3 | V = 1217.17 (6) Å3 |
Mr = 205.30 | Z = 4 |
Monoclinic, P21/c | Cu Kα radiation |
a = 10.5993 (3) Å | µ = 0.53 mm−1 |
b = 9.7641 (3) Å | T = 100 K |
c = 12.4435 (4) Å | 0.15 × 0.10 × 0.09 mm |
β = 109.065 (1)° |
Bruker D8 Platinum135 diffractometer | 2183 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2016) | 2037 reflections with I > 2σ(I) |
Tmin = 0.211, Tmax = 0.320 | Rint = 0.040 |
11126 measured reflections |
R[F2 > 2σ(F2)] = 0.037 | 0 restraints |
wR(F2) = 0.096 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.05 | Δρmax = 0.21 e Å−3 |
2183 reflections | Δρmin = −0.19 e Å−3 |
150 parameters |
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. |
x | y | z | Uiso*/Ueq | Occ. (<1) | |
N1 | 0.75868 (11) | 0.50824 (12) | 0.79507 (11) | 0.0384 (3) | |
N2 | 0.49278 (10) | 0.84937 (10) | 0.55771 (8) | 0.0189 (2) | |
H2 | 0.425 (3) | 0.897 (3) | 0.520 (2) | 0.020 (6)* | 0.5 |
N3 | 0.61616 (9) | 0.90020 (10) | 0.56683 (8) | 0.0182 (2) | |
H3 | 0.622 (2) | 0.975 (3) | 0.534 (2) | 0.013 (6)* | 0.5 |
C1 | 0.70672 (11) | 0.59805 (12) | 0.73785 (10) | 0.0238 (3) | |
C2 | 0.64420 (11) | 0.70939 (11) | 0.66689 (9) | 0.0172 (2) | |
C3 | 0.50608 (11) | 0.73346 (11) | 0.61695 (9) | 0.0165 (2) | |
C4 | 0.70997 (11) | 0.81784 (11) | 0.63223 (9) | 0.0160 (2) | |
C5 | 0.38860 (11) | 0.65176 (11) | 0.62665 (9) | 0.0179 (3) | |
C6 | 0.25914 (12) | 0.70092 (14) | 0.53837 (11) | 0.0289 (3) | |
H6A | 0.2429 | 0.7966 | 0.5537 | 0.043* | |
H6B | 0.1847 | 0.6441 | 0.5426 | 0.043* | |
H6C | 0.2668 | 0.6936 | 0.4622 | 0.043* | |
C7 | 0.40648 (13) | 0.49897 (13) | 0.60832 (12) | 0.0313 (3) | |
H7A | 0.4089 | 0.4842 | 0.5311 | 0.047* | |
H7B | 0.3317 | 0.4478 | 0.6185 | 0.047* | |
H7C | 0.4903 | 0.4671 | 0.6636 | 0.047* | |
C8 | 0.38019 (13) | 0.67309 (13) | 0.74628 (10) | 0.0283 (3) | |
H8A | 0.4647 | 0.6455 | 0.8031 | 0.043* | |
H8B | 0.3074 | 0.6174 | 0.7553 | 0.043* | |
H8C | 0.3631 | 0.7700 | 0.7569 | 0.043* | |
C9 | 0.85791 (11) | 0.84303 (11) | 0.65776 (9) | 0.0188 (3) | |
C10 | 0.88128 (12) | 0.97784 (13) | 0.60457 (10) | 0.0251 (3) | |
H10A | 0.8377 | 0.9740 | 0.5220 | 0.038* | |
H10B | 0.9773 | 0.9923 | 0.6217 | 0.038* | |
H10C | 0.8437 | 1.0537 | 0.6360 | 0.038* | |
C11 | 0.92803 (12) | 0.84933 (12) | 0.78699 (10) | 0.0248 (3) | |
H11A | 0.8899 | 0.9241 | 0.8191 | 0.037* | |
H11B | 1.0236 | 0.8656 | 0.8030 | 0.037* | |
H11C | 0.9153 | 0.7623 | 0.8214 | 0.037* | |
C12 | 0.91653 (12) | 0.72457 (13) | 0.60780 (11) | 0.0295 (3) | |
H12A | 0.9014 | 0.6379 | 0.6414 | 0.044* | |
H12B | 1.0126 | 0.7389 | 0.6249 | 0.044* | |
H12C | 0.8729 | 0.7214 | 0.5252 | 0.044* |
U11 | U22 | U33 | U12 | U13 | U23 | |
N1 | 0.0241 (6) | 0.0312 (6) | 0.0507 (7) | −0.0030 (5) | −0.0004 (5) | 0.0191 (5) |
N2 | 0.0160 (5) | 0.0200 (5) | 0.0209 (5) | −0.0003 (4) | 0.0062 (4) | 0.0026 (4) |
N3 | 0.0150 (5) | 0.0202 (5) | 0.0191 (5) | 0.0002 (4) | 0.0052 (4) | 0.0033 (4) |
C1 | 0.0171 (6) | 0.0230 (6) | 0.0285 (6) | −0.0030 (4) | 0.0036 (5) | 0.0048 (5) |
C2 | 0.0168 (6) | 0.0171 (5) | 0.0168 (5) | 0.0005 (4) | 0.0042 (4) | 0.0015 (4) |
C3 | 0.0174 (6) | 0.0170 (5) | 0.0150 (5) | −0.0010 (4) | 0.0052 (4) | −0.0010 (4) |
C4 | 0.0160 (6) | 0.0173 (5) | 0.0144 (5) | 0.0004 (4) | 0.0047 (4) | −0.0010 (4) |
C5 | 0.0158 (6) | 0.0182 (6) | 0.0202 (6) | −0.0019 (4) | 0.0065 (4) | 0.0005 (4) |
C6 | 0.0171 (6) | 0.0366 (7) | 0.0307 (7) | −0.0043 (5) | 0.0047 (5) | 0.0086 (5) |
C7 | 0.0244 (7) | 0.0213 (6) | 0.0510 (8) | −0.0056 (5) | 0.0161 (6) | −0.0072 (5) |
C8 | 0.0332 (7) | 0.0303 (7) | 0.0258 (6) | −0.0101 (5) | 0.0153 (5) | −0.0012 (5) |
C9 | 0.0139 (5) | 0.0209 (6) | 0.0212 (6) | 0.0002 (4) | 0.0050 (4) | 0.0016 (4) |
C10 | 0.0179 (6) | 0.0279 (6) | 0.0294 (6) | −0.0025 (4) | 0.0074 (5) | 0.0059 (5) |
C11 | 0.0184 (6) | 0.0280 (6) | 0.0240 (6) | −0.0025 (5) | 0.0015 (5) | 0.0027 (5) |
C12 | 0.0220 (6) | 0.0307 (7) | 0.0388 (7) | 0.0029 (5) | 0.0142 (5) | −0.0035 (5) |
N1—C1 | 1.1502 (16) | C7—H7B | 0.9800 |
N2—H2 | 0.86 (3) | C7—H7C | 0.9800 |
N2—N3 | 1.3683 (13) | C8—H8A | 0.9800 |
N2—C3 | 1.3328 (14) | C8—H8B | 0.9800 |
N3—H3 | 0.85 (3) | C8—H8C | 0.9800 |
N3—C4 | 1.3301 (14) | C9—C10 | 1.5295 (16) |
C1—C2 | 1.4207 (16) | C9—C11 | 1.5366 (16) |
C2—C3 | 1.4107 (15) | C9—C12 | 1.5372 (16) |
C2—C4 | 1.4107 (15) | C10—H10A | 0.9800 |
C3—C5 | 1.5165 (15) | C10—H10B | 0.9800 |
C4—C9 | 1.5148 (15) | C10—H10C | 0.9800 |
C5—C6 | 1.5281 (16) | C11—H11A | 0.9800 |
C5—C7 | 1.5303 (16) | C11—H11B | 0.9800 |
C5—C8 | 1.5343 (15) | C11—H11C | 0.9800 |
C6—H6A | 0.9800 | C12—H12A | 0.9800 |
C6—H6B | 0.9800 | C12—H12B | 0.9800 |
C6—H6C | 0.9800 | C12—H12C | 0.9800 |
C7—H7A | 0.9800 | ||
N3—N2—H2 | 117.6 (18) | H7A—C7—H7C | 109.5 |
C3—N2—H2 | 132.6 (18) | H7B—C7—H7C | 109.5 |
C3—N2—N3 | 109.67 (9) | C5—C8—H8A | 109.5 |
N2—N3—H3 | 119.1 (17) | C5—C8—H8B | 109.5 |
C4—N3—N2 | 109.55 (9) | C5—C8—H8C | 109.5 |
C4—N3—H3 | 131.3 (17) | H8A—C8—H8B | 109.5 |
N1—C1—C2 | 179.21 (13) | H8A—C8—H8C | 109.5 |
C3—C2—C1 | 127.41 (10) | H8B—C8—H8C | 109.5 |
C4—C2—C1 | 125.99 (10) | C4—C9—C10 | 110.60 (9) |
C4—C2—C3 | 106.60 (9) | C4—C9—C11 | 109.86 (9) |
N2—C3—C2 | 106.99 (9) | C4—C9—C12 | 108.69 (9) |
N2—C3—C5 | 123.33 (10) | C10—C9—C11 | 109.09 (9) |
C2—C3—C5 | 129.66 (10) | C10—C9—C12 | 109.18 (10) |
N3—C4—C2 | 107.19 (10) | C11—C9—C12 | 109.40 (9) |
N3—C4—C9 | 123.09 (10) | C9—C10—H10A | 109.5 |
C2—C4—C9 | 129.71 (10) | C9—C10—H10B | 109.5 |
C3—C5—C6 | 110.21 (9) | C9—C10—H10C | 109.5 |
C3—C5—C7 | 110.86 (9) | H10A—C10—H10B | 109.5 |
C3—C5—C8 | 108.38 (9) | H10A—C10—H10C | 109.5 |
C6—C5—C7 | 108.96 (10) | H10B—C10—H10C | 109.5 |
C6—C5—C8 | 109.37 (10) | C9—C11—H11A | 109.5 |
C7—C5—C8 | 109.04 (10) | C9—C11—H11B | 109.5 |
C5—C6—H6A | 109.5 | C9—C11—H11C | 109.5 |
C5—C6—H6B | 109.5 | H11A—C11—H11B | 109.5 |
C5—C6—H6C | 109.5 | H11A—C11—H11C | 109.5 |
H6A—C6—H6B | 109.5 | H11B—C11—H11C | 109.5 |
H6A—C6—H6C | 109.5 | C9—C12—H12A | 109.5 |
H6B—C6—H6C | 109.5 | C9—C12—H12B | 109.5 |
C5—C7—H7A | 109.5 | C9—C12—H12C | 109.5 |
C5—C7—H7B | 109.5 | H12A—C12—H12B | 109.5 |
C5—C7—H7C | 109.5 | H12A—C12—H12C | 109.5 |
H7A—C7—H7B | 109.5 | H12B—C12—H12C | 109.5 |
D—H···A | D—H | H···A | D···A | D—H···A |
N2—H2···N3i | 0.86 (3) | 2.23 (3) | 2.9232 (14) | 138 (2) |
N3—H3···N2i | 0.85 (3) | 2.19 (3) | 2.9232 (14) | 144 (2) |
Symmetry code: (i) −x+1, −y+2, −z+1. |
D—H···A | D—H | H···A | D···A | D—H···A |
N2—H2···N3i | 0.86 (3) | 2.23 (3) | 2.9232 (14) | 138 (2) |
N3—H3···N2i | 0.85 (3) | 2.19 (3) | 2.9232 (14) | 144 (2) |
Symmetry code: (i) −x+1, −y+2, −z+1. |
Experimental details
Crystal data | |
Chemical formula | C12H19N3 |
Mr | 205.30 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 100 |
a, b, c (Å) | 10.5993 (3), 9.7641 (3), 12.4435 (4) |
β (°) | 109.065 (1) |
V (Å3) | 1217.17 (6) |
Z | 4 |
Radiation type | Cu Kα |
µ (mm−1) | 0.53 |
Crystal size (mm) | 0.15 × 0.10 × 0.09 |
Data collection | |
Diffractometer | Bruker D8 Platinum135 |
Absorption correction | Multi-scan (SADABS; Bruker, 2016) |
Tmin, Tmax | 0.211, 0.320 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 11126, 2183, 2037 |
Rint | 0.040 |
(sin θ/λ)max (Å−1) | 0.602 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.037, 0.096, 1.05 |
No. of reflections | 2183 |
No. of parameters | 150 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.21, −0.19 |
Computer programs: APEX3 (Bruker, 2016), SAINT (Bruker, 2016), SHELXT (Sheldrick, 2015a), SHELXL2014 (Sheldrick, 2015b), Mercury (Macrae et al., 2008), OLEX2 (Dolomanov et al., 2009).
Acknowledgements
The authors thank Dr Curtis Moore, Director of X-ray Crystallography Facility at University of California, San Diego, for providing the single-crystal X-ray diffraction data, and the Department of Chemistry at Jacksonville University for supporting the research.
References
Bruker (2016). APEX3, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Dolomanov, O. V., Bourhis, L. J., Gildea, R. J., Howard, J. A. K. & Puschmann, H. (2009). J. Appl. Cryst. 42, 339–341. Web of Science CrossRef CAS IUCr Journals Google Scholar
Macrae, C. F., Bruno, I. J., Chisholm, J. A., Edgington, P. R., McCabe, P., Pidcock, E., Rodriguez-Monge, L., Taylor, R., van de Streek, J. & Wood, P. A. (2008). J. Appl. Cryst. 41, 466–470. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
Sheldrick, G. M. (2015a). Acta Cryst. A71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Sheldrick, G. M. (2015b). Acta Cryst. C71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
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