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ISSN: 2414-3146

3,5-Di-tert-butyl-1H-pyrazole-4-carbo­nitrile

aDepartment of Chemistry, Jacksonville University, Jacksonville, FL 32211, USA
*Correspondence e-mail: pzhao@ju.edu

Edited by H. Stoeckli-Evans, University of Neuchâtel, Switzerland (Received 13 April 2016; accepted 20 April 2016; online 22 April 2016)

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.

3D view (loading...)
[Scheme 3D1]
Chemical scheme
[Scheme 1]

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[link], 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)°.

[Figure 1]
Figure 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.

In the crystal, mol­ecules are linked by pairs of N—H⋯N hydrogen bonds, forming inversion dimers with an [R_{2}^{2}](6) ring motif (Fig. 2[link] and Table 1[link]). There are no other significant inter­molecular inter­actions present.

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA 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.
[Figure 2]
Figure 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.

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 refinement details are summarized in Table 2[link]. 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.

Table 2
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)
V3) 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[Bruker (2016). APEX3, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.])
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−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, −0.20
Computer programs: APEX3 and SAINT (Bruker, 2016[Bruker (2016). APEX3, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]), SHELXT (Sheldrick, 2015a[Sheldrick, G. M. (2015a). Acta Cryst. A71, 3-8.]), SHELXL2014 (Sheldrick, 2015b[Sheldrick, G. M. (2015b). Acta Cryst. C71, 3-8.]), Mercury (Macrae et al., 2008[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.]) and OLEX2 (Dolomanov et al., 2009[Dolomanov, O. V., Bourhis, L. J., Gildea, R. J., Howard, J. A. K. & Puschmann, H. (2009). J. Appl. Cryst. 42, 339-341.]).

Structural data


Experimental top

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%).

Refinement top

Crystal data, data collection and structure refinement 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.

Structure description top

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—C1N1, 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.

Computing details top

Data collection: APEX3 (Bruker, 2016); cell refinement: 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).

Figures top
[Figure 1] 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.
[Figure 2] 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.
3,5-Di-tert-butyl-1H-pyrazole-4-carbonitrile top
Crystal data top
C12H19N3F(000) = 448
Mr = 205.30Dx = 1.120 Mg m3
Monoclinic, P21/cCu Kα radiation, λ = 1.54178 Å
a = 10.5993 (3) ÅCell parameters from 7895 reflections
b = 9.7641 (3) Åθ = 4.4–68.3°
c = 12.4435 (4) ŵ = 0.53 mm1
β = 109.065 (1)°T = 100 K
V = 1217.17 (6) Å3Block, colourless
Z = 40.15 × 0.10 × 0.09 mm
Data collection top
Bruker D8 Platinum135
diffractometer
2183 independent reflections
Radiation source: Micro Focus Rotating Anode, Bruker FR-5912037 reflections with I > 2σ(I)
Multilayer Mirrors monochromatorRint = 0.040
Detector resolution: 7.9 pixels mm-1θmax = 68.2°, θmin = 4.4°
ω and φ scansh = 1012
Absorption correction: multi-scan
(SADABS; Bruker, 2016)
k = 1111
Tmin = 0.211, Tmax = 0.320l = 1413
11126 measured reflections
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.037Hydrogen site location: mixed
wR(F2) = 0.096H 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 parametersΔρmax = 0.21 e Å3
0 restraintsΔρmin = 0.19 e Å3
Crystal data top
C12H19N3V = 1217.17 (6) Å3
Mr = 205.30Z = 4
Monoclinic, P21/cCu Kα radiation
a = 10.5993 (3) ŵ = 0.53 mm1
b = 9.7641 (3) ÅT = 100 K
c = 12.4435 (4) Å0.15 × 0.10 × 0.09 mm
β = 109.065 (1)°
Data collection top
Bruker D8 Platinum135
diffractometer
2183 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2016)
2037 reflections with I > 2σ(I)
Tmin = 0.211, Tmax = 0.320Rint = 0.040
11126 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0370 restraints
wR(F2) = 0.096H atoms treated by a mixture of independent and constrained refinement
S = 1.05Δρmax = 0.21 e Å3
2183 reflectionsΔρmin = 0.19 e Å3
150 parameters
Special details top

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
N10.75868 (11)0.50824 (12)0.79507 (11)0.0384 (3)
N20.49278 (10)0.84937 (10)0.55771 (8)0.0189 (2)
H20.425 (3)0.897 (3)0.520 (2)0.020 (6)*0.5
N30.61616 (9)0.90020 (10)0.56683 (8)0.0182 (2)
H30.622 (2)0.975 (3)0.534 (2)0.013 (6)*0.5
C10.70672 (11)0.59805 (12)0.73785 (10)0.0238 (3)
C20.64420 (11)0.70939 (11)0.66689 (9)0.0172 (2)
C30.50608 (11)0.73346 (11)0.61695 (9)0.0165 (2)
C40.70997 (11)0.81784 (11)0.63223 (9)0.0160 (2)
C50.38860 (11)0.65176 (11)0.62665 (9)0.0179 (3)
C60.25914 (12)0.70092 (14)0.53837 (11)0.0289 (3)
H6A0.24290.79660.55370.043*
H6B0.18470.64410.54260.043*
H6C0.26680.69360.46220.043*
C70.40648 (13)0.49897 (13)0.60832 (12)0.0313 (3)
H7A0.40890.48420.53110.047*
H7B0.33170.44780.61850.047*
H7C0.49030.46710.66360.047*
C80.38019 (13)0.67309 (13)0.74628 (10)0.0283 (3)
H8A0.46470.64550.80310.043*
H8B0.30740.61740.75530.043*
H8C0.36310.77000.75690.043*
C90.85791 (11)0.84303 (11)0.65776 (9)0.0188 (3)
C100.88128 (12)0.97784 (13)0.60457 (10)0.0251 (3)
H10A0.83770.97400.52200.038*
H10B0.97730.99230.62170.038*
H10C0.84371.05370.63600.038*
C110.92803 (12)0.84933 (12)0.78699 (10)0.0248 (3)
H11A0.88990.92410.81910.037*
H11B1.02360.86560.80300.037*
H11C0.91530.76230.82140.037*
C120.91653 (12)0.72457 (13)0.60780 (11)0.0295 (3)
H12A0.90140.63790.64140.044*
H12B1.01260.73890.62490.044*
H12C0.87290.72140.52520.044*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
N10.0241 (6)0.0312 (6)0.0507 (7)0.0030 (5)0.0004 (5)0.0191 (5)
N20.0160 (5)0.0200 (5)0.0209 (5)0.0003 (4)0.0062 (4)0.0026 (4)
N30.0150 (5)0.0202 (5)0.0191 (5)0.0002 (4)0.0052 (4)0.0033 (4)
C10.0171 (6)0.0230 (6)0.0285 (6)0.0030 (4)0.0036 (5)0.0048 (5)
C20.0168 (6)0.0171 (5)0.0168 (5)0.0005 (4)0.0042 (4)0.0015 (4)
C30.0174 (6)0.0170 (5)0.0150 (5)0.0010 (4)0.0052 (4)0.0010 (4)
C40.0160 (6)0.0173 (5)0.0144 (5)0.0004 (4)0.0047 (4)0.0010 (4)
C50.0158 (6)0.0182 (6)0.0202 (6)0.0019 (4)0.0065 (4)0.0005 (4)
C60.0171 (6)0.0366 (7)0.0307 (7)0.0043 (5)0.0047 (5)0.0086 (5)
C70.0244 (7)0.0213 (6)0.0510 (8)0.0056 (5)0.0161 (6)0.0072 (5)
C80.0332 (7)0.0303 (7)0.0258 (6)0.0101 (5)0.0153 (5)0.0012 (5)
C90.0139 (5)0.0209 (6)0.0212 (6)0.0002 (4)0.0050 (4)0.0016 (4)
C100.0179 (6)0.0279 (6)0.0294 (6)0.0025 (4)0.0074 (5)0.0059 (5)
C110.0184 (6)0.0280 (6)0.0240 (6)0.0025 (5)0.0015 (5)0.0027 (5)
C120.0220 (6)0.0307 (7)0.0388 (7)0.0029 (5)0.0142 (5)0.0035 (5)
Geometric parameters (Å, º) top
N1—C11.1502 (16)C7—H7B0.9800
N2—H20.86 (3)C7—H7C0.9800
N2—N31.3683 (13)C8—H8A0.9800
N2—C31.3328 (14)C8—H8B0.9800
N3—H30.85 (3)C8—H8C0.9800
N3—C41.3301 (14)C9—C101.5295 (16)
C1—C21.4207 (16)C9—C111.5366 (16)
C2—C31.4107 (15)C9—C121.5372 (16)
C2—C41.4107 (15)C10—H10A0.9800
C3—C51.5165 (15)C10—H10B0.9800
C4—C91.5148 (15)C10—H10C0.9800
C5—C61.5281 (16)C11—H11A0.9800
C5—C71.5303 (16)C11—H11B0.9800
C5—C81.5343 (15)C11—H11C0.9800
C6—H6A0.9800C12—H12A0.9800
C6—H6B0.9800C12—H12B0.9800
C6—H6C0.9800C12—H12C0.9800
C7—H7A0.9800
N3—N2—H2117.6 (18)H7A—C7—H7C109.5
C3—N2—H2132.6 (18)H7B—C7—H7C109.5
C3—N2—N3109.67 (9)C5—C8—H8A109.5
N2—N3—H3119.1 (17)C5—C8—H8B109.5
C4—N3—N2109.55 (9)C5—C8—H8C109.5
C4—N3—H3131.3 (17)H8A—C8—H8B109.5
N1—C1—C2179.21 (13)H8A—C8—H8C109.5
C3—C2—C1127.41 (10)H8B—C8—H8C109.5
C4—C2—C1125.99 (10)C4—C9—C10110.60 (9)
C4—C2—C3106.60 (9)C4—C9—C11109.86 (9)
N2—C3—C2106.99 (9)C4—C9—C12108.69 (9)
N2—C3—C5123.33 (10)C10—C9—C11109.09 (9)
C2—C3—C5129.66 (10)C10—C9—C12109.18 (10)
N3—C4—C2107.19 (10)C11—C9—C12109.40 (9)
N3—C4—C9123.09 (10)C9—C10—H10A109.5
C2—C4—C9129.71 (10)C9—C10—H10B109.5
C3—C5—C6110.21 (9)C9—C10—H10C109.5
C3—C5—C7110.86 (9)H10A—C10—H10B109.5
C3—C5—C8108.38 (9)H10A—C10—H10C109.5
C6—C5—C7108.96 (10)H10B—C10—H10C109.5
C6—C5—C8109.37 (10)C9—C11—H11A109.5
C7—C5—C8109.04 (10)C9—C11—H11B109.5
C5—C6—H6A109.5C9—C11—H11C109.5
C5—C6—H6B109.5H11A—C11—H11B109.5
C5—C6—H6C109.5H11A—C11—H11C109.5
H6A—C6—H6B109.5H11B—C11—H11C109.5
H6A—C6—H6C109.5C9—C12—H12A109.5
H6B—C6—H6C109.5C9—C12—H12B109.5
C5—C7—H7A109.5C9—C12—H12C109.5
C5—C7—H7B109.5H12A—C12—H12B109.5
C5—C7—H7C109.5H12A—C12—H12C109.5
H7A—C7—H7B109.5H12B—C12—H12C109.5
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N2—H2···N3i0.86 (3)2.23 (3)2.9232 (14)138 (2)
N3—H3···N2i0.85 (3)2.19 (3)2.9232 (14)144 (2)
Symmetry code: (i) x+1, y+2, z+1.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N2—H2···N3i0.86 (3)2.23 (3)2.9232 (14)138 (2)
N3—H3···N2i0.85 (3)2.19 (3)2.9232 (14)144 (2)
Symmetry code: (i) x+1, y+2, z+1.

Experimental details

Crystal data
Chemical formulaC12H19N3
Mr205.30
Crystal system, space groupMonoclinic, P21/c
Temperature (K)100
a, b, c (Å)10.5993 (3), 9.7641 (3), 12.4435 (4)
β (°) 109.065 (1)
V3)1217.17 (6)
Z4
Radiation typeCu Kα
µ (mm1)0.53
Crystal size (mm)0.15 × 0.10 × 0.09
Data collection
DiffractometerBruker D8 Platinum135
Absorption correctionMulti-scan
(SADABS; Bruker, 2016)
Tmin, Tmax0.211, 0.320
No. of measured, independent and
observed [I > 2σ(I)] reflections
11126, 2183, 2037
Rint0.040
(sin θ/λ)max1)0.602
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.037, 0.096, 1.05
No. of reflections2183
No. of parameters150
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)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

First citationBruker (2016). APEX3, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
First citationDolomanov, 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
First citationMacrae, 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
First citationSheldrick, G. M. (2015a). Acta Cryst. A71, 3–8.  Web of Science CrossRef IUCr Journals Google Scholar
First citationSheldrick, G. M. (2015b). Acta Cryst. C71, 3–8.  Web of Science CrossRef IUCr Journals Google Scholar

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