1,4-Bis(2-nitro­benz­yl)piperazine

Crundwell, H.I.; Grimmett, R.I.; Crundwell, G.; Westcott, B.L.

doi:10.1107/S2414314619014688

organic compounds

IUCrDATA

ISSN: 2414-3146

Volume 4| Part 11| November 2019| x191468

https://doi.org/10.1107/S2414314619014688

Open

access

1,4-Bis(2-nitrobenzyl)piperazine

Hugh I. Crundwell,^a ^* Rhiannon I. Grimmett,^a Guy Crundwell ^a and Barry L. Westcott ^a

^aDepartment of Chemistry & Biochemistry, Central Connecticut State University, 1619 Stanley Street, New Britain, CT 06053, USA
^*Correspondence e-mail: crundwellg@ccsu.edu

Edited by W. T. A. Harrison, University of Aberdeen, Scotland (Received 28 October 2019; accepted 29 October 2019; online 5 November 2019)

The title compound, C₁₈H₂₀N₄O₄, was synthesized via the base-assisted reaction of piperazine and 2-nitrobenyl bromide in toluene: the complete molecule is generated by a crystallographic inversion centre in the solid state.

Keywords: crystal structure; piperazine.

CCDC references: 1962337; 1962337

Structure description

The title compound, C₁₈H₂₀N₄O₄, has been previously studied by Schlager et al. (1996 ) and Cameron & Fréchet (1991 ). In the solid state, the complete molecule is generated by a crystallographic inversion center and the exocyclic N—C bonds have equatorial orientations (bond-angle sum for N1 = 332.4°). The nitro group makes a torsion angle of 45.36 (6)° with its attached C4–C9 phenyl ring. All bond lengths and angles fall within expected values. The molecular structure is shown in Fig. 1 and a view of the unit-cell packing along [100] is shown in Fig. 2. No directional intermolecular interactions beyond normal van der Waals contacts could be identified in the extended structure.

Figure 1
The molecular structure of the title compound with displacement ellipsoids drawn at the 50% probability level. Unlabelled atoms are generated by the symmetry operation (1 − x, −y, −z) and H atoms are omitted for clarity.

Figure 2
A view approximately along [100] of the unit-cell packing.

Synthesis and crystallization

1,4-Bis(2-nitrobenzyl)piperazine was made according to the published method of Schlager et al. (1996). In an Erlenmeyer flask placed in an 60°C oil bath, 40 mmol (3.45 g) of 1,4-diazacyclohexane was added to 100 ml of toluene with stirring. To that solution, 80 mmol (17.3 g) of 2-nitrobenzyl bromide was added. Once dissolved, 90 mmol of powdered KOH (4.98 g) were slowly added with stirring. The mixture was allowed to stir overnight in the oil bath. Upon removal from the oil bath and subsequent cooling, large block-like yellow crystals of the title compound formed. The title compound melts at 409 K. ¹H NMR data (Schlager et al., 1996) and FTIR data (Cameron & Fréchet, 1991) are in agreement with published values.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 1. Reflections affected by the beam stop were omitted from the refinement.

Table 1
Experimental details

Crystal data
Chemical formula	C₁₈H₂₀N₄O₄
M_r	356.38
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	293
a, b, c (Å)	6.0338 (3), 12.9814 (6), 11.4890 (5)
β (°)	91.185 (4)
V (Å³)	899.71 (7)
Z	2
Radiation type	Mo Kα
μ (mm⁻¹)	0.10
Crystal size (mm)	0.41 × 0.40 × 0.22

Data collection
Diffractometer	Oxford Diffraction Xcalibur, Sapphire3
Absorption correction	Multi-scan (CrysAlis PRO; Oxford Diffraction, 2009 $[Oxford Diffraction (2009). CrysAlis CCD, CrysAlis RED and CrysAlis PRO. Oxford Diffraction Ltd, Yarnton, England.]$ )
T_min, T_max	0.801, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	22354, 3335, 2339
R_int	0.029
(sin θ/λ)_max (Å⁻¹)	0.779

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.056, 0.153, 1.03
No. of reflections	3335
No. of parameters	118
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.19, −0.21
Computer programs: CrysAlis CCD and CrysAlis RED (Oxford Diffraction, 2009 $[Oxford Diffraction (2009). CrysAlis CCD, CrysAlis RED and CrysAlis PRO. Oxford Diffraction Ltd, Yarnton, England.]$ ), SHELXS2014 (Sheldrick, 2008 ), SHELXL2014 (Sheldrick, 2015 ), ORTEP-3 for Windows (Farrugia, 2012 ) and OLEX2 (Bourhis et al., 2015 ).

Structural data

CCDC references: 1962337; 1962337

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S2414314619014688/hb4325sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314619014688/hb4325Isup2.hkl

Supporting information file. DOI: https://doi.org/10.1107/S2414314619014688/hb4325Isup3.cml

checkCIF report

Computing details top

Data collection: CrysAlis CCD (Oxford Diffraction, 2009); cell refinement: CrysAlis RED (Oxford Diffraction, 2009); data reduction: CrysAlis RED (Oxford Diffraction, 2009); program(s) used to solve structure: SHELXS2014 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: OLEX2 (Bourhis et al., 2015).

1,4-Bis(2-nitrobenzyl)piperazine top

Crystal data top

C₁₈H₂₀N₄O₄	F(000) = 376.1911
M_r = 356.38	D_x = 1.315 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
a = 6.0338 (3) Å	Cell parameters from 5355 reflections
b = 12.9814 (6) Å	θ = 4.8–31.0°
c = 11.4890 (5) Å	µ = 0.10 mm⁻¹
β = 91.185 (4)°	T = 293 K
V = 899.71 (7) Å³	Block, yellow
Z = 2	0.41 × 0.40 × 0.22 mm

Data collection top

Oxford Diffraction Xcalibur, Sapphire3 diffractometer	3335 independent reflections
Radiation source: Enhance (Mo) X-ray Source	2339 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.029
Detector resolution: 16.1790 pixels mm^-1	θ_max = 33.6°, θ_min = 4.7°
ω scans	h = −9→9
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2009)	k = −19→19
T_min = 0.801, T_max = 1.000	l = −17→17
22354 measured reflections

Refinement top

Refinement on F²	Primary atom site location: iterative
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.056	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.153	H-atom parameters constrained
S = 1.03	w = 1/[σ²(F_o²) + (0.0652P)² + 0.1367P] where P = (F_o² + 2F_c²)/3
3335 reflections	(Δ/σ)_max < 0.001
118 parameters	Δρ_max = 0.19 e Å⁻³
0 restraints	Δρ_min = −0.21 e Å⁻³

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.

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 > 2sigma(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.

H atoms were included in calculated positions with C–H = 0.93–0.97 Å and were included in the refinement in the riding motion approximation with U_iso = 1.2U_eq(carrier).

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
O1	0.40223 (19)	0.01928 (9)	0.36223 (11)	0.0757 (3)
O2	0.7134 (2)	−0.06112 (8)	0.37260 (12)	0.0810 (4)
N1	0.50057 (15)	0.06204 (8)	0.10262 (8)	0.0423 (2)
N2	0.6030 (2)	0.01681 (8)	0.35741 (9)	0.0543 (3)
C1	0.29557 (18)	0.01964 (11)	0.05348 (10)	0.0479 (3)
H1A	0.2284	0.0690	0.0000	0.058*
H1B	0.1921	0.0067	0.1153	0.058*
C2	0.65771 (19)	0.07935 (10)	0.01003 (10)	0.0478 (3)
H2A	0.7949	0.1067	0.0430	0.057*
H2B	0.5975	0.1297	−0.0444	0.057*
C3	0.4604 (2)	0.15692 (11)	0.16799 (11)	0.0538 (3)
H3A	0.3272	0.1492	0.2130	0.065*
H3B	0.4378	0.2137	0.1142	0.065*
C4	0.6537 (2)	0.18024 (9)	0.24814 (10)	0.0460 (3)
C5	0.7236 (2)	0.11288 (9)	0.33597 (10)	0.0444 (3)
C6	0.9076 (2)	0.13108 (11)	0.40618 (12)	0.0582 (3)
H6	0.9492	0.0840	0.4636	0.070*
C7	1.0285 (3)	0.21903 (12)	0.39046 (15)	0.0669 (4)
H7	1.1513	0.2326	0.4382	0.080*
C8	0.9686 (3)	0.28655 (12)	0.30476 (15)	0.0688 (4)
H8	1.0525	0.3457	0.2934	0.083*
C9	0.7835 (3)	0.26779 (10)	0.23431 (12)	0.0609 (4)
H9	0.7452	0.3149	0.1764	0.073*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0701 (7)	0.0770 (8)	0.0805 (8)	−0.0093 (6)	0.0174 (6)	0.0004 (6)
O2	0.1077 (9)	0.0464 (6)	0.0885 (8)	0.0106 (6)	−0.0089 (7)	0.0041 (5)
N1	0.0397 (4)	0.0547 (6)	0.0325 (4)	0.0097 (4)	0.0008 (3)	−0.0032 (4)
N2	0.0721 (7)	0.0484 (6)	0.0422 (5)	0.0029 (5)	0.0009 (5)	−0.0028 (4)
C1	0.0367 (5)	0.0678 (8)	0.0394 (5)	0.0076 (5)	0.0042 (4)	−0.0029 (5)
C2	0.0422 (5)	0.0606 (7)	0.0407 (5)	0.0005 (5)	0.0026 (4)	−0.0008 (5)
C3	0.0590 (7)	0.0590 (7)	0.0433 (6)	0.0228 (6)	−0.0049 (5)	−0.0061 (5)
C4	0.0560 (6)	0.0437 (6)	0.0384 (5)	0.0127 (5)	0.0029 (5)	−0.0056 (4)
C5	0.0520 (6)	0.0414 (5)	0.0400 (5)	0.0076 (5)	0.0005 (4)	−0.0061 (4)
C6	0.0649 (8)	0.0552 (7)	0.0540 (7)	0.0142 (6)	−0.0142 (6)	−0.0113 (6)
C7	0.0583 (8)	0.0660 (9)	0.0761 (10)	0.0030 (7)	−0.0061 (7)	−0.0261 (8)
C8	0.0742 (9)	0.0568 (8)	0.0764 (10)	−0.0126 (7)	0.0212 (8)	−0.0227 (7)
C9	0.0864 (10)	0.0461 (7)	0.0507 (7)	0.0066 (7)	0.0140 (7)	−0.0015 (5)

Geometric parameters (Å, º) top

O1—N2	1.2143 (15)	C3—H3B	0.9700
O2—N2	1.2218 (15)	C3—C4	1.5015 (17)
N1—C1	1.4570 (15)	C4—C5	1.3941 (16)
N1—C2	1.4570 (14)	C4—C9	1.3912 (19)
N1—C3	1.4653 (15)	C5—C6	1.3792 (17)
N2—C5	1.4673 (16)	C6—H6	0.9300
C1—H1A	0.9700	C6—C7	1.369 (2)
C1—H1B	0.9700	C7—H7	0.9300
C1—C2ⁱ	1.5072 (18)	C7—C8	1.361 (2)
C2—C1ⁱ	1.5072 (18)	C8—H8	0.9300
C2—H2A	0.9700	C8—C9	1.388 (2)
C2—H2B	0.9700	C9—H9	0.9300
C3—H3A	0.9700

C1—N1—C2	109.60 (9)	H3A—C3—H3B	108.1
C1—N1—C3	111.61 (9)	C4—C3—H3A	109.6
C2—N1—C3	111.20 (10)	C4—C3—H3B	109.6
O1—N2—O2	123.83 (13)	C5—C4—C3	122.48 (12)
O1—N2—C5	118.94 (11)	C9—C4—C3	121.77 (12)
O2—N2—C5	117.19 (12)	C9—C4—C5	115.62 (12)
N1—C1—H1A	109.6	C4—C5—N2	120.72 (11)
N1—C1—H1B	109.6	C6—C5—N2	116.33 (11)
N1—C1—C2ⁱ	110.12 (9)	C6—C5—C4	122.95 (12)
H1A—C1—H1B	108.2	C5—C6—H6	120.3
C2ⁱ—C1—H1A	109.6	C7—C6—C5	119.36 (14)
C2ⁱ—C1—H1B	109.6	C7—C6—H6	120.3
N1—C2—C1ⁱ	110.67 (10)	C6—C7—H7	120.0
N1—C2—H2A	109.5	C8—C7—C6	119.91 (14)
N1—C2—H2B	109.5	C8—C7—H7	120.0
C1ⁱ—C2—H2A	109.5	C7—C8—H8	119.8
C1ⁱ—C2—H2B	109.5	C7—C8—C9	120.48 (14)
H2A—C2—H2B	108.1	C9—C8—H8	119.8
N1—C3—H3A	109.6	C4—C9—H9	119.2
N1—C3—H3B	109.6	C8—C9—C4	121.67 (14)
N1—C3—C4	110.45 (9)	C8—C9—H9	119.2

Symmetry code: (i) −x+1, −y, −z.

Acknowledgements

This research was funded by a CCSU–AAUP research grant.

References

Bourhis, L. J., Dolomanov, O. V., Gildea, R. J., Howard, J. A. K. & Puschmann, H. (2015). Acta Cryst. A71, 59–75. Web of Science CrossRef IUCr Journals Google Scholar
Cameron, J. F. & Fréchet, J. M. J. (1991). J. Am. Chem. Soc. 113, 4303–4313. CrossRef CAS Web of Science Google Scholar
Farrugia, L. J. (2012). J. Appl. Cryst. 45, 849–854. Web of Science CrossRef CAS IUCr Journals Google Scholar
Oxford Diffraction (2009). CrysAlis CCD, CrysAlis RED and CrysAlis PRO. Oxford Diffraction Ltd, Yarnton, England. Google Scholar
Schlager, O., Wieghardt, K., Rufińska, A. & Nuber, B. (1996). J. Chem. Soc. Dalton Trans. pp. 1659–1668. CSD CrossRef Web of Science Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Sheldrick, G. M. (2015). Acta Cryst. C71, 3–8. Web of Science CrossRef IUCr Journals 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.