Acta Crystallographica Section E: Crystallographic Communications

Acta Crystallogr E Crystallogr Commun. 73(Pt 6): 832-834

Crystal structure of 2,2′-(ethane-1,2-diyl)bis(2,3-dihydro-1H-naphtho[1,2-e][1,3]oxazine): a prospective raw material for polybenzoxazines

Augusto Riveraa*, Juan E. Cepeda-Santamaríaa, Jaime Ríos-Mottaa, Michael Bolteb

a. Universidad Nacional de Colombia, Sede Bogotá, Facultad de Ciencias, Departamento de Química, Cra 30 No. 45-03, Bogotá, Código Postal 111321, Colombia

b. Institut für Anorganische Chemie, J. W. Goethe-Universität Frankfurt, Max-von Laue-Strasse 7, 60438 Frankfurt/Main, Germany

Correspondence e-mail: ariverau@unal.edu.co

© Rivera et al. 2017

DOI: 10.1107/S2056989017006673

Published online: 09 May 2017

Abstract

The molecular and crystal structures of the centrosymmetric naphthoxazine derivative is reported. In the absence of hydrogen-bonding and π–π stacking interactions, the crystal structure is stabilized by short C—H⋯π contacts.

Abstract

In the title compound, C₂₆H₂₄N₂O₂, the oxazine moiety is fused to a naphthalene ring system. The asymmetric unit consists of one half of the molecule, which lies about an inversion centre. The C atoms of the ethylene spacer group adopt an antiperiplanar arrangement. The oxazine ring adopts a half-chair conformation. In the crystal, supramolecular chains running along the b axis are formed via short C—H⋯π contacts. The crystal studied was a non-merohedral twin with a fractional contribution of 0.168 (2) of the minor twin component.

Chemical context  

The oxazine moiety is well known as a building block for high-performance phenolic resins, which are of great interest in industry due to their superior mechanical and physical properties together with unusually high thermal resistance (Kiskan & Yagci, 2005 ▸). Recently, because of their high flexibility in molecular design and performance-to-cost ratio, these monomers have gained attention for the preparation of cured thermosetting resins (Song et al., 2014 ▸; Yeganeh & Jangi, 2010 ▸). Benzoxazines and naphthoxazines, originally proposed by Holly & Cope (1944 ▸) and subsequently elaborated by Burke and co-workers (Burke et al., 1952 ▸), are obtained by Mannich-type condensation–cyclization reactions of phenols or naphthols with formaldehyde and primary amines in a 1:2:1 ratio (Deck et al., 2014 ▸). Interest in the synthesis of polybenzoxazines and polynaphthoxazines has greatly increased during the past few years as they have a great deal of molecular design flexibility compared to ordinary phenolics (Yildirim et al., 2006 ▸). The title bisnapthoxazine, 2,2′-(ethane-1,2-diyl)bis(2,3-dihydro-1H-naphtho[1,2-e][1,3]oxazine), C₂₆H₂₄N₂O₂, was prepared by condensation of 2-naphthol with ethylenediamine and formaldehyde in a 2:1:4 molar ratio at room temperature for 15 min in methanol solution. Evaporation at room temperature afforded the title compound in 73% yield after recrystallization.

Structural commentary  

In general terms, the structure of the title compound (Fig. 1 ▸) is similar to those of other naphthoxazine derivatives that have been reported in that the oxazine moiety adopts a half-chair conformation (Yang et al., 2007 ▸; Rivera et al., 2015 ▸), with puckering parameters Q = 0.478 (3) Å, θ = 51.5 (4)°, φ = 86.6 (4)°, and the ethylene spacer group adopts an antiperiplanar arrangement as observed in 3,3′-(ethane-1,2-diyl)bis(3,4-dihydro-2H-1,3-benzoxazine) (Rivera et al., 2012 ▸), with a N1—C13—C13i—N1i torsion angle of 180.0° [symmetry code: (i) 1 − x, 1 − y, 1 − z]. However, unlike the related structures, which crystallized in monoclinic space groups with one molecule in the asymmetric unit (Yang et al., 2007 ▸; Rivera et al., 2012 ▸, 2015 ▸), the title compound (I) crystallizes with just half a molecule in the asymmetric unit in the space group P2₁/c, utilizing the crystallographic inversion centre in the molecular symmetry. The other half of the molecule is generated by the symmetry operation (1 − x, 1 − y, 1 − z).

The aromatic C—C bonds of naphthalene ring system have a narrow range of distances [from 1.365 (5) to 1.431 (4) Å]. The central C5—C10 bond at 1.415 (4) Å is, however, shorter by 0.014 Å than those in related structures (Yang et al., 2007 ▸; Rivera et al., 2015 ▸). The N1—C1 and O1—C1 bond lengths are normal and comparable to the corresponding values observed in these related structures.

Supramolecular features  

In the crystal, the packing of the title compound is dominated by short contacts (Table 1 ▸), as indicated by a PLATON (Spek, 2009 ▸) analysis. These contacts result from short C12—H12B⋯C2 and C12—H12B⋯C3 separations, which at 2.75 Å are both 0.15 Å shorter than the sum of the van der Waals radii, while the C—H⋯Cg1 contact to the mid-point of the C2–-C3 bond is even shorter at approximately 2.65 Å. These contacts are also much shorter than the C—H⋯Cg2 contact to the centroid of the C2–C4/C11/C12 ring (Fig. 2 ▸). The molecules are by these short C—H⋯π contacts linked into chains propagating along the b-axis direction (Fig. 3 ▸).

Database survey  

The title compound is the first example of two naphtho-oxazine moieties linked by an ethylene bridge.

Synthesis and crystallization  

The title compound was prepared as described by Rivera et al. (2006 ▸). Crystals were obtained by slow evaporation of the reaction solution at ambient temperature and were isolated from the solution before complete evaporation of the solvent mixture.

Refinement details  

Crystal data, data collection and structure refinement details are summarized in Table 2 ▸. All H atoms were located in the difference electron-density map. C-bound H atoms were fixed geometrically (C—H = 0.95 or 0.99 Å) and refined using a riding-model approximation, with U iso(H) set to 1.2U eq of the parent atom. The crystal was a non-merohedral twin with a fractional contribution of 0.168 (2) of the minor twin component.

Figure 1View larger versionFigure 1. The molecular structure of the title compound, with displacement ellipsoids drawn at the 50% probability level. Atoms labelled with the suffix A are generated using the symmetry operator (1 − x, 1 − y, 1 − z).

Figure 2View larger versionFigure 2. Possible C—H⋯π contacts, shown as dotted green lines, between molecules of (I). Bond mid-points and ring centroids are shown as colored spheres.

Figure 3View larger versionFigure 3. Crystal packing of (I), showing C—H⋯(C,C) short contacts that result in chains propagating along the b-axis direction.

See full tableTable 1. Selected short-contact geometry (Å, °) Cg1 is the mid-point of the C2—C3 bond and Cg2 is the centroid of the C2–C4/C11/C12 ring.

See full table Table 2. Experimental details

Supplementary Material

Open In Web Browser

Acknowledgments

We acknowledge the Dirección de Investigaciones, Sede Bogotá (DIB) de la Universidad Nacional de Colombia for financial support of this work (research project No. 35816).

supplementary crystallographic information

Crystal data

See full table

Data collection

See full table

Refinement

See full table

Special details

See full table

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

See full table

Atomic displacement parameters (Å²)

See full table

Geometric parameters (Å, º)

See full table

Symmetry code: (i) −x+1, −y+1, −z+1.

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References

Burke, W. J., Kolbezen, M. J. & Stephens, C. W. (1952). J. Am. Chem. Soc. 74, 3601–3605.

Deck, L. M., Paine, R. T., Bright, E. R., Ouizem, S. & Dickie, D. A. (2014). Tetrahedron Lett. 55, 2434–2437.

Holly, F. W. & Cope, A. C. (1944). J. Am. Chem. Soc. 66, 1875–1879.

Kiskan, B. & Yagci, Y. (2005). Polymer, 46, 11690–11697.

Rivera, A., Camacho, J., Ríos-Motta, J., Fejfarová, K. & Dušek, M. (2012). Acta Cryst. E68, o148.

Rivera, A., Rojas, J. J., Ríos-Motta, J. & Bolte, M. (2015). Acta Cryst. E71, 1089–1092.

Rivera, A., Ríos-Motta, J. & Angel Navarro, M. (2006). Heterocycles, 68, 531–537.

Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122.

Sheldrick, G. M. (2015a). Acta Cryst. A71, 3–8.

Sheldrick, G. M. (2015b). Acta Cryst. C71, 3–8.

Song, J., Lee, J. & Kim, H. (2014). Macromol. Res. 22, 179–186.

Spek, A. L. (2009). Acta Cryst. D65, 148–155.

Stoe & Cie (2001). X-AREA and X-RED32. Stoe & Cie, Darmstadt, Germany.

Westrip, S. P. (2010). J. Appl. Cryst. 43, 920–925.

Yang, X.-H., Chen, X.-L., Diao, X.-J. & Wu, M.-H. (2007). Acta Cryst. E63, o3312.

Yeganeh, H. & Jangi, A. (2010). Polym. Int. 59, 1375–1383.

Yildirim, A., Kiskan, B., Demirel, A. L. & Yagci, Y. (2006). Eur. Polym. J. 42, 3006–3014.

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C₂₆H₂₄N₂O₂ | F(000) = 420
Mr = 396.47 | Dx = 1.347 Mg m⁻³
Monoclinic, P2₁/c | Mo Kα radiation, λ = 0.71073 Å
a = 9.8658 (10) Å | Cell parameters from 9056 reflections
b = 5.0979 (4) Å | θ = 2.8–26.4°
c = 19.551 (2) Å | µ = 0.09 mm⁻¹
β = 96.033 (8)° | T = 173 K
V = 977.87 (16) Å³ | Needle, colourless
Z = 2 | 0.27 × 0.11 × 0.04 mm

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Stoe IPDS II two-circle diffractometer | 9335 independent reflections
Radiation source: Genix 3D IµS microfocus X-ray source | 5706 reflections with I > 2σ(I)
ω scans | θmax = 26.4°, θmin = 2.8°
Absorption correction: multi-scan (X-AREA; Stoe & Cie, 2001) | h = −12→12
Tmin = 0.443, Tmax = 1.000 | k = −6→6
9335 measured reflections | l = −24→24

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Refinement on F² | 0 restraints
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.063 | H-atom parameters constrained
wR(F²) = 0.130 | w = 1/[σ²(Fo²) + (0.050P)²] where P = (Fo² + 2Fc²)/3
S = 0.94 | (Δ/σ)max < 0.001
9335 reflections | Δρmax = 0.53 e Å⁻³
137 parameters | Δρmin = −0.34 e Å⁻³

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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. Refined as a 2-component twin

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| x | y | z | Uiso*/Ueq |
N1 | 0.3328 (2) | 0.3467 (5) | 0.51587 (12) | 0.0291 (6) |
O1 | 0.14340 (19) | 0.6404 (5) | 0.52587 (10) | 0.0346 (5) |
C1 | 0.1935 (3) | 0.4104 (7) | 0.49256 (16) | 0.0351 (8) |
H1A | 0.135064 | 0.258586 | 0.501152 | 0.042* |
H1B | 0.185528 | 0.440900 | 0.442290 | 0.042* |
C2 | 0.1675 (3) | 0.6281 (6) | 0.59661 (15) | 0.0302 (7) |
C3 | 0.0926 (3) | 0.8089 (6) | 0.63272 (17) | 0.0350 (8) |
H3 | 0.029986 | 0.925542 | 0.608217 | 0.042* |
C4 | 0.1107 (3) | 0.8150 (7) | 0.70288 (17) | 0.0370 (8) |
H4 | 0.061911 | 0.939265 | 0.726968 | 0.044* |
C5 | 0.2015 (3) | 0.6382 (7) | 0.74028 (15) | 0.0319 (7) |
C6 | 0.2182 (3) | 0.6366 (7) | 0.81341 (16) | 0.0397 (8) |
H6 | 0.169242 | 0.759116 | 0.837964 | 0.048* |
C7 | 0.3039 (3) | 0.4611 (7) | 0.84895 (16) | 0.0419 (9) |
H7 | 0.313599 | 0.460117 | 0.897805 | 0.050* |
C8 | 0.3771 (3) | 0.2834 (7) | 0.81263 (17) | 0.0421 (9) |
H8 | 0.436829 | 0.162438 | 0.837424 | 0.051* |
C9 | 0.3648 (3) | 0.2792 (7) | 0.74225 (15) | 0.0355 (8) |
H9 | 0.415732 | 0.155997 | 0.718946 | 0.043* |
C10 | 0.2761 (3) | 0.4585 (6) | 0.70373 (15) | 0.0295 (7) |
C11 | 0.2593 (3) | 0.4567 (6) | 0.63016 (15) | 0.0276 (7) |
C12 | 0.3413 (3) | 0.2746 (6) | 0.58900 (14) | 0.0288 (7) |
H12A | 0.437938 | 0.278593 | 0.608671 | 0.035* |
H12B | 0.307562 | 0.092959 | 0.593092 | 0.035* |
C13 | 0.4289 (2) | 0.5552 (6) | 0.50126 (15) | 0.0290 (7) |
H13A | 0.430945 | 0.691415 | 0.537435 | 0.035* |
H13B | 0.397638 | 0.638414 | 0.456628 | 0.035* |

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| U ¹¹ | U ²² | U ³³ | U ¹² | U ¹³ | U ²³
N1 | 0.0234 (11) | 0.0348 (16) | 0.0294 (13) | −0.0034 (11) | 0.0031 (9) | 0.0008 (11)
O1 | 0.0264 (10) | 0.0434 (14) | 0.0335 (12) | 0.0053 (9) | 0.0002 (8) | 0.0001 (10)
C1 | 0.0240 (14) | 0.047 (2) | 0.0339 (16) | −0.0011 (13) | 0.0013 (12) | −0.0078 (15)
C2 | 0.0194 (13) | 0.0348 (18) | 0.0365 (17) | −0.0036 (13) | 0.0034 (12) | −0.0013 (14)
C3 | 0.0233 (13) | 0.035 (2) | 0.047 (2) | 0.0023 (13) | 0.0047 (13) | −0.0013 (15)
C4 | 0.0284 (14) | 0.033 (2) | 0.051 (2) | −0.0017 (13) | 0.0120 (14) | −0.0119 (15)
C5 | 0.0270 (14) | 0.0336 (18) | 0.0358 (18) | −0.0090 (13) | 0.0070 (12) | −0.0041 (14)
C6 | 0.0412 (17) | 0.040 (2) | 0.0398 (19) | −0.0157 (16) | 0.0151 (14) | −0.0116 (16)
C7 | 0.0501 (19) | 0.048 (2) | 0.0286 (17) | −0.0210 (17) | 0.0061 (14) | 0.0037 (15)
C8 | 0.0444 (17) | 0.043 (2) | 0.038 (2) | −0.0089 (16) | −0.0002 (15) | 0.0075 (16)
C9 | 0.0355 (15) | 0.034 (2) | 0.0377 (19) | −0.0048 (14) | 0.0057 (13) | 0.0047 (15)
C10 | 0.0244 (13) | 0.0273 (17) | 0.0374 (17) | −0.0071 (12) | 0.0067 (12) | −0.0008 (13)
C11 | 0.0232 (12) | 0.0280 (17) | 0.0322 (16) | −0.0049 (12) | 0.0058 (11) | −0.0010 (13)
C12 | 0.0266 (13) | 0.0287 (17) | 0.0319 (16) | 0.0005 (12) | 0.0067 (12) | 0.0002 (13)
C13 | 0.0250 (13) | 0.0322 (18) | 0.0302 (15) | 0.0019 (12) | 0.0047 (12) | 0.0014 (14)

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N1—C1 | 1.439 (3) | C6—C7 | 1.369 (5)
N1—C13 | 1.472 (4) | C6—H6 | 0.9500
N1—C12 | 1.470 (4) | C7—C8 | 1.398 (5)
O1—C2 | 1.380 (4) | C7—H7 | 0.9500
O1—C1 | 1.453 (4) | C8—C9 | 1.369 (4)
C1—H1A | 0.9900 | C8—H8 | 0.9500
C1—H1B | 0.9900 | C9—C10 | 1.425 (4)
C2—C11 | 1.375 (4) | C9—H9 | 0.9500
C2—C3 | 1.415 (4) | C10—C11 | 1.431 (4)
C3—C4 | 1.365 (5) | C11—C12 | 1.517 (4)
C3—H3 | 0.9500 | C12—H12A | 0.9900
C4—C5 | 1.418 (4) | C12—H12B | 0.9900
C4—H4 | 0.9500 | C13—C13i | 1.518 (5)
C5—C10 | 1.415 (4) | C13—H13A | 0.9900
C5—C6 | 1.422 (4) | C13—H13B | 0.9900
C1—N1—C13 | 112.9 (2) | C6—C7—H7 | 120.3
C1—N1—C12 | 108.6 (2) | C8—C7—H7 | 120.3
C13—N1—C12 | 113.4 (2) | C9—C8—C7 | 121.7 (3)
C2—O1—C1 | 112.5 (2) | C9—C8—H8 | 119.2
N1—C1—O1 | 113.5 (2) | C7—C8—H8 | 119.2
N1—C1—H1A | 108.9 | C8—C9—C10 | 120.4 (3)
O1—C1—H1A | 108.9 | C8—C9—H9 | 119.8
N1—C1—H1B | 108.9 | C10—C9—H9 | 119.8
O1—C1—H1B | 108.9 | C5—C10—C9 | 118.1 (3)
H1A—C1—H1B | 107.7 | C5—C10—C11 | 120.0 (3)
C11—C2—O1 | 122.9 (3) | C9—C10—C11 | 121.8 (3)
C11—C2—C3 | 121.9 (3) | C2—C11—C10 | 118.5 (3)
O1—C2—C3 | 115.2 (3) | C2—C11—C12 | 119.8 (3)
C4—C3—C2 | 119.7 (3) | C10—C11—C12 | 121.7 (3)
C4—C3—H3 | 120.1 | N1—C12—C11 | 112.6 (2)
C2—C3—H3 | 120.1 | N1—C12—H12A | 109.1
C3—C4—C5 | 120.8 (3) | C11—C12—H12A | 109.1
C3—C4—H4 | 119.6 | N1—C12—H12B | 109.1
C5—C4—H4 | 119.6 | C11—C12—H12B | 109.1
C10—C5—C4 | 119.0 (3) | H12A—C12—H12B | 107.8
C10—C5—C6 | 119.5 (3) | N1—C13—C13i | 110.8 (3)
C4—C5—C6 | 121.5 (3) | N1—C13—H13A | 109.5
C7—C6—C5 | 120.9 (3) | C13i—C13—H13A | 109.5
C7—C6—H6 | 119.5 | N1—C13—H13B | 109.5
C5—C6—H6 | 119.5 | C13i—C13—H13B | 109.5
C6—C7—C8 | 119.4 (3) | H13A—C13—H13B | 108.1
C13—N1—C1—O1 | −62.2 (3) | C6—C5—C10—C11 | 179.5 (3)
C12—N1—C1—O1 | 64.5 (3) | C8—C9—C10—C5 | −0.3 (4)
C2—O1—C1—N1 | −50.6 (3) | C8—C9—C10—C11 | −179.0 (3)
C1—O1—C2—C11 | 16.5 (4) | O1—C2—C11—C10 | −179.6 (3)
C1—O1—C2—C3 | −164.7 (2) | C3—C2—C11—C10 | 1.6 (4)
C11—C2—C3—C4 | −0.2 (5) | O1—C2—C11—C12 | 1.3 (4)
O1—C2—C3—C4 | −179.0 (3) | C3—C2—C11—C12 | −177.5 (3)
C2—C3—C4—C5 | −1.5 (5) | C5—C10—C11—C2 | −1.4 (4)
C3—C4—C5—C10 | 1.6 (4) | C9—C10—C11—C2 | 177.2 (3)
C3—C4—C5—C6 | −178.0 (3) | C5—C10—C11—C12 | 177.6 (3)
C10—C5—C6—C7 | −1.0 (5) | C9—C10—C11—C12 | −3.7 (4)
C4—C5—C6—C7 | 178.6 (3) | C1—N1—C12—C11 | −43.2 (3)
C5—C6—C7—C8 | 0.8 (5) | C13—N1—C12—C11 | 83.2 (3)
C6—C7—C8—C9 | −0.3 (5) | C2—C11—C12—N1 | 12.7 (4)
C7—C8—C9—C10 | 0.1 (5) | C10—C11—C12—N1 | −166.3 (3)
C4—C5—C10—C9 | −178.8 (3) | C1—N1—C13—C13i | −156.7 (3)
C6—C5—C10—C9 | 0.8 (4) | C12—N1—C13—C13i | 79.2 (4)
C4—C5—C10—C11 | −0.1 (4) |  |

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Figure 1.

The molecular structure of the title compound, with displacement ellipsoids drawn at the 50% probability level. Atoms labelled with the suffix A are generated using the symmetry operator (1 − x, 1 − y, 1 − z).

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Figure 2.

Possible C—H⋯π contacts, shown as dotted green lines, between molecules of (I). Bond mid-points and ring centroids are shown as colored spheres.

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Figure 3.

Crystal packing of (I), showing C—H⋯(C,C) short contacts that result in chains propagating along the b-axis direction.

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Table 1. Selected short-contact geometry (Å, °)

Cg1 is the mid-point of the C2—C3 bond and Cg2 is the centroid of the C2–C4/C11/C12 ring.

C—H⋯C | H⋯C | C—H⋯C
C12—H12B⋯C2i | 2.75 | 169
C12—H12B⋯C3i | 2.75 | 142
C12–H12B⋯Cg1 | 2.654 | 157
C12–H12B⋯Cg2 | 3.073 | 155

Symmetry code: (i) x, −1 + y, z.

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Table 2. Experimental details

Crystal data
Chemical formula | C₂₆H₂₄N₂O₂
M r | 396.47
Crystal system, space group | Monoclinic, P2₁/c
Temperature (K) | 173
a, b, c (Å) | 9.8658 (10), 5.0979 (4), 19.551 (2)
β (°) | 96.033 (8)
V (Å³) | 977.87 (16)
Z | 2
Radiation type | Mo Kα
μ (mm⁻¹) | 0.09
Crystal size (mm) | 0.27 × 0.11 × 0.04
Data collection
Diffractometer | Stoe IPDS II two-circle
Absorption correction | Multi-scan (X-AREA; Stoe & Cie, 2001 ▸)
T min, T max | 0.443, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections | 9335, 9335, 5706
(sin θ/λ)max (Å⁻¹) | 0.625
Refinement
R[F ² > 2σ(F ²)], wR(F ²), S | 0.063, 0.130, 0.94
No. of reflections | 9335
No. of parameters | 137
H-atom treatment | H-atom parameters constrained
Δρmax, Δρmin (e Å⁻³) | 0.53, −0.34

Computer programs: X-AREA (Stoe & Cie, 2001 ▸), SHELXT (Sheldrick, 2015a ▸), XP in SHELXTL-Plus (Sheldrick, 2008 ▸), SHELXL2016 (Sheldrick, 2015b ▸) and publCIF (Westrip, 2010 ▸).

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