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Acta Crystallogr Sect E Struct Rep Online. 2009 October 1; 65(Pt 10): o2553.
Published online 2009 September 26. doi:  10.1107/S1600536809038380
PMCID: PMC2970222

2,9-Dimethyl-6H,13H-5:12,7:14-dimethano­dibenzo[d,i][1,3,6,8]tetraazecine

Abstract

In the title structure, C18H20N4, the aromatic rings are almost orthogonal [81.6 (2)°]. The mol­ecule has symmetry 2 since it is situated on a crystallographic twofold axis. There are only weak inter­molecular inter­actions present in the structure, notably C—H(...)π-electron ring inter­actions. The 1H and 13C NMR spectra are in accordance with the X-ray structure analysis.

Related literature

For the synthesis of the title compound, see: Volpp (1962 [triangle]); Kuznetsov et al. (2007 [triangle]). For related structures, see: Dickinson & Raymond (1923 [triangle]); Murray-Rust (1974 [triangle]); Murray-Rust & Ridell (1975 [triangle]); Murray-Rust & Smith (1975 [triangle]); Glister et al. (2005 [triangle]); Rivera et al. (2007 [triangle]); Volpp (1962 [triangle]). For the chemical reactivity of cyclic aminals, see: Rivera et al. (2005 [triangle]); Rivera & Maldonado (2006 [triangle]).

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Object name is e-65-o2553-scheme1.jpg

Experimental

Crystal data

  • C18H20N4
  • M r = 292.38
  • Orthorhombic, An external file that holds a picture, illustration, etc.
Object name is e-65-o2553-efi2.jpg
  • a = 9.9777 (3) Å
  • b = 18.8351 (4) Å
  • c = 7.6963 (2) Å
  • V = 1446.37 (7) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 0.08 mm−1
  • T = 100 K
  • 0.16 × 0.15 × 0.06 mm

Data collection

  • Bruker APEXII CCD diffractometer
  • Absorption correction: multi-scan (SADABS; Sheldrick, 2006 [triangle]) T min = 0.872, T max = 0.995
  • 10245 measured reflections
  • 807 independent reflections
  • 737 reflections with I > 2σ(I)
  • R int = 0.041

Refinement

  • R[F 2 > 2σ(F 2)] = 0.033
  • wR(F 2) = 0.090
  • S = 1.06
  • 807 reflections
  • 102 parameters
  • 1 restraint
  • H-atom parameters constrained
  • Δρmax = 0.18 e Å−3
  • Δρmin = −0.18 e Å−3

Data collection: APEX2 (Bruker, 2005 [triangle]); cell refinement: SAINT (Bruker, 2005 [triangle]); data reduction: SAINT; program(s) used to solve structure: SIR97 (Altomare et al., 1999 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 [triangle]); software used to prepare material for publication: WinGX (Farrugia, 1999 [triangle]).

Table 1
Geometry of C—H(...) Cg interactions (Å,°)

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809038380/fb2167sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809038380/fb2167Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Acknowledgments

Financial support of this research from the Division de Investigación sede Bogotá (DIB), and from the Departamento de Química, Universidad Nacional de Colombia, is gratefully acknowledged. DG-S thanks COLCIENCIAS for a fellowship.

supplementary crystallographic information

Comment

For many years, cyclic aminals (gem-diamine) have attracted intense attention because of their intriguing molecular structures, many of which have been determined by the X-ray crystallography (Murray-Rust, 1974; Murray-Rust & Ridell, 1975; Murray-Rust & Smith, 1975; Glister et al., 2005) and/or by 1H- and 13C-NMR spectroscopy (Kuznetsov et al., 2007). In the course of the research of the reactivity of aminals we have synthesized crystals of the title compound that contains a cyclic aminal, i. e. 2,9-dimethyl-6H,13H-5:12,7:14-dimethanedibenzo [d,i][1,3,6,8]tetraazecine.

The title molecule is shown in Fig. 1. The planes through the symmetry-related aromatic rings are almost perpendicular: the interplanar angle through the atoms C1//C2//C3//C4//C5//C6 and its mentioned symmetry-related plane by (2-x,-y,z) is 81.6 (2)°.

There are only weak intermolecular interactions present in the structure, notably C-H···π-electron ring interactions (Tab. 1, Fig. 2).

Experimental

A solution of 4-methyl-1,2-diaminebenzene (100 mg, 0.82 mmol) in water (8 ml) and methanol (2 ml) was added dropwise at 278 K to 5 ml of 37% aqueous formaldehyde while stirring it. The reaction mixture was removed from the cooling bath and allowed to warm to room temperature while still stirring it. After stirring at room temperature for 1 h the resultant precipitate was filtered off, washed with water, dried in vacuum and recrystallized from 2-propanol to give the title compound with 65% yield. The melting point of the title structure is 465 K. The melting point was determined visually using glass capillary tube with an Electrothermal melting point apparatus, model 9100, accuracy ±0.5 K, manufacturer: Electrothermal Thermo Scientific.

The NMR spectra were acquired at room temperature on a Bruker AMX 400 Advance spectrometer. 1H NMR (δ, 399.9 MHz, CDCl3): 2.33, 4.34, 6.92, 6.98. 13C NMR (δ, 100.0 MHz, CDCl3): 21.0, 68.6, 126.1, 126.7, 136.2, 150.3, 153.2. m/z (EI): 292.2 (M+).

Refinement

All the H atoms were discernible in the difference electron density maps. However, the H atoms were constrained by the riding model approximation: C—Hmethyl=0.96 Å; C—Haryl=0.93 Å; UisoHmethyl=1.5UeqCmethyl; UisoHaryl=1.2UeqCaryl. In the absence of significant anomalous scattering effects 667 Friedel pairs have been merged.

Figures

Fig. 1.
A view of the title molecule with the displacement ellipsoids shown at the 50% probability level with the atomic labelling scheme. The symmetry-related atoms by a crystallographic two-fold axis are indicated by "i".
Fig. 2.
C—H···π-electron arene intermolecular weak contacts in the title structure. The ring centroids are also depicted as red circles. [Symmetry code: (i) 3/2-x,y,1/2+z; (ii) 2-x,1/2-y,-1/2+z.]

Crystal data

C18H20N4Dx = 1.343 Mg m3
Mr = 292.38Melting point: 465 K
Orthorhombic, Aba2Mo Kα radiation, λ = 0.71073 Å
Hall symbol: A 2 -2acCell parameters from 3533 reflections
a = 9.9777 (3) Åθ = 3.0–26.1°
b = 18.8351 (4) ŵ = 0.08 mm1
c = 7.6963 (2) ÅT = 100 K
V = 1446.37 (7) Å3Prism, colourless
Z = 40.16 × 0.15 × 0.06 mm
F(000) = 624

Data collection

Bruker APEXII CCD diffractometer737 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.041
ω and [var phi] scansθmax = 26.4°, θmin = 2.2°
Absorption correction: multi-scan (SADABS; Sheldrick, 2006)h = −12→12
Tmin = 0.872, Tmax = 0.995k = −23→23
10245 measured reflectionsl = −9→9
807 independent reflections

Refinement

Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.033Hydrogen site location: difference Fourier map
wR(F2) = 0.090H-atom parameters constrained
S = 1.06w = 1/[σ2(Fo2) + (0.0593P)2 + 0.5089P] where P = (Fo2 + 2Fc2)/3
807 reflections(Δ/σ)max < 0.001
102 parametersΔρmax = 0.18 e Å3
1 restraintΔρmin = −0.18 e Å3
47 constraints

Special details

Experimental. The temperature was set with accuracy ±2 K.
Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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.

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

xyzUiso*/UeqOcc. (<1)
C10.8848 (2)0.09201 (10)0.1159 (3)0.0154 (5)
C20.7950 (2)0.14289 (11)0.1743 (3)0.0179 (5)
H20.72730.13030.25550.021*
C30.8041 (2)0.21256 (11)0.1138 (3)0.0189 (5)
H30.74070.24690.15160.023*
C40.9044 (2)0.23234 (10)−0.0007 (3)0.0179 (5)
C50.9937 (2)0.18036 (11)−0.0609 (3)0.0183 (5)
H51.06280.1932−0.13980.022*
C60.9825 (2)0.11024 (11)−0.0067 (3)0.0161 (5)
C71.00000.0000−0.1714 (4)0.0185 (7)
H7A0.93370.0235−0.24790.022*0.50
H7B1.0663−0.0235−0.24790.022*0.50
C80.8318 (2)−0.03101 (10)0.0540 (3)0.0173 (5)
H8A0.7966−0.07280.11730.021*
H8B0.7556−0.0095−0.00930.021*
C91.00000.00000.2796 (4)0.0157 (7)
H9A0.9756−0.04020.35620.019*0.50
H9B1.02440.04020.35620.019*0.50
C100.9187 (2)0.30907 (11)−0.0569 (3)0.0229 (5)
H10A0.83080.3322−0.05380.034*
H10B0.95450.3109−0.17540.034*
H10C0.98000.33370.02210.034*
N11.07122 (18)0.05643 (9)−0.0750 (2)0.0177 (4)
N20.87874 (17)0.02065 (8)0.1833 (2)0.0155 (4)

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
C10.0184 (10)0.0147 (9)0.0131 (10)−0.0011 (7)−0.0031 (9)0.0001 (9)
C20.0181 (10)0.0192 (10)0.0163 (11)−0.0007 (8)−0.0019 (9)−0.0009 (9)
C30.0212 (10)0.0174 (9)0.0179 (11)0.0028 (8)−0.0042 (9)−0.0003 (9)
C40.0235 (11)0.0157 (10)0.0146 (10)0.0019 (8)−0.0050 (10)−0.0007 (8)
C50.0228 (11)0.0176 (9)0.0145 (10)−0.0032 (8)−0.0006 (9)0.0008 (9)
C60.0177 (10)0.0171 (10)0.0136 (10)−0.0003 (8)−0.0008 (9)0.0003 (8)
C70.0250 (18)0.0191 (15)0.0115 (16)0.0031 (13)0.0000.000
C80.0171 (10)0.0164 (9)0.0185 (11)−0.0012 (8)−0.0021 (9)−0.0029 (9)
C90.0235 (18)0.0126 (14)0.0110 (17)−0.0001 (12)0.0000.000
C100.0295 (12)0.0169 (10)0.0223 (12)0.0004 (9)0.0031 (10)0.0023 (9)
N10.0213 (9)0.0153 (8)0.0166 (10)0.0011 (7)0.0018 (8)0.0010 (7)
N20.0192 (9)0.0127 (8)0.0147 (9)0.0002 (7)−0.0005 (8)0.0001 (7)

Geometric parameters (Å, °)

C1—C21.386 (3)C7—H7A0.9900
C1—C61.399 (3)C7—H7B0.9900
C1—N21.442 (3)C8—N1i1.467 (3)
C2—C31.395 (3)C8—N21.468 (3)
C2—H20.9500C8—H8A0.9900
C3—C41.385 (3)C8—H8B0.9900
C3—H30.9500C9—N21.471 (2)
C4—C51.403 (3)C9—N2i1.471 (2)
C4—C101.515 (3)C9—H9A0.9900
C5—C61.390 (3)C9—H9B0.9900
C5—H50.9500C10—H10A0.9800
C6—N11.445 (3)C10—H10B0.9800
C7—N1i1.478 (2)C10—H10C0.9800
C7—N11.478 (2)N1—C8i1.467 (3)
C2—C1—C6119.92 (19)N1i—C8—N2117.66 (16)
C2—C1—N2120.06 (19)N1i—C8—H8A107.9
C6—C1—N2120.01 (18)N2—C8—H8A107.9
C1—C2—C3120.0 (2)N1i—C8—H8B107.9
C1—C2—H2120.0N2—C8—H8B107.9
C3—C2—H2120.0H8A—C8—H8B107.2
C4—C3—C2120.8 (2)N2—C9—N2i119.5 (3)
C4—C3—H3119.6N2—C9—H9A107.4
C2—C3—H3119.6N2i—C9—H9A107.4
C3—C4—C5118.80 (19)N2—C9—H9B107.4
C3—C4—C10120.40 (19)N2i—C9—H9B107.4
C5—C4—C10120.8 (2)H9A—C9—H9B107.0
C6—C5—C4120.8 (2)C4—C10—H10A109.5
C6—C5—H5119.6C4—C10—H10B109.5
C4—C5—H5119.6H10A—C10—H10B109.5
C5—C6—C1119.49 (19)C4—C10—H10C109.5
C5—C6—N1120.5 (2)H10A—C10—H10C109.5
C1—C6—N1120.00 (18)H10B—C10—H10C109.5
N1i—C7—N1119.8 (3)C6—N1—C8i112.77 (17)
N1i—C7—H7A107.4C6—N1—C7113.10 (15)
N1—C7—H7A107.4C8i—N1—C7114.98 (15)
N1i—C7—H7B107.4C1—N2—C8112.79 (17)
N1—C7—H7B107.4C1—N2—C9113.17 (14)
H7A—C7—H7B106.9C8—N2—C9115.38 (15)
C6—C1—C2—C3−1.4 (3)C1—C6—N1—C8i−70.2 (2)
N2—C1—C2—C3177.63 (19)C5—C6—N1—C7−118.0 (2)
C1—C2—C3—C4−1.9 (3)C1—C6—N1—C762.4 (3)
C2—C3—C4—C52.7 (3)N1i—C7—N1—C6−77.89 (15)
C2—C3—C4—C10−176.2 (2)N1i—C7—N1—C8i53.62 (14)
C3—C4—C5—C6−0.2 (3)C2—C1—N2—C8110.4 (2)
C10—C4—C5—C6178.7 (2)C6—C1—N2—C8−70.6 (2)
C4—C5—C6—C1−3.1 (3)C2—C1—N2—C9−116.4 (2)
C4—C5—C6—N1177.34 (19)C6—C1—N2—C962.7 (3)
C2—C1—C6—C53.9 (3)N1i—C8—N2—C179.7 (2)
N2—C1—C6—C5−175.2 (2)N1i—C8—N2—C9−52.5 (3)
C2—C1—C6—N1−176.53 (19)N2i—C9—N2—C1−78.27 (15)
N2—C1—C6—N14.4 (3)N2i—C9—N2—C853.75 (14)
C5—C6—N1—C8i109.4 (2)

Symmetry codes: (i) −x+2, −y, z.

Table 1 Geometry of C—H··· Cg interactions (Å,°).

Cg denotes the centroid of the benzene ring (C1//C2//C3//C4//C5//C6).

ContactC–HC···CgH···CgC—H···Cg
C2–H2···Cgi0.953.509 (2)2.68147
C10–H10B···Cgii0.983.559 (2)2.61163

Symmetry codes: (i) 3/2-x,y,1/2+z; (ii) 2-x,1/2-y,-1/2+z.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: FB2167).

References

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