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Acta Crystallogr Sect E Struct Rep Online. 2010 May 1; 66(Pt 5): o1093.
Published online 2010 April 17. doi:  10.1107/S1600536810013498
PMCID: PMC2979075

3,4-Dimethyl-1H-1,2,4-triazepino[2,3-a]benzimidazol-2(3H)-one

Abstract

In the mol­ecule of the title compound, C12H12N4O, a C atom and an N atom of the benzimidazole fused-ring portion are part of a seven-membered ring; this ring adopts a boat-shaped conformation (with the fused-ring atoms representing the stern and the sp 3-hybridized C atom the prow). The amino group is a hydrogen-bond donor to the imidazole group of an inversion-related mol­ecule, the pair of N—H(...)N hydrogen bonds giving rise to a hydrogen-bonded dimer.

Related literature

For the synthesis, see: Romano et al. (1988 [triangle]).

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Object name is e-66-o1093-scheme1.jpg

Experimental

Crystal data

  • C12H12N4O
  • M r = 228.26
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-66-o1093-efi1.jpg
  • a = 7.2899 (3) Å
  • b = 14.4888 (5) Å
  • c = 10.9932 (4) Å
  • β = 104.314 (1)°
  • V = 1125.08 (7) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 0.09 mm−1
  • T = 293 K
  • 0.21 × 0.19 × 0.16 mm

Data collection

  • Bruker X8 APEXII diffractometer
  • 14670 measured reflections
  • 3095 independent reflections
  • 1823 reflections with I > 2σ(I)
  • R int = 0.034

Refinement

  • R[F 2 > 2σ(F 2)] = 0.049
  • wR(F 2) = 0.157
  • S = 1.01
  • 3095 reflections
  • 160 parameters
  • 1 restraint
  • H atoms treated by a mixture of independent and constrained refinement
  • Δρmax = 0.24 e Å−3
  • Δρmin = −0.19 e Å−3

Data collection: APEX2 (Bruker, 2008 [triangle]); cell refinement: SAINT (Bruker, 2008 [triangle]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: X-SEED (Barbour, 2001 [triangle]); software used to prepare material for publication: publCIF (Westrip, 2010 [triangle]).

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810013498/si2255sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810013498/si2255Isup2.hkl

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

Acknowledgments

We thank Université Mohammed V-Agdal and the University of Malaya for supporting this study.

supplementary crystallographic information

Comment

1,2-Diaminobenzimidazoles react with β-dicarbonyl compounds to form 1,2,4-triazepino[2,3-a]benzimidazoles (Romano et al., 1988), a class of compounds used in the treatment of neuronal disorders. The title compound (Scheme I, Fig. 1) was synthesized from 2-aminobenzimidazole and ethyl 2-methylacetoacetate. A carbon atom and a nitrogen atom of the benzimidazole fused-ring portion are part of a seven-membered ring; this ring adopts a boat-shaped conformation (with the fused-ring atoms representing the stern and the sp3-hybridized carbon atom the prow). Its methyl substitent occupies a quasi-equatorial position. The amino group is hydrogen-bond donor to the imidazole group (Table 1) of an inversion-related molecule, the pair of N—H···N hydrogen bonds (Fig. 1) giving rise to a hydrogen-bonded dimer.

Experimental

2-Aminobenzimidazole (1 g, 6.75 mmol) and a slight excess of ethyl 2-methylacetoacetate (1.69 ml) were refluxed in xylene (10 ml) and acetic acid (0.5 ml) for 3 hours. The mixture was concentrated under reduced pressure and the resulting residue was recrystallized from ethanol. Brown crystals were isolated when the solvent was allowed to evaporate.

Refinement

Carbon-bound H-atoms were placed in calculated positions (C—H 0.93–0.98 Å) and were included in the refinement in the riding model approximation, with Uiso(H) set to 1.2Ueq(C). The amino H-atom was located in a difference Fourier map, and was refined with a distance restraint of N–H 0.86 (1) Å.

Figures

Fig. 1.
Thermal ellipsoid plot (Barbour, 2001) of the hydrogen-bonded dimeric structure of C12H12N4O at the 50% probability level; hydrogen atoms are drawn as arbitrary radius. Symmetry code for the inversion related molecule: 1 - x, 1 - y, 1 - z.

Crystal data

C12H12N4OF(000) = 480
Mr = 228.26Dx = 1.348 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 3188 reflections
a = 7.2899 (3) Åθ = 2.4–24.8°
b = 14.4888 (5) ŵ = 0.09 mm1
c = 10.9932 (4) ÅT = 293 K
β = 104.314 (1)°Prism, brown
V = 1125.08 (7) Å30.21 × 0.19 × 0.16 mm
Z = 4

Data collection

Bruker X8 APEXII diffractometer1823 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.034
graphiteθmax = 29.4°, θmin = 2.4°
[var phi] and ω scansh = −9→10
14670 measured reflectionsk = −20→19
3095 independent reflectionsl = −15→13

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)] = 0.049Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.157H atoms treated by a mixture of independent and constrained refinement
S = 1.01w = 1/[σ2(Fo2) + (0.0742P)2 + 0.1838P] where P = (Fo2 + 2Fc2)/3
3095 reflections(Δ/σ)max < 0.001
160 parametersΔρmax = 0.24 e Å3
1 restraintΔρmin = −0.19 e Å3

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

xyzUiso*/Ueq
O10.40956 (19)0.51793 (12)0.14398 (13)0.0762 (5)
N10.5626 (2)0.53766 (12)0.34574 (15)0.0574 (4)
H10.486 (3)0.5002 (13)0.3696 (19)0.075 (7)*
N20.95622 (19)0.59291 (9)0.32932 (14)0.0508 (4)
N30.86966 (19)0.60627 (9)0.42759 (13)0.0475 (4)
N40.6799 (2)0.58224 (10)0.55706 (13)0.0552 (4)
C10.6977 (2)0.57641 (11)0.44172 (16)0.0488 (4)
C20.5294 (2)0.55903 (14)0.22125 (17)0.0569 (5)
C30.6491 (2)0.63705 (13)0.18892 (16)0.0551 (5)
H30.64280.68860.24540.066*
C40.8529 (2)0.60475 (11)0.21815 (17)0.0498 (4)
C50.5699 (3)0.67076 (16)0.05638 (19)0.0797 (7)
H5A0.64720.72020.03870.120*
H5B0.44290.69260.04750.120*
H5C0.56920.6210−0.00140.120*
C60.9446 (3)0.58710 (16)0.11287 (19)0.0694 (6)
H6A1.07190.56590.14630.104*
H6B0.94660.64320.06670.104*
H6C0.87420.54090.05800.104*
C70.9748 (2)0.62947 (10)0.54769 (16)0.0486 (4)
C81.1602 (3)0.65870 (13)0.59037 (19)0.0636 (5)
H81.23990.66640.53690.076*
C91.2194 (3)0.67573 (16)0.7180 (2)0.0790 (7)
H91.34320.69500.75170.095*
C101.0993 (4)0.66492 (16)0.7969 (2)0.0780 (7)
H101.14440.67820.88190.094*
C110.9147 (3)0.63502 (14)0.75350 (18)0.0653 (5)
H110.83480.62790.80700.078*
C120.8542 (3)0.61603 (11)0.62561 (16)0.0516 (4)

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
O10.0480 (8)0.1131 (12)0.0627 (9)−0.0193 (7)0.0049 (6)−0.0313 (8)
N10.0401 (8)0.0756 (10)0.0538 (9)−0.0152 (7)0.0068 (7)−0.0171 (7)
N20.0385 (7)0.0536 (8)0.0580 (9)−0.0022 (6)0.0074 (7)−0.0016 (6)
N30.0368 (7)0.0521 (8)0.0487 (8)−0.0038 (6)0.0012 (6)−0.0036 (6)
N40.0461 (8)0.0639 (9)0.0520 (9)−0.0080 (7)0.0055 (7)−0.0121 (7)
C10.0378 (8)0.0540 (9)0.0505 (9)−0.0027 (7)0.0035 (7)−0.0103 (7)
C20.0349 (9)0.0763 (12)0.0565 (10)0.0011 (8)0.0056 (8)−0.0202 (9)
C30.0468 (10)0.0591 (10)0.0536 (10)0.0051 (8)0.0014 (8)−0.0080 (8)
C40.0404 (9)0.0497 (9)0.0563 (10)−0.0035 (7)0.0066 (8)−0.0038 (7)
C50.0758 (15)0.0797 (14)0.0688 (13)0.0114 (11)−0.0103 (11)−0.0030 (11)
C60.0578 (12)0.0891 (15)0.0640 (12)−0.0009 (10)0.0202 (10)−0.0015 (10)
C70.0439 (9)0.0417 (8)0.0517 (9)−0.0036 (7)−0.0045 (8)0.0010 (7)
C80.0482 (10)0.0662 (11)0.0657 (11)−0.0128 (8)−0.0065 (9)0.0088 (9)
C90.0628 (13)0.0825 (14)0.0724 (14)−0.0247 (11)−0.0200 (11)0.0067 (11)
C100.0816 (16)0.0786 (14)0.0575 (12)−0.0199 (11)−0.0137 (11)−0.0014 (10)
C110.0708 (13)0.0655 (11)0.0521 (10)−0.0082 (10)0.0009 (9)−0.0061 (8)
C120.0501 (10)0.0467 (9)0.0507 (9)−0.0036 (7)−0.0012 (8)−0.0047 (7)

Geometric parameters (Å, °)

O1—C21.213 (2)C5—H5B0.9600
N1—C21.365 (2)C5—H5C0.9600
N1—C11.373 (2)C6—H6A0.9600
N1—H10.864 (9)C6—H6B0.9600
N2—C41.279 (2)C6—H6C0.9600
N2—N31.393 (2)C7—C81.383 (2)
N3—C11.371 (2)C7—C121.385 (3)
N3—C71.394 (2)C8—C91.384 (3)
N4—C11.309 (2)C8—H80.9300
N4—C121.396 (2)C9—C101.386 (3)
C2—C31.523 (3)C9—H90.9300
C3—C51.510 (3)C10—C111.382 (3)
C3—C41.515 (2)C10—H100.9300
C3—H30.9800C11—C121.393 (2)
C4—C61.495 (3)C11—H110.9300
C5—H5A0.9600
C2—N1—C1126.41 (17)H5A—C5—H5C109.5
C2—N1—H1118.6 (14)H5B—C5—H5C109.5
C1—N1—H1114.7 (14)C4—C6—H6A109.5
C4—N2—N3116.74 (14)C4—C6—H6B109.5
C1—N3—N2130.27 (13)H6A—C6—H6B109.5
C1—N3—C7105.84 (14)C4—C6—H6C109.5
N2—N3—C7121.30 (14)H6A—C6—H6C109.5
C1—N4—C12104.53 (15)H6B—C6—H6C109.5
N4—C1—N3113.68 (14)C8—C7—C12123.37 (17)
N4—C1—N1123.18 (16)C8—C7—N3131.12 (19)
N3—C1—N1122.98 (16)C12—C7—N3105.50 (14)
O1—C2—N1120.60 (19)C7—C8—C9115.6 (2)
O1—C2—C3123.76 (18)C7—C8—H8122.2
N1—C2—C3115.63 (14)C9—C8—H8122.2
C5—C3—C4115.20 (18)C8—C9—C10121.89 (19)
C5—C3—C2111.16 (15)C8—C9—H9119.1
C4—C3—C2108.05 (14)C10—C9—H9119.1
C5—C3—H3107.4C11—C10—C9122.06 (19)
C4—C3—H3107.4C11—C10—H10119.0
C2—C3—H3107.4C9—C10—H10119.0
N2—C4—C6116.53 (16)C10—C11—C12116.7 (2)
N2—C4—C3124.01 (16)C10—C11—H11121.7
C6—C4—C3119.45 (16)C12—C11—H11121.7
C3—C5—H5A109.5C7—C12—C11120.37 (17)
C3—C5—H5B109.5C7—C12—N4110.36 (15)
H5A—C5—H5B109.5C11—C12—N4129.27 (19)
C3—C5—H5C109.5
C4—N2—N3—C145.3 (2)C5—C3—C4—C6−14.2 (2)
C4—N2—N3—C7−155.63 (15)C2—C3—C4—C6110.73 (19)
C12—N4—C1—N3−1.68 (19)C1—N3—C7—C8176.13 (18)
C12—N4—C1—N1173.69 (17)N2—N3—C7—C812.6 (3)
N2—N3—C1—N4164.44 (16)C1—N3—C7—C12−2.84 (17)
C7—N3—C1—N42.94 (19)N2—N3—C7—C12−166.39 (14)
N2—N3—C1—N1−10.9 (3)C12—C7—C8—C9−1.1 (3)
C7—N3—C1—N1−172.44 (16)N3—C7—C8—C9−179.90 (18)
C2—N1—C1—N4152.30 (18)C7—C8—C9—C10−0.6 (3)
C2—N1—C1—N3−32.8 (3)C8—C9—C10—C111.2 (4)
C1—N1—C2—O1177.59 (18)C9—C10—C11—C120.0 (3)
C1—N1—C2—C3−3.3 (3)C8—C7—C12—C112.3 (3)
O1—C2—C3—C513.2 (3)N3—C7—C12—C11−178.66 (16)
N1—C2—C3—C5−165.91 (17)C8—C7—C12—N4−177.09 (16)
O1—C2—C3—C4−114.2 (2)N3—C7—C12—N41.99 (18)
N1—C2—C3—C466.8 (2)C10—C11—C12—C7−1.6 (3)
N3—N2—C4—C6−177.91 (15)C10—C11—C12—N4177.58 (18)
N3—N2—C4—C33.5 (2)C1—N4—C12—C7−0.27 (19)
C5—C3—C4—N2164.30 (17)C1—N4—C12—C11−179.55 (19)
C2—C3—C4—N2−70.7 (2)

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
N1—H1···N4i0.86 (1)2.01 (1)2.867 (2)174 (2)

Symmetry codes: (i) −x+1, −y+1, −z+1.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: SI2255).

References

  • Barbour, L. J. (2001). J. Supramol. Chem.1, 189–191.
  • Bruker (2008). APEX2 and SAINT Bruker AXS Inc., Madison, Wisconsin, USA.
  • Romano, C., De la Cuesta, E., Avendano, C., Florencio, F. & Sainz-Aparicio, J. (1988). Tetrahedron, 44, 7185–7192.
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Westrip, S. P. (2010). publCIF In preparation.

Articles from Acta Crystallographica Section E: Structure Reports Online are provided here courtesy of International Union of Crystallography