1,1′-[(2,3,3a,4,5,6,7,7a-Octa­hydro-1H-1,3-benzimidazole-1,3-di­yl)bis­(methyl­ene)]bis­(1H-benzotriazole)

Rivera, A.; Pacheco, D.J.; Ríos-Motta, J.; Pojarová, M.; Dušek, M.

doi:10.1107/S160053681104044X

1,1'-[(2,3,3a,4,5,6,7,7a-Octahydro-1H-1,3-benzimidazole-1,3-diyl)bis(methylene)]bis(1H-benzotriazole)

A. Rivera, D. J. Pacheco, J. Ríos-Motta, M. Pojarová and M. Dusek

The cyclohexane ring in the title compound, C₂₁H₂₄N₈, adopts a chair conformation and the five-membered heterocyclic ring to which it is fused adopts a twist conformation on their common C-C bond. The substituents on the N atoms of the central five-membered heterocycle are arranged trans with respect to the central ring. The terminal benzotriazole rings are oriented at angles of 74.66 (8) and 84.18 (8)° with respect to the mean plane of the central heterocycle. The angle between the two benzotriazole rings is 30.80 (9)°. The bond lengths and angles are within normal ranges; the largest deviation from expectation is for a long N-CH₂ bond length [1.476 (2) Å] as a consequence of an anomeric effect. In the crystal, molecules are connected by C-H

N hydrogen bonds.

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Supporting information

	Crystallographic Information File (CIF) https://doi.org/10.1107/S160053681104044X/bh2381sup1.cif Contains datablocks I, global
	Structure factor file (CIF format) https://doi.org/10.1107/S160053681104044X/bh2381Isup2.hkl Contains datablock I
	Chemical Markup Language (CML) file https://doi.org/10.1107/S160053681104044X/bh2381Isup3.cml Supplementary material

CCDC reference: 852288

checkCIF report

Key indicators

Single-crystal X-ray study
T = 120 K
Mean (C-C) = 0.002 Å
R factor = 0.052
wR factor = 0.137
Data-to-parameter ratio = 13.2

checkCIF/PLATON results

No syntax errors found



Alert level C
RINTA01_ALERT_3_C  The value of Rint is greater than 0.12
            Rint given   0.172
PLAT911_ALERT_3_C Missing # FCF Refl Between THmin & STh/L=  0.598         12

Alert level G
PLAT005_ALERT_5_G No _iucr_refine_instructions_details in CIF ....          ?
PLAT195_ALERT_1_G Missing _cell_measurement_theta_max   datum ....          ?
PLAT793_ALERT_4_G The Model has Chirality at C9      (Verify) ....          R
PLAT793_ALERT_4_G The Model has Chirality at C14     (Verify) ....          R
PLAT909_ALERT_3_G Percentage of Observed Data at Theta(Max) still          75 Perc.

   0 ALERT level A = Most likely a serious problem - resolve or explain
   0 ALERT level B = A potentially serious problem, consider carefully
   2 ALERT level C = Check. Ensure it is not caused by an omission or oversight
   5 ALERT level G = General information/check it is not something unexpected

   1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   3 ALERT type 3 Indicator that the structure quality may be low
   2 ALERT type 4 Improvement, methodology, query or suggestion
   1 ALERT type 5 Informative message, check

Comment top

Among the most thoroughly studied stereoelectronic effects, the interactions between lone pairs have attracted much interest. These interactions between a non bonded electron pair and antibonding σ* sigma bonds usually play a feature role in the preferred conformations of such systems (Carey & Sundberg, 2000). The data of the crystal structure of the title compound indicate the occurrence of a n(N)→σ^*(C—N) electron delocalization, characteristic of the anomeric effect, as evidenced by the lengthened bond N6—C15 [1.476 (2) Å], shortened bond C15—N5 [1.433 (2)] and distorted C—N—C bond angles, C8—N5—C14 = 106.11 (13)°, C8—N5—C15 = 115.53 (13)°, and C14—N5—C15 = 118.03 (14)°. These results exhibit the same pattern of C—N shortened bond lengths that the crystal structure of 1,3-bis[(1H-benzotriazol-1-yl)methyl]-2,3-dihydro-1H-benzimidazole recently reported (Rivera et al., 2011). The structural parameters suggest an increase in p-character of nitrogen and reduction in N-pyramidality. The title compound was obtained by the reaction of racemic cyclic aminal (2R,7R,11S,16S)-1,8,10,17-tetraazapentacyclo-[8.8.1.1^8,17.0^2,7.0^11,16]icosane with two equivalents of benzotriazole. The molecular structure and atom-numbering scheme are shown in Fig. 1. The asymmetric unit comprises of one molecule of the title compound (Fig 1). The bond lengths (Allen et al., 1987) and angles are generally within normal ranges (Wang et al., 2008).

The cyclohexane ring adopts a chair conformation and the five-membered ring to which it is fused adopts a twist conformation on C9—C14 with Q(2) = 0.455 (2) Å and ϕ = 311.1 (2)° (Cremer & Pople, 1975) and a trans disubstitution. The benzotriazole rings (N1—N3/C1—C6; N6—N8/C16—C21) are essentially planar with the maximum deviations from planarity being 0.0220 (19) Å for atom C3 and -0.0161 (19) for atom C18. The central heterocyclic ring makes an angle of 74.66 (8)° and 84.18 (8)° with the planar benzotriazole rings. The angle between the two benzotriazole rings is 30.80 (9)°. The two exocyclic bonds of methylene carbon atoms occupy pseudo-axial positions.

The crystal structure contains an intermolecular C7—H7B···N1 hydrogen bond between one H atom of the N—CH₂—N group (aminal group) and one N atom of the benzotriazole ring of neighboring molecule linking adjacent molecules to form a one-dimensional chain running parallel to the b axis (Fig. 2), and further linked by weak C15—H15B···N intermolecular interactions. The distance of 3.4502 (9) Å between the centroids of the rings N1/N2/N3/C6/C1 related by the symmetry code (-x, 2 - y, -z) suggests a possible π–π interaction in the crystal.

Related literature top

For general background to anomeric effects, see: Carey & Sundberg (2000). For related structures see: Rivera et al. (2011); Wang et al. (2008). For ring conformations, see: Cremer & Pople (1975). For standard bond lengths, see: Allen et al. (1987).

Experimental top

A solution of (2R,7R,11S,16S)-1,8,10,17-tetraazapentacyclo-[8.8.1.1^8,17.0^2,7.0^11,16]icosane (276 mg, 1.00 mmol) in dioxane (3 ml) and water (4 ml), previously prepared following described procedures, was added dropwise in a dioxane solution (3 ml) containing two equivalents of benzotriazole (238 mg, 2.00 mmol) in a two-necked round-bottomed flask. The mixture was stirred for about 6 h. and then the solvent was evaporated under reduced pressure until a sticky residue appeared. The product was purified by chromatography on a silica column, and subjected to gradient elution with benzene:ethyl acetate (yield 75%, m.p. = 424–425 K). Single crystals of the racemic title compound were grown from a chloroform solution by slow evaporation of the solvent at room temperature over a period of about 2 weeks.

Computing details top

Data collection: CrysAlis PRO (Oxford Diffraction, 2010); cell refinement: CrysAlis PRO (Oxford Diffraction, 2010); data reduction: CrysAlis PRO (Oxford Diffraction, 2010); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg & Putz, 2005); software used to prepare material for publication: publCIF (Westrip, 2010).

Figures top

	Fig. 1. A view of the title compound, with displacement ellipsoids drawn at the 50% probability level.
	Fig. 2. Crystal packing of the title compound viewed along b axis.

1,1'-[(2,3,3a,4,5,6,7,7a-Octahydro-1H-1,3-benzimidazole-1,3- diyl)bis(methylene)]bis(1H-benzotriazole) top

Crystal data top

C₂₁H₂₄N₈	F(000) = 824
M_r = 388.48	D_x = 1.328 Mg m⁻³
Monoclinic, P2₁/c	Melting point: 424 K
Hall symbol: -P 2ybc	Cu Kα radiation, λ = 1.5418 Å
a = 11.9474 (2) Å	Cell parameters from 13493 reflections
b = 5.9406 (1) Å	θ = 3.2°
c = 27.3861 (4) Å	µ = 0.68 mm⁻¹
β = 90.861 (1)°	T = 120 K
V = 1943.50 (5) Å³	Plate, colourless
Z = 4	0.31 × 0.18 × 0.11 mm

Data collection top

Oxford Diffraction Xcalibur Atlas Gemini ultra diffractometer	2990 reflections with I > 2σ(I)
Radiation source: Enhance Ultra (Cu) X-ray Source	R_int = 0.172
Mirror monochromator	θ_max = 67.1°, θ_min = 3.2°
Detector resolution: 10.3784 pixels mm^-1	h = −14→14
Rotation method data acquisition using ω scans	k = −7→7
37999 measured reflections	l = −32→32
3461 independent reflections

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.052	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.137	H-atom parameters constrained
S = 1.06	w = 1/[σ²(F_o²) + (0.0756P)² + 0.4705P] where P = (F_o² + 2F_c²)/3
3461 reflections	(Δ/σ)_max < 0.001
262 parameters	Δρ_max = 0.23 e Å⁻³
0 restraints	Δρ_min = −0.31 e Å⁻³
0 constraints

Crystal data top

C₂₁H₂₄N₈	V = 1943.50 (5) Å³
M_r = 388.48	Z = 4
Monoclinic, P2₁/c	Cu Kα radiation
a = 11.9474 (2) Å	µ = 0.68 mm⁻¹
b = 5.9406 (1) Å	T = 120 K
c = 27.3861 (4) Å	0.31 × 0.18 × 0.11 mm
β = 90.861 (1)°

Data collection top

Oxford Diffraction Xcalibur Atlas Gemini ultra diffractometer	2990 reflections with I > 2σ(I)
37999 measured reflections	R_int = 0.172
3461 independent reflections

Refinement top

R[F² > 2σ(F²)] = 0.052	0 restraints
wR(F²) = 0.137	H-atom parameters constrained
S = 1.06	Δρ_max = 0.23 e Å⁻³
3461 reflections	Δρ_min = −0.31 e Å⁻³
262 parameters

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

	x	y	z	U_iso*/U_eq
N1	0.06576 (12)	1.3038 (2)	0.03014 (5)	0.0301 (4)
N2	0.06561 (12)	1.1599 (2)	0.06570 (5)	0.0298 (3)
N3	0.12624 (11)	0.9755 (2)	0.05292 (5)	0.0256 (3)
N4	0.21777 (12)	0.7711 (2)	0.12114 (5)	0.0277 (3)
N5	0.34776 (11)	0.9703 (2)	0.16832 (5)	0.0250 (3)
N6	0.31150 (11)	0.9133 (2)	0.25550 (5)	0.0240 (3)
N7	0.34948 (11)	0.7097 (3)	0.27089 (5)	0.0296 (4)
N8	0.27753 (12)	0.6222 (3)	0.30094 (5)	0.0302 (3)
C1	0.12747 (13)	1.2136 (3)	−0.00732 (6)	0.0249 (4)
C2	0.14940 (14)	1.3000 (3)	−0.05407 (6)	0.0293 (4)
H2	0.1233	1.4406	−0.0639	0.035*
C3	0.21134 (15)	1.1660 (3)	−0.08439 (7)	0.0332 (4)
H3	0.2266	1.2157	−0.1158	0.040*
C4	0.25227 (15)	0.9548 (3)	−0.06892 (7)	0.0334 (4)
H4	0.2949	0.8705	−0.0904	0.040*
C5	0.23166 (14)	0.8690 (3)	−0.02351 (7)	0.0299 (4)
H5	0.2591	0.7296	−0.0136	0.036*
C6	0.16690 (13)	1.0034 (3)	0.00695 (6)	0.0239 (4)
C7	0.12758 (14)	0.7809 (3)	0.08616 (7)	0.0288 (4)
H7A	0.0577	0.7797	0.1038	0.035*
H7B	0.1296	0.6450	0.0666	0.035*
C8	0.22853 (13)	0.9669 (3)	0.15340 (6)	0.0270 (4)
H8A	0.1810	0.9509	0.1816	0.032*
H8B	0.2083	1.1041	0.1362	0.032*
C9	0.33087 (14)	0.7201 (3)	0.10497 (6)	0.0265 (4)
H9	0.3541	0.8339	0.0813	0.032*
C10	0.35246 (16)	0.4874 (3)	0.08427 (7)	0.0350 (4)
H10A	0.3126	0.4691	0.0534	0.042*
H10B	0.3265	0.3730	0.1067	0.042*
C11	0.47850 (16)	0.4632 (3)	0.07680 (8)	0.0391 (5)
H11A	0.5017	0.5670	0.0515	0.047*
H11B	0.4945	0.3117	0.0657	0.047*
C12	0.54586 (16)	0.5107 (3)	0.12368 (8)	0.0391 (5)
H12A	0.6251	0.5020	0.1167	0.047*
H12B	0.5292	0.3956	0.1476	0.047*
C13	0.51985 (14)	0.7429 (3)	0.14530 (7)	0.0338 (4)
H13A	0.5590	0.7621	0.1763	0.041*
H13B	0.5437	0.8607	0.1233	0.041*
C14	0.39463 (14)	0.7551 (3)	0.15242 (6)	0.0265 (4)
H14	0.3728	0.6377	0.1755	0.032*
C15	0.37030 (13)	1.0415 (3)	0.21750 (6)	0.0270 (4)
H15A	0.3498	1.1989	0.2204	0.032*
H15B	0.4502	1.0302	0.2238	0.032*
C16	0.21029 (13)	0.9579 (3)	0.27606 (6)	0.0235 (4)
C17	0.13513 (14)	1.1384 (3)	0.27189 (6)	0.0284 (4)
H17	0.1497	1.2636	0.2526	0.034*
C18	0.03858 (15)	1.1180 (3)	0.29813 (7)	0.0333 (4)
H18	−0.0144	1.2324	0.2960	0.040*
C19	0.01666 (14)	0.9313 (3)	0.32806 (6)	0.0313 (4)
H19	−0.0497	0.9267	0.3454	0.038*
C20	0.09064 (14)	0.7563 (3)	0.33234 (6)	0.0297 (4)
H20	0.0762	0.6333	0.3523	0.036*
C21	0.18967 (14)	0.7708 (3)	0.30514 (6)	0.0255 (4)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
N1	0.0331 (8)	0.0264 (8)	0.0309 (8)	0.0061 (6)	−0.0009 (6)	−0.0036 (6)
N2	0.0288 (7)	0.0288 (8)	0.0320 (8)	0.0062 (6)	0.0007 (6)	−0.0046 (6)
N3	0.0240 (7)	0.0252 (7)	0.0275 (8)	0.0008 (5)	0.0001 (6)	−0.0031 (6)
N4	0.0231 (7)	0.0284 (8)	0.0316 (8)	−0.0020 (5)	−0.0018 (6)	0.0023 (6)
N5	0.0199 (7)	0.0294 (8)	0.0258 (8)	−0.0033 (5)	0.0033 (5)	0.0013 (6)
N6	0.0203 (6)	0.0282 (7)	0.0233 (7)	−0.0007 (5)	0.0004 (5)	0.0026 (5)
N7	0.0238 (7)	0.0329 (8)	0.0320 (8)	0.0046 (6)	0.0004 (6)	0.0050 (6)
N8	0.0263 (7)	0.0314 (8)	0.0329 (8)	0.0032 (6)	0.0028 (6)	0.0057 (6)
C1	0.0228 (8)	0.0221 (8)	0.0298 (9)	−0.0012 (6)	−0.0019 (6)	−0.0047 (6)
C2	0.0281 (8)	0.0257 (9)	0.0338 (10)	−0.0039 (7)	−0.0051 (7)	0.0021 (7)
C3	0.0281 (9)	0.0409 (10)	0.0308 (9)	−0.0068 (7)	0.0025 (7)	0.0020 (8)
C4	0.0283 (9)	0.0375 (10)	0.0345 (10)	0.0027 (7)	0.0063 (7)	−0.0074 (8)
C5	0.0267 (8)	0.0271 (9)	0.0361 (10)	0.0033 (7)	0.0018 (7)	−0.0047 (7)
C6	0.0204 (7)	0.0258 (8)	0.0255 (9)	−0.0025 (6)	−0.0025 (6)	−0.0034 (6)
C7	0.0256 (8)	0.0261 (9)	0.0345 (10)	−0.0034 (6)	−0.0024 (7)	0.0021 (7)
C8	0.0218 (8)	0.0345 (9)	0.0247 (9)	−0.0010 (7)	0.0016 (6)	0.0004 (7)
C9	0.0249 (8)	0.0247 (9)	0.0299 (9)	−0.0019 (6)	0.0020 (7)	0.0035 (7)
C10	0.0373 (10)	0.0263 (9)	0.0412 (11)	0.0003 (7)	−0.0049 (8)	−0.0014 (8)
C11	0.0403 (11)	0.0298 (10)	0.0473 (12)	0.0066 (8)	0.0055 (9)	−0.0036 (8)
C12	0.0282 (9)	0.0362 (11)	0.0530 (13)	0.0040 (8)	0.0008 (8)	0.0004 (9)
C13	0.0230 (9)	0.0353 (10)	0.0431 (11)	−0.0004 (7)	0.0007 (7)	0.0002 (8)
C14	0.0236 (8)	0.0259 (9)	0.0299 (9)	−0.0024 (6)	0.0028 (7)	0.0046 (7)
C15	0.0223 (8)	0.0304 (9)	0.0283 (9)	−0.0073 (6)	0.0021 (6)	0.0022 (7)
C16	0.0204 (8)	0.0276 (9)	0.0225 (8)	−0.0011 (6)	−0.0003 (6)	−0.0027 (6)
C17	0.0319 (9)	0.0243 (9)	0.0291 (9)	0.0023 (7)	0.0012 (7)	−0.0005 (7)
C18	0.0324 (9)	0.0346 (10)	0.0330 (10)	0.0088 (7)	0.0013 (7)	−0.0074 (7)
C19	0.0252 (8)	0.0393 (10)	0.0297 (10)	−0.0011 (7)	0.0067 (7)	−0.0085 (7)
C20	0.0284 (9)	0.0333 (10)	0.0274 (9)	−0.0055 (7)	0.0037 (7)	0.0010 (7)
C21	0.0247 (8)	0.0268 (9)	0.0250 (9)	0.0005 (6)	0.0006 (6)	0.0004 (6)

Geometric parameters (Å, º) top

N1—N2	1.296 (2)	C8—H8B	0.9700
N1—C1	1.380 (2)	C9—C14	1.511 (2)
N2—N3	1.3619 (19)	C9—C10	1.517 (2)
N3—C6	1.366 (2)	C9—H9	0.9800
N3—C7	1.471 (2)	C10—C11	1.529 (3)
N4—C7	1.432 (2)	C10—H10A	0.9700
N4—C9	1.460 (2)	C10—H10B	0.9700
N4—C8	1.465 (2)	C11—C12	1.531 (3)
N5—C15	1.433 (2)	C11—H11A	0.9700
N5—C14	1.464 (2)	C11—H11B	0.9700
N5—C8	1.476 (2)	C12—C13	1.535 (3)
N6—N7	1.357 (2)	C12—H12A	0.9700
N6—C16	1.367 (2)	C12—H12B	0.9700
N6—C15	1.476 (2)	C13—C14	1.513 (2)
N7—N8	1.307 (2)	C13—H13A	0.9700
N8—C21	1.378 (2)	C13—H13B	0.9700
C1—C6	1.389 (2)	C14—H14	0.9800
C1—C2	1.408 (2)	C15—H15A	0.9700
C2—C3	1.375 (3)	C15—H15B	0.9700
C2—H2	0.9300	C16—C21	1.391 (2)
C3—C4	1.409 (3)	C16—C17	1.402 (2)
C3—H3	0.9300	C17—C18	1.374 (2)
C4—C5	1.370 (3)	C17—H17	0.9300
C4—H4	0.9300	C18—C19	1.406 (3)
C5—C6	1.397 (2)	C18—H18	0.9300
C5—H5	0.9300	C19—C20	1.369 (3)
C7—H7A	0.9700	C19—H19	0.9300
C7—H7B	0.9700	C20—C21	1.410 (2)
C8—H8A	0.9700	C20—H20	0.9300

N2—N1—C1	108.00 (14)	C9—C10—H10A	110.1
N1—N2—N3	109.32 (13)	C11—C10—H10A	110.1
N2—N3—C6	109.70 (13)	C9—C10—H10B	110.1
N2—N3—C7	118.30 (13)	C11—C10—H10B	110.1
C6—N3—C7	131.64 (14)	H10A—C10—H10B	108.4
C7—N4—C9	119.73 (14)	C10—C11—C12	112.13 (16)
C7—N4—C8	115.44 (13)	C10—C11—H11A	109.2
C9—N4—C8	105.94 (13)	C12—C11—H11A	109.2
C15—N5—C14	118.03 (14)	C10—C11—H11B	109.2
C15—N5—C8	115.53 (13)	C12—C11—H11B	109.2
C14—N5—C8	106.11 (13)	H11A—C11—H11B	107.9
N7—N6—C16	109.79 (13)	C11—C12—C13	112.45 (16)
N7—N6—C15	121.24 (13)	C11—C12—H12A	109.1
C16—N6—C15	128.57 (14)	C13—C12—H12A	109.1
N8—N7—N6	109.28 (13)	C11—C12—H12B	109.1
N7—N8—C21	107.87 (14)	C13—C12—H12B	109.1
N1—C1—C6	108.83 (15)	H12A—C12—H12B	107.8
N1—C1—C2	130.01 (16)	C14—C13—C12	107.41 (14)
C6—C1—C2	121.12 (16)	C14—C13—H13A	110.2
C3—C2—C1	116.57 (16)	C12—C13—H13A	110.2
C3—C2—H2	121.7	C14—C13—H13B	110.2
C1—C2—H2	121.7	C12—C13—H13B	110.2
C2—C3—C4	121.44 (17)	H13A—C13—H13B	108.5
C2—C3—H3	119.3	N5—C14—C9	100.73 (13)
C4—C3—H3	119.3	N5—C14—C13	117.62 (14)
C5—C4—C3	122.54 (17)	C9—C14—C13	111.67 (14)
C5—C4—H4	118.7	N5—C14—H14	108.8
C3—C4—H4	118.7	C9—C14—H14	108.8
C4—C5—C6	115.99 (16)	C13—C14—H14	108.8
C4—C5—H5	122.0	N5—C15—N6	115.18 (13)
C6—C5—H5	122.0	N5—C15—H15A	108.5
N3—C6—C1	104.14 (14)	N6—C15—H15A	108.5
N3—C6—C5	133.54 (16)	N5—C15—H15B	108.5
C1—C6—C5	122.31 (16)	N6—C15—H15B	108.5
N4—C7—N3	116.54 (13)	H15A—C15—H15B	107.5
N4—C7—H7A	108.2	N6—C16—C21	104.25 (14)
N3—C7—H7A	108.2	N6—C16—C17	133.15 (15)
N4—C7—H7B	108.2	C21—C16—C17	122.59 (15)
N3—C7—H7B	108.2	C18—C17—C16	115.60 (16)
H7A—C7—H7B	107.3	C18—C17—H17	122.2
N4—C8—N5	104.68 (13)	C16—C17—H17	122.2
N4—C8—H8A	110.8	C17—C18—C19	122.65 (16)
N5—C8—H8A	110.8	C17—C18—H18	118.7
N4—C8—H8B	110.8	C19—C18—H18	118.7
N5—C8—H8B	110.8	C20—C19—C18	121.58 (16)
H8A—C8—H8B	108.9	C20—C19—H19	119.2
N4—C9—C14	99.64 (13)	C18—C19—H19	119.2
N4—C9—C10	117.77 (14)	C19—C20—C21	117.01 (16)
C14—C9—C10	111.14 (14)	C19—C20—H20	121.5
N4—C9—H9	109.3	C21—C20—H20	121.5
C14—C9—H9	109.3	N8—C21—C16	108.80 (14)
C10—C9—H9	109.3	N8—C21—C20	130.64 (16)
C9—C10—C11	107.98 (15)	C16—C21—C20	120.56 (15)

N3—C7—N4—C8	56.8 (4)	C8—N5—C15—N6	55.5 (4)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C8—H8a···N6	0.97	2.55	2.970 (2)	106
C8—H8b···N3	0.97	2.58	2.995 (2)	106
C7—H7b···N1ⁱ	0.97	2.38	3.301 (2)	159
C15—H15b···N7ⁱⁱ	0.97	2.62	3.504 (2)	151

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

Experimental details

Crystal data
Chemical formula	C₂₁H₂₄N₈
M_r	388.48
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	120
a, b, c (Å)	11.9474 (2), 5.9406 (1), 27.3861 (4)
β (°)	90.861 (1)
V (Å³)	1943.50 (5)
Z	4
Radiation type	Cu Kα
µ (mm⁻¹)	0.68
Crystal size (mm)	0.31 × 0.18 × 0.11

Data collection
Diffractometer	Oxford Diffraction Xcalibur Atlas Gemini ultra diffractometer
Absorption correction	–
No. of measured, independent and observed [I > 2σ(I)] reflections	37999, 3461, 2990
R_int	0.172
(sin θ/λ)_max (Å⁻¹)	0.598

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.052, 0.137, 1.06
No. of reflections	3461
No. of parameters	262
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.23, −0.31

Computer programs: CrysAlis PRO (Oxford Diffraction, 2010), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), DIAMOND (Brandenburg & Putz, 2005), publCIF (Westrip, 2010).