Diimidazo[1,5-a;1′,5′-d]pyrazine-5,10-dione

The title compound, C₈H₄N₄O₂, was prepared to explore the synthesis of some 4-substituted imidazoles. The mol­ecule is centrosymmetric and almost planar. In the crystal structure, centrosymmetric dimers are formed via C—H...N hydrogen bonds. The dimers are linked by further C—H...N hydrogen bonds, forming a three-dimensional network.

Key indicators

• Single-crystal X-ray study
• T = 173 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.041
• wR factor = 0.104
• Data-to-parameter ratio = 6.5

checkCIF/PLATON results

No syntax errors found



Alert level A
REFLT03_ALERT_3_A  Reflection count < 85% complete (theta max?)
           From the CIF: _diffrn_reflns_theta_max           25.62
           From the CIF: _diffrn_reflns_theta_full          25.00
           From the CIF: _reflns_number_total                471
           TEST2: Reflns within _diffrn_reflns_theta_max
           Count of symmetry unique reflns          691
           Completeness (_total/calc)             68.16%

Author Response: ...see _publ_section_exptl_refinement

PLAT022_ALERT_3_A Ratio Unique / Expected Reflections too Low ....       0.68

Author Response: ...see _publ_section_exptl_refinement

PLAT028_ALERT_3_A _diffrn_measured_fraction_theta_max  Low .......       0.68

Author Response: ...see _publ_section_exptl_refinement

Alert level B
PLAT088_ALERT_3_B Poor Data / Parameter Ratio ....................       6.45

   3 ALERT level A = In general: serious problem
   1 ALERT level B = Potentially serious problem
   0 ALERT level C = Check and explain
   0 ALERT level G = General alerts; check

   0 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
   4 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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Computing details

Data collection: X-AREA (Stoe & Cie, 2005); cell refinement: X-AREA; data reduction: X-RED32 (Stoe & Cie, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97.

Diimidazo[1,5 - a;1',5'-d]pyrazine-5,10-dione

Crystal data

C8H4N4O2	F(000) = 192
Mr = 188.15	Dx = 1.722 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 2055 reflections
a = 5.4047 (19) Å	θ = 3.6–26.0°
b = 6.9777 (18) Å	µ = 0.13 mm^−1
c = 9.678 (4) Å	T = 173 K
β = 96.23 (3)°	Rod, pale yellow
V = 362.8 (2) Å^3	0.23 × 0.13 × 0.10 mm
Z = 2

Data collection

Stoe IPDS-2 diffractometer	338 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.051
Graphite monochromator	θmax = 25.6°, θmin = 4.8°
Detector resolution: 6.67 pixels mm^-1	h = −6→6
ω and φ scans	k = −8→8
1582 measured reflections	l = −11→11
471 independent reflections

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.041	All H-atom parameters refined
wR(F^2) = 0.104	w = 1/[σ^2(Fo^2) + (0.0657P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 0.97	(Δ/σ)max < 0.001
471 reflections	Δρmax = 0.19 e Å^−3
73 parameters	Δρmin = −0.16 e Å^−3
0 restraints	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.065 (16)

Special details

Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles

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

	x	y	z	Uiso*/Ueq
O1	0.8612 (4)	−0.2727 (3)	0.6735 (2)	0.0399 (7)
N1	0.8136 (4)	0.0322 (3)	0.5832 (2)	0.0305 (7)
N2	0.5770 (4)	0.2850 (3)	0.6149 (2)	0.0352 (8)
C1	0.6301 (5)	0.1053 (4)	0.6531 (3)	0.0311 (8)
C2	0.7343 (6)	0.3279 (4)	0.5177 (3)	0.0327 (9)
C3	0.8827 (5)	0.1761 (4)	0.4951 (3)	0.0267 (8)
C4	0.9248 (5)	−0.1525 (3)	0.5953 (3)	0.0296 (8)
H1	0.545 (6)	0.027 (4)	0.716 (3)	0.041 (8)*
H2	0.733 (6)	0.454 (4)	0.478 (3)	0.044 (8)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0451 (12)	0.0337 (11)	0.0420 (12)	−0.0017 (8)	0.0098 (9)	0.0112 (9)
N1	0.0344 (14)	0.0259 (11)	0.0317 (12)	0.0024 (9)	0.0054 (10)	−0.0006 (9)
N2	0.0376 (14)	0.0306 (13)	0.0384 (13)	0.0038 (10)	0.0090 (11)	0.0008 (10)
C1	0.0329 (16)	0.0300 (14)	0.0313 (14)	0.0020 (11)	0.0073 (12)	−0.0027 (11)
C2	0.0371 (17)	0.0248 (13)	0.0375 (15)	0.0032 (12)	0.0100 (12)	0.0020 (11)
C3	0.0300 (15)	0.0202 (11)	0.0306 (13)	0.0009 (10)	0.0067 (11)	0.0015 (10)
C4	0.0326 (16)	0.0244 (12)	0.0312 (14)	0.0008 (11)	0.0010 (11)	0.0016 (11)

Geometric parameters (Å, º)

O1—C4	1.205 (3)	N2—C2	1.368 (4)
N1—C1	1.359 (4)	C2—C3	1.361 (4)
N1—C3	1.394 (4)	C3—C4^i	1.440 (4)
N1—C4	1.422 (3)	C1—H1	0.97 (3)
N2—C1	1.330 (4)	C2—H2	0.96 (3)
O1···C2^ii	3.207 (4)	C1···N1^vi	3.273 (4)
O1···C1^iii	3.400 (4)	C1···C1^vi	3.466 (4)
O1···C1^iv	3.178 (4)	C1···C3^vi	3.568 (4)
O1···N1^iv	3.097 (3)	C1···C2^ix	3.543 (4)
O1···C3^iv	3.372 (4)	C2···O1^x	3.207 (4)
O1···H1	2.76 (3)	C2···N2^viii	3.362 (4)
O1···H2^ii	2.72 (3)	C2···C2^viii	3.480 (5)
O1···H1^iii	2.90 (3)	C2···C1^xi	3.543 (4)
N1···O1^v	3.097 (3)	C3···C1^vi	3.568 (4)
N1···N1^i	2.749 (3)	C3···O1^v	3.372 (4)
N1···C1^vi	3.273 (4)	C4···N2^vi	3.339 (4)
N2···C1^vii	3.440 (4)	C2···H2^viii	2.95 (3)
N2···C2^viii	3.362 (4)	H1···O1	2.76 (3)
N2···C4^vi	3.339 (4)	H1···O1^vii	2.90 (3)
N2···H1^vii	2.49 (3)	H1···N2^iii	2.49 (3)
N2···H2^viii	2.57 (3)	H2···O1^x	2.72 (3)
C1···O1^vii	3.400 (4)	H2···N2^viii	2.57 (3)
C1···O1^v	3.178 (4)	H2···C2^viii	2.95 (3)
C1···N2^iii	3.440 (4)
C1—N1—C3	107.0 (2)	C2—C3—C4^i	131.6 (3)
C1—N1—C4	128.6 (2)	O1—C4—N1	122.4 (2)
C3—N1—C4	124.4 (2)	O1—C4—C3^i	125.2 (2)
C1—N2—C2	105.4 (2)	N1—C4—C3^i	112.4 (2)
N1—C1—N2	111.3 (2)	N1—C1—H1	121.5 (18)
N2—C2—C3	111.2 (2)	N2—C1—H1	127.1 (18)
N1—C3—C2	105.1 (2)	N2—C2—H2	119.9 (19)
N1—C3—C4^i	123.3 (2)	C3—C2—H2	128.9 (19)
C3—N1—C1—N2	0.4 (3)	C3—N1—C4—C3^i	−0.5 (4)
C4—N1—C1—N2	179.1 (2)	C2—N2—C1—N1	−0.4 (3)
C1—N1—C3—C2	−0.1 (3)	C1—N2—C2—C3	0.4 (3)
C1—N1—C3—C4^i	179.4 (3)	N2—C2—C3—N1	−0.1 (3)
C4—N1—C3—C2	−179.0 (2)	N2—C2—C3—C4^i	−179.6 (3)
C4—N1—C3—C4^i	0.6 (4)	N1—C3—C4^i—O1^i	179.4 (3)
C1—N1—C4—O1	0.9 (4)	N1—C3—C4^i—N1^i	−0.5 (4)
C1—N1—C4—C3^i	−179.1 (3)	C2—C3—C4^i—O1^i	−1.2 (5)
C3—N1—C4—O1	179.4 (3)	C2—C3—C4^i—N1^i	178.9 (3)

Symmetry codes: (i) −x+2, −y, −z+1; (ii) x, y−1, z; (iii) −x+1, y−1/2, −z+3/2; (iv) −x+2, y−1/2, −z+3/2; (v) −x+2, y+1/2, −z+3/2; (vi) −x+1, −y, −z+1; (vii) −x+1, y+1/2, −z+3/2; (viii) −x+1, −y+1, −z+1; (ix) x, −y+1/2, z+1/2; (x) x, y+1, z; (xi) x, −y+1/2, z−1/2.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C1—H1···N2^iii	0.97 (3)	2.49 (3)	3.440 (4)	166 (3)
C2—H2···N2^viii	0.96 (3)	2.57 (3)	3.362 (4)	140 (3)

Symmetry codes: (iii) −x+1, y−1/2, −z+3/2; (viii) −x+1, −y+1, −z+1.