3,6-Di-3-pyridylpyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione

The title compound, C₁₆H₁₀N₄O₂, is an organic red pigment utilized for hydrogen gas sensors. The centrosymmetric diketopyrrolopyrrole is nearly planar and is linked to four neighbouring mol­ecules via N—H...N hydrogen bonds to form a two-dimensional network in the (201) plane.

Key indicators

• Single-crystal X-ray study
• T = 100 K
• Mean [sigma](C-C) = 0.005 Å
• R factor = 0.068
• wR factor = 0.213
• Data-to-parameter ratio = 10.4

checkCIF/PLATON results

No syntax errors found



Alert level C
RINTA01_ALERT_3_C  The value of Rint is greater than 0.10
            Rint given   0.109
PLAT020_ALERT_3_C The value of Rint is greater than 0.10 .........       0.11
PLAT026_ALERT_3_C Ratio Observed / Unique Reflections too Low ....         47 Perc.
PLAT250_ALERT_2_C Large U3/U1 Ratio for Average U(i,j) Tensor ....       2.34
PLAT340_ALERT_3_C Low Bond Precision on C-C bonds (x 1000) Ang ...          5
PLAT353_ALERT_3_C Long    N-H Bond (0.87A)   N1     -   H1N    ...       1.02 Ang.

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   6 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
   1 ALERT type 2 Indicator that the structure model may be wrong or deficient
   5 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion

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S1. Comment

Diketodiphenylpyrrolopyrroles are industrially important red pigments (Herbst & Hunger, 1993). The title compound (m-DPPP) is a dipyridyl derivative whose N atom of the pyridyl ring is located at the meta-site. There are also o- and p-derivatives. Among these, only p-DPPP was found to exhibit a high proton affinity due to the N atom of the pyridyl ring (Mizuguchi, 1993). Because of this, p-DPPP has recently attracted attention as a high-performance hydrogen gas sensor (Takahashi & Mizuguchi, 2005). In phase I of p-DPPP, there are N—H···O bifurcated hydrogen bonds between the NH group of one molecule and the O atom of the neighboring one, and the two N atoms of the pyridyl rings remain free (i.e. unbonded) to accept protons, as is necessary for hydrogen gas sensors (Mizuguchi et al., 2005). Phase II of p-DPPP is rather insensitive to protons because one N atom of the two pyridyl rings is blocked by N—H···N hydrogen bonds (Mizuguchi et al., 2002). Quite recently, we have also carried out the structure analysis of o-DPPP in order to elucidate its poor sensitivity to protons (Imoda et al., 2005). Then, we found that there are N—H···N bifurcated hydrogen bonds between the NH group of one molecule and the N atom of the pyridyl ring of the neighboring one where one molecule is bonded to two neighboring molecules through four N—H···N hydrogen bonds. Therefore, the N atom of the pyridyl ring required for the proton acceptor is totally blocked by N—H···N hydrogen bonds and thus quite insensitive to protons. The purpose of the present investigation is to analyze the crystal structure of m-DPPP in order to clarify why this compound is insensitive to protons.

Fig. 1 shows the ORTEPIII (Burnett et al., 1996) plots of m-DPPP, (I). The central heterocyclic ring system is planar, as shown by the dihedral angle of 0.1 (2)° between the least-squares planes of the heterocyclic five-membered rings. The pyridyl rings are slightly rotated from the central ring system by 3.6 (1)°. As shown in Fig. 2, one molecule is bonded to four neighboring molecules through N—H···N hydrogen bonds (Table 2). This constitutes a two-dimensional network on the (201) plane. The present hydrogen-bond network is strikingly different from those of phases I and II of p-DPPP and also from that of o-DPPP. In addition, it should be noted that in the crystals of ordinary pyrrolopyrrole pigments without any pyridyl rings the molecule is bonded to two molecules through four bifurcated N—H···O hydrogen bonds (Mizuguchi, 2000). As is evident from Fig. 2, the N atom of the pyridyl ring is totally blocked by the N—H···N bonds. This indicates that m-DPPP is quite insensitive to protons.

S2. Experimental

m-DPPP was synthesized according to the method reported previously (Rochat et al., 1986) and purified three times by sublimation, using a two-zone furnace (Mizuguchi, 1981). Crystals of m-DPPP were dissolved in dimethylformamide at 423 K in an autoclave and crystallized with a cooling rate of two degrees per hour. A number of needle-like crystals were obtained. However, these crystals were extremely small.

S3. Refinement

The H atom of the NH group was found in difference maps and refined isotropically. All other H atoms were positioned geometrically and included in the riding-model approximation, with C—H distances of 0.95 Å and with U_iso(H) = 1.2U_eq(C).

Computing details

Data collection: PROCESS-AUTO (Rigaku, 1998); cell refinement: PROCESS-AUTO; data reduction: CrystalStructure (Rigaku/MSC, 2005); program(s) used to solve structure: SIR2002 (Burla et al., 2003); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPIII (Burnett & Johnson, 1996); software used to prepare material for publication: CrystalStructure.

Figures

	Fig. 1. A view of the molecular structure of (I), showing 50% probability displacement ellipsoids for non-H atoms. The unlabeled atoms are related to the labeled ones by the symmetry code (1 − x, 1 − y, 1 − z).
	Fig. 2. Molecular arrangement, showing N—H···N intermolecular hydrogen bonds as dashed lines. One molecule is hydrogen-bonded to four different molecules on the (201) plane.

3,6-Di-3-pyridylpyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione

Crystal data

C16H10N4O2	F(000) = 300.00
Mr = 290.28	Dx = 1.617 Mg m^−3
Monoclinic, P21/c	Cu Kα radiation, λ = 1.5419 Å
Hall symbol: -P 2ybc	Cell parameters from 4298 reflections
a = 3.6616 (5) Å	θ = 4.1–68.2°
b = 15.0089 (19) Å	µ = 0.92 mm^−1
c = 10.9791 (13) Å	T = 100 K
β = 98.823 (9)°	Needle, red
V = 596.23 (13) Å^3	0.10 × 0.03 × 0.02 mm
Z = 2

Data collection

Rigaku R-AXIS RAPID Imaging Plate diffractometer	520 reflections with F^2 > 2σ(F^2)
Detector resolution: 10.00 pixels mm^-1	Rint = 0.109
48 frames, δ ω = 15° scans	θmax = 68.2°
Absorption correction: multi-scan (ABSCOR; Higashi, 1995)	h = −4→4
Tmin = 0.896, Tmax = 0.982	k = −18→18
6375 measured reflections	l = −13→13
1097 independent reflections

Refinement

Refinement on F^2	H atoms treated by a mixture of independent and constrained refinement
R[F^2 > 2σ(F^2)] = 0.068	w = 1/[σ^2(Fo^2) + (0.0947P)^2] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.213	(Δ/σ)max < 0.001
S = 1.03	Δρmax = 0.25 e Å^−3
1097 reflections	Δρmin = −0.30 e Å^−3
105 parameters

Special details

Geometry. ENTER SPECIAL DETAILS OF THE MOLECULAR GEOMETRY

Refinement. Refinement using all reflections. The weighted R-factor (wR) and goodness of fit (S) are based on F². R-factor (gt) are based on F. The threshold expression of F² > 2 σ(F²) is used only for calculating R-factor (gt).

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

	x	y	z	Uiso*/Ueq
O1	0.9707 (8)	0.53957 (18)	0.7393 (2)	0.0446 (9)
N1	0.7172 (10)	0.4109 (2)	0.6433 (3)	0.0407 (10)
N2	0.1158 (11)	0.1880 (2)	0.3538 (3)	0.0422 (10)
C1	0.5818 (12)	0.5369 (2)	0.5340 (3)	0.0387 (11)
C2	0.7810 (13)	0.5033 (2)	0.6503 (3)	0.0392 (12)
C3	0.5027 (13)	0.3863 (2)	0.5322 (3)	0.0351 (11)
C4	0.4115 (13)	0.2931 (2)	0.5045 (3)	0.0372 (11)
C5	0.5168 (12)	0.2234 (2)	0.5861 (4)	0.0408 (12)
C6	0.4220 (13)	0.1375 (2)	0.5514 (3)	0.0419 (12)
C7	0.2236 (13)	0.1226 (2)	0.4355 (3)	0.0402 (12)
C8	0.2078 (13)	0.2722 (2)	0.3887 (3)	0.0421 (12)
H1N	0.844 (12)	0.369 (2)	0.710 (4)	0.064 (15)*
H5	0.6532	0.2352	0.6652	0.049*
H6	0.4915	0.0892	0.6060	0.050*
H7	0.1598	0.0630	0.4123	0.048*
H8	0.1319	0.3193	0.3328	0.050*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.062 (2)	0.0398 (18)	0.0270 (16)	−0.0020 (16)	−0.0097 (15)	−0.0034 (14)
N1	0.056 (2)	0.033 (2)	0.028 (2)	−0.0001 (19)	−0.0102 (18)	−0.0012 (17)
N2	0.053 (2)	0.039 (2)	0.031 (2)	0.0013 (19)	−0.0041 (18)	0.0028 (17)
C1	0.053 (3)	0.034 (2)	0.026 (2)	−0.003 (2)	−0.004 (2)	0.0023 (18)
C2	0.050 (3)	0.037 (2)	0.029 (2)	−0.001 (2)	0.001 (2)	−0.005 (2)
C3	0.043 (2)	0.035 (2)	0.025 (2)	−0.002 (2)	−0.0019 (19)	−0.0001 (18)
C4	0.040 (3)	0.036 (2)	0.032 (2)	0.003 (2)	−0.006 (2)	0.002 (2)
C5	0.049 (3)	0.037 (2)	0.033 (2)	0.004 (2)	−0.008 (2)	−0.002 (2)
C6	0.059 (3)	0.037 (2)	0.028 (2)	0.001 (2)	−0.002 (2)	0.0062 (19)
C7	0.057 (3)	0.034 (2)	0.026 (2)	0.001 (2)	−0.006 (2)	0.0010 (19)
C8	0.056 (3)	0.039 (2)	0.028 (2)	−0.003 (2)	−0.007 (2)	0.001 (2)

Geometric parameters (Å, º)

O1—C2	1.235 (4)	C3—C4	1.459 (5)
N1—C2	1.406 (5)	C4—C5	1.392 (5)
N1—C3	1.396 (5)	C4—C8	1.407 (5)
N1—H1N	1.02 (4)	C5—C6	1.374 (5)
N2—C7	1.347 (5)	C5—H5	0.950
N2—C8	1.348 (5)	C6—C7	1.383 (5)
C1—C1^i	1.417 (5)	C6—H6	0.950
C1—C2	1.460 (5)	C7—H7	0.950
C1—C3^i	1.372 (5)	C8—H8	0.950
C2—N1—C3	112.1 (3)	C3—C4—C8	118.3 (3)
C2—N1—H1N	121 (2)	C5—C4—C8	118.0 (3)
C3—N1—H1N	126 (2)	C4—C5—C6	119.5 (3)
C7—N2—C8	117.3 (3)	C4—C5—H5	120.2
C1^i—C1—C2	107.7 (3)	C6—C5—H5	120.2
C1^i—C1—C3^i	109.6 (3)	C5—C6—C7	118.8 (3)
C2—C1—C3^i	142.7 (3)	C5—C6—H6	120.6
O1—C2—N1	123.2 (3)	C7—C6—H6	120.6
O1—C2—C1	133.2 (4)	N2—C7—C6	123.6 (3)
N1—C2—C1	103.7 (3)	N2—C7—H7	118.2
N1—C3—C1^i	106.9 (3)	C6—C7—H7	118.2
N1—C3—C4	121.1 (3)	N2—C8—C4	122.7 (3)
C1^i—C3—C4	132.0 (3)	N2—C8—H8	118.6
C3—C4—C5	123.6 (3)	C4—C8—H8	118.6

Symmetry code: (i) −x+1, −y+1, −z+1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1N···N2^ii	1.02 (4)	1.93 (4)	2.939 (4)	168 (3)

Symmetry code: (ii) x+1, −y+1/2, z+1/2.