Ethyl 5-cyano-1H-pyrrole-2-carboxyl­ate

The title compound, C₈H₈N₂O₂, was prepared by dehydration of a pyrrole­oxime in the presence of triphosgene. The mol­ecules self-assemble into a layered structure through hydrogen bonding. All non-H atoms lie on a crystallographic mirror plane.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.053
• wR factor = 0.159
• Data-to-parameter ratio = 12.4

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT021_ALERT_1_B Ratio Unique / Expected Reflections too High ...       1.21
PLAT029_ALERT_3_B _diffrn_measured_fraction_theta_full Low .......       0.99

Alert level C
THETM01_ALERT_3_C  The value of sine(theta_max)/wavelength is less than 0.590
            Calculated sin(theta_max)/wavelength =    0.5833
PLAT023_ALERT_3_C Resolution (too) Low [sin(th)/Lambda < 0.6].....      24.49 Deg.
PLAT250_ALERT_2_C Large U3/U1 ratio for average U(i,j) tensor ....       2.52
PLAT371_ALERT_2_C Long   C(sp2)-C(sp1) Bond  C4     -   C8       =       1.42 Ang.

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

   1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   2 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
   0 ALERT type 4 Improvement, methodology, query or suggestion

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Computing details

Data collection: SMART (Bruker, 1997); cell refinement: SMART; data reduction: SAINT (Bruker, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 1997); software used to prepare material for publication: SHELXTL.

Ethyl 5-cyano-1H-pyrrole-2-carboxylate

Crystal data

C8H8N2O2	Dx = 1.295 Mg m^−3
Mr = 164.16	Melting point: 392 K
Orthorhombic, Pnma	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2n	Cell parameters from 762 reflections
a = 7.866 (3) Å	θ = 2.6–24.5°
b = 6.710 (3) Å	µ = 0.10 mm^−1
c = 15.959 (7) Å	T = 293 K
V = 842.3 (6) Å^3	Block, colorless
Z = 4	0.32 × 0.28 × 0.20 mm
F(000) = 344

Data collection

Bruker SMART CCD area-detector diffractometer	664 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.022
Graphite monochromator	θmax = 24.5°, θmin = 2.6°
φ and ω scans	h = −5→9
2209 measured reflections	k = −8→4
921 independent reflections	l = −19→19

Refinement

Refinement on F^2	0 restraints
Least-squares matrix: full	H-atom parameters constrained
R[F^2 > 2σ(F^2)] = 0.053	w = 1/[σ^2(Fo^2) + (0.084P)^2] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.159	(Δ/σ)max = 0.002
S = 1.12	Δρmax = 0.24 e Å^−3
921 reflections	Δρmin = −0.26 e Å^−3
74 parameters

Special details

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

	x	y	z	Uiso*/Ueq
N1	0.5804 (3)	0.7500	1.09215 (13)	0.0422 (7)
H1	0.6573	0.7500	1.1304	0.051*
N2	0.2838 (4)	0.7500	1.25259 (18)	0.0785 (10)
O1	0.9057 (3)	0.7500	1.02467 (14)	0.0743 (9)
O2	0.7951 (3)	0.7500	0.89583 (12)	0.0614 (7)
C1	0.6089 (3)	0.7500	1.00804 (15)	0.0392 (7)
C2	0.4552 (4)	0.7500	0.96829 (17)	0.0451 (7)
H2	0.4381	0.7500	0.9106	0.054*
C3	0.3295 (4)	0.7500	1.02884 (17)	0.0473 (8)
H3	0.2127	0.7500	1.0197	0.057*
C4	0.4104 (4)	0.7500	1.10534 (16)	0.0426 (7)
C5	0.7856 (4)	0.7500	0.97889 (18)	0.0491 (8)
C6	0.9669 (5)	0.7500	0.8613 (2)	0.0876 (15)
H6A	1.0282	0.8673	0.8801	0.105*
C7	0.9538 (6)	0.7500	0.7708 (3)	0.0944 (15)
H7A	0.8935	0.6332	0.7528	0.142*
H7B	1.0656	0.7500	0.7467	0.142*
C8	0.3400 (4)	0.7500	1.18726 (19)	0.0538 (8)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0354 (13)	0.0617 (16)	0.0296 (12)	0.000	−0.0006 (9)	0.000
N2	0.071 (2)	0.116 (3)	0.0479 (16)	0.000	0.0235 (16)	0.000
O1	0.0332 (13)	0.138 (3)	0.0517 (13)	0.000	−0.0047 (11)	0.000
O2	0.0400 (13)	0.1052 (19)	0.0390 (12)	0.000	0.0100 (9)	0.000
C1	0.0351 (16)	0.0516 (17)	0.0308 (13)	0.000	0.0015 (11)	0.000
C2	0.0399 (17)	0.0626 (19)	0.0328 (13)	0.000	−0.0021 (11)	0.000
C3	0.0316 (15)	0.064 (2)	0.0460 (16)	0.000	0.0001 (13)	0.000
C4	0.0358 (16)	0.0538 (18)	0.0383 (15)	0.000	0.0070 (12)	0.000
C5	0.0388 (16)	0.068 (2)	0.0404 (16)	0.000	0.0059 (13)	0.000
C6	0.045 (2)	0.165 (5)	0.053 (2)	0.000	0.0150 (17)	0.000
C7	0.071 (3)	0.142 (4)	0.071 (3)	0.000	0.025 (2)	0.000
C8	0.0448 (18)	0.070 (2)	0.0469 (18)	0.000	0.0090 (15)	0.000

Geometric parameters (Å, º)

N1—C4	1.353 (4)	C2—C3	1.382 (4)
N1—C1	1.361 (3)	C2—H2	0.9300
N1—H1	0.8600	C3—C4	1.377 (4)
N2—C8	1.132 (4)	C3—H3	0.9300
O1—C5	1.194 (4)	C4—C8	1.420 (4)
O2—C5	1.328 (3)	C6—C7	1.449 (5)
O2—C6	1.460 (4)	C6—H6A	0.9700
C1—C2	1.365 (4)	C7—H7A	0.9597
C1—C5	1.466 (4)	C7—H7B	0.9597
C4—N1—C1	108.4 (2)	N1—C4—C3	108.6 (2)
C4—N1—H1	125.8	N1—C4—C8	121.9 (3)
C1—N1—H1	125.8	C3—C4—C8	129.5 (3)
C5—O2—C6	115.4 (2)	O1—C5—O2	124.5 (3)
N1—C1—C2	108.2 (2)	O1—C5—C1	123.8 (3)
N1—C1—C5	118.0 (2)	O2—C5—C1	111.7 (3)
C2—C1—C5	133.8 (3)	C7—C6—O2	108.1 (3)
C1—C2—C3	108.0 (2)	C7—C6—H6A	110.1
C1—C2—H2	126.0	O2—C6—H6A	110.1
C3—C2—H2	126.0	C6—C7—H7A	109.5
C4—C3—C2	106.8 (3)	C6—C7—H7B	109.5
C4—C3—H3	126.6	H7A—C7—H7B	109.5
C2—C3—H3	126.6	N2—C8—C4	180.0 (3)