3-Aminocyclo­pent-2-en-1-one

The title compound, C₅H₇NO, was synthesized by the reaction of 1,3-cyclo­penta­nedione with ammonium acetate under microwave conditions in 81% yield. The crystal packing is determined by intermolecular N—H...O and C—H...O hydrogen bonds.

Key indicators

• Single-crystal X-ray study
• T = 103 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.054
• wR factor = 0.145
• Data-to-parameter ratio = 16.9

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT066_ALERT_1_C Predicted and Reported Transmissions Identical .          ?
PLAT125_ALERT_4_C No _symmetry_space_group_name_Hall Given .......          ?
PLAT250_ALERT_2_C Large U3/U1 Ratio for Average U(i,j) Tensor ....       2.20

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

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Computing details

Data collection: SMART (Bruker, 2001); cell refinement: SMART; data reduction: SAINT (Bruker, 2002); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 2000); software used to prepare material for publication: SHELXTL.

3-Amino-2-cyclopent-2-en-1-one

Crystal data

C5H7NO	F(000) = 208
Mr = 97.12	Dx = 1.314 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 5.6444 (17) Å	Cell parameters from 3168 reflections
b = 12.085 (4) Å	θ = 2.8–27.1°
c = 7.356 (2) Å	µ = 0.09 mm^−1
β = 102.026 (4)°	T = 103 K
V = 490.8 (3) Å^3	Chunk, colorless
Z = 4	0.44 × 0.42 × 0.35 mm

Data collection

Bruker APEX-2 CCD area-detector diffractometer	1084 independent reflections
Radiation source: fine-focus sealed tube	998 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.036
φ and ω scans	θmax = 27.1°, θmin = 3.3°
Absorption correction: multi-scan (SADABS; Bruker, 2000)	h = −7→7
Tmin = 0.960, Tmax = 0.968	k = −15→15
4315 measured reflections	l = −8→9

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.054	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.145	H-atom parameters constrained
S = 1.10	w = 1/[σ^2(Fo^2) + (0.0876P)^2 + 0.1689P] where P = (Fo^2 + 2Fc^2)/3
1084 reflections	(Δ/σ)max < 0.001
64 parameters	Δρmax = 0.37 e Å^−3
0 restraints	Δρmin = −0.27 e Å^−3

Special details

Experimental. ¹H NMR (400 MHz, DMSO-d₆): δ 7.21 (br, 2H), 4.774 (s, 1H), 2.445–2.420 (m, 2H), 2.140–2.08 (m, 2H); ¹³C NMR (100 MHz, DMSO-d₆): δ 202.318 (C), 178.437 (C), 99.085 (CH), 33.819 (CH₂), 27.444 (CH₂). MS m/z 97 (M +) 68, 55, 41. IR (CHCl₃, cm^-1): 3687, 1622, and 1582.

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
O1	0.32396 (17)	0.58198 (8)	0.15752 (15)	0.0302 (3)
C1	0.5074 (2)	0.63130 (11)	0.24429 (18)	0.0222 (4)
C2	0.5427 (2)	0.74659 (10)	0.26634 (19)	0.0230 (4)
H2A	0.4265	0.8013	0.2164	0.028*
C3	0.7698 (2)	0.76800 (11)	0.37067 (19)	0.0211 (4)
N3	0.8698 (2)	0.86561 (9)	0.41992 (16)	0.0251 (3)
H3A	0.7881	0.9267	0.3850	0.030*
H3B	1.0178	0.8693	0.4875	0.030*
C4	0.9104 (2)	0.66306 (10)	0.42613 (19)	0.0230 (3)
H4A	0.9609	0.6573	0.5630	0.028*
H4B	1.0561	0.6599	0.3712	0.028*
C5	0.7315 (2)	0.57105 (10)	0.3481 (2)	0.0240 (4)
H5A	0.7992	0.5227	0.2630	0.029*
H5B	0.6927	0.5253	0.4497	0.029*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0225 (5)	0.0179 (5)	0.0458 (7)	−0.0013 (4)	−0.0033 (4)	−0.0028 (4)
C1	0.0190 (6)	0.0178 (7)	0.0286 (7)	0.0008 (4)	0.0020 (5)	0.0000 (4)
C2	0.0220 (7)	0.0146 (6)	0.0301 (7)	0.0032 (4)	−0.0001 (5)	0.0006 (4)
C3	0.0220 (7)	0.0160 (6)	0.0249 (7)	0.0011 (4)	0.0036 (5)	0.0009 (4)
N3	0.0229 (6)	0.0159 (6)	0.0329 (7)	−0.0006 (4)	−0.0024 (4)	−0.0004 (4)
C4	0.0186 (6)	0.0179 (6)	0.0308 (7)	0.0022 (4)	0.0009 (5)	0.0011 (5)
C5	0.0213 (7)	0.0155 (7)	0.0340 (8)	0.0019 (5)	0.0027 (5)	0.0029 (5)

Geometric parameters (Å, º)

O1—C1	1.2487 (16)	N3—H3A	0.8800
C1—C2	1.4121 (18)	N3—H3B	0.8800
C1—C5	1.5204 (17)	C4—C5	1.5310 (18)
C2—C3	1.3745 (19)	C4—H4A	0.9900
C2—H2A	0.9500	C4—H4B	0.9900
C3—N3	1.3253 (17)	C5—H5A	0.9900
C3—C4	1.5066 (17)	C5—H5B	0.9900
O1—C1—C2	127.72 (12)	C3—C4—C5	103.94 (10)
O1—C1—C5	122.87 (12)	C3—C4—H4A	111.0
C2—C1—C5	109.40 (11)	C5—C4—H4A	111.0
C3—C2—C1	110.04 (11)	C3—C4—H4B	111.0
C3—C2—H2A	125.0	C5—C4—H4B	111.0
C1—C2—H2A	125.0	H4A—C4—H4B	109.0
N3—C3—C2	127.93 (12)	C1—C5—C4	104.78 (10)
N3—C3—C4	120.33 (12)	C1—C5—H5A	110.8
C2—C3—C4	111.73 (11)	C4—C5—H5A	110.8
C3—N3—H3A	120.0	C1—C5—H5B	110.8
C3—N3—H3B	120.0	C4—C5—H5B	110.8
H3A—N3—H3B	120.0	H5A—C5—H5B	108.9
O1—C1—C2—C3	−179.67 (13)	C2—C3—C4—C5	−2.65 (15)
C5—C1—C2—C3	1.41 (16)	O1—C1—C5—C4	178.04 (12)
C1—C2—C3—N3	179.52 (12)	C2—C1—C5—C4	−2.97 (14)
C1—C2—C3—C4	0.83 (17)	C3—C4—C5—C1	3.24 (14)
N3—C3—C4—C5	178.56 (12)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N3—H3A···O1^i	0.88	1.98	2.8458 (16)	166
N3—H3B···O1^ii	0.88	2.00	2.8567 (16)	165
C4—H4B···O1^iii	0.99	2.58	3.4979 (19)	155

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