2-Ethyl-5H-1,3,4-thia­diazolo[3,2-a]pyrimidin-5-one

The molecule of the title compound, C₇H₇N₃OS, is nearly planar, with a maximum deviation of 0.095 Å from the mean plane for the ethyl group. An inter­molecular C—H...O hydrogen bond is observed in the crystal structure.

Key indicators

• Single-crystal X-ray study
• T = 299 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.036
• wR factor = 0.096
• Data-to-parameter ratio = 13.4

checkCIF/PLATON results

No syntax errors found



Alert level C
ABSTM02_ALERT_3_C  The ratio of Tmax/Tmin expected RT(exp) is > 1.10
            Absorption corrections should be applied.
            Tmin and Tmax expected:      0.369     0.416
            RT(exp) =      1.128
PLAT057_ALERT_3_C Correction for Absorption Required   RT(exp) ...       1.12
PLAT322_ALERT_2_C Check Hybridisation of  S1     in Main Residue .          ?
PLAT601_ALERT_2_C Structure Contains Solvent Accessible VOIDS of .      55.00 A   3 

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   4 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
   2 ALERT type 2 Indicator that the structure model may be wrong or deficient
   2 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: CAD-4-PC (Enraf–Nonius, 1996); cell refinement: CAD-4-P; data reduction: REDU4 (Stoe & Cie, 1987); 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.

2-Ethyl-5H-1,3,4-thiadiazolo[3,2-a]pyrimidin-5-one

Crystal data

C7H7N3OS	Dx = 1.466 Mg m^−3
Mr = 181.22	Cu Kα radiation, λ = 1.54180 Å
Trigonal, R3	Cell parameters from 25 reflections
Hall symbol: -R 3	θ = 2.7–22.4°
a = 32.347 (5) Å	µ = 3.13 mm^−1
c = 4.0784 (7) Å	T = 299 K
V = 3695.6 (10) Å^3	Prism, colourless
Z = 18	0.48 × 0.30 × 0.28 mm
F(000) = 1692

Data collection

Enraf–Nonius CAD-4 diffractometer	Rint = 0.034
Radiation source: fine-focus sealed tube	θmax = 67.0°, θmin = 2.7°
Graphite monochromator	h = −38→1
ω/2θ scans	k = −33→38
2610 measured reflections	l = −4→0
1461 independent reflections	3 standard reflections every 120 min
1300 reflections with I > 2σ(I)	intensity decay: none

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)] = 0.036	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.096	H-atom parameters constrained
S = 1.11	w = 1/[σ^2(Fo^2) + (0.0354P)^2 + 5.1533P] where P = (Fo^2 + 2Fc^2)/3
1461 reflections	(Δ/σ)max = 0.001
109 parameters	Δρmax = 0.17 e Å^−3
0 restraints	Δρmin = −0.22 e Å^−3

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
C1	0.55518 (7)	0.05415 (7)	0.7714 (6)	0.0447 (5)
C2	0.58484 (9)	0.00476 (8)	0.7603 (7)	0.0583 (6)
H2	0.5817	−0.0245	0.7014	0.070*
C3	0.62488 (8)	0.03589 (8)	0.9224 (7)	0.0550 (6)
H3	0.6479	0.0274	0.9664	0.066*
C4	0.63301 (7)	0.08141 (8)	1.0282 (6)	0.0503 (5)
C5	0.55557 (7)	0.12711 (7)	0.9159 (5)	0.0421 (5)
C6	0.54357 (8)	0.16538 (8)	0.9765 (6)	0.0503 (5)
H6A	0.5172	0.1537	1.1302	0.060*
H6B	0.5332	0.1727	0.7724	0.060*
C7	0.58523 (9)	0.21070 (9)	1.1117 (7)	0.0655 (7)
H7A	0.6113	0.2228	0.9590	0.079*
H7B	0.5951	0.2039	1.3169	0.079*
H7C	0.5757	0.2341	1.1450	0.079*
N1	0.54876 (7)	0.01286 (7)	0.6765 (6)	0.0566 (5)
N2	0.59440 (6)	0.08808 (6)	0.9367 (4)	0.0431 (4)
N3	0.59451 (6)	0.12968 (6)	1.0188 (5)	0.0448 (4)
O1	0.66693 (6)	0.11216 (6)	1.1798 (5)	0.0680 (5)
S1	0.515621 (18)	0.074899 (19)	0.71057 (15)	0.0490 (2)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0367 (10)	0.0382 (10)	0.0556 (13)	0.0160 (9)	0.0008 (9)	0.0013 (9)
C2	0.0545 (13)	0.0415 (12)	0.0815 (18)	0.0259 (11)	0.0013 (12)	−0.0053 (11)
C3	0.0464 (12)	0.0462 (12)	0.0777 (17)	0.0272 (10)	0.0009 (11)	0.0008 (11)
C4	0.0380 (11)	0.0441 (12)	0.0693 (15)	0.0209 (10)	−0.0012 (10)	0.0030 (10)
C5	0.0375 (10)	0.0393 (10)	0.0472 (12)	0.0174 (8)	0.0042 (8)	0.0018 (9)
C6	0.0481 (12)	0.0525 (12)	0.0578 (14)	0.0307 (10)	0.0016 (10)	−0.0029 (10)
C7	0.0662 (16)	0.0551 (14)	0.0824 (18)	0.0357 (13)	−0.0059 (13)	−0.0175 (13)
N1	0.0492 (11)	0.0407 (10)	0.0789 (14)	0.0216 (8)	−0.0088 (10)	−0.0109 (9)
N2	0.0349 (8)	0.0343 (8)	0.0580 (11)	0.0158 (7)	0.0004 (7)	−0.0005 (7)
N3	0.0396 (9)	0.0371 (9)	0.0577 (11)	0.0192 (7)	−0.0008 (8)	−0.0035 (8)
O1	0.0478 (9)	0.0517 (9)	0.1054 (15)	0.0255 (8)	−0.0224 (9)	−0.0128 (9)
S1	0.0377 (3)	0.0418 (3)	0.0657 (4)	0.0186 (2)	−0.0061 (2)	−0.0042 (2)

Geometric parameters (Å, º)

C1—N1	1.304 (3)	C5—N3	1.290 (3)
C1—N2	1.370 (3)	C5—C6	1.492 (3)
C1—S1	1.734 (2)	C5—S1	1.744 (2)
C2—C3	1.351 (3)	C6—C7	1.514 (3)
C2—N1	1.362 (3)	C6—H6A	0.9700
C2—H2	0.9300	C6—H6B	0.9700
C3—C4	1.427 (3)	C7—H7A	0.9600
C3—H3	0.9300	C7—H7B	0.9600
C4—O1	1.218 (3)	C7—H7C	0.9600
C4—N2	1.419 (3)	N2—N3	1.385 (2)
N1—C1—N2	125.20 (19)	C7—C6—H6A	109.0
N1—C1—S1	125.69 (17)	C5—C6—H6B	109.0
N2—C1—S1	109.12 (14)	C7—C6—H6B	109.0
C3—C2—N1	125.0 (2)	H6A—C6—H6B	107.8
C3—C2—H2	117.5	C6—C7—H7A	109.5
N1—C2—H2	117.5	C6—C7—H7B	109.5
C2—C3—C4	122.0 (2)	H7A—C7—H7B	109.5
C2—C3—H3	119.0	C6—C7—H7C	109.5
C4—C3—H3	119.0	H7A—C7—H7C	109.5
O1—C4—N2	120.7 (2)	H7B—C7—H7C	109.5
O1—C4—C3	128.5 (2)	C1—N1—C2	114.2 (2)
N2—C4—C3	110.81 (19)	C1—N2—N3	116.66 (16)
N3—C5—C6	122.91 (19)	C1—N2—C4	122.71 (17)
N3—C5—S1	116.45 (15)	N3—N2—C4	120.61 (17)
C6—C5—S1	120.60 (16)	C5—N3—N2	109.31 (17)
C5—C6—C7	112.89 (19)	C1—S1—C5	88.46 (10)
C5—C6—H6A	109.0
N1—C2—C3—C4	0.9 (4)	O1—C4—N2—C1	−178.8 (2)
C2—C3—C4—O1	178.7 (3)	C3—C4—N2—C1	0.5 (3)
C2—C3—C4—N2	−0.5 (3)	O1—C4—N2—N3	−0.1 (3)
N3—C5—C6—C7	10.9 (3)	C3—C4—N2—N3	179.13 (19)
S1—C5—C6—C7	−171.47 (18)	C6—C5—N3—N2	177.48 (19)
N2—C1—N1—C2	1.1 (4)	S1—C5—N3—N2	−0.3 (2)
S1—C1—N1—C2	−178.74 (19)	C1—N2—N3—C5	0.0 (3)
C3—C2—N1—C1	−1.1 (4)	C4—N2—N3—C5	−178.76 (19)
N1—C1—N2—N3	−179.5 (2)	N1—C1—S1—C5	179.5 (2)
S1—C1—N2—N3	0.3 (2)	N2—C1—S1—C5	−0.34 (16)
N1—C1—N2—C4	−0.8 (3)	N3—C5—S1—C1	0.37 (18)
S1—C1—N2—C4	178.99 (17)	C6—C5—S1—C1	−177.44 (19)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C6—H6A···O1^i	0.97	2.49	3.450 (3)	172

Symmetry code: (i) y+1/3, −x+y+2/3, −z+8/3.