Crystal structure of 4-amino-1-benzyl-1,2,4-triazolin-5-one

The title compound, C₉H₁₀N₄O, was obtained unintentionally by hydrolysis of 4-amino-1-benzyl-5-methyl­sulfanyl-1,2,4-triazolium tetra­fluoro­borate in the presence of sodium azide. In the crystal, alternating layers of polar amino­triazolinone and apolar benzene moieties are observed. N—H...O hydrogen bonds between the amino and carbonyl groups form infinite chains along [010]. These infinite chains are linked by additional C—H...O contacts.

Key indicators

• Single-crystal X-ray study
• T = 173 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.034
• wR factor = 0.092
• Data-to-parameter ratio = 12.1

checkCIF/PLATON results

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Alert level C
PLAT911_ALERT_3_C Missing # FCF Refl Between THmin & STh/L=  0.600         10 Report

Alert level G
PLAT002_ALERT_2_G Number of Distance or Angle Restraints on AtSite          3 Note
PLAT005_ALERT_5_G No _iucr_refine_instructions_details  in the CIF     Please Do !
PLAT860_ALERT_3_G Number of Least-Squares Restraints .............          2 Note
PLAT909_ALERT_3_G Percentage of Observed Data at Theta(Max) still          75 %
PLAT910_ALERT_3_G Missing # of FCF Reflections Below Th(Min) .....          1 Report
PLAT912_ALERT_4_G Missing # of FCF Reflections Above STh/L=  0.600          3 Note

   0 ALERT level A = Most likely a serious problem - resolve or explain
   0 ALERT level B = A potentially serious problem, consider carefully
   1 ALERT level C = Check. Ensure it is not caused by an omission or oversight
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   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
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S1. Comment

1,2,4-Triazole derivatives possess a wide spectrum of pharmacological activities (Sheng et al., 2011; Singla & Bhat, 2010; Dayan et al., 2009; Li et al., 2003; Todoulou et al., 1994). Only three 1-substituted 4-amino-1,2,4-triazolin-5-ones (Thamotharan et al., 2003; Kaur et al., 2013; Sahin et al., 2014) are found in the Cambridge Structural Database (Groom & Allen, 2014). The molecular structure of 4-amino-1-benzyl-1,2,4-triazolin-5-one is shown in Figure 1. In the crystal structure of the title compound, alternating layers of polar aminotriazolinone and apolar benzene moieties parallel to the bc plane are observed (Figure 2). The triazole rings are arranged parallel to (13 4 3) and (13 4 3) planes, with an interplanar angle of 76° (Figure 3). The amino group donates two hydrogen bonds to two neighbouring molecules, N3—H···O1ⁱ and N3—H···O1ⁱⁱ, forming infinite chains (Figure 4). In turn, the O atom receives a hydrogen bond from each of these two molecules. The triazole rings within the chain are parallel, with interplanar distances of 0.730 and 2.558 Å, respectively. These infinite chains are linked by additional C2—H···O1ⁱⁱⁱ contacts. Symmetry operators (i): 1 - x, -1 - y, 2 - z; (ii): 1 - x, -y, 2 - z; (iii): x, -1/2 - y, -1/2 + z. Hydrogen bond geometry is shown in Table 1.

Related literature

For the pharmacological activity of 1,2,4-triazoles, see: Sheng et al. (2011); Singla & Bhat (2010); Dayan et al. (2009); Li et al. (2003); Todoulou et al. (1994). For related structures, see: Thamotharan et al. (2003); Kaur et al. (2013); Sahin et al. (2014). For details of the synthesis, see: Becker et al. (1973a,b). For a description of the Cambridge Structural Database, see: Groom & Allen (2014).

S2. Experimental

The title compound was prepared from 4-amino-1-benzyl-5-methylthio-1,2,4- triazolium tetrafluoroborate (the respective iodide has been described by Becker et al., 1973b) which, in turn, was prepared from the corresponding 4-amino-1-benzyl-1,2,4-triazoline-5-thione (Becker et al., 1973a). When the 5-methylthio precursor was treated with NaN₃ in MeOH/H₂O, MeSH was evolved, and the triazolin-5-one was obtained. It is assumed that the intermediate 5-azido compound is highly prone to hydrolysis and therefore could not be isolated. In contrast, the 5-methylthio precursor could be stirred in H₂O for 20 h without any change. Single crystals were obtained from MeOH/H₂O. Melting point 119–120 °C. IR (neat): 1680 cm^-1. ¹H NMR (DMSO-d₆, 300 MHz): 4.85 (s, 2H), 5.43 (s, 2H), 7.23–7.33 (m, 5H), 7.93 (s, 1H) p.p.m.. ¹³C NMR (DMSO-d₆, 75 MHz): 48.7, 127.5 (3C), 128.5 (2C), 137.1, 138.4, 152.8 p.p.m..

S3. Refinement

Positions of hydrogen atoms bonded to carbon were generated in idealized geometries using a riding model with U_iso(H) = 1.2 U_eq(C). The fractional coordinates of the H atoms attached to N3 were identified from difference Fourier maps and refined freely with isotropic thermal displacement parameters.

Computing details

Data collection: CrysAlis PRO (Oxford Diffraction, 2010); cell refinement: CrysAlis PRO (Oxford Diffraction, 2010); data reduction: CrysAlis PRO (Oxford Diffraction, 2010); program(s) used to solve structure: SIR2002 (Burla et al., 2002); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures

	Fig. 1. The molecular structure of the title compound, with atom labels and 50% probability displacement ellipsoids for non-H atoms.
	Fig. 2. Alternating layers of polar aminotriazolinone and apolar benzene moieties.
	Fig. 3. Arrangement of the triazole rings parallel to (13 4 3) and (13 4 3) planes.
	Fig. 4. Hydrogen bonds between the amino and carbonyl groups form infinite chains. Symmetry operators (i): 1 - x, -1 - y, 2 - z; (ii): 1 - x, -y, 2 - z.

4-Amino-1-benzyl-1,2,4-triazolin-5-one

Crystal data

C9H10N4O	F(000) = 400
Mr = 190.21	Dx = 1.396 Mg m^−3
Monoclinic, P21/c	Cu Kα radiation, λ = 1.5418 Å
Hall symbol: -P 2ybc	Cell parameters from 4064 reflections
a = 18.0861 (8) Å	θ = 3.7–67.9°
b = 4.1690 (2) Å	µ = 0.80 mm^−1
c = 12.3694 (6) Å	T = 173 K
β = 104.003 (5)°	Plate, colourless
V = 904.95 (7) Å^3	0.2 × 0.2 × 0.08 mm
Z = 4

Data collection

Oxford Diffraction Xcalibur (Ruby, Gemini ultra) diffractometer	1613 independent reflections
Graphite monochromator	1448 reflections with I > 2σ(I)
Detector resolution: 10.3575 pixels mm^-1	Rint = 0.030
ω scans	θmax = 68.0°, θmin = 5.0°
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2010)	h = −21→21
Tmin = 0.867, Tmax = 1	k = −4→4
7377 measured reflections	l = −14→14

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)] = 0.034	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.092	H atoms treated by a mixture of independent and constrained refinement
S = 1.03	w = 1/[σ^2(Fo^2) + (0.0489P)^2 + 0.2066P] where P = (Fo^2 + 2Fc^2)/3
1613 reflections	(Δ/σ)max = 0.001
133 parameters	Δρmax = 0.17 e Å^−3
2 restraints	Δρmin = −0.14 e Å^−3

Special details

Experimental. Absorption correction: CrysAlisPro, Oxford Diffraction Ltd., Version 1.171.34.44 (release 25-10-2010 CrysAlis171 .NET) (compiled Oct 25 2010,18:11:34) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm.

Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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	0.41353 (5)	−0.0910 (2)	1.01696 (7)	0.0378 (3)
N3	0.47943 (7)	−0.4111 (3)	0.84565 (10)	0.0398 (3)
H31	0.5197 (9)	−0.283 (4)	0.8730 (13)	0.048*
H32	0.4789 (10)	−0.550 (4)	0.9007 (12)	0.048*
N1	0.32531 (6)	0.0899 (3)	0.85723 (8)	0.0315 (3)
N4	0.41310 (6)	−0.2253 (2)	0.83245 (8)	0.0301 (3)
N2	0.31212 (6)	0.0442 (3)	0.74333 (9)	0.0376 (3)
C1	0.38691 (7)	−0.0749 (3)	0.91540 (10)	0.0290 (3)
C5	0.14844 (8)	0.0222 (3)	0.81353 (11)	0.0368 (3)
H5	0.1579	0.0711	0.743	0.044*
C4	0.20132 (7)	0.1088 (3)	0.91021 (11)	0.0322 (3)
C6	0.08204 (8)	−0.1351 (4)	0.81894 (12)	0.0404 (3)
H6	0.0465	−0.1967	0.7523	0.049*
C7	0.06730 (8)	−0.2024 (4)	0.92066 (13)	0.0448 (4)
H7	0.0215	−0.3082	0.9243	0.054*
C9	0.18659 (8)	0.0385 (4)	1.01228 (12)	0.0417 (3)
H9	0.2225	0.0957	1.0791	0.05*
C2	0.36666 (7)	−0.1467 (3)	0.73250 (10)	0.0349 (3)
H2	0.3732	−0.2221	0.6629	0.042*
C3	0.27350 (7)	0.2839 (3)	0.90400 (12)	0.0384 (3)
H3A	0.2596	0.4788	0.8578	0.046*
H3B	0.3003	0.3534	0.9799	0.046*
C8	0.11940 (9)	−0.1154 (4)	1.01708 (13)	0.0492 (4)
H8	0.1093	−0.161	1.0874	0.059*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0376 (5)	0.0452 (6)	0.0301 (5)	−0.0017 (4)	0.0073 (4)	0.0004 (4)
N3	0.0338 (6)	0.0376 (7)	0.0490 (7)	0.0064 (5)	0.0116 (5)	0.0002 (5)
N1	0.0302 (5)	0.0293 (6)	0.0356 (6)	−0.0001 (4)	0.0094 (4)	0.0003 (4)
N4	0.0291 (5)	0.0287 (6)	0.0338 (5)	−0.0001 (4)	0.0102 (4)	−0.0002 (4)
N2	0.0363 (6)	0.0427 (7)	0.0332 (6)	0.0007 (5)	0.0070 (5)	0.0045 (5)
C1	0.0293 (6)	0.0255 (6)	0.0336 (6)	−0.0050 (5)	0.0101 (5)	0.0009 (5)
C5	0.0363 (7)	0.0378 (7)	0.0369 (7)	0.0016 (6)	0.0101 (5)	0.0006 (6)
C4	0.0308 (6)	0.0256 (7)	0.0406 (7)	0.0052 (5)	0.0093 (5)	−0.0033 (5)
C6	0.0330 (7)	0.0420 (8)	0.0446 (8)	−0.0002 (6)	0.0060 (6)	−0.0033 (6)
C7	0.0363 (7)	0.0423 (8)	0.0592 (9)	−0.0018 (6)	0.0181 (6)	0.0035 (7)
C9	0.0394 (7)	0.0463 (8)	0.0379 (7)	0.0050 (6)	0.0065 (6)	−0.0040 (6)
C2	0.0345 (7)	0.0402 (8)	0.0310 (6)	−0.0022 (6)	0.0097 (5)	−0.0003 (5)
C3	0.0345 (7)	0.0289 (7)	0.0533 (8)	0.0005 (5)	0.0136 (6)	−0.0073 (6)
C8	0.0507 (9)	0.0584 (10)	0.0428 (8)	0.0025 (7)	0.0197 (7)	0.0076 (7)

Geometric parameters (Å, º)

O1—C1	1.2335 (15)	C4—C9	1.383 (2)
N3—N4	1.4040 (15)	C4—C3	1.5138 (18)
N3—H31	0.900 (14)	C6—C7	1.377 (2)
N3—H32	0.895 (14)	C6—H6	0.95
N1—C1	1.3577 (17)	C7—C8	1.378 (2)
N1—N2	1.3840 (15)	C7—H7	0.95
N1—C3	1.4592 (16)	C9—C8	1.388 (2)
N4—C2	1.3561 (17)	C9—H9	0.95
N4—C1	1.3803 (16)	C2—H2	0.95
N2—C2	1.2993 (18)	C3—H3A	0.99
C5—C6	1.384 (2)	C3—H3B	0.99
C5—C4	1.3861 (19)	C8—H8	0.95
C5—H5	0.95
N4—N3—H31	107.9 (11)	C7—C6—H6	119.9
N4—N3—H32	106.2 (11)	C5—C6—H6	119.9
H31—N3—H32	104.7 (15)	C6—C7—C8	119.63 (13)
C1—N1—N2	112.77 (10)	C6—C7—H7	120.2
C1—N1—C3	126.43 (11)	C8—C7—H7	120.2
N2—N1—C3	120.72 (10)	C4—C9—C8	120.05 (13)
C2—N4—C1	108.65 (10)	C4—C9—H9	120
C2—N4—N3	124.24 (11)	C8—C9—H9	120
C1—N4—N3	126.97 (11)	N2—C2—N4	111.85 (11)
C2—N2—N1	103.95 (10)	N2—C2—H2	124.1
O1—C1—N1	129.42 (12)	N4—C2—H2	124.1
O1—C1—N4	127.80 (12)	N1—C3—C4	113.40 (11)
N1—C1—N4	102.77 (10)	N1—C3—H3A	108.9
C6—C5—C4	120.48 (12)	C4—C3—H3A	108.9
C6—C5—H5	119.8	N1—C3—H3B	108.9
C4—C5—H5	119.8	C4—C3—H3B	108.9
C9—C4—C5	119.16 (13)	H3A—C3—H3B	107.7
C9—C4—C3	120.48 (12)	C7—C8—C9	120.47 (13)
C5—C4—C3	120.35 (12)	C7—C8—H8	119.8
C7—C6—C5	120.20 (13)	C9—C8—H8	119.8
C1—N1—N2—C2	−0.71 (14)	C5—C6—C7—C8	−0.7 (2)
C3—N1—N2—C2	−177.58 (11)	C5—C4—C9—C8	−0.3 (2)
N2—N1—C1—O1	−178.86 (12)	C3—C4—C9—C8	178.48 (13)
C3—N1—C1—O1	−2.2 (2)	N1—N2—C2—N4	0.32 (14)
N2—N1—C1—N4	0.78 (13)	C1—N4—C2—N2	0.15 (15)
C3—N1—C1—N4	177.44 (11)	N3—N4—C2—N2	−175.76 (12)
C2—N4—C1—O1	179.10 (12)	C1—N1—C3—C4	−97.82 (15)
N3—N4—C1—O1	−5.1 (2)	N2—N1—C3—C4	78.60 (15)
C2—N4—C1—N1	−0.55 (13)	C9—C4—C3—N1	114.42 (14)
N3—N4—C1—N1	175.21 (11)	C5—C4—C3—N1	−66.81 (16)
C6—C5—C4—C9	−0.6 (2)	C6—C7—C8—C9	−0.2 (2)
C6—C5—C4—C3	−179.35 (12)	C4—C9—C8—C7	0.7 (2)
C4—C5—C6—C7	1.1 (2)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N3—H32···O1^i	0.90 (1)	2.47 (2)	3.0583 (15)	124 (1)
N3—H31···O1^ii	0.90 (1)	2.22 (2)	3.0701 (16)	156 (2)
C2—H2···O1^iii	0.95	2.24	3.181 (2)	168

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