1-Acetyl-3-(p-chloro­benzyl)-4-(p-chloro­benzyl­iden­amino)-4,5-di­hydro-1H-1,2,4-triazol-5-one

In the title compound, C₁₈H₁₄Cl₂N₄O₂, the triazole ring and benzyl­iden­amino moiety are each planar, and approximately coplanar with respect to each other. The crystal structure is stabilized by C—H...O and C—H...N intra- and intermol­ecular hydrogen bonds.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.005 Å
• R factor = 0.060
• wR factor = 0.133
• Data-to-parameter ratio = 11.6

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


 Alert Level C:



REFLT_03
         From the CIF: _diffrn_reflns_theta_max           24.79
         From the CIF: _reflns_number_total               2730
         TEST2: Reflns within _diffrn_reflns_theta_max
         Count of symmetry unique reflns         3010
         Completeness (_total/calc)             90.70%
          Alert C: < 95% complete

THETM_01  Alert C The value of sine(theta_max)/wavelength is less than 0.590
          Calculated sin(theta_max)/wavelength =    0.5899


 0 Alert Level A = Potentially serious problem

 0 Alert Level B = Potential problem

 2 Alert Level C = Please check

---

S1. Comment

The 1,2,4-triazole ring systems are very interesting because of their similarity to the 1,3-imidazole bridging found in the copper–zinc protein superoxide dismutase (Feiters, 1990) and for their ability to act as a doubly bidentate chelating ligand (Wang et al., 1998). Compounds containing these systems have been structurally characterized as part of a study of Schiff bases of amine- and thione-substituted triazoles (McCarrick et al., 1999; Sen et al., 1998) and their metal complexes (Sen et al., 1996, 1997; Clark et al., 1999). Most Schiff bases possess antibacterial, anticancer, antiinflamunantory and antitoxic activities (Williams, 1972), and sulfur-containing Schiff bases are particularly effective. The 4-amino-3-methyl-1,2,4-triazole-5-thione derivative of p-nitrophenyl aldehyde has been structurally characterized and it has been shown to be highly effective as an inhibitor of Staphylococcus aureus (Liu et al., 1999). Therefore, the crystal structure analysis of the title compound, (I), has been carried out.

The title compound consists of one 1,2,4-triazole ring (ring A: N3/C8/N2/C9/N4) with an acetly group substituted at N3, a benzylidenamino group, a p-chlorobenzyl group and an O atom substituted at C9, N2, and C8, respectively.

The N═C bond lengths [N1═C7 = 1.276 (4) Å and N4═C9 = 1.280 (4) Å] are close to the values quoted in the literature (Puviarasan et al., 1999; Liu et al., 1999; Zhu et al., 2000), while the presence of the acetyl group at N3 and the benzylidenamino group at C9 causes a small even if significant stretching of the N—N bond [N3—N4 = 1.404 (4) Å].

The Cl1—C14 and Cl2—C3 bond lengths [1.744 (4) and 1.742 (4) Å, respectively] conform with those previously found (Wang et al., 1998; Puviarasan et al., 1999).

The title compound consists of three planar rings. One is the triazole ring, ring A, others are ring B (C1—C6) and ring C (C11—C16). In the triazole ring, the observed maximum deviation is 0.008 (3) Å for C9 atom. The O1 atom is 0.024 (3) Å from the plane. The dihedral angle between rings A/B, A/C and B/C are 11.1 (1), 84.0 (1) and 89.1 (1)°, respectively.

The crystal structure of (I) is stabilized by four intramolecular and two intermolecular hydrogen bonds. Indeed all intramolecular hydrogen bonds seem to drive the orientation of the substituents with respect to the triazole rings as indicated by the near coplanarity of the groups involved. In the molecule, the p-chlorobenzyl and the acetyl group are able to form hydrogen bonds with the benzylidenamino and atom O1 of a symmetry-related molecule. All details of the C—H···N and C—H···O inter- and intramolecular hydrogen bonds found in the crystal are quoted in Table 2. These contacts generate infinite chains in the crystal and seem to force the molecule to adapt a twisted conformation.

S2. Experimental

3-(p-Chlorobenzyl)-4-(p-chlorobenzylidenamino)-4,5-dihydro-1H-1,2,4-triazol- 5-one (0.01 mol) was treated with 10 ml of acetic anhydride and the mixture was refluxed for 1 h. The resulting product was filtered off and dried in vacuo. Several recrystallizations from ethyl acetate gave the pure title compound. Yield: 84%, m.p.: 461–462 K.

S3. Refinement

The H atoms were located geometrically and refined using a riding model, fixing the aromatic C—H distance at 0.93 Å, the methylene C—H distance 0.97 Å and methyl group C—H distance 0.96 Å.

Computing details

Data collection: SMART (Bruker, 1998); cell refinement: SMART; data reduction: SAINT (Bruker, 1998); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPIII (Burnett & Johnson, 1996); software used to prepare material for publication: WinGX (Farrugia, 1997) and PARST (Nardelli, 1995).

Figures

	Fig. 1. An ORTEPIII drawing of the title compound, showing the atomic numbering scheme. Displacement ellipsoids of non-H atoms are shown at the 50% probability level.
	Fig. 2. A packing diagram of title compound, illustrating the hydrogen-bonding network.

1-Acetyl-3-(p-chlorobenzyl)-4-benzylidenamino-4,5-dihydro- 1H-1,2,4-triazole-5-one

Crystal data

C18H14Cl2N4O2	Z = 2
Mr = 389.23	F(000) = 400
Triclinic, P1	Dx = 1.478 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 6.7109 (10) Å	Cell parameters from 870 reflections
b = 8.6329 (12) Å	θ = 2.4–22.2°
c = 15.833 (2) Å	µ = 0.39 mm^−1
α = 84.144 (3)°	T = 293 K
β = 79.466 (3)°	Prism, colourless
γ = 76.252 (3)°	0.42 × 0.10 × 0.10 mm
V = 874.3 (2) Å^3

Data collection

Bruker SMART CCD area-detector diffractometer	1873 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.027
Graphite monochromator	θmax = 24.8°, θmin = 2.4°
ϕ and ω scans	h = −7→7
4127 measured reflections	k = −8→10
2730 independent reflections	l = −18→17

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)] = 0.060	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.133	H-atom parameters constrained
S = 1.04	w = 1/[σ^2(Fo^2) + (0.0538P)^2 + 0.3745P] where P = (Fo^2 + 2Fc^2)/3
2730 reflections	(Δ/σ)max < 0.001
235 parameters	Δρmax = 0.33 e Å^−3
0 restraints	Δρmin = −0.35 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
O2	−1.1800 (4)	1.7986 (3)	1.00736 (17)	0.0572 (8)
C15	−1.1525 (7)	1.7652 (5)	0.5174 (3)	0.0533 (11)
H15	−1.1149	1.8476	0.4800	0.064*
C17	−1.2249 (6)	1.7657 (4)	0.9423 (2)	0.0402 (9)
C18	−1.4333 (6)	1.8221 (5)	0.9154 (3)	0.0538 (11)
H18A	−1.4302	1.7809	0.8610	0.081*
H18B	−1.4677	1.9367	0.9101	0.081*
H18C	−1.5360	1.7848	0.9579	0.081*
Cl1	−1.5014 (2)	1.82542 (15)	0.44684 (8)	0.0794 (5)
C16	−1.0211 (6)	1.6824 (5)	0.5728 (2)	0.0482 (10)
H16	−0.8947	1.7094	0.5723	0.058*
O1	−0.7919 (4)	1.5751 (3)	0.96023 (16)	0.0450 (7)
N3	−1.0756 (4)	1.6646 (3)	0.88547 (18)	0.0362 (7)
C14	−1.3371 (6)	1.7252 (5)	0.5182 (2)	0.0447 (10)
C8	−0.8808 (6)	1.5775 (4)	0.9002 (2)	0.0368 (9)
N4	−1.1222 (5)	1.6352 (4)	0.80651 (18)	0.0396 (8)
N2	−0.8117 (4)	1.4923 (3)	0.82625 (18)	0.0370 (7)
C9	−0.9615 (5)	1.5344 (4)	0.7732 (2)	0.0351 (9)
C11	−1.0747 (5)	1.5607 (4)	0.6287 (2)	0.0361 (9)
C7	−0.4901 (6)	1.3436 (4)	0.8489 (2)	0.0400 (9)
H7	−0.5061	1.3935	0.8998	0.048*
C5	−0.1342 (6)	1.1938 (4)	0.8636 (2)	0.0430 (10)
H5	−0.1426	1.2496	0.9119	0.052*
N1	−0.6310 (4)	1.3795 (3)	0.80140 (18)	0.0382 (7)
C13	−1.3938 (6)	1.6057 (5)	0.5726 (3)	0.0547 (11)
H13	−1.5202	1.5790	0.5727	0.066*
C10	−0.9282 (6)	1.4656 (5)	0.6873 (2)	0.0463 (10)
H10A	−0.9473	1.3569	0.6958	0.056*
H10B	−0.7860	1.4618	0.6594	0.056*
C6	−0.3024 (5)	1.2219 (4)	0.8210 (2)	0.0354 (8)
C4	0.0470 (6)	1.0837 (4)	0.8356 (2)	0.0462 (10)
H4	0.1605	1.0664	0.8641	0.055*
C12	−1.2630 (6)	1.5247 (5)	0.6276 (3)	0.0513 (11)
H12	−1.3027	1.4431	0.6651	0.062*
C3	0.0562 (6)	1.0005 (4)	0.7648 (2)	0.0413 (9)
C1	−0.2889 (6)	1.1329 (4)	0.7510 (2)	0.0458 (10)
H1	−0.4030	1.1484	0.7229	0.055*
Cl2	0.28328 (17)	0.86281 (13)	0.72774 (7)	0.0627 (4)
C2	−0.1114 (6)	1.0229 (4)	0.7224 (2)	0.0481 (10)
H2	−0.1041	0.9646	0.6753	0.058*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O2	0.0571 (18)	0.0689 (19)	0.0462 (17)	−0.0008 (15)	−0.0156 (14)	−0.0252 (14)
C15	0.067 (3)	0.043 (2)	0.049 (3)	−0.009 (2)	−0.015 (2)	0.0058 (19)
C17	0.043 (2)	0.038 (2)	0.037 (2)	−0.0055 (18)	−0.0054 (18)	−0.0040 (17)
C18	0.044 (2)	0.063 (3)	0.051 (3)	0.000 (2)	−0.011 (2)	−0.014 (2)
Cl1	0.0939 (10)	0.0774 (9)	0.0656 (8)	0.0140 (7)	−0.0530 (7)	−0.0047 (6)
C16	0.044 (2)	0.055 (3)	0.048 (3)	−0.012 (2)	−0.014 (2)	−0.004 (2)
O1	0.0454 (16)	0.0528 (17)	0.0387 (15)	−0.0028 (13)	−0.0188 (13)	−0.0096 (12)
N3	0.0350 (18)	0.0422 (18)	0.0308 (17)	−0.0006 (14)	−0.0125 (13)	−0.0053 (14)
C14	0.049 (2)	0.049 (2)	0.033 (2)	0.007 (2)	−0.0178 (18)	−0.0089 (19)
C8	0.039 (2)	0.039 (2)	0.033 (2)	−0.0045 (17)	−0.0100 (18)	−0.0033 (17)
N4	0.0405 (18)	0.0461 (19)	0.0318 (17)	−0.0023 (16)	−0.0125 (14)	−0.0055 (14)
N2	0.0349 (17)	0.0423 (18)	0.0323 (17)	−0.0004 (15)	−0.0102 (14)	−0.0064 (14)
C9	0.037 (2)	0.036 (2)	0.031 (2)	−0.0023 (18)	−0.0108 (17)	0.0006 (16)
C11	0.036 (2)	0.040 (2)	0.029 (2)	0.0031 (18)	−0.0082 (16)	−0.0130 (17)
C7	0.044 (2)	0.046 (2)	0.031 (2)	−0.0077 (19)	−0.0086 (18)	−0.0047 (17)
C5	0.044 (2)	0.051 (2)	0.036 (2)	−0.0035 (19)	−0.0164 (18)	−0.0085 (18)
N1	0.0347 (17)	0.0418 (18)	0.0348 (17)	0.0006 (14)	−0.0093 (14)	−0.0029 (14)
C13	0.042 (2)	0.063 (3)	0.062 (3)	−0.011 (2)	−0.017 (2)	0.000 (2)
C10	0.045 (2)	0.055 (3)	0.035 (2)	0.0034 (19)	−0.0128 (18)	−0.0088 (18)
C6	0.039 (2)	0.033 (2)	0.034 (2)	−0.0033 (17)	−0.0138 (17)	−0.0007 (16)
C4	0.040 (2)	0.049 (2)	0.049 (2)	−0.0020 (19)	−0.0153 (19)	−0.007 (2)
C12	0.051 (3)	0.056 (3)	0.045 (2)	−0.010 (2)	−0.011 (2)	0.010 (2)
C3	0.038 (2)	0.038 (2)	0.044 (2)	−0.0010 (18)	−0.0084 (18)	−0.0043 (18)
C1	0.047 (2)	0.050 (2)	0.044 (2)	0.000 (2)	−0.0271 (19)	−0.0072 (19)
Cl2	0.0496 (6)	0.0592 (7)	0.0724 (8)	0.0082 (5)	−0.0099 (5)	−0.0204 (6)
C2	0.058 (3)	0.045 (2)	0.042 (2)	−0.003 (2)	−0.016 (2)	−0.0114 (19)

Geometric parameters (Å, º)

O2—C17	1.202 (4)	C11—C12	1.375 (5)
C15—C14	1.361 (6)	C11—C10	1.515 (5)
C15—C16	1.383 (5)	C7—N1	1.276 (4)
C15—H15	0.9300	C7—C6	1.465 (5)
C17—N3	1.411 (4)	C7—H7	0.9300
C17—C18	1.492 (5)	C5—C6	1.379 (5)
C18—H18A	0.9600	C5—C4	1.385 (5)
C18—H18B	0.9600	C5—H5	0.9300
C18—H18C	0.9600	C13—C12	1.372 (5)
Cl1—C14	1.744 (4)	C13—H13	0.9300
C16—C11	1.374 (5)	C10—H10A	0.9700
C16—H16	0.9300	C10—H10B	0.9700
O1—C8	1.208 (4)	C6—C1	1.390 (5)
N3—C8	1.391 (4)	C4—C3	1.376 (5)
N3—N4	1.404 (4)	C4—H4	0.9300
C14—C13	1.355 (6)	C12—H12	0.9300
C8—N2	1.393 (4)	C3—C2	1.378 (5)
N4—C9	1.280 (4)	C3—Cl2	1.742 (4)
N2—N1	1.384 (4)	C1—C2	1.371 (5)
N2—C9	1.386 (4)	C1—H1	0.9300
C9—C10	1.498 (5)	C2—H2	0.9300
C14—C15—C16	119.4 (4)	N1—C7—C6	118.3 (3)
C14—C15—H15	120.3	N1—C7—H7	120.8
C16—C15—H15	120.3	C6—C7—H7	120.8
O2—C17—N3	119.9 (3)	C6—C5—C4	121.0 (3)
O2—C17—C18	125.0 (4)	C6—C5—H5	119.5
N3—C17—C18	115.0 (3)	C4—C5—H5	119.5
C17—C18—H18A	109.5	C7—N1—N2	119.9 (3)
C17—C18—H18B	109.5	C14—C13—C12	119.3 (4)
H18A—C18—H18B	109.5	C14—C13—H13	120.3
C17—C18—H18C	109.5	C12—C13—H13	120.3
H18A—C18—H18C	109.5	C9—C10—C11	113.0 (3)
H18B—C18—H18C	109.5	C9—C10—H10A	109.0
C11—C16—C15	120.9 (4)	C11—C10—H10A	109.0
C11—C16—H16	119.5	C9—C10—H10B	109.0
C15—C16—H16	119.5	C11—C10—H10B	109.0
C8—N3—N4	112.7 (3)	H10A—C10—H10B	107.8
C8—N3—C17	127.0 (3)	C5—C6—C1	118.4 (3)
N4—N3—C17	120.2 (3)	C5—C6—C7	120.6 (3)
C13—C14—C15	120.9 (4)	C1—C6—C7	121.0 (3)
C13—C14—Cl1	119.2 (3)	C3—C4—C5	118.9 (3)
C15—C14—Cl1	119.9 (3)	C3—C4—H4	120.5
O1—C8—N3	130.2 (3)	C5—C4—H4	120.5
O1—C8—N2	128.3 (3)	C13—C12—C11	121.7 (4)
N3—C8—N2	101.5 (3)	C13—C12—H12	119.1
C9—N4—N3	104.5 (3)	C11—C12—H12	119.1
N1—N2—C9	119.7 (3)	C4—C3—C2	121.4 (3)
N1—N2—C8	131.3 (3)	C4—C3—Cl2	119.8 (3)
C9—N2—C8	109.0 (3)	C2—C3—Cl2	118.9 (3)
N4—C9—N2	112.2 (3)	C2—C1—C6	121.5 (3)
N4—C9—C10	126.5 (3)	C2—C1—H1	119.3
N2—C9—C10	121.3 (3)	C6—C1—H1	119.3
C16—C11—C12	117.7 (3)	C1—C2—C3	118.8 (3)
C16—C11—C10	121.2 (3)	C1—C2—H2	120.6
C12—C11—C10	121.1 (4)	C3—C2—H2	120.6
C14—C15—C16—C11	−0.2 (6)	C6—C7—N1—N2	179.1 (3)
O2—C17—N3—C8	8.9 (6)	C9—N2—N1—C7	178.0 (3)
C18—C17—N3—C8	−170.2 (3)	C8—N2—N1—C7	−3.1 (5)
O2—C17—N3—N4	−175.3 (3)	C15—C14—C13—C12	0.1 (6)
C18—C17—N3—N4	5.6 (5)	Cl1—C14—C13—C12	178.7 (3)
C16—C15—C14—C13	0.2 (6)	N4—C9—C10—C11	17.2 (6)
C16—C15—C14—Cl1	−178.5 (3)	N2—C9—C10—C11	−162.5 (3)
N4—N3—C8—O1	179.2 (4)	C16—C11—C10—C9	91.1 (4)
C17—N3—C8—O1	−4.8 (6)	C12—C11—C10—C9	−91.1 (4)
N4—N3—C8—N2	−0.5 (4)	C4—C5—C6—C1	2.3 (6)
C17—N3—C8—N2	175.6 (3)	C4—C5—C6—C7	−177.3 (3)
C8—N3—N4—C9	−0.4 (4)	N1—C7—C6—C5	171.4 (3)
C17—N3—N4—C9	−176.8 (3)	N1—C7—C6—C1	−8.2 (5)
O1—C8—N2—N1	2.5 (6)	C6—C5—C4—C3	−0.9 (6)
N3—C8—N2—N1	−177.8 (3)	C14—C13—C12—C11	−0.4 (6)
O1—C8—N2—C9	−178.5 (4)	C16—C11—C12—C13	0.4 (6)
N3—C8—N2—C9	1.2 (4)	C10—C11—C12—C13	−177.5 (4)
N3—N4—C9—N2	1.2 (4)	C5—C4—C3—C2	−0.9 (6)
N3—N4—C9—C10	−178.5 (3)	C5—C4—C3—Cl2	179.4 (3)
N1—N2—C9—N4	177.5 (3)	C5—C6—C1—C2	−2.1 (6)
C8—N2—C9—N4	−1.6 (4)	C7—C6—C1—C2	177.5 (4)
N1—N2—C9—C10	−2.8 (5)	C6—C1—C2—C3	0.3 (6)
C8—N2—C9—C10	178.1 (3)	C4—C3—C2—C1	1.2 (6)
C15—C16—C11—C12	−0.1 (5)	Cl2—C3—C2—C1	−179.1 (3)
C15—C16—C11—C10	177.8 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C10—H10B···N1	0.97	2.61	2.853 (5)	94
C1—H1···N1	0.93	2.50	2.792 (4)	99
C18—H18A···N4	0.96	2.22	2.754 (4)	114
C7—H7···O1	0.93	2.29	2.949 (4)	127
C12—H12···N1^i	0.93	2.90	3.678 (5)	142
C18—H18C···O1^i	0.96	2.77	3.513 (5)	135

Symmetry code: (i) x−1, y, z.