4-(4-Hydro­xy­benzyl­idene­amino)-4H-1,2,4-triazole hemihydrate

In the title compound, 4-(4H-1,2,4-triazol-4-yl­imino­methyl)­phenol hemi­hydrate, C₉H₈N₄O·0.5H₂O or (I)·0.5H₂O, mol­ecules of (I) are arranged as layers running along the b axis through intermolecular O—H...N and C—H...O hydrogen bonds. These layers are stabilized by hydrogen-bonded water mol­ecules to form three-dimensional networks.

S1. Comment

The aroyl Schiff bases of 4-amino-1,2,4-triazole have received considerable attention over the past few decades (Kitaev et al., 1971; Mazza et al., 1976; Kargin et al., 1988). It is of interest that some of them are anti-inflammatory agents (Gupta & Bhargava, 1978) and new coccidiostatic drugs (Colautti et al., 1971). As a continuation of our study on the structure of Schiff-base containing substituted 1,2,4-triazole (Raj et al., 1999), we report here the title structure, (I).

An ORTEPII (Johnson, 1976) diagram with numbering scheme is shown in Fig.1. Compared to 9-(4H-1,2,4-triazol-4-ylimino)-4,5-diazafluorene (Raj et al., 1999), molecules of (I) are essentially planar [the maximum displacement from the least-squares mean plane through the whole molecule is 0.073 (2) Å for C9]. The bond lengths and angles observed in the structure are in the normal ranges. In contrast with 2-(2-hydroxybenzylidene)-1-(2-picoloyl)-hydrazine hemihydrate (Wang et al., 1998), molecules of (I) are arranged as layers running along the b axis through the strong intermolecular O1—H11···N4 (−1/2 + x, −1/2 − y, 1/2 + z) hydrogen bonds and the weak C9—H9···O1 (1/2 − x, −1/2 + y, −1/2 − z) ones. These layers are stabilized by water molecules to form three-dimensional networks through the strong O1W—H1W···N3 hydrogen bonds and the weak C7—H7···O1W (x, −y, 1/2 + z) ones. The geometry of these interactions are listed in Table 2. The packing diagram of the molecules showing the hydrogen bonds is shown in Fig.2. The water molecules (O1W) lie on crystallographic twofold axes.

S2. Experimental

The title compound was prepared by condensation of equivalent amounts of p-hydroxybenzaldehyde and 4-amino-1,2,4-triazole in ethanol for 5 h (Kitaev et al., 1971). Diffraction quality crystals were obtained by recrystallization from ethanol.

Computing details

Data collection: XSCANS (Siemens, 1994); cell refinement: XSCANS; data reduction: SHELXTL (Siemens, 1995); program(s) used to solve structure: SHELXTL; program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Figures

Fig. 1. The structure of (I) showing 50% probability displacement ellipsoids with the numbering scheme. Fig. 2. A view of the crystal packing along the b axis. The hydrogen bonds are shown as broken lines.

4-[(4-Hydroxybenzylidene)amino]-1,2,4-triazole Hemihydrate

Crystal data

C9H8N4O·0.5H2O	F(000) = 824
Mr = 197.20	Dx = 1.413 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
a = 14.134 (2) Å	Cell parameters from 36 reflections
b = 12.491 (2) Å	θ = 5.2–9.0°
c = 12.063 (2) Å	µ = 0.10 mm^−1
β = 119.483 (10)°	T = 293 K
V = 1854.0 (5) Å^3	Block, colourless
Z = 8	0.30 × 0.26 × 0.20 mm

Data collection

Siemens P4 diffractometer	1100 reflections with I > 2σ(I)
Radiation source: sealed tube	Rint = 0.021
Graphite monochromator	θmax = 25.0°, θmin = 2.3°
2θ/ω scans	h = −1→16
Absorption correction: empirical (using intensity measurements) (North et al., 1968)	k = −1→14
Tmin = 0.954, Tmax = 0.968	l = −14→12
2043 measured reflections	3 standard reflections every 97 reflections
1642 independent reflections	intensity decay: 5.8%

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.057	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.155	Calculated w = 1/[σ^2(Fo^2) + (0.0851P)^2 + 1.2289P] where P = (Fo^2 + 2Fc^2)/3
S = 1.10	(Δ/σ)max = −0.006
1637 reflections	Δρmax = 0.28 e Å^−3
133 parameters	Δρmin = −0.21 e Å^−3
6 restraints	Extinction correction: SHELXLTL (Siemens, 1995), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0022 (6)

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 on F² for ALL reflections except for 5 with very negative F² or flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The observed criterion of F² > σ(F²) is used only for calculating R factor obs 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	0.36269 (10)	−0.22004 (12)	−0.36220 (12)	0.0592 (4)
N2	0.42052 (10)	−0.21906 (12)	−0.42969 (12)	0.0555 (4)
N3	0.50164 (10)	−0.17763 (14)	−0.53779 (13)	0.0684 (4)
N4	0.51432 (10)	−0.28616 (13)	−0.51165 (13)	0.0654 (5)
C1	0.15648 (12)	−0.07820 (15)	−0.14843 (14)	0.0547 (4)
C2	0.18684 (13)	0.0064 (2)	−0.1978 (2)	0.0674 (5)
H2	0.18893	0.0928	−0.1669	0.081*
C3	0.24364 (13)	−0.0127 (2)	−0.2618 (2)	0.0664 (5)
H3	0.28024	0.0600	−0.2960	0.080*
C4	0.27119 (12)	−0.11595 (14)	−0.27746 (14)	0.0512 (4)
C5	0.24019 (12)	−0.20009 (14)	−0.22722 (15)	0.0578 (5)
H5	0.25066	−0.28161	−0.24444	0.069*
C6	0.18306 (12)	−0.1821 (2)	−0.16360 (15)	0.0579 (5)
H6	0.16998	−0.2554	−0.11770	0.070*
C7	0.33137 (12)	−0.1293 (2)	−0.34578 (14)	0.0571 (5)
H7	0.34949	−0.0561	−0.38294	0.068*
C8	0.44556 (12)	−0.1390 (2)	−0.4875 (2)	0.0640 (5)
H8	0.43028	−0.0563	−0.4773	0.077*
C9	0.46542 (12)	−0.3090 (2)	−0.4471 (2)	0.0611 (5)
H9	0.44066	−0.3905	−0.4192	0.073*
O1	0.10159 (9)	−0.05461 (11)	−0.08634 (11)	0.0718 (4)
H11	0.07073	−0.12318	−0.07222	0.086*
O1W	0.5000	−0.0672 (2)	−0.7500	0.0933 (6)
HW1	0.5097	−0.1098 (2)	−0.6731	0.112*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0714 (5)	0.0627 (9)	0.0720 (6)	0.0007 (6)	0.0573 (4)	−0.0025 (6)
N2	0.0643 (5)	0.0590 (8)	0.0663 (6)	−0.0027 (6)	0.0500 (4)	−0.0033 (6)
N3	0.0786 (6)	0.0777 (10)	0.0797 (6)	−0.0026 (8)	0.0627 (5)	0.0006 (7)
N4	0.0686 (6)	0.0775 (10)	0.0756 (7)	−0.0004 (7)	0.0551 (5)	−0.0053 (7)
C1	0.0617 (6)	0.0610 (10)	0.0637 (6)	−0.0037 (7)	0.0481 (5)	−0.0055 (7)
C2	0.0953 (8)	0.0492 (10)	0.0965 (8)	−0.0026 (8)	0.0771 (6)	−0.0040 (8)
C3	0.0949 (8)	0.0476 (10)	0.0943 (8)	−0.0053 (8)	0.0754 (6)	−0.0022 (8)
C4	0.0594 (6)	0.0524 (9)	0.0587 (6)	−0.0052 (7)	0.0421 (5)	−0.0056 (7)
C5	0.0707 (7)	0.0504 (10)	0.0744 (8)	−0.0026 (8)	0.0526 (6)	−0.0021 (7)
C6	0.0712 (7)	0.0524 (10)	0.0727 (7)	−0.0043 (8)	0.0528 (5)	0.0006 (7)
C7	0.0694 (7)	0.0545 (10)	0.0696 (7)	−0.0060 (8)	0.0513 (6)	−0.0067 (7)
C8	0.0757 (7)	0.0663 (11)	0.0776 (8)	−0.0034 (9)	0.0590 (6)	0.0017 (8)
C9	0.0666 (7)	0.0657 (11)	0.0754 (7)	−0.0004 (8)	0.0537 (5)	−0.0070 (8)
O1	0.0866 (5)	0.0743 (8)	0.0895 (5)	−0.0024 (6)	0.0703 (4)	−0.0038 (5)
O1W	0.1481 (11)	0.0615 (12)	0.1233 (10)	0.000	0.1077 (8)	0.000

Geometric parameters (Å, º)

N1—C7	1.267 (2)	C1—C2	1.381 (3)
N1—N2	1.409 (2)	C1—C6	1.388 (3)
N2—C9	1.357 (2)	C2—C3	1.382 (3)
N2—C8	1.362 (2)	C3—C4	1.386 (3)
N3—C8	1.304 (3)	C4—C5	1.388 (3)
N3—N4	1.383 (2)	C4—C7	1.456 (3)
N4—C9	1.302 (2)	C5—C6	1.379 (3)
C1—O1	1.350 (2)
C7—N1—N2	115.4 (2)	C2—C3—C4	121.1 (2)
C9—N2—C8	105.7 (2)	C3—C4—C5	118.4 (2)
C9—N2—N1	122.0 (2)	C3—C4—C7	117.7 (2)
C8—N2—N1	132.3 (2)	C5—C4—C7	123.9 (2)
C8—N3—N4	107.3 (2)	C6—C5—C4	121.1 (2)
C9—N4—N3	107.7 (2)	C5—C6—C1	119.8 (2)
O1—C1—C2	117.2 (2)	N1—C7—C4	122.5 (2)
O1—C1—C6	123.0 (2)	N3—C8—N2	109.7 (2)
C2—C1—C6	119.8 (2)	N4—C9—N2	109.7 (2)
C1—C2—C3	119.9 (2)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H11···N4^i	1.01	1.74	2.717 (2)	161
C9—H9···O1^ii	1.18	2.15	3.293 (3)	164
O1W—H1W···N3	1.02	1.89	2.898 (2)	169
C7—H7···O1W^iii	1.10	2.47	3.214 (2)	123

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