2,4-Dihydr­oxy-N′-(4-methoxy­benzyl­idene)benzohydrazide

The mol­ecule of the title compound, C₁₅H₁₄N₂O₄, displays a trans configuration with respect to the hydrazide C=N bond. The dihedral angle between the two benzene rings is 15.0 (2)°. In the crystal structure, mol­ecules are linked through inter­molecular O—H...N and O—H...O hydrogen bonds, forming layers parallel to the ab plane; an intramolecular N—H...O hydrogen bond is also present.

Key indicators

• Single-crystal X-ray study
• T = 298 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.031
• wR factor = 0.080
• Data-to-parameter ratio = 7.8

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT066_ALERT_1_C Predicted and Reported Transmissions Identical .          ?
PLAT089_ALERT_3_C Poor Data / Parameter Ratio (Zmax .LT. 18) .....       7.75
PLAT432_ALERT_2_C Short Inter X...Y Contact  O4     ..  C15     ..       2.97 Ang.

Alert level G
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
            correct. If it is not, please give the correct count in the
            _publ_section_exptl_refinement section of the submitted CIF.
           From the CIF: _diffrn_reflns_theta_max           27.00
           From the CIF: _reflns_number_total               1519
           Count of symmetry unique reflns         1520
           Completeness (_total/calc)             99.93%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured         0
           Fraction of Friedel pairs measured     0.000
           Are heavy atom types Z>Si present         no
PLAT804_ALERT_5_G ARU-Pack Problem in PLATON Analysis ............          6 Times
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......          2

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

---

S1. Comment

Schiff base compounds have received much attention in recent years. Some Schiff base metal complexes have been found to have pharmacological and antitumor properties (Brückner et al., 2000; Harrop et al., 2003; Ren et al., 2002). As part of our research programme on the synthesis and characterization of Schiff base compounds (Diao et al., 2007; Diao, 2007; Li et al., 2007; Huang et al., 2007), we report here the structure of the title ligand.

The molecule of the title compound displays a trans configuration with respect to the C=N bond (Fig. 1). The dihedral angle between the two benzene rings is 15.0 (2)°. The molecular conformation is stabilized by an intramolecular N—H···O hydrogen interaction (Table 1). In the crystal, molecules are linked through intermolecular O—H···N and O—H···O hydrogen bonds (Table 1), forming layers parallel to the ab plane (Fig. 2).

Related literature

For the biological properties of Schiff base compounds, see: Brückner et al. (2000); Harrop et al. (2003); Ren et al. (2002). For related structures, see: Diao (2007); Diao et al. (2007); Li et al. (2007); Huang et al. (2007).

S2. Experimental

4-Methoxybenzaldehyde (0.1 mmol, 13.6 mg) and 2,4-dihydroxybenzoic acid hydrazide (0.1 mmol, 16.8 mg) were dissolved in a 95% ethanol solution (10 ml). The mixture was stirred at room temperature to give a clear colourless solution. Crystals of the title compound were formed by gradual evaporation of the solvent over a period of three days at room temperature.

S3. Refinement

Atom H2A was located in a difference Fourier map and refined isotropically, with the N—H distance restrained to 0.90 (1) Å. All other H atoms were placed in idealized positions and constrained to ride on their parent atoms, with O—H = 0.82 Å, C—H = 0.93–0.96 Å, and with U_iso(H) = 1.2U_eq(C) or 1.5U_eq(C, O) for methyl and hydroxy H atoms. In the absence of significant anomalous scattering effects, Friedel opposites were merged in the final refinement.

Computing details

Data collection: SMART (Bruker, 2000); cell refinement: SAINT (Bruker, 2000); data reduction: SAINT (Bruker, 2000); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures

	Fig. 1. The structure of the title compound with displacement ellipsoids drawn at the 30% probability level.
	Fig. 2. Crystal packing of the title compound viewed along the b axis. Intermolecular hydrogen bonds are shown as dashed lines.

2,4-Dihydroxy-N'-(4-methoxybenzylidene)benzohydrazide

Crystal data

C15H14N2O4	F(000) = 600
Mr = 286.28	Dx = 1.407 Mg m^−3
Orthorhombic, Pna21	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2c -2n	Cell parameters from 3064 reflections
a = 12.494 (3) Å	θ = 2.7–27.2°
b = 5.196 (1) Å	µ = 0.10 mm^−1
c = 20.825 (4) Å	T = 298 K
V = 1351.9 (5) Å^3	Block, colourless
Z = 4	0.22 × 0.20 × 0.20 mm

Data collection

Bruker SMART CCD area-detector diffractometer	1519 independent reflections
Radiation source: fine-focus sealed tube	1382 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.025
ω scans	θmax = 27.0°, θmin = 2.0°
Absorption correction: multi-scan (SADABS; Bruker, 2000)	h = −15→15
Tmin = 0.978, Tmax = 0.980	k = −6→5
7661 measured reflections	l = −25→26

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)] = 0.031	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.079	H atoms treated by a mixture of independent and constrained refinement
S = 1.06	w = 1/[σ^2(Fo^2) + (0.0468P)^2 + 0.123P] where P = (Fo^2 + 2Fc^2)/3
1519 reflections	(Δ/σ)max < 0.001
196 parameters	Δρmax = 0.13 e Å^−3
2 restraints	Δρmin = −0.15 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
O1	−0.07270 (13)	0.0953 (3)	0.95352 (10)	0.0550 (5)
O2	0.05579 (11)	1.2801 (3)	0.67387 (9)	0.0461 (4)
O3	0.37031 (11)	1.3774 (3)	0.73708 (8)	0.0411 (4)
H3	0.4359	1.3777	0.7357	0.062*
O4	0.41377 (12)	2.0606 (3)	0.58664 (8)	0.0438 (4)
H4	0.4607	2.1038	0.6120	0.066*
N1	0.11530 (13)	0.9630 (3)	0.76750 (9)	0.0358 (4)
N2	0.18526 (13)	1.1298 (3)	0.73763 (9)	0.0354 (4)
C1	0.09837 (17)	0.6230 (4)	0.84516 (11)	0.0361 (4)
C2	−0.01216 (19)	0.5952 (5)	0.83938 (12)	0.0461 (6)
H2	−0.0499	0.6974	0.8105	0.055*
C3	−0.06553 (18)	0.4174 (5)	0.87614 (13)	0.0490 (6)
H3A	−0.1392	0.3994	0.8717	0.059*
C4	−0.01114 (18)	0.2637 (4)	0.91993 (11)	0.0394 (5)
C5	0.09840 (18)	0.2886 (4)	0.92608 (12)	0.0421 (5)
H5	0.1360	0.1855	0.9548	0.051*
C6	0.15162 (17)	0.4694 (4)	0.88882 (12)	0.0424 (5)
H6	0.2253	0.4876	0.8934	0.051*
C7	0.15821 (17)	0.8097 (4)	0.80745 (11)	0.0377 (5)
H7	0.2320	0.8173	0.8129	0.045*
C8	0.15001 (14)	1.2894 (4)	0.69171 (10)	0.0317 (4)
C9	0.22691 (14)	1.4776 (4)	0.66456 (10)	0.0304 (4)
C10	0.33078 (14)	1.5226 (4)	0.68779 (10)	0.0306 (4)
C11	0.39332 (15)	1.7176 (4)	0.66248 (10)	0.0324 (4)
H11	0.4610	1.7489	0.6793	0.039*
C12	0.35562 (16)	1.8657 (4)	0.61231 (10)	0.0335 (4)
C13	0.25493 (16)	1.8182 (4)	0.58614 (11)	0.0394 (5)
H13	0.2303	1.9129	0.5512	0.047*
C14	0.19282 (16)	1.6282 (4)	0.61303 (10)	0.0373 (5)
H14	0.1250	1.5987	0.5961	0.045*
C15	−0.0203 (2)	−0.0748 (5)	0.99722 (14)	0.0540 (6)
H15A	0.0135	0.0235	1.0306	0.081*
H15B	0.0328	−0.1729	0.9746	0.081*
H15C	−0.0720	−0.1893	1.0159	0.081*
H2A	0.2547 (11)	1.133 (6)	0.7492 (17)	0.080*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0502 (9)	0.0531 (9)	0.0618 (11)	−0.0010 (8)	0.0024 (9)	0.0263 (8)
O2	0.0247 (7)	0.0480 (8)	0.0657 (11)	−0.0043 (6)	−0.0063 (7)	0.0119 (8)
O3	0.0221 (6)	0.0521 (9)	0.0490 (9)	−0.0013 (6)	−0.0039 (6)	0.0161 (8)
O4	0.0398 (8)	0.0458 (9)	0.0458 (8)	−0.0114 (7)	−0.0038 (7)	0.0110 (7)
N1	0.0311 (8)	0.0368 (9)	0.0395 (9)	−0.0081 (7)	0.0034 (7)	0.0004 (8)
N2	0.0258 (8)	0.0401 (9)	0.0404 (9)	−0.0046 (7)	0.0007 (8)	0.0049 (7)
C1	0.0364 (10)	0.0354 (10)	0.0364 (10)	−0.0019 (8)	−0.0005 (8)	−0.0012 (8)
C2	0.0383 (11)	0.0517 (13)	0.0481 (13)	−0.0061 (10)	−0.0100 (10)	0.0175 (11)
C3	0.0346 (10)	0.0557 (13)	0.0567 (14)	−0.0070 (10)	−0.0084 (11)	0.0186 (11)
C4	0.0422 (12)	0.0360 (10)	0.0399 (11)	−0.0009 (9)	0.0012 (9)	0.0062 (9)
C5	0.0439 (12)	0.0400 (11)	0.0425 (11)	0.0066 (9)	−0.0042 (9)	0.0068 (10)
C6	0.0347 (10)	0.0451 (12)	0.0476 (13)	0.0029 (9)	−0.0033 (10)	0.0006 (10)
C7	0.0311 (10)	0.0418 (11)	0.0404 (11)	−0.0033 (9)	−0.0001 (9)	−0.0023 (9)
C8	0.0239 (9)	0.0318 (9)	0.0394 (10)	0.0013 (7)	0.0020 (8)	−0.0037 (8)
C9	0.0233 (8)	0.0324 (9)	0.0356 (10)	0.0009 (7)	0.0000 (8)	−0.0020 (8)
C10	0.0240 (8)	0.0333 (9)	0.0346 (10)	0.0032 (7)	0.0006 (8)	0.0007 (8)
C11	0.0227 (8)	0.0371 (10)	0.0376 (10)	−0.0001 (7)	−0.0016 (8)	−0.0006 (8)
C12	0.0296 (9)	0.0346 (10)	0.0363 (10)	−0.0020 (8)	0.0024 (8)	−0.0004 (8)
C13	0.0333 (10)	0.0460 (11)	0.0389 (11)	−0.0003 (9)	−0.0065 (9)	0.0089 (10)
C14	0.0262 (9)	0.0437 (11)	0.0419 (11)	−0.0031 (8)	−0.0081 (8)	0.0019 (9)
C15	0.0663 (16)	0.0453 (12)	0.0504 (14)	0.0093 (13)	0.0052 (13)	0.0159 (11)

Geometric parameters (Å, º)

O1—C4	1.359 (3)	C4—C5	1.381 (3)
O1—C15	1.427 (3)	C5—C6	1.388 (3)
O2—C8	1.235 (2)	C5—H5	0.9300
O3—C10	1.366 (2)	C6—H6	0.9300
O3—H3	0.8200	C7—H7	0.9300
O4—C12	1.356 (2)	C8—C9	1.483 (3)
O4—H4	0.8200	C9—C14	1.394 (3)
N1—C7	1.270 (3)	C9—C10	1.405 (3)
N1—N2	1.379 (2)	C10—C11	1.384 (3)
N2—C8	1.340 (3)	C11—C12	1.380 (3)
N2—H2A	0.901 (10)	C11—H11	0.9300
C1—C6	1.381 (3)	C12—C13	1.393 (3)
C1—C2	1.394 (3)	C13—C14	1.375 (3)
C1—C7	1.455 (3)	C13—H13	0.9300
C2—C3	1.373 (3)	C14—H14	0.9300
C2—H2	0.9300	C15—H15A	0.9600
C3—C4	1.390 (3)	C15—H15B	0.9600
C3—H3A	0.9300	C15—H15C	0.9600
C4—O1—C15	117.86 (19)	O2—C8—N2	120.23 (18)
C10—O3—H3	109.5	O2—C8—C9	121.91 (18)
C12—O4—H4	109.5	N2—C8—C9	117.85 (16)
C7—N1—N2	114.96 (16)	C14—C9—C10	117.00 (17)
C8—N2—N1	120.15 (16)	C14—C9—C8	117.74 (17)
C8—N2—H2A	120 (2)	C10—C9—C8	125.23 (17)
N1—N2—H2A	120 (2)	O3—C10—C11	119.10 (16)
C6—C1—C2	118.3 (2)	O3—C10—C9	120.06 (16)
C6—C1—C7	119.57 (19)	C11—C10—C9	120.82 (17)
C2—C1—C7	122.1 (2)	C12—C11—C10	120.26 (17)
C3—C2—C1	120.2 (2)	C12—C11—H11	119.9
C3—C2—H2	119.9	C10—C11—H11	119.9
C1—C2—H2	119.9	O4—C12—C11	122.14 (18)
C2—C3—C4	121.0 (2)	O4—C12—C13	117.50 (18)
C2—C3—H3A	119.5	C11—C12—C13	120.36 (18)
C4—C3—H3A	119.5	C14—C13—C12	118.52 (19)
O1—C4—C5	125.0 (2)	C14—C13—H13	120.7
O1—C4—C3	115.5 (2)	C12—C13—H13	120.7
C5—C4—C3	119.5 (2)	C13—C14—C9	122.94 (18)
C4—C5—C6	119.1 (2)	C13—C14—H14	118.5
C4—C5—H5	120.4	C9—C14—H14	118.5
C6—C5—H5	120.4	O1—C15—H15A	109.5
C1—C6—C5	121.9 (2)	O1—C15—H15B	109.5
C1—C6—H6	119.0	H15A—C15—H15B	109.5
C5—C6—H6	119.0	O1—C15—H15C	109.5
N1—C7—C1	123.69 (19)	H15A—C15—H15C	109.5
N1—C7—H7	118.2	H15B—C15—H15C	109.5
C1—C7—H7	118.2

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N2—H2A···O3	0.90 (1)	1.94 (2)	2.646 (2)	134 (3)
O4—H4···O2^i	0.82	1.85	2.671 (2)	174
O3—H3···N1^ii	0.82	2.48	3.234 (2)	154
O3—H3···O2^ii	0.82	2.14	2.788 (2)	136

Symmetry codes: (i) x+1/2, −y+7/2, z; (ii) x+1/2, −y+5/2, z.