(Z)-Ethyl 4-chloro-2-[2-(2-methoxy­phen­yl)hydrazono]-3-oxobutanoate

The title compound, C₁₃H₁₅ClN₂O₄, adopts a keto–hydrazo tautomeric form stabilized by intra­molecular N—H...O hydrogen bonds. The phenyl­hydrazone fragment is planar within ±0.028 (2) Å. The dihedral angle between the phenyl­hydrazone and oxobutanoate planes is 8.15 (9)°. Symmetry-related mol­ecules are linked via C—H...O hydrogen bonds to form chains along [101].

Key indicators

• Single-crystal X-ray study
• T = 296 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.040
• wR factor = 0.117
• Data-to-parameter ratio = 14.7

checkCIF/PLATON results

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Alert level C
PLAT250_ALERT_2_C Large U3/U1 Ratio for Average U(i,j) Tensor ....       2.12

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   1 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
   1 ALERT type 2 Indicator that the structure model may be wrong or deficient
   0 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion

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S1. Comment

Various hydrazone compounds possess strong bactericidal, herbicidal, insecticidal and fungicidal properties (Sahni et al., 1977). Some phenylhydrazone derivatives have been shown to be potentially DNA-damaging and are mutagenic agents (Okabe et al., 1993). In addition, hydrazones have analytical applications (Heit & Ryan, 1966; Jensen & Pflaum, 1967; Dey et al., 1985). Hydrazones have interesting ligational properties as a result of the presence of several potential coordination sites (Dutta & Hossain, 1985), and both transition and non-transition metal complexes of these ligands have been synthesized previously (Dey et al., 1992).

As part of our ongoing research on phenylhydrazonodiones, the title compound, (I), has been synthesized and its crystal structure is reported here. Previously we reported the structure of ethyl 4-chloro- 3-oxo-2-(phenylhydrazono)butyrate (Alpaslan et al., 2005a), (E)-ethyl 4-chloro-3-[2-(2-fluorophenyl)hydrazono]butanoate (Alpaslan et al., 2005b), ethyl 4-chloro-2-[(2-nitrophenyl) hydrazono]-3-oxobutyrate (Odabaşoǧlu et al., 2005a) and ethyl 4-chloro-2-[(4-nitrophenyl)hydrazono]-3-oxobutyrate (Odabaşoǧlu et al., 2005b).

Our investigations show that, in the solid state, the molecular structure of (I) adopts the keto–hydrazo tautomeric form with intramolecular hydrogen bonds (Fig. 1). The phenylhydrazone fragment is planar within ±0.028 (2) Å, and atoms O4 and C7 deviate from that plane by 0.014 (3) and −0.165 (4) Å, respectively. The oxobutanoate fragment (O1–O3/C8–C13) is planar (r.m.s deviation 0.020 Å). The dihedral angle between the phenylhydrazone and O1–O3/C8–C13 planes is 8.15 (9)°.

It is remarkable that the Z isomer of the methoxyphenylhydrazone derivative was formed preferentially over the E isomer since the latter would almost certainly feature an N—H···O═C intramolecular hydrogen bond. In (I), the imine group adopts a Z configuration, with bond lengths C1—N1 = 1.408 (2) Å, C8—N2 = 1.311 (2) Å and N1—N2 = 1.300 (2) Å. These data show that there is significant elongation of the N1—N2 bond and contraction of the C1—C2 bond in comparsion with azo compounds. For example, the N═N and C—N bonds in azobenzene are 1.255 (2) Å and 1.432 (2) Å, respectively (Patai, 1975), while the C═N double bonds in imine compounds are in the range 1.270 (5)–1.303 (3) Å (Ersanlı, Odabaşoǧlu, et al., 2004; Baughman et al., 2004; Ersanlı, Albayrak et al., 2004; Odabaşoǧlu et al., 2005; Şahin et al., 2005; Butcher et al., 2005). There is a moderately strong intramolecular N1—H1···O1 hydrogen bond, which is a common feature of similar systems {N—H···O = 1.99 (2) Å in ethyl 4-chloro-3-oxo-2-(phenlyhydrazono)butyrate (Alpaslan et al., 2005a); N—H···O = 1.96 (2) Å in (E)-ethyl 4-chloro-3-[2-(2-fluorophenly) hydrazono]butanoate (Alpaslan et al., 2005b)}. The carbonyl groups point in opposite sides of the C9—C11 chain and their bond distances of 1.203 (2) and 1.215 (2) Å are shorter than those observed in similar compounds (Chen et al., 2004; Odabaşoǧlu et al., 2003) but within the normal range for carbonyl compounds (Loudon, 2002).

In the crystal structure, C5—H5···O3ⁱ intermolecular hydrogen bonds link the molecules into a chain along [101] (Fig. 2); symmetry code (i) is given in Table 2.

S2. Experimental

A mixture of o-methoxyaniline (10 mmol), water (50 ml) and concentrated hydrochloric acid (30 mmol) was heated with stirring until a clear solution was obtained. This solution was cooled to 273–278 K and a solution of sodium nitrite (14 mmol) in water was added dropwise while the temperature was maintained below 278 K. The resulting mixture was stirred for 30 min in an ice bath. The pH was raised to 8–9 by adding dilute NaOH solution. Ethyl 4-chloroacetoacetate (10 mmol) solution in ethanol was gradually added to a cooled solution of the o-methoxybenzenediazonium chloride, prepared as described above. The resulting mixture was stirred at 273–278 K for 60 min in an ice bath and the pH was lowered to 5 with dilute HCl. The product was recrystallized from glacial acetic acid to obtain well shaped crystals of (I) (yield 86%, m.p. 423–424 K).

S3. Refinement

The H atom bonded to N1 was refined freely. All other H atoms were placed in calculated positions and constrained to ride on their parent atoms, with C—H = 0.93–0.97 Å and U_iso(H) = 1.2 U_eq(C) [1.5U_eq(methyl C)].

Computing details

Data collection: X-AREA (Stoe & Cie, 2002); cell refinement: X-AREA; data reduction: X-RED32 (Stoe & Cie, 2002); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures

	Fig. 1. A view of (I), with the atomic numbering scheme and 50% probability displacement ellipsoids. Intramolecular hydrogen bonds are drawn as dashed lines.
	Fig. 2. Part of the crystal packing of (I). Hydrogen bonds are drawn as dashed lines.

(Z)-ethyl 4-chloro-2-(2-(2-methoxyphenyl)hydrazono)-3-oxobutanoate

Crystal data

C13H15ClN2O4	Z = 2
Mr = 298.72	F(000) = 312
Triclinic, P1	Dx = 1.409 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71069 Å
a = 8.605 (5) Å	Cell parameters from 8830 reflections
b = 8.981 (5) Å	θ = 2.4–27.2°
c = 9.974 (5) Å	µ = 0.29 mm^−1
α = 107.615 (5)°	T = 296 K
β = 103.543 (5)°	Prism, yellow
γ = 94.952 (5)°	0.49 × 0.36 × 0.14 mm
V = 703.9 (7) Å^3

Data collection

STOE IPDS-II diffractometer	2741 independent reflections
Radiation source: fine-focus sealed tube	1906 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.027
Detector resolution: 6.67 pixels mm^-1	θmax = 26.0°, θmin = 2.4°
w scans	h = −10→10
Absorption correction: integration (X-RED32; Stoe & Cie, 2002)	k = −11→11
Tmin = 0.885, Tmax = 0.964	l = −12→12
10993 measured reflections

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)] = 0.040	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.117	H atoms treated by a mixture of independent and constrained refinement
S = 1.03	w = 1/[σ^2(Fo^2) + (0.0645P)^2 + 0.0281P] where P = (Fo^2 + 2Fc^2)/3
2741 reflections	(Δ/σ)max = 0.001
187 parameters	Δρmax = 0.15 e Å^−3
0 restraints	Δρmin = −0.18 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	0.1950 (2)	0.5853 (2)	0.4889 (2)	0.0594 (5)
C2	0.1743 (3)	0.7305 (3)	0.5723 (2)	0.0744 (6)
H2	0.2404	0.7782	0.6673	0.089*
C3	0.0556 (3)	0.8064 (3)	0.5156 (3)	0.0921 (7)
H3	0.0405	0.9043	0.5725	0.110*
C4	−0.0399 (3)	0.7356 (4)	0.3742 (4)	0.0964 (9)
H4	−0.1204	0.7861	0.3361	0.116*
C5	−0.0184 (3)	0.5927 (4)	0.2894 (3)	0.0833 (7)
H5	−0.0828	0.5474	0.1935	0.100*
C6	0.0993 (2)	0.5143 (3)	0.3454 (2)	0.0655 (5)
C7	0.0222 (3)	0.2850 (4)	0.1324 (2)	0.0999 (8)
H7A	−0.0867	0.2728	0.1408	0.120*
H7B	0.0507	0.1824	0.0953	0.120*
H7C	0.0293	0.3426	0.0665	0.120*
C8	0.4985 (2)	0.4883 (2)	0.74401 (18)	0.0521 (4)
C9	0.5891 (2)	0.5861 (2)	0.89488 (19)	0.0554 (4)
C10	0.5456 (3)	0.7501 (2)	0.9452 (2)	0.0768 (6)
H10A	0.4391	0.7408	0.9618	0.092*
H10B	0.5400	0.7961	0.8682	0.092*
C11	0.5138 (2)	0.3230 (2)	0.67202 (19)	0.0568 (4)
C12	0.6319 (3)	0.1000 (2)	0.6823 (2)	0.0728 (6)
H12A	0.6634	0.0902	0.5931	0.087*
H12B	0.5289	0.0308	0.6572	0.087*
C13	0.7580 (3)	0.0549 (3)	0.7864 (3)	0.0876 (7)
H13A	0.8588	0.1253	0.8119	0.105*
H13B	0.7719	−0.0519	0.7413	0.105*
H13C	0.7243	0.0623	0.8731	0.105*
N1	0.30838 (19)	0.5002 (2)	0.54512 (17)	0.0570 (4)
N2	0.39947 (17)	0.56386 (17)	0.67872 (15)	0.0536 (4)
O1	0.43650 (18)	0.24860 (17)	0.54691 (14)	0.0750 (4)
O2	0.61716 (17)	0.26297 (15)	0.75319 (13)	0.0645 (4)
O3	0.68687 (18)	0.54210 (16)	0.97574 (14)	0.0745 (4)
O4	0.13042 (18)	0.3696 (2)	0.27202 (15)	0.0792 (4)
Cl1	0.68642 (8)	0.87846 (7)	1.10700 (6)	0.0881 (2)
H1	0.307 (3)	0.412 (3)	0.499 (3)	0.074 (7)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0548 (10)	0.0677 (12)	0.0561 (10)	0.0082 (9)	0.0013 (8)	0.0322 (9)
C2	0.0797 (14)	0.0692 (13)	0.0743 (13)	0.0188 (11)	0.0049 (11)	0.0345 (11)
C3	0.0944 (17)	0.0855 (17)	0.1098 (19)	0.0348 (14)	0.0165 (15)	0.0550 (16)
C4	0.0746 (15)	0.113 (2)	0.120 (2)	0.0290 (15)	0.0056 (15)	0.077 (2)
C5	0.0612 (12)	0.117 (2)	0.0773 (14)	0.0083 (13)	−0.0049 (11)	0.0605 (16)
C6	0.0543 (11)	0.0858 (15)	0.0559 (11)	0.0069 (10)	0.0002 (9)	0.0357 (11)
C7	0.0833 (16)	0.132 (2)	0.0541 (12)	0.0032 (15)	−0.0121 (11)	0.0154 (13)
C8	0.0550 (10)	0.0515 (10)	0.0448 (8)	0.0088 (8)	0.0018 (7)	0.0180 (7)
C9	0.0594 (10)	0.0522 (10)	0.0473 (9)	0.0079 (8)	0.0005 (8)	0.0176 (8)
C10	0.0890 (15)	0.0580 (11)	0.0575 (11)	0.0137 (10)	−0.0155 (10)	0.0089 (9)
C11	0.0562 (10)	0.0590 (11)	0.0493 (9)	0.0110 (9)	0.0043 (8)	0.0172 (8)
C12	0.0932 (15)	0.0572 (11)	0.0577 (11)	0.0294 (11)	0.0055 (10)	0.0116 (9)
C13	0.1139 (19)	0.0707 (14)	0.0689 (14)	0.0370 (14)	0.0027 (13)	0.0210 (11)
N1	0.0586 (9)	0.0589 (10)	0.0445 (8)	0.0112 (8)	−0.0041 (7)	0.0178 (7)
N2	0.0542 (8)	0.0565 (8)	0.0437 (7)	0.0071 (7)	−0.0008 (6)	0.0190 (6)
O1	0.0829 (9)	0.0651 (8)	0.0530 (8)	0.0236 (7)	−0.0093 (7)	0.0038 (6)
O2	0.0781 (9)	0.0546 (7)	0.0503 (7)	0.0203 (6)	−0.0010 (6)	0.0140 (6)
O3	0.0829 (9)	0.0653 (8)	0.0560 (7)	0.0185 (7)	−0.0161 (7)	0.0177 (6)
O4	0.0683 (9)	0.1021 (12)	0.0498 (7)	0.0104 (8)	−0.0073 (6)	0.0196 (8)
Cl1	0.1087 (5)	0.0644 (3)	0.0593 (3)	0.0090 (3)	−0.0121 (3)	0.0034 (2)

Geometric parameters (Å, º)

C1—C2	1.370 (3)	C8—C9	1.475 (2)
C1—C6	1.392 (3)	C9—O3	1.203 (2)
C1—N1	1.408 (2)	C9—C10	1.516 (3)
C2—C3	1.382 (3)	C10—Cl1	1.766 (2)
C2—H2	0.93	C10—H10A	0.97
C3—C4	1.376 (4)	C10—H10B	0.97
C3—H3	0.93	C11—O1	1.215 (2)
C4—C5	1.362 (4)	C11—O2	1.321 (2)
C4—H4	0.93	C12—O2	1.451 (2)
C5—C6	1.389 (3)	C12—C13	1.491 (3)
C5—H5	0.93	C12—H12A	0.97
C6—O4	1.368 (3)	C12—H12B	0.97
C7—O4	1.419 (3)	C13—H13A	0.96
C7—H7A	0.96	C13—H13B	0.96
C7—H7B	0.96	C13—H13C	0.96
C7—H7C	0.96	N1—N2	1.300 (2)
C8—N2	1.311 (2)	N1—H1	0.79 (2)
C8—C11	1.473 (3)
C2—C1—C6	120.45 (19)	C8—C9—C10	114.38 (15)
C2—C1—N1	121.94 (18)	C9—C10—Cl1	112.93 (14)
C6—C1—N1	117.6 (2)	C9—C10—H10A	109.0
C1—C2—C3	120.2 (2)	Cl1—C10—H10A	109.0
C1—C2—H2	119.9	C9—C10—H10B	109.0
C3—C2—H2	119.9	Cl1—C10—H10B	109.0
C4—C3—C2	119.4 (3)	H10A—C10—H10B	107.8
C4—C3—H3	120.3	O1—C11—O2	123.04 (18)
C2—C3—H3	120.3	O1—C11—C8	121.8 (2)
C5—C4—C3	120.9 (2)	O2—C11—C8	115.15 (15)
C5—C4—H4	119.5	O2—C12—C13	107.74 (17)
C3—C4—H4	119.5	O2—C12—H12A	110.2
C4—C5—C6	120.3 (2)	C13—C12—H12A	110.2
C4—C5—H5	119.8	O2—C12—H12B	110.2
C6—C5—H5	119.8	C13—C12—H12B	110.2
O4—C6—C5	125.7 (2)	H12A—C12—H12B	108.5
O4—C6—C1	115.59 (18)	C12—C13—H13A	109.5
C5—C6—C1	118.7 (2)	C12—C13—H13B	109.5
O4—C7—H7A	109.5	H13A—C13—H13B	109.5
O4—C7—H7B	109.5	C12—C13—H13C	109.5
H7A—C7—H7B	109.5	H13A—C13—H13C	109.5
O4—C7—H7C	109.5	H13B—C13—H13C	109.5
H7A—C7—H7C	109.5	N2—N1—C1	118.9 (2)
H7B—C7—H7C	109.5	N2—N1—H1	121.6 (18)
N2—C8—C11	122.51 (15)	C1—N1—H1	119.1 (18)
N2—C8—C9	112.68 (16)	N1—N2—C8	122.97 (16)
C11—C8—C9	124.8 (2)	C11—O2—C12	115.11 (15)
O3—C9—C8	124.6 (2)	C6—O4—C7	117.03 (19)
O3—C9—C10	121.01 (16)
C6—C1—C2—C3	1.4 (3)	C8—C9—C10—Cl1	−166.16 (14)
N1—C1—C2—C3	−176.44 (19)	N2—C8—C11—O1	1.0 (3)
C1—C2—C3—C4	−0.8 (4)	C9—C8—C11—O1	−179.55 (18)
C2—C3—C4—C5	−0.5 (4)	N2—C8—C11—O2	−179.07 (16)
C3—C4—C5—C6	1.1 (4)	C9—C8—C11—O2	0.4 (3)
C4—C5—C6—O4	178.8 (2)	C2—C1—N1—N2	−2.2 (3)
C4—C5—C6—C1	−0.5 (3)	C6—C1—N1—N2	179.89 (16)
C2—C1—C6—O4	179.86 (18)	C1—N1—N2—C8	174.2 (2)
N1—C1—C6—O4	−2.2 (2)	C11—C8—N2—N1	−0.8 (3)
C2—C1—C6—C5	−0.8 (3)	C9—C8—N2—N1	179.69 (16)
N1—C1—C6—C5	177.21 (18)	O1—C11—O2—C12	−0.2 (3)
N2—C8—C9—O3	−179.88 (17)	C8—C11—O2—C12	179.9 (2)
C11—C8—C9—O3	0.6 (3)	C13—C12—O2—C11	177.42 (18)
N2—C8—C9—C10	2.1 (2)	C5—C6—O4—C7	−7.0 (3)
C11—C8—C9—C10	−177.41 (18)	C1—C6—O4—C7	172.30 (19)
O3—C9—C10—Cl1	15.7 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C5—H5···O3^i	0.93	2.56	3.413 (3)	153
N1—H1···O1	0.79 (2)	2.02 (2)	2.602 (2)	131 (2)
N1—H1···O4	0.79 (2)	2.31 (2)	2.635 (2)	106 (2)

Symmetry code: (i) x−1, y, z−1.