4-[(3-Chloro­phenyl)­diazenyl]-2-{[tris(hydroxy­methyl)­methyl]amino­methyl­ene}cyclo­hexa-3,5-dien-1(2H)-one

The title compound, C₁₇H₁₈ClN₃O₄, adopts the keto-amine tautomeric form and displays an intramolecular N-H...O hydrogen bond [N...O = 2.639 (2) Å]. The configuration around the azo N=N double bond is trans, and the dihedral angle between the planes of the two aromatic rings is 20.5 (2)°. The mol­ecules are linked by O-H...O hydrogen bonds to form a three-dimensional network.

S1. Comment

There is considerable interest in Schiff base ligands and their complexes because of their striking antitumour activities (Zhou et al., 2000). N-substituted ortho-hydroxy imines have been reported to display thermochromism and photochromism in the solid state by proton transfer from the hydroxy O atom to the N atom (Hadjoudis et al., 1987; Xu et al., 1994). Azoazomethines have been extensively used as dyestuff for wool, leather and synthetic fabric because of their extraordinary painting properties (Kamel et al., 1971; Gopal & Srinivasan, 1986; Karaer, 1997). As part of our ongoing work on the synthesis and structural characterization of polyhydroxyazoazomethine derivatives, the title compound, (I), was synthesized, and we report here its crystal structure.

An ORTEP (Farrugia, 1997) view of (I) and a packing diagram are shown in Figs. 1 and 2, respectively. The structure of (I) reveals several points of interest. First, the molecule exists primarily as the keto-amine tautomer, as indicated by the following bond lengths: C10—O1=1.286 (2) Å, C9—C13=1.441 (3) Å, C13—N3=1.298 (3) Å and C9—C10=1.436 (3) Å. These bonds are 1.356 (3) Å, 1.448 (3) Å, 1.270 (3) Å and 1.288 (4) Å, respectively, in the phenol-imine tautomer (Scheme 2) of 1,8-di[N-2-oxyphenylsalicylidene]-3,6-dioxaoctane (Yıldız et al., 1998). These data show that there is significant elongation of the C13—N3 bond and contraction of the C10—O1 bond. Secondly, the `hydroxyl' H atom was located on atom N3, thus confirming a preference for the keto-amine tautomer in the solid state. Finally, there is a strong intramolecular N3—H33···O1 hydrogen bond, which is a common feature of ortho-hydroxysalicylidene systems (Filarowski et al., 2003; Nazır et al., 2000; Yıldız et al., 1998).

It has been reported that there may be an orientational disorder in azobenzene, resulting in a shortening of the Nδb N bond [1.189 (6) Å] and an elongation of the N—Ph bonds [1.473 (4) Å], while these bond lengths are 1.249 (4) Å and 1.431 (4) Å, respectively, in azobenzene with no disorder (Harada et al., 1997). The N1δb N2, N1—C1 and N2—C7 bonds were found to be 1.256 (2) Å, 1.429 (3) Å and 1.414 (2) Å, respectively, indicating that there is no orientational disorder. In (I), the two phenyl rings are planar but not coplanar with each other. The dihedral angle, θ₁, between the mean planes of the chlorophenyl ring and the C—N—N—C bridge is 11.6 (3)° and the angle, θ₂, between the planes of the C—N—N—C link and the salicylidene ring is 8.9 (3)°. The angle, θ₃, between the planes of the chlorophenyl and salicylidene rings is 20.47 (10)°, which is equal to the sum of θ₁ and θ₂ [20.5 (3)°]. This value of θ₃ is a little larger than those of E-azobenzenes (5–15°; Brown, 1966). The C1 and C7 atoms are angularly asymmetric (Table 1). This asymmetry seems to be caused by the tendency of the azo system to be partly coplanar with aromatic rings because of the π-conjugation and steric hindrance involving the C2—H2 group with N2 and C12—H12 group with N1. The same angularly asymmetry occurs for atoms C13, N3 and C14 because of their asymmetric coordination, and so the N3—C13—C9, C13—N3—C14 and N3—C14—C17 angles are larger according to their optimal hybridization degree.

Apart from the intramolecular hydrogen bond, (I) displays intermolecular O—H···O hydrogen bonds that form a three dimensional network (Fig. 2 and Table 2). There is also a π-ring interaction [3.318 (19) Å] between C12—H12 and the salicylidene ring (symmetry code: x, −y + 3/2, z + 1/2).

S2. Experimental

A mixture of 3-chloroaniline (1.275 g, 10 mmol), water (50 ml) and concentrated hydrochloric acid (2.5 ml, 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 (0.96 g, 14 mmol) in water was then added dropwise, maintaining the temperature below 278 K. The resulting mixture was stirred for 30 min in an ice bath. Salicylaldehyde (1.22 g, 10 mmol) solution (pH=9) was gradually added to the solution of the cooled 3-chlorobenzenediazoniumchloride, prepared as described above, and the resulting mixture was continually stirred at 273–278 K for 60 min in an ice bath. The product was recrystallized from ethyl alcohol to obtain solid 5-(3-chlorophenylazo)salicylaldehyde (m.p. 400–402 K). To a solution of this solid (1.302 g, 5 mmol) in butane-1-ol (75 ml) was added a solution of tris(hydroxymethyl)aminomethane (0.605 g, 5 mmol) in butane-1-ol (25 ml). The mixture was stirred at reflux temperature and the water produced in the reaction was distilled out of reaction mixture. The resulting orange precipitate was filtered off and recrystallized from ethyl alcohol, and crystals of (I) were obtained by slow evaporation from acetonitrile after 2 d (Yield 90%; m.p. 455–457 K).

S3. Refinement

H atoms attached to atoms O2, O3 and O4 were refined using a riding model, with O—H distances free to refine and U_iso values equal to 1.2U_eq of the parent atom. H atoms attached to atoms C15, C16 and C17 were refined using a riding model with C—H distances of 0.96 Å. The other H atoms bonded to C atoms and H33 (bonded to N) were refined isotropically. The calculated C—H bond lengths are 0.89 (3)–0.98 (2) Å.

Computing details

Data collection: STADI4 (Stoe & Cie, 1996); cell refinement: STADI4; data reduction: X-RED (Stoe & Cie, 1996); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); 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, 1998).

Figures

	Fig. 1. An ORTEP view of (I), showing the atom-numbering scheme and displacement ellipsoids at the 50% probability level.
	Fig. 2. An ORTEP packing diagram of (I), viewed along the b axis.

4-[(3-Chlorophenyl)diazenyl]-2- {[tris(hydroxymethyl)methyl]aminomethylene}cyclohexa-3,5-dien-1(2H)-one

Crystal data

C17H18ClN3O4	F(000) = 760
Mr = 363.79	Dx = 1.415 Mg m^−3
Monoclinic, P21/c	Melting point: 182-184 °C K
Hall symbol: -P 2ybc	Mo Kα radiation, λ = 0.71073 Å
a = 18.418 (4) Å	Cell parameters from 100 reflections
b = 9.821 (2) Å	θ = 3.0–25.0°
c = 9.5020 (19) Å	µ = 0.25 mm^−1
β = 96.64 (3)°	T = 295 K
V = 1707.2 (6) Å^3	Prism, orange
Z = 4	0.40 × 0.30 × 0.10 mm

Data collection

STOE STADI 4 diffractometer	Rint = 0.020
Radiation source: fine-focus sealed tube	θmax = 25.0°, θmin = 2.2°
Graphite monochromator	h = −21→21
ω scans	k = −11→0
6136 measured reflections	l = −11→11
3005 independent reflections	2 standard reflections every 120 min
2314 reflections with I > 2σ(I)	intensity decay: 2%

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)] = 0.037	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.104	H atoms treated by a mixture of independent and constrained refinement
S = 1.06	w = 1/[σ^2(Fo^2) + (0.0496P)^2 + 0.5398P] where P = (Fo^2 + 2Fc^2)/3
3005 reflections	(Δ/σ)max < 0.001
265 parameters	Δρmax = 0.50 e Å^−3
0 restraints	Δρmin = −0.27 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	0.50992 (11)	0.3273 (2)	0.0912 (2)	0.0386 (5)
C2	0.46428 (11)	0.4236 (2)	0.1425 (2)	0.0385 (5)
C3	0.39160 (11)	0.4255 (2)	0.0881 (2)	0.0406 (5)
C4	0.36303 (13)	0.3364 (3)	−0.0161 (3)	0.0532 (6)
C5	0.40916 (14)	0.2424 (3)	−0.0652 (3)	0.0638 (8)
C6	0.48259 (13)	0.2371 (3)	−0.0130 (3)	0.0524 (6)
C7	0.68233 (10)	0.3861 (2)	0.2880 (2)	0.0357 (5)
C8	0.70445 (11)	0.4473 (2)	0.4150 (2)	0.0370 (5)
C9	0.77873 (10)	0.4509 (2)	0.47043 (19)	0.0326 (4)
C10	0.83307 (10)	0.3904 (2)	0.3933 (2)	0.0340 (4)
C11	0.80741 (11)	0.3296 (2)	0.2606 (2)	0.0396 (5)
C12	0.73524 (11)	0.3274 (2)	0.2102 (2)	0.0391 (5)
C13	0.79820 (10)	0.5200 (2)	0.5996 (2)	0.0345 (5)
C14	0.88801 (10)	0.6104 (2)	0.79021 (19)	0.0315 (4)
C15	0.96395 (10)	0.6664 (2)	0.7750 (2)	0.0368 (5)
H151	0.9611	0.7309	0.6972	0.044*
H152	0.9830	0.7136	0.8611	0.044*
C16	0.88988 (11)	0.5094 (2)	0.91321 (19)	0.0342 (4)
H161	0.8415	0.4717	0.9177	0.041*
H162	0.9230	0.4352	0.8992	0.041*
C17	0.83521 (11)	0.7282 (2)	0.8112 (2)	0.0398 (5)
H171	0.7938	0.6921	0.8538	0.048*
H172	0.8600	0.7928	0.8775	0.048*
N1	0.58654 (9)	0.31841 (19)	0.13606 (18)	0.0409 (4)
N2	0.60628 (9)	0.38859 (19)	0.24430 (18)	0.0397 (4)
N3	0.86467 (9)	0.53397 (18)	0.65986 (17)	0.0332 (4)
O1	0.90115 (7)	0.39307 (17)	0.44224 (15)	0.0448 (4)
O2	1.01125 (7)	0.55697 (15)	0.74875 (15)	0.0406 (4)
H21	1.0376 (8)	0.5802 (7)	0.6874 (18)	0.049*
O3	0.91371 (9)	0.57881 (16)	1.04071 (15)	0.0446 (4)
H31	0.9364 (8)	0.5291 (17)	1.0930 (17)	0.054*
O4	0.80888 (8)	0.79803 (17)	0.68641 (16)	0.0498 (4)
H41	0.8496 (11)	0.8449 (13)	0.6486 (11)	0.060*
Cl1	0.33404 (3)	0.54567 (7)	0.15236 (7)	0.0574 (2)
H2	0.4818 (11)	0.489 (2)	0.215 (2)	0.040 (6)*
H4	0.3145 (14)	0.345 (3)	−0.056 (3)	0.060 (7)*
H5	0.3901 (14)	0.184 (3)	−0.131 (3)	0.066 (8)*
H6	0.5136 (13)	0.172 (3)	−0.044 (3)	0.057 (7)*
H8	0.6687 (12)	0.487 (2)	0.469 (2)	0.041 (6)*
H11	0.8423 (11)	0.292 (2)	0.208 (2)	0.038 (6)*
H12	0.7176 (12)	0.289 (2)	0.118 (2)	0.047 (6)*
H13	0.7589 (12)	0.562 (2)	0.645 (2)	0.041 (6)*
H33	0.8966 (13)	0.493 (3)	0.616 (3)	0.054 (7)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0316 (10)	0.0511 (13)	0.0328 (10)	−0.0083 (9)	0.0018 (8)	0.0001 (10)
C2	0.0366 (11)	0.0451 (13)	0.0328 (11)	−0.0076 (9)	−0.0006 (9)	0.0012 (10)
C3	0.0351 (11)	0.0519 (13)	0.0347 (11)	−0.0036 (10)	0.0040 (9)	0.0050 (10)
C4	0.0314 (12)	0.0822 (19)	0.0446 (13)	−0.0100 (12)	−0.0017 (10)	−0.0052 (13)
C5	0.0435 (14)	0.092 (2)	0.0540 (15)	−0.0173 (14)	−0.0013 (11)	−0.0318 (16)
C6	0.0395 (13)	0.0690 (17)	0.0488 (14)	−0.0058 (12)	0.0053 (11)	−0.0210 (13)
C7	0.0296 (10)	0.0408 (12)	0.0361 (11)	−0.0033 (9)	0.0010 (8)	0.0006 (9)
C8	0.0286 (10)	0.0457 (12)	0.0370 (11)	−0.0011 (9)	0.0052 (8)	−0.0032 (10)
C9	0.0282 (10)	0.0411 (11)	0.0281 (10)	−0.0020 (8)	0.0020 (8)	0.0003 (9)
C10	0.0287 (10)	0.0397 (11)	0.0336 (10)	−0.0011 (8)	0.0035 (8)	0.0015 (9)
C11	0.0349 (11)	0.0475 (13)	0.0373 (11)	0.0012 (10)	0.0075 (9)	−0.0066 (10)
C12	0.0394 (12)	0.0440 (12)	0.0333 (11)	−0.0031 (9)	0.0012 (9)	−0.0049 (10)
C13	0.0274 (10)	0.0450 (12)	0.0315 (10)	−0.0007 (9)	0.0051 (8)	0.0010 (9)
C14	0.0274 (9)	0.0396 (11)	0.0270 (9)	0.0003 (8)	0.0010 (7)	−0.0012 (8)
C15	0.0308 (10)	0.0433 (12)	0.0360 (11)	0.0006 (9)	0.0025 (8)	0.0003 (9)
C16	0.0330 (10)	0.0414 (11)	0.0273 (10)	0.0008 (9)	−0.0005 (8)	−0.0004 (9)
C17	0.0393 (11)	0.0474 (13)	0.0324 (11)	0.0087 (10)	0.0026 (9)	0.0013 (9)
N1	0.0324 (9)	0.0519 (11)	0.0374 (10)	−0.0056 (8)	0.0001 (7)	−0.0032 (9)
N2	0.0311 (9)	0.0487 (11)	0.0381 (10)	−0.0052 (8)	−0.0015 (7)	−0.0022 (8)
N3	0.0276 (9)	0.0448 (10)	0.0271 (8)	0.0022 (8)	0.0026 (7)	−0.0025 (8)
O1	0.0272 (7)	0.0681 (10)	0.0386 (8)	0.0027 (7)	0.0016 (6)	−0.0088 (7)
O2	0.0298 (7)	0.0558 (9)	0.0368 (7)	0.0074 (7)	0.0060 (6)	0.0077 (7)
O3	0.0543 (9)	0.0482 (9)	0.0286 (7)	0.0098 (7)	−0.0065 (6)	−0.0023 (6)
O4	0.0402 (8)	0.0560 (10)	0.0513 (9)	0.0067 (7)	−0.0034 (7)	0.0099 (8)
Cl1	0.0432 (3)	0.0643 (4)	0.0649 (4)	0.0078 (3)	0.0079 (3)	0.0018 (3)

Geometric parameters (Å, º)

C1—C6	1.379 (3)	C11—H11	0.94 (2)
C1—C2	1.390 (3)	C12—H12	0.97 (2)
C1—N1	1.429 (3)	C13—N3	1.298 (3)
C2—C3	1.378 (3)	C13—H13	0.98 (2)
C2—H2	0.97 (2)	C14—N3	1.470 (2)
C3—C4	1.379 (3)	C14—C15	1.525 (3)
C3—Cl1	1.743 (2)	C14—C16	1.530 (3)
C4—C5	1.372 (4)	C14—C17	1.539 (3)
C4—H4	0.93 (3)	C15—O2	1.424 (2)
C5—C6	1.387 (3)	C15—H151	0.9700
C5—H5	0.89 (3)	C15—H152	0.9700
C6—H6	0.93 (2)	C16—O3	1.415 (2)
C7—C8	1.367 (3)	C16—H161	0.9700
C7—C12	1.413 (3)	C16—H162	0.9700
C7—N2	1.414 (2)	C17—O4	1.407 (2)
C8—C9	1.408 (3)	C17—H171	0.9700
C8—H8	0.96 (2)	C17—H172	0.9700
C9—C13	1.411 (3)	N1—N2	1.256 (2)
C9—C10	1.436 (3)	N3—H33	0.86 (3)
C10—O1	1.286 (2)	O2—H21	0.8322
C10—C11	1.426 (3)	O3—H31	0.7822
C11—C12	1.360 (3)	O4—H41	0.9819
C6—C1—C2	120.2 (2)	N3—C13—C9	124.52 (19)
C6—C1—N1	116.2 (2)	N3—C13—H13	117.9 (13)
C2—C1—N1	123.59 (19)	C9—C13—H13	117.6 (12)
C3—C2—C1	118.6 (2)	N3—C14—C15	106.65 (15)
C3—C2—H2	119.2 (12)	N3—C14—C16	106.92 (16)
C1—C2—H2	122.2 (12)	C15—C14—C16	111.48 (16)
C2—C3—C4	122.3 (2)	N3—C14—C17	111.44 (15)
C2—C3—Cl1	118.78 (17)	C15—C14—C17	109.97 (17)
C4—C3—Cl1	118.95 (17)	C16—C14—C17	110.30 (16)
C5—C4—C3	118.1 (2)	O2—C15—C14	109.32 (17)
C5—C4—H4	121.5 (16)	O2—C15—H151	109.8
C3—C4—H4	120.3 (16)	C14—C15—H151	109.8
C4—C5—C6	121.3 (2)	O2—C15—H152	109.8
C4—C5—H5	117.6 (17)	C14—C15—H152	109.8
C6—C5—H5	121.1 (17)	H151—C15—H152	108.3
C1—C6—C5	119.5 (2)	O3—C16—C14	108.59 (17)
C1—C6—H6	118.9 (15)	O3—C16—H161	110.0
C5—C6—H6	121.5 (15)	C14—C16—H161	110.0
C8—C7—C12	119.23 (18)	O3—C16—H162	110.0
C8—C7—N2	115.82 (18)	C14—C16—H162	110.0
C12—C7—N2	124.94 (18)	H161—C16—H162	108.4
C7—C8—C9	121.22 (19)	O4—C17—C14	114.75 (16)
C7—C8—H8	119.6 (13)	O4—C17—H171	108.6
C9—C8—H8	119.1 (13)	C14—C17—H171	108.6
C8—C9—C13	118.38 (18)	O4—C17—H172	108.6
C8—C9—C10	120.21 (18)	C14—C17—H172	108.6
C13—C9—C10	121.36 (17)	H171—C17—H172	107.6
O1—C10—C11	122.53 (18)	N2—N1—C1	113.14 (17)
O1—C10—C9	121.02 (18)	N1—N2—C7	114.46 (18)
C11—C10—C9	116.45 (17)	C13—N3—C14	126.55 (18)
C12—C11—C10	121.9 (2)	C13—N3—H33	113.5 (16)
C12—C11—H11	120.7 (13)	C14—N3—H33	120.0 (16)
C10—C11—H11	117.4 (13)	C15—O2—H21	109.5
C11—C12—C7	121.0 (2)	C16—O3—H31	109.5
C11—C12—H12	122.2 (13)	C17—O4—H41	109.5
C7—C12—H12	116.8 (13)
C6—C1—C2—C3	0.7 (3)	N2—C7—C12—C11	−179.9 (2)
N1—C1—C2—C3	177.86 (19)	C8—C9—C13—N3	−178.0 (2)
C1—C2—C3—C4	−0.7 (3)	C10—C9—C13—N3	−0.6 (3)
C1—C2—C3—Cl1	179.78 (16)	N3—C14—C15—O2	−56.2 (2)
C2—C3—C4—C5	0.7 (4)	C16—C14—C15—O2	60.2 (2)
Cl1—C3—C4—C5	−179.9 (2)	C17—C14—C15—O2	−177.18 (15)
C3—C4—C5—C6	−0.6 (4)	N3—C14—C16—O3	178.76 (15)
C2—C1—C6—C5	−0.6 (4)	C15—C14—C16—O3	62.6 (2)
N1—C1—C6—C5	−178.0 (2)	C17—C14—C16—O3	−59.9 (2)
C4—C5—C6—C1	0.6 (4)	N3—C14—C17—O4	−39.4 (2)
C12—C7—C8—C9	−1.1 (3)	C15—C14—C17—O4	78.6 (2)
N2—C7—C8—C9	179.64 (19)	C16—C14—C17—O4	−158.00 (17)
C7—C8—C9—C13	177.8 (2)	C6—C1—N1—N2	−170.3 (2)
C7—C8—C9—C10	0.4 (3)	C2—C1—N1—N2	12.5 (3)
C8—C9—C10—O1	179.83 (19)	C1—N1—N2—C7	−177.64 (17)
C13—C9—C10—O1	2.5 (3)	C8—C7—N2—N1	−172.18 (19)
C8—C9—C10—C11	0.5 (3)	C12—C7—N2—N1	8.6 (3)
C13—C9—C10—C11	−176.79 (19)	C9—C13—N3—C14	176.77 (19)
O1—C10—C11—C12	179.9 (2)	C15—C14—N3—C13	−148.3 (2)
C9—C10—C11—C12	−0.8 (3)	C16—C14—N3—C13	92.4 (2)
C10—C11—C12—C7	0.1 (3)	C17—C14—N3—C13	−28.2 (3)
C8—C7—C12—C11	0.8 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N3—H33···O1	0.86 (3)	1.93 (2)	2.639 (2)	139 (2)
O2—H21···O1^i	0.83 (2)	1.78 (2)	2.610 (2)	172 (1)
O3—H31···O2^ii	0.78 (2)	1.89 (2)	2.655 (2)	166 (2)
O4—H41···O3^iii	0.98 (2)	1.81 (2)	2.780 (2)	167 (1)

Symmetry codes: (i) −x+2, −y+1, −z+1; (ii) −x+2, −y+1, −z+2; (iii) x, −y+3/2, z−1/2.