The crystal structure of (3Z)-4-[(3-hy­droxy­phen­yl)amino]­pent-3-en-2-one: helices and π-stacking inter­actions of hy­dro­gen-bridged rings

The title com­pound displays a strong intra­molecular N—H⋯O inter­action resulting in a six-membered hy­dro­gen-bridged ring. An inter­molecular O—H⋯O hy­dro­gen bond leads to a helix formation. The Hirshfeld surface analysis of inter­molecular inter­actions is pre­sent­ed.

Abstract

The title com­pound, C₁₁H₁₃NO₂, crystallizes in the monoclinic space group P2₁/c with four mol­ecular units per unit cell and Z′ = 1. A strong intra­molecular N—H⋯O inter­action results in a six-membered hy­dro­gen-bridged ring. An inter­molecular O—H⋯O hy­dro­gen bond leads to a helix formation. The Hirshfeld surface analysis of inter­molecular inter­actions is pre­sent­ed.

1. Chemical context

A direct condensation of acetyl­acetone (acac) with primary amines or di­amines provides a simple route to a broad family of potential coordination ligands (Hernández-Molina & Mederos, 2003 ▸). Particularly prominent are the nacnac ligands, in which both carbonyl groups of the keto tautomer are replaced by imine functionalities, for example, in reactions with aniline and its 2,6-dialkyl derivatives (Hadzovic & Song, 2008a ▸; Hadzovic & Song, 2008b ▸). Also common are the so-called ‘half units,’ O,N-donor ligands that retain one unreacted carbonyl group (Hernández-Molina & Mederos, 2003 ▸). Designing polydentate systems is straightforward for both nacnacs and half units when the amine com­ponent bears additional donor groups.

Despite their structural richness and widespread use in coordination chemistry, the free nacnac and half-unit ligands themselves have received com­paratively little crystallographic attention. This contrasts with classical Schiff bases, which require an aryl-substituted carbonyl group and have been extensively analysed for intra- and inter­molecular inter­actions (Dominiak et al., 2003 ▸; Karabıyık et al., 2012 ▸). To extend similar structural studies to half units and nacnacs, we report here the structure and detailed analysis of the condensation product of acac with one equivalent of 3-amino­phenol.

2. Structural commentary

The asymmetric unit of (3Z)-4-[(3-hy­droxy­phen­yl)amino]­pent-3-en-2-one (I) contains one independent mol­ecule (Fig. 1 ▸). The com­pound, formed through condensation of acetyl­acetone (acac) and 3-amino­phenol, exists as a keto–amine tautomer. Selected bond lengths and angles are provided in Table 1 ▸. Atoms O1, C2, C3, C4 and N1 are essentially coplanar (least-squares plane: −5.1098x + 7.0367y + 1.9389z = 2.6891, r.m.s. deviation = 0.0195 Å, the furthest atom from the plane is C2 at −0.0315 Å). Methyl atoms C1 and C5 lie −0.169 (2) and 0.0079 (17) Å, respectively, from this plane, while ipso atom C6 of the benzene ring is −0.1980 (16) Å away. The benzene ring is tilted by 20.38 (8)° with respect to the remainder of the mol­ecule.

Figure 1.

The mol­ecular structure and atom-labeling scheme for I, with displacement ellipsoids drawn at the 50% probability level.

Table 1. Selected geometric parameters (Å, °).

O1—C2	1.2627 (18)	C1—C2	1.503 (2)
N1—C4	1.3352 (19)	C2—C3	1.401 (2)
N1—C6	1.4253 (18)	C3—C4	1.379 (2)
N1—H1N	0.902 (18)	C4—C5	1.495 (2)
C4—N1—H1N	115.6 (11)	C4—C3—C2	125.24 (14)
C6—N1—H1N	116.6 (11)	N1—C4—C3	120.05 (14)
O1—C2—C3	123.26 (13)

A six-membered hy­dro­gen-bridged (HB) ring, a quasi-chelate ring that strongly resembles and can act as a covalently formed classical ring (Blagojević et al., 2015 ▸), is formed through a strong intra­molecular N1—H1N⋯O1 hy­dro­gen bond (Table 2 ▸; for discussion of the remaining hy­dro­gen bonds, see Supra­molecular features) with S(6) graph-set notation (Etter, 1990 ▸). The bond lengths within the six-membered ring (Table 1 ▸) lie between typical single and double bonds for all bonding partners (Allen et al., 1987 ▸). Together with the bond angles, these values are consistent with a heteroconjugated system and with N1—H1N⋯O1 as a resonance-assisted hy­dro­gen bond (RAHB; Bertolasi et al., 1995 ▸; Filarowski et al., 2005 ▸; Steiner, 2002 ▸). Elongation of the N1—C6 bond relative to typical N(amine)—C(aromatic) distances (1.355 and 1.394 Å for planar and pyramidal N atoms, respectively; Allen et al., 1987 ▸) is also consistent with conjugation of the N-atom lone electron pair within the acac-derived backbone.

Table 2. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1N⋯O1	0.903 (18)	1.936 (18)	2.6651 (18)	136.6 (14)
O2—H1O⋯O1i	0.90 (2)	1.80 (2)	2.6886 (17)	173 (2)
C9—H9⋯O1ii	0.93	2.65 (2)	3.576 (2)	175 (2)

Symmetry codes: (i) ; (ii) .

The aromaticity of this conjugated system was further assessed using Krygowski’s harmonic oscillator measure of aromaticity (HOMA) index (Krygowski, 1993 ▸):

where n is the number of bonds, R_ij and R_opt are experimental and optimal bond lengths, respectively, and α is a dimensionless normalization constant set to give HOMA value of 0 for a non-aromatic system and 1 for a fully aromatic one. Using the bond lengths from Table 1 ▸ and literature values for α (CC 257.7, CN 93.52 and CO 157.38; Krygowski, 1993 ▸; Krygowski & Cyrański, 2001 ▸) and R_opt (CC 1.388 Å, CN 1.334 Å and CO 1.265 Å; Krygowski, 1993 ▸; Krygowski & Cyrański, 2001 ▸) gives HOMA = 0.983, indicating a high level of aromaticity in I. In com­parison, the HOMA index for acetyl­acetone is 0.964 based on the single-crystal X-ray analysis data at 210 K from Boese et al. (1998 ▸).

3. Supra­molecular features

The mol­ecules of I link via O2—H1O⋯O1ⁱ [symmetry code: (i) −x, y + , −z + ] inter­molecular hy­dro­gen bonds to form helices parallel to the crystallographic b axis [Fig. 2 ▸(a)], corresponding to a C(10) graph-set assignment (Etter, 1990 ▸). The helices wrap around 2₁ screw axes and have two mol­ecules per turn as imposed by symmetry. The left- and right-handed helices, ^supM and ^supP, respectively, inter­lock in each others grooves, forming a helix layer in the c direction [Fig. 2 ▸(b)]. There is one contact just below the sum of the van der Waals radii between two inter­locked helices: C3⋯C11ⁱⁱⁱ [symmetry code: (iii) x, −y + , z − ] at 3.388 (2) Å [purple dotted lines on Fig. 2 ▸(a) and 3(a)]. The helix layers stack along a so that helices of the same handedness lie adjacent to each other, as expected for the space group P2₁/c [Figs. 2 ▸(b); Miyata et al., 2015 ▸]. The only close contact between the layers is a weak C9—H9⋯O2ⁱⁱ [symmetry code: (ii), −x + 1, −y + 1, −z + 2] inter­molecular hy­dro­gen bond connecting helices of opposite handedness (Table 2 ▸). The geometrical parameters of this inter­action are consistent with a hy­dro­gen bond rather than packing effects.

Figure 2.

Compound I forms helices through intra­molecular hy­dro­gen bonds, (a) viewed along the crystallographic a axis, showing both left- and right-handed helices (^supM and ^supP, respectively) and (b) viewed along the crystallographic b axis emphasizing the packing of helices (blue are left- while red are right-handed). Green dashed lines indicate hy­dro­gen bonds (both intra- and inter­molecular), while purple dotted lines show short contacts between the helices.

The helix grooves, in which one mol­ecule of I ‘docks’, have an opening of 8.260 (3) Å and are com­posed of three mol­ecules [Fig. 3 ▸(a)]. The HB ring docking inter­actions were analysed using PLATON (Spek, 2020 ▸) and the findings are summarized in Fig. 3 ▸(b). The three rings, two from the groove and one from the docking mol­ecule, are stacked in an off-centre anti­parallel [α = 0.03 (8)°] fashion and are not equidistant. The Cg1⋯Cg1^iv [symmetry code: (iv) −x, −y + 1, −z + 1] pair displays a short centroid–centroid distance and only minimal lateral displacement, consistent with π–π stacking (Molčanov et al., 2019 ▸). Similar parameters have already been reported for the RAHB rings (Blagojević Filipović et al., 2019 ▸).

Figure 3.

Helix groove and docking, showing (a) one groove and its docked mol­ecule, with the centroids of the HB rings indicated, and (b) centroid–centroid inter­action parameters.

In contrast, although the the second centroid pair, Cg1⋯Cg1^v [symmetry code: (v) −x, −y, −z + 1], has a short inter­planar separation [3.4396 (7) Å], its long centroid–centroid distance [4.8131 (11) Å] and substantial slippage (3.367 Å) are not indicative of π–π stacking. Instead, this geometry corresponds to a slipped non-stacking inter­action dominated by electrostatic dipole–dipole contributions arising from the inter­action between C=O groups. Since carbonyl C atoms are planar (no pyramidalization is observed) and the C2⋯O1^v distance of 3.557 (2) Å is significantly above the 3.22 Å cut-off (Newberry & Raines, 2017 ▸), n→π* inter­actions between C=O groups can be exculded.

There are no significant contacts between benzene rings, with the closest centroid–centroid distance being 5.0134 (11) Å for Cg2⋯Cg2^vi [symmetry code: (vi) −x + 1, y − , −z + ].

4. Hirshfeld surface, fingerprint plots and lattice energy

To further analyse the inter­molecular inter­actions in the crystal structure of I, the Hirshfeld surface, with different functions mapped, and the fingerprint plots were generated using CrystalExplorer 17.5 (Turner et al., 2017 ▸). The fragment patch Hirshfeld surface reveals 16 nearest neighbours for each mol­ecule of I (Fig. 4 ▸). About 58% of the fragment patch surface belongs to five neighbours: three from the groove (patches 1, 3 and 5) and two from the mol­ecules of the next helix of the opposite handedness (patches 2 and 4), directed along the crystallographic c axis. The two hy­dro­gen-bonded mol­ecules of the same helix com­prise just under 10% of the surface combined (patches 8 and 9). The remaining nine contacts are distributed among layers along the crystallographic a axis.

Figure 4.

Hirshfeld surface with fragment patch analysis mapped for (a) 16 fragments and their contributions to the surface area, (b) helix groove contacts and their fragment patches, and (c) two large surface and (d) fragment patches corresponding to hy­dro­gen bonds within the helix.

The d_norm Hirshfeld surface [Fig. 5 ▸(a)], in the standard colour scheme, is dominated by white areas indicative of contacts close to the sum of the van der Waals radii. Two prominent red spots, at keto atom O1 and hydroxyl atom O2, highlight short contacts and coincide with the O—H⋯O hy­dro­gen bonds within a helix. Less prominent red areas correspond to the C9—H9⋯O2 contacts between helices of opposite handedness.

Figure 5.

Hirshfeld surfaces, showing (a) d_norm surface, (b) shape index (S) surface, (c) hy­dro­gen bonding and S surface, (d) inter­actions within one helix groove showing π–π inter­actions between the HB rings and (e) C—H⋯π contacts.

In contrast to the relatively featureless d_norm, the shape index Hirshfeld surface, S, provides significant inter­action detail [Fig. 5 ▸(b)]. The S surface reveals ‘hollows’ (concave red regions) and ‘bumps’ (convex blue regions) on the surface where neighbouring mol­ecules inter­lock. A deep concave region at O1 and a high convex region at OH group [dark-red arrows; Fig. 5 ▸(b)] highlight the strong hy­dro­gen bonds responsible for helix formation [Fig. 5 ▸(c)]. A similar concave/convex pair is noticeable for the weaker C9—H9⋯O2 inter­helix inter­actions [dark dashed red arrows of Fig. 5 ▸(b)]. The bow-tie pattern of green and red/blue triangles [black circle; Fig. 5 ▸(b)], characteristic of stacking of flat rings and particularly π–π stacking (McKinnon et al., 2004 ▸), supports the off-centre π–π stacking for the Cg1⋯Cg1^iv centroid pair [Fig. 5 ▸(d)]. The black arrows indicate convex regions where the second HB ring, defining Cg1^v, docks. No bow-tie pattern is observed for these two HB rings. A deep concave region (dashed circle) below the benzene ring arises from inter­action with the C5 methyl group from a helix of opposite handedness [Fig. 5 ▸(e)]. The geometric parameters indicate a weak dispersion C—H⋯π inter­action involving part of the benzene ring, specifically the C8—C9 segment, with a C5—H⋯C9 distance of 2.871 Å (Nishio, 2011 ▸).

The fingerprint plot (Spackman & McKinnon, 2002 ▸) (Fig. 6 ▸) spans a broad range of d_i and d_e values, from about 1.2 to over 2.4 Å. The colour distribution, with a clear lack of red areas indicative of strong dominant inter­actions, suggests a significant proportion of small but non-zero contacts. The most prominent feature is a two-pronged shape of the plot, typical for hy­dro­gen-bonded systems (McKinnon et al., 2004 ▸). Three inter­actions make up more than 95% of the total: H⋯H, O⋯H and C⋯H (pie chart in Fig. 6 ▸). The filtered fingerprint plots and S surfaces are shown in Fig. 6 ▸. The H⋯H contacts are absent around the HB and benzene rings. The small winged regions (marked with squares) correspond to contacts between mol­ecules of the same helix. A small tip at about 1.2 Å (circle) corresponds to the short contacts between helix layers. The central teal region of the filtered plot is dominated by contacts between stacked helices.

Figure 6.

Distribution of contacts and fingerprint plots for I.

The O⋯H contacts span a broad range of d_i/d_e values and the filtered S surface places them predominantly within a single helix. The tips of the two prongs correspond to the closest O—H⋯O contacts. The C⋯H fingerprint plot shows small wings (ellipses), characteristic of C—H⋯π inter­actions (McKinnon et al., 2004 ▸). The tips of these wings correspond to the centre of a deep depression on the S surface, seen as a red region near the benzene ring. PLATON (Spek, 2020 ▸) ring analysis did not reveal any inter­action involving the delocalised π-system of the entire benzene ring. A detailed evaluation places the minimum of the concave (red) region around C9 and the corresponding convex (blue) region at H5C with points of closest approach of C9⋯H5C^vi [symmetry code: (vii) x, −y + , z + ] = 2.87 Å, C8⋯H5C^vi = 3.15 Å and C10⋯H5C^vii = 3.08 Å between the helices of the opposite handedness within one helix layer. The remaining important C⋯H contacts form a part of a bow-tie pattern with d_i/d_e values in the range 1.8–2.0 Å. Another part of this pattern appears in the C⋯C inter­actions and lies in the teal-coloured region of the fingerprint plot. The tip of the plot corresponds to the short C3⋯C11ⁱⁱⁱ contact and appears as a small green patch on the corresponding Hirshfeld surface. Although they represent less than 2% of all contacts, O⋯C and N⋯C contacts com­plete the bow-tie pattern associated with HB ring stacking and are therefore essential for understanding the ring inter­actions.

The CE-B3LYP/6-31G(d,p) lattice energy, E_latt (Turner et al., 2014 ▸), converged at −140 kJ mol⁻¹ [Fig. 7 ▸(a)]. The principal contributor to E_latt is the dispersion term at −107.1 kJ mol⁻¹, followed by the electrostatic and polarization terms at −90.16 and −18.35 kJ mol⁻¹, respectively. The repulsion–exchange term destabilizes the lattice by +75.9 kJ mol⁻¹.

Figure 7.

(a) Lattice energy convergence plot and (b) total energy, (c) dispersion, (d) Coulombic and (e) annotated total energy framework diagrams calculated using the CE-B3LYP/6-31G(p,d) benchmark electron-density model. The tube size is set at 40, and the energy cut-off at 3.00 kJ mol⁻¹ for all framework diagrams. All diagrams are viewed along the crystallographic a axis.

The energy framework diagrams (Mackenzie et al., 2017 ▸) show that the bulk of the Coulombic forces occur within a single helix [Fig. 7 ▸(d)], while the dispersion is almost equally distributed throughout the lattice but is somewhat stronger between inter­locking helices [Fig. 7 ▸(c)], consistent with previous findings on π-stacking (Molčanov et al., 2019 ▸). As the annotated energies indicate, the strongest inter­acting is the pair of two hy­dro­gen-bonded molecules within a helix followed by the inter­actions within the helix grove [Fig. 7 ▸(e)].

5. Database survey

A search of the Cambridge Structural Database (CSD, Version 5.44, April 2023 update; Groom et al., 2016 ▸) targeting structures derived from the condensation of acetyl­acetone and an aromatic amine provided 91 results (organic structures only). The closest relative to com­pound I is 4-[(2-hy­droxy­phen­yl)amino]­pent-3-en-2-one, the keto–imine derived from the condensation of acetyl­acetone and 2-amino­phenol. There are six deposits for this com­pound (all ortho­rhom­bic, space group P2₁2₁2₁): CSD refcodes MEHTEY (Kabak et al., 1998 ▸), MEHTEY1 (Chen et al., 1999 ▸), MEHTEY2 (Rajnikant et al., 2006 ▸), MEHTEY3 (Basu et al., 2010 ▸), MEHTEY4 (Fatiha et al., 2012 ▸) and MEHTEY5 (Salehi et al., 2012 ▸). Inter­molecular hy­dro­gen bonding (also producing helical supra­molecular structure) has been discussed briefly in all cases. Salehi et al. (2012 ▸) also include a brief discussion on resonance-assisted hy­dro­gen bonds.

6. Synthesis and crystallization

Acetyl­acetone (2.3 mmol, 2.3 ml) was added dropwise to a stirred solution of 3-amino­phenol (2.3 mmol, 0.25 g) in 95% ethanol (10 ml). The reaction was stirred at ambient temperature for 45 min, covered and then left to stand. After two days, colourless crystals were collected giving an 88% yield (1.8 g) of the title com­pound.

6.1. Analytical data

¹H NMR (CHCl₃, δ from TMS): 2.08 (s, 3H, –CH₃), 2.14 (s, 3H, –CH₃), 5.20 (s, 1H, CH), ¹³C NMR (CHCl₃, δ from TMS): 20.16, 28.46 (–CH₃), 97.5 (CH, acac backbone), 111.5, 114.2, 115.7, 130.6, 138.8, 158.67 (benzene ring carbons), 163.0 (CN) and 169.1 (CO). Elemental analysis calculated (%) for C₁₁H₁₃NO₂: C 69.09, N 7.32; found: C 69.07, N 7.56. MS–ESI: 190.097 (base peak, M – H⁺), 148.038 [M – C(=O)CH₃]^.−.

7. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 3 ▸. The positional parameters of the H atoms bonded to N1 and O2, i.e. H1N and H1O, were refined while their displacement parameters were constrained in the usual manner. See the figures in the supporting information for the residual electron-density maps before and after the refinement of atoms H1N and H1O.

Table 3. Experimental details.

Crystal data
Chemical formula	C11H13NO2
M r	191.22
Crystal system, space group	Monoclinic, P21/c
Temperature (K)	295
a, b, c (Å)	10.109 (1), 8.2598 (8), 12.2074 (13)
β (°)	92.539 (4)
V (Å3)	1018.30 (18)
Z	4
Radiation type	Mo Kα
μ (mm−1)	0.09
Crystal size (mm)	0.39 × 0.32 × 0.09
Data collection
Diffractometer	Bruker SMART X2S
Absorption correction	Multi-scan (SADABS; Bruker, 2004 ▸)
No. of measured, independent and observed [I > 2σ(I)] reflections	12414, 2304, 1661
R int	0.037
(sin θ/λ)max (Å−1)	0.649
Refinement
R[F2 > 2σ(F2)], wR(F2), S	0.043, 0.131, 1.05
No. of reflections	2304
No. of parameters	135
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å−3)	0.16, −0.17

Computer programs: XPREP (Bruker, 2004 ▸), SAINT (Bruker, 2004 ▸) and SHELXL2019 (Lübben et al., 2019 ▸).

Supplementary Material

CCDC reference: 1818233

Additional supporting information: crystallographic information; 3D view; checkCIF report

supplementary crystallographic information

(3Z)-4-[(3-Hydroxyphenyl)amino]pent-3-en-2-one . Crystal data

C11H13NO2	F(000) = 408
Mr = 191.22	Dx = 1.247 Mg m−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 10.109 (1) Å	Cell parameters from 3910 reflections
b = 8.2598 (8) Å	θ = 3.0–25.5°
c = 12.2074 (13) Å	µ = 0.09 mm−1
β = 92.539 (4)°	T = 295 K
V = 1018.30 (18) Å3	Prism, white
Z = 4	0.39 × 0.32 × 0.09 mm

(3Z)-4-[(3-Hydroxyphenyl)amino]pent-3-en-2-one . Data collection

Bruker SMART X2S diffractometer	1661 reflections with I > 2σ(I)
θ/2θ scans	Rint = 0.037
Absorption correction: multi-scan (SADABS; Bruker, 2004)	θmax = 27.5°, θmin = 2.0°
	h = −13→12
12414 measured reflections	k = −10→8
2304 independent reflections	l = −15→15

(3Z)-4-[(3-Hydroxyphenyl)amino]pent-3-en-2-one . Refinement

Refinement on F2	0 restraints
Least-squares matrix: full	Hydrogen site location: mixed
R[F2 > 2σ(F2)] = 0.043	H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.131	w = 1/[σ2(Fo2) + (0.0587P)2 + 0.1926P] where P = (Fo2 + 2Fc2)/3
S = 1.05	(Δ/σ)max = 0.001
2304 reflections	Δρmax = 0.16 e Å−3
135 parameters	Δρmin = −0.17 e Å−3

(3Z)-4-[(3-Hydroxyphenyl)amino]pent-3-en-2-one . Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

(3Z)-4-[(3-Hydroxyphenyl)amino]pent-3-en-2-one . Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
O1	0.43035 (10)	0.81490 (15)	0.54180 (8)	0.0599 (3)
O2	0.81010 (12)	0.44803 (18)	0.93832 (10)	0.0748 (4)
H1O	0.728 (2)	0.407 (3)	0.9392 (16)	0.090*
N1	0.65951 (13)	0.66563 (17)	0.58920 (10)	0.0518 (3)
H1N	0.5874 (18)	0.719 (2)	0.6112 (13)	0.062*
C1	0.35690 (18)	0.8435 (2)	0.35503 (14)	0.0701 (5)
H1A	0.390076	0.818741	0.284480	0.105*
H2A	0.348530	0.958690	0.362603	0.105*
H3A	0.271802	0.793723	0.361572	0.105*
C2	0.45131 (14)	0.77987 (19)	0.44339 (12)	0.0507 (4)
C3	0.55872 (15)	0.68582 (19)	0.41245 (12)	0.0512 (4)
H3	0.561171	0.656140	0.339084	0.061*
C4	0.66112 (14)	0.63373 (18)	0.48205 (12)	0.0486 (4)
C5	0.77347 (17)	0.5391 (2)	0.43852 (15)	0.0674 (5)
H5A	0.743665	0.482666	0.373259	0.101*
H5B	0.804881	0.462392	0.492717	0.101*
H5C	0.843976	0.611567	0.421641	0.101*
C6	0.76327 (14)	0.63947 (19)	0.67015 (12)	0.0477 (4)
C7	0.88744 (15)	0.7068 (2)	0.65909 (15)	0.0627 (5)
H7	0.906071	0.766290	0.596935	0.075*
C8	0.98306 (15)	0.6842 (2)	0.74194 (15)	0.0642 (5)
H8	1.067104	0.727533	0.734505	0.077*
C9	0.95668 (14)	0.5991 (2)	0.83511 (14)	0.0566 (4)
H9	1.021965	0.586059	0.890515	0.068*
C10	0.83197 (14)	0.53259 (19)	0.84595 (13)	0.0494 (4)
C11	0.73545 (13)	0.55284 (18)	0.76281 (12)	0.0461 (4)
H11	0.651851	0.507906	0.769582	0.055*

(3Z)-4-[(3-Hydroxyphenyl)amino]pent-3-en-2-one . Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
O1	0.0502 (6)	0.0799 (8)	0.0490 (6)	0.0070 (5)	−0.0035 (5)	−0.0044 (5)
O2	0.0536 (7)	0.1028 (11)	0.0667 (8)	−0.0156 (7)	−0.0118 (6)	0.0267 (7)
N1	0.0422 (6)	0.0632 (8)	0.0497 (7)	0.0027 (6)	−0.0027 (5)	−0.0012 (6)
C1	0.0693 (11)	0.0823 (13)	0.0570 (10)	0.0084 (9)	−0.0150 (8)	−0.0004 (9)
C2	0.0476 (8)	0.0552 (9)	0.0487 (8)	−0.0089 (7)	−0.0037 (6)	0.0023 (7)
C3	0.0526 (8)	0.0576 (10)	0.0433 (8)	−0.0071 (7)	0.0008 (6)	−0.0004 (7)
C4	0.0482 (8)	0.0473 (8)	0.0506 (8)	−0.0085 (6)	0.0035 (6)	0.0008 (7)
C5	0.0629 (10)	0.0683 (11)	0.0715 (11)	0.0053 (9)	0.0076 (8)	−0.0079 (9)
C6	0.0413 (7)	0.0477 (8)	0.0535 (8)	0.0018 (6)	−0.0041 (6)	−0.0034 (7)
C7	0.0510 (9)	0.0659 (11)	0.0706 (11)	−0.0122 (8)	−0.0031 (7)	0.0138 (8)
C8	0.0415 (8)	0.0670 (11)	0.0832 (12)	−0.0123 (7)	−0.0069 (8)	0.0117 (9)
C9	0.0407 (7)	0.0571 (10)	0.0707 (10)	0.0001 (7)	−0.0119 (7)	0.0022 (8)
C10	0.0430 (7)	0.0498 (9)	0.0550 (8)	0.0017 (6)	−0.0028 (6)	0.0013 (7)
C11	0.0350 (6)	0.0490 (8)	0.0541 (8)	−0.0020 (6)	0.0007 (6)	−0.0054 (7)

(3Z)-4-[(3-Hydroxyphenyl)amino]pent-3-en-2-one . Geometric parameters (Å, º)

O1—C2	1.2627 (18)	C5—H5A	0.9600
O2—C10	1.3528 (19)	C5—H5B	0.9600
O2—H1O	0.89 (2)	C5—H5C	0.9600
N1—C4	1.3352 (19)	C6—C11	1.378 (2)
N1—C6	1.4253 (18)	C6—C7	1.385 (2)
N1—H1N	0.902 (18)	C7—C8	1.380 (2)
C1—C2	1.503 (2)	C7—H7	0.9300
C1—H1A	0.9600	C8—C9	1.374 (2)
C1—H2A	0.9600	C8—H8	0.9300
C1—H3A	0.9600	C9—C10	1.387 (2)
C2—C3	1.401 (2)	C9—H9	0.9300
C3—C4	1.379 (2)	C10—C11	1.3865 (19)
C3—H3	0.9300	C11—H11	0.9300
C4—C5	1.495 (2)
C10—O2—H1O	113.0 (13)	C4—C5—H5C	109.5
C4—N1—C6	127.50 (14)	H5A—C5—H5C	109.5
C4—N1—H1N	115.6 (11)	H5B—C5—H5C	109.5
C6—N1—H1N	116.6 (11)	C11—C6—C7	120.49 (13)
C2—C1—H1A	109.5	C11—C6—N1	118.50 (13)
C2—C1—H2A	109.5	C7—C6—N1	120.92 (14)
H1A—C1—H2A	109.5	C8—C7—C6	118.84 (16)
C2—C1—H3A	109.5	C8—C7—H7	120.6
H1A—C1—H3A	109.5	C6—C7—H7	120.6
H2A—C1—H3A	109.5	C9—C8—C7	121.38 (15)
O1—C2—C3	123.26 (13)	C9—C8—H8	119.3
O1—C2—C1	118.34 (15)	C7—C8—H8	119.3
C3—C2—C1	118.40 (14)	C8—C9—C10	119.50 (14)
C4—C3—C2	125.24 (14)	C8—C9—H9	120.3
C4—C3—H3	117.4	C10—C9—H9	120.3
C2—C3—H3	117.4	O2—C10—C11	122.46 (13)
N1—C4—C3	120.05 (14)	O2—C10—C9	117.82 (13)
N1—C4—C5	119.58 (14)	C11—C10—C9	119.72 (14)
C3—C4—C5	120.36 (14)	C6—C11—C10	120.06 (13)
C4—C5—H5A	109.5	C6—C11—H11	120.0
C4—C5—H5B	109.5	C10—C11—H11	120.0
H5A—C5—H5B	109.5
O1—C2—C3—C4	−6.9 (3)	N1—C6—C7—C8	177.12 (16)
C1—C2—C3—C4	172.60 (15)	C6—C7—C8—C9	−1.1 (3)
C6—N1—C4—C3	−171.48 (14)	C7—C8—C9—C10	0.8 (3)
C6—N1—C4—C5	9.5 (2)	C8—C9—C10—O2	179.29 (15)
C2—C3—C4—N1	3.4 (2)	C8—C9—C10—C11	0.0 (3)
C2—C3—C4—C5	−177.56 (15)	C7—C6—C11—C10	0.1 (2)
C4—N1—C6—C11	−127.36 (17)	N1—C6—C11—C10	−176.49 (14)
C4—N1—C6—C7	56.1 (2)	O2—C10—C11—C6	−179.66 (15)
C11—C6—C7—C8	0.7 (3)	C9—C10—C11—C6	−0.4 (2)

(3Z)-4-[(3-Hydroxyphenyl)amino]pent-3-en-2-one . Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1N···O1	0.903 (18)	1.936 (18)	2.6651 (18)	136.6 (14)
O2—H1O···O1i	0.90 (2)	1.80 (2)	2.6886 (17)	173 (2)
C9—H9···O1ii	0.93	2.65 (2)	3.576 (2)	175 (2)

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