4-(2,5-Dioxo-2,5-di­hydro-1H-pyrrol-1-yl)benzoic acid: X-ray and DFT-calculated structure

In the title compound, C₁₁H₇NO₄, there is a dihedral angle of 45.80 (7)° between the planes of the benzene and maleimide rings. The presence of O—H⋯O hydrogen bonding and weak C—H⋯O inter­actions allows the formation of R₃³(19) edge-connected rings parallel to the (010) plane. Structural, spectroscopic and theoretical studies were carried out. Density functional theory (DFT) optimized structures at the B3LYP/6–311 G(d,p) and 6–31++G(d,p) levels are compared with the experimentally determined mol­ecular structure in the solid state. Additional IR and UV theoretical studies allowed the presence of functional groups and the transition bands of the system to be identified.

Comment

The structure determination of 4-carb­oxy­phenyl­maleimide [systematic name: 4-(2,5-dioxo-2,5-dihydro-1H-pyrrol-1-yl)ben­zoic acid], (I), is part of a series of structure determinations on phenyl­maleimide derivatives (Moreno-Fuquen et al., 2003, 2006, 2008). There is considerable inter­est in the development of N-substituted maleimides as photoionizers for free radical polymerization, where the maleimide can produce the initiating radical species (Andersson et al., 1996; Teerenstra et al., 2000). Miller et al. (2001) synthesized a good number of N-arylmaleimides to evaluate their utility as free radical photoinitiators. As a result of this evaluation they found that the photochemical properties of N-aryl­maleimide systems depend on the values of the dihedral angle between the benzene and imidic rings (Miller et al., 2000). Even with good crystallographic information on N-phenyl­maleimide derivatives reported in the literature, the search for new related systems remains important for the analysis of polymerization processes in which they are involved. Calculations by density functional theory (DFT) on N-phenyl­maleimide compounds, modelling the torsional deformation between the rings and showing the energy barrier to planarity, are also reported (Miller et al., 1999). The present work describes structural, spectroscopic and theoretical studies on 4-carb­oxy­phenyl­maleimide.

The title compound shows a dihedral angle of 45.80 (7)° between the mean planes of the benzene and maleimide rings (see Fig. 1). This structural behaviour is repeated in similar systems, e.g. p-nitro­phenyl­maleimide [42.98 (5)°; Moreno-Fuquen et al., 2003], p-chloro­phenyl­maleimide [47.54 (9)°; Moreno-Fuquen et al., 2008] and 2-p-toluidino-N-p-tolyl­maleimide [42.6 (1)°; Watson et al., 2004], where the inter­planar angles of these systems are close to that observed in (I), and their bond distances and angles are very similar. O—H⋯O hydrogen bonds of moderate character (Emsley, 1984) and weak inter­molecular C—H⋯O inter­actions are observed in (I) (see Table 1; Nardelli, 1995). Although C—H⋯O inter­actions appear to be very weak, these contacts may have a determining effect on the formation of different packing motifs (Desiraju et al., 1993), they can play significant roles in mol­ecular conformation (Saenger & Steiner, 1998) and they are essential in mol­ecular recognition processes (Shimon et al., 1990). With regard to the structure (I), atom O2 acts as a hydrogen-bond donor to carboxyl atom O1 in the mol­ecule at (x − , −y + , −z + 2). At the same time, atom C3 acts as a donor to atom O3 in the mol­ecule at (x − 1, y, z). The mol­ecules of (I) form an infinite chain of edge-connected R₃³(19) rings (Etter, 1990) running parallel to the (010) plane (see Fig. 2). Neighbouring chains inter­act through very weak C—H⋯O contacts in which atom C6 acts as a hydrogen-bond donor to carbonyl atom O4 in the mol­ecule at (x + , −y + , −z + 1), forming R₂²(12) rings, completing the two-dimensional array.

The presence of substituents in the benzene ring forces the system to produce several conformations between the benzene and maleimide rings (Miller et al., 2000). The position of the substituent on the benzene ring, the volume of the substituent and its intra- and inter­molecular inter­actions are essential factors when analysing the structural behaviour of these systems. The presence of the carboxyl group in the para position allows the analysis of the influence of the substituent on the inter-ring torsion angle along N1—C5. To gain a better understanding of the properties of compound (I), we further explored the stability of this compound in the gaseous state, calculating the harmonic frequencies and comparing the results with those observed in the fundamental vibrational frequencies. Additionally, theoretical studies of the UV spectra were undertaken. Previous studies on similar systems (Miller et al., 1999) showed that calculations at the DFT-B3LYP level were consistently close to experimental values.

Calculations by density functional theory DFT-B3LYP, with basis sets 6–31++G(d,p) and 6–311 G(d,p), of bond lengths and angles were performed. These values were compared with experimental values of the title system (see Table 2). From these results we can conclude that basis set 6–311 G(d,p) is better suited in its approach to the experimental data.

Calculations using basis set 6–311(d,p) modelled torsional deformations between the aryl and maleimide rings, showing different conformations with different energy barriers. Calculations on isolated 4-carb­oxy­phenyl­maleimide showed a minimum rotational energy for a rotamer with an inter-ring dihedral angle of 35.11°. This result shows a significant correlation with the experimental value of 45.80 (7)°.

The vibrational analysis of the title compound shows the expected IR bands attributed to the constituents of the complex. The spectrum shows several well defined bands: an intense and broad band in the IR spectrum at 1720 cm⁻¹ can be assigned to the axial deformation of carbonyl C=O which is also observed in the simulated spectrum at 1793 cm⁻¹. The C=O band of the carboxyl group is masked within the same carbonyl C=O band. These and other observed and calculated bands with their assignments are shown in Table 3. The comparison of the observed fundamental frequencies of (I) and the IR spectrum simulated by DFT calculation (B3LYP) showed a good agreement between frequencies (see Fig. 3).

Compound (I) shows an absorption band in the UV region at α = 246.5 nm in methanol. The most intense bands obtained near this region in B3LYP/6–311 G(d,p) calculations for an isolated mol­ecule are around λ = 243 nm [oscillator strength = 0.413 (exp) and 0.330 (calc)]. These bands are attributed to an intra­molecular charge transfer (ICT) from the highest occupied mol­ecular orbital (HOMO) to an orbital close to the lowest unoccupied mol­ecular orbital (LUMO+1). The calculations reveal that these are π orbitals, primarily localized in the plane extending from the benzene to the maleimide ring; these orbitals are shown in Fig. 4.

Figure 1 An ORTEP-3 (Farrugia, 1997) plot of (I), showing the atom-labelling scheme. Ellipsoids are drawn at the 50% probability level and H atoms are shown as spheres of arbitrary radius.

Figure 2 The packing in the unit cell of (I) parallel to the (010) plane, showing the R3^3(19) edge-fused rings. Dashed lines denote the inter­molecular O—H⋯O hydrogen bonds and the inter­molecular C—H⋯O contacts. [Symmetry codes: (i) x − , −y + , −z + 2; (ii) x − 1, y, z.]

Figure 3 Comparison of observed and calculated IR spectra of (I).

Figure 4 Electron distribution of (a) the HOMO and (b) the LUMO+1 energy levels for (I).

Experimental

Starting materials and reagents were purchased from Aldrich and used as received. The title compound was prepared by mixing equimolar quanti­ties of 4-amino­benzoic acid (1.00 g, 7.3 mmol) and maleic anhydride in N,N-dimethyl­formamide (20 ml) under a nitro­gen atmosphere at ambient temperature for 1 h. Cyclo­dehydration of the maleamic acid to maleimide was carried out by treating the acid with fused sodium acetate and acetic anhydride for 2 h at 343 K. A yellow–orange precipitate was obtained by adding water to the solution. Crystals were dissolved in methanol and left to evaporate, giving pale-yellow prismatic crystals [m.p. 491 (1) K, 60% yield].

Crystal data

• C₁₁H₇NO₄

• M_r = 217.18

• Orthorhombic, P 2₁ 2₁ 2₁

• a = 7.3326 (5) Å

• b = 9.8832 (5) Å

• c = 13.3922 (11) Å

• V = 970.53 (11) ų

• Z = 4

• Mo Kα radiation

• μ = 0.12 mm⁻¹

• T = 294 K

• 0.18 × 0.13 × 0.10 mm

Data collection

• Bruker–Nonius KappaCCD diffractometer

• 6051 measured reflections

• 1278 independent reflections

• 895 reflections with I > 2σ(I)

• R_int = 0.063

Refinement

• R[F² > 2σ(F²)] = 0.049

• wR(F²) = 0.128

• S = 1.13

• 1278 reflections

• 145 parameters

• H-atom parameters constrained

• Δρ_max = 0.19 e Å⁻³

• Δρ_min = −0.21 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O2—H2⋯O1^i	0.82	1.90	2.672 (3)	156
C3—H3⋯O3^ii	0.93	2.39	3.103 (4)	134
C6—H6⋯O4^iii	0.93	2.68	3.392 (4)	134
Symmetry codes: (i) ; (ii) x-1, y, z; (iii) .

Table 2
Comparison of selected geometric data for (I) (Å, °) from calculated (DFT) and X-ray data

	X-ray	B3LYP/6–31++G(d,p)	B3LYP/6–311G(d,p)
O1—C1	1.212 (4)	1.2168	1.2080
O2—C1	1.327 (4)	1.3593	1.3565
C5—N1	1.424 (4)	1.4251	1.4243
C8—O4	1.202 (4)	1.2128	1.2038
C11—O3	1.210 (5)	1.2127	1.2036
C1—C2	1.480 (5)	1.4856	1.4854
O4—C8—N1	124.9 (3)	126.32	126.58
O3—C11—N1	124.8 (3)	126.31	126.57
C11—N1—C5	125.2 (3)	125.31	125.26
N1—C5—C4	119.6 (3)	119.83	119.95
C2—C1—O2	112.6 (3)	113.19	112.90
C2—C1—O1	125.3 (3)	124.97	124.99

Table 3
Comparison of the observed and calculated vibrational frequencies in cm⁻¹ for (I)

Assignment	Observed	Calculated
C—H angular deformation out of the aromatic plane	767	717
	831	849
	855	873
C—H scissor deformation at C=C of the maleimide plane	1027	1076
Vibrational axial deformation of C—O of the carboxyl group	1146	1109
Axial deformation of C—N at the maleimidic skeleton	1180	1125
C—H angular deformation in the aromatic plane	1293	1192
	1214	1218
	1312	1226
Axial deformation of C—N between maleimide and benzene rings	1398	1386
Axial deformation of carbon­yl C=O	1720	1793

All H atoms were located from difference maps, then their positions were geometrically optimized and refined using a riding model, with C—H = 0.93 Å and O—H = 0.82 Å, and with U_iso(H) = 1.2U_eq(C) or 1.5U_eq(O). Friedel pairs were merged in the data set used for the final structure refinement. The DFT quantum-chemical calculations were performed at the B3LYP/6–311 G(d,p) level (Becke, 1993; Lee et al., 1988). The performance of 6–31++G(d,p) and 6–311 G(d,p) basis functions (Bauschlicher & Partridge, 1995) was checked in these calculations as implemented in GAUSSIAN03 (Frisch et al., 2004). DFT structure optimization of (I) was performed, starting from the X-ray geometry. The harmonic vibrational analysis at the same level of theory confirmed the stability of the ground state as denoted by the absence of imaginary frequencies.

Data collection: COLLECT (Nonius, 2000); cell refinement: SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO (Otwinowski & Minor, 1997) and SCALEPACK; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997) and Mercury (Macrae et al., 2006); software used to prepare material for publication: WinGX (Farrugia, 1999).

Supporting information

S1. Comment

The structure determination of 4-carboxyphenylmaleimide [systematic name: 4-(2,5-dioxo-2,5-dihydro-1H-pyrrol-1-yl)benzoic acid], (I), is part of a series of structure determinations on phenylmaleimide derivatives (Moreno-Fuquen et al., 2003, 2006, 2008). There is considerable interest in the development of N-substituted maleimides as photoionizers for free radical polymerization, where the maleimide can produce the initiating radical species (Andersson et al., 1996; Teerenstra et al., 2000). Miller et al. (2001) synthesized a good number of N-aromatic maleimides to evaluate their utility as free radical photoinitiators. As a result of this evaluation they found that the photochemical properties of N-arylmaleimide systems depend on the values of the dihedral angle between the benzene and imidic rings (Miller et al., 2000). Even with good crystallographic information on N-phenylmaleimide derivatives reported in the literature, the search for new, related systems remains important for the analysis of polymerization processes in which they are involved. Calculations by density functional theory (DFT) on N-phenylmaleimide compounds, modelling the torsional deformation between the rings and showing the energy barrier to planarity, are also reported (Miller et al., 1999). The present work describes structural, spectroscopic and theoretical studies on 4-carboxyphenylmaleimide.

The title compound shows a dihedral angle of 45.80 (7)° between the mean planes of the benzene and maleimide rings (see Fig. 1). This structural behaviour is repeated in similar systems, e.g. p-nitrophenylmaleimide, 42.98 (5)° (Moreno-Fuquen et al., 2003), p-chlorophenylmaleimide, 47.54 (9)° (Moreno-Fuquen et al., 2008) and 2-p-toluidino-N-p-tolylmaleimide, 42.6 (1)° (Watson et al., 2004), where the interplanar angles of these systems are close to that observed in (I), and their bond distances and bond angles are very similar. O—H···O hydrogen bonds of moderate character (Emsley, 1984) and weak C—H···O intermolecular interactions are observed in (I) (see Table 1; Nardelli, 1995). Although C—H···O interactions appear to be very weak, these contacts may have a determining effect on the formation of different packing motifs (Desiraju et al., 1993), they can play significant roles in molecular conformation (Saenger & Steiner, 1998) and they are essential in molecular recognition processes (Shimon et al., 1990). With regard to the structure (I), the O2 atom acts as hydrogen-bond donor to the carboxyl atom, O1ⁱ, in the molecule at (x - 1/2, -y + 1/2, -z + 2). At the same time, the C3 atom acts as donor to the O3ⁱⁱ atom in the molecule at (x - 1, y, z). The molecules of (I) form an infinite chain of edge-connected R³₃(19) rings (Etter, 1990) running parallel to the (010) plane (see Fig. 2). Neighbouring chains interact through very weak C—H···O contacts in which the C6 atom acts as hydrogen-bond donor to the carbonyl atom O4ⁱⁱⁱ in the molecule at (x + 1/2, -y + 1/2, -z + 1), forming R²₂(12) rings, completing the two-dimensional array.

The presence of substituents in the benzene ring forces the system to produce several conformations between the benzene and maleimide rings (Miller et al., 2000). The position of the substituent on the benzene ring, the volume of the substituent and its intra- and intermolecular interactions are essential factors when analysing the structural behaviour of these systems. The presence of the carboxyl group in the para position allows the analysis of the influence of the substituent on the inter-ring torsion angle along N1—C5. To gain a better understanding of the properties of compound (I), we further explored the stability of this compound in the gaseous state, calculating the harmonic frequencies and comparing the results with those observed in the fundamental vibrational frequencies. Additionally, theoretical studies of the UV spectra were undertaken. Previous studies on similar systems (Miller et al., 1999) showed that calculations at the DFT-B3LYP level were consistently closer to experimental values.

Calculations by density functional theory DFT-B3LYP, with two basis sets 6–31++G(d,p) and 6–311 G(d,p) of bond lengths and bond angles, were performed. These values were compared with experimental values of the title system (see Table 2). From these results we can conclude that basis set 6–311 G(d,p) is better behaved in its approach [better suited?] to the experimental data.

Calculations using basis set 6–311(d,p) modelled torsional deformations between aryl and maleimide rings, showing different conformations with different energy barriers. Calculations on isolated 4-carboxyphenylmaleimide showed a minimum rotational energy for a rotamer with an inter-ring dihedral angle of 35.11°. This result shows a significant correlation with the experimental value of 45.80 (7)°.

The vibrational analysis of the title compound shows the expected infrared bands attributed to the constituents of the complex. The spectrum shows several well defined bands: an intense and broad band in the IR spectrum at 1720 cm^-1 can be assigned to the axial deformation of carbonyl C═O which is also observed in the simulated spectrum at 1793 cm^-1. The C═O band of the carboxyl group is masked within the same carbonyl C═O band. These and other observed and calculated bands with their assignements are shown in Table 3. The comparison of the observed fundamental frequencies of (I) and the IR spectrum simulated by DFT calculation (B3LYP) showed a good agreement between frequencies (see Fig. 3).

Compound (I) shows an absorption band in the UV region at α = 246.5 nm in methanol. The most intense bands obtained near this region in B3LYP/6–311 G(d,p) calculations for an isolated molecule are around λ = 243 nm [oscillator strength = 0.413 (exp) and 0.330 (calc)]. These bands are attributed to an intramolecular charge transfer (ICT) from the highest occupied molecular orbital (HOMO) to an orbital close to the lowest unoccupied molecular orbital (LUMO+1). The calculations reveal that these are π orbitals, primarily localized in the plane extending from the phenyl to the maleimide ring. These orbitals are shown in Fig. 4.

Related literature

For background information on phenylmaleimide derivatives see: Moreno-Fuquen et al., 2003; Moreno-Fuquen et al., 2008; Miller et al., 2000. For background information on photochemical properties of N-phenylmaleimide derivatives see: Andersson et al., 1996; Teerenstra et al., 2000; Miller et al., 2001; Watson et al., 2004. For hydrogen bonding, see: Etter (1990); Nardelli (1995); Emsley (1984). For a description of the Cambridge Structural Database, see: Allen (2002).

S2. Experimental

Starting materials and reagents were purchased from Aldrich and used as received. The title compound was prepared by taking [mixing?] equimolar quantities of p-aminobenzoic acid (1.00 g, 7.3 mmol) and maleic anhydride in DMF [N,N-dimethylformamide?] (20 ml) under a nitrogen atmosphere at ambient temperature for 1 h. Cyclodehydration of the maleamic acid, intermediate to maleimide, was carried out by treating it with fused sodium acetate and acetic anhydride for 2 h at 343 K. A yellow–orange precipitate was obtained by adding water to the solution. Crystals were dissolved in methanol and left evaporating to give a yellowish prism with a melting point of 491 (1) K. The synthesis showed a 60% yield.

S3. Refinement

All H atoms were located from difference maps, positioned geometrically and refined using a riding model with C—H = 0.93–0.97 Å and U_iso(H) = 1.2U_eq(C). Friedel pairs were merged in the data set used for final structure refinement. The DFT quantum-chemical calculations were performed at the B3LYP/6–311 G(d,p) level (Becke, 1993; Lee et al., 1988). The performance of 6–31++G(d,p) and 6–311 G(d,p) basis functions (Bauschlicher & Partridge, 1995) was checked in these calculations as implemented in GAUSSIAN03 (Frisch et al., 2004). DFT structure optimization of (I) was performed, starting from the X-ray geometry. The harmonic vibrational analysis at the same level of theory confirmed the stability of the ground state as denoted by the absence of imaginary frequencies.

Computing details

Data collection: COLLECT (Nonius, 2000); cell refinement: SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO and SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997) and Mercury (Macrae et al., 2006); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures

	Fig. 1. An ORTEP-3 (Farrugia, 1997) plot of (I), with the atom-labelling scheme. Ellipsoids are drawn at the 50% probability level. H atoms are shown as spheres of arbitrary radius.
	Fig. 2. The packing in the unit cell of (I) parallel to the (0 1 0) plane, showing the R3^3(19) edge-fused rings. Dashed lines denote the intermolecular O—H···O intermolecular hydrogen bond and C—H···O intermolecular contact. [Symmetry codes: (i) x - 1/2, -y + 1/2, -z + 2; (ii) x - 1, y, z.]
	Fig. 3. Comparison of observed and calculated infrared spectra of (I).
	Fig. 4. Electron distribution of HOMO (a) and LUMO+1 (b) energy levels for (I).

4-(2,5-dioxo-2,5-dihydro-1H-pyrrol-1-yl)benzoic acid

Crystal data

C11H7NO4	Dx = 1.486 Mg m^−3
Mr = 217.18	Melting point: 361.0(10) K
Orthorhombic, P212121	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2ab	Cell parameters from 3141 reflections
a = 7.3326 (5) Å	θ = 2.9–27.5°
b = 9.8832 (5) Å	µ = 0.12 mm^−1
c = 13.3922 (11) Å	T = 294 K
V = 970.53 (11) Å^3	Prisms, pale-yellow
Z = 4	0.18 × 0.13 × 0.10 mm
F(000) = 448

Data collection

KappaCCD diffractometer	895 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.063
Graphite monochromator	θmax = 27.5°, θmin = 3.2°
CCD rotation images, thick slices scans	h = −8→9
6051 measured reflections	k = −12→12
1278 independent reflections	l = −17→16

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)] = 0.049	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.128	H-atom parameters constrained
S = 1.13	w = 1/[σ^2(Fo^2) + (0.0644P)^2 + 0.0425P] where P = (Fo^2 + 2Fc^2)/3
1278 reflections	(Δ/σ)max < 0.001
145 parameters	Δρmax = 0.19 e Å^−3
0 restraints	Δρmin = −0.21 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	0.7660 (3)	0.2398 (3)	0.97977 (17)	0.0591 (6)
O2	0.5223 (3)	0.1942 (3)	0.88701 (19)	0.0612 (7)
H2	0.4692	0.2131	0.9391	0.092*
O3	1.3783 (4)	0.0171 (3)	0.6183 (2)	0.0773 (9)
O4	0.8918 (4)	0.1485 (3)	0.4308 (2)	0.0784 (8)
N1	1.1066 (3)	0.0912 (2)	0.55032 (19)	0.0486 (6)
C1	0.7010 (4)	0.2050 (3)	0.9006 (3)	0.0482 (8)
C2	0.8062 (4)	0.1723 (3)	0.8095 (2)	0.0435 (7)
C3	0.7299 (4)	0.0990 (3)	0.7323 (3)	0.0515 (8)
H3	0.6100	0.0691	0.7376	0.062*
C4	0.8283 (4)	0.0696 (3)	0.6478 (3)	0.0513 (8)
H4	0.7765	0.0187	0.5968	0.062*
C5	1.0061 (4)	0.1167 (3)	0.6394 (2)	0.0465 (7)
C6	1.0854 (4)	0.1896 (3)	0.7166 (3)	0.0505 (8)
H6	1.2047	0.2205	0.7108	0.061*
C7	0.9863 (4)	0.2159 (3)	0.8017 (3)	0.0494 (8)
H7	1.0398	0.2630	0.8542	0.059*
C8	1.0436 (5)	0.1128 (3)	0.4524 (3)	0.0565 (9)
C9	1.2005 (6)	0.0837 (3)	0.3871 (3)	0.0685 (11)
H9	1.1991	0.0882	0.3177	0.082*
C10	1.3412 (6)	0.0508 (4)	0.4410 (4)	0.0715 (11)
H10	1.4567	0.0306	0.4165	0.086*
C11	1.2885 (5)	0.0505 (3)	0.5466 (3)	0.0559 (8)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0516 (13)	0.0840 (14)	0.0416 (13)	0.0015 (12)	−0.0062 (10)	−0.0078 (12)
O2	0.0425 (11)	0.0877 (16)	0.0535 (15)	−0.0054 (12)	0.0030 (11)	−0.0186 (13)
O3	0.0540 (15)	0.0934 (19)	0.085 (2)	0.0122 (14)	−0.0166 (15)	−0.0259 (17)
O4	0.0872 (19)	0.0975 (19)	0.0507 (16)	0.0296 (17)	−0.0090 (16)	0.0009 (14)
N1	0.0446 (14)	0.0603 (15)	0.0409 (15)	0.0026 (13)	0.0018 (12)	−0.0028 (13)
C1	0.0433 (16)	0.0540 (16)	0.047 (2)	−0.0028 (14)	−0.0039 (14)	0.0002 (14)
C2	0.0435 (15)	0.0519 (15)	0.0351 (16)	−0.0003 (14)	−0.0038 (13)	−0.0014 (13)
C3	0.0421 (16)	0.0652 (18)	0.047 (2)	−0.0076 (15)	−0.0012 (15)	−0.0065 (15)
C4	0.0466 (16)	0.0628 (18)	0.0444 (18)	−0.0049 (15)	−0.0045 (15)	−0.0100 (15)
C5	0.0444 (16)	0.0536 (16)	0.0415 (19)	0.0017 (15)	−0.0016 (15)	−0.0010 (14)
C6	0.0438 (15)	0.0614 (17)	0.046 (2)	−0.0064 (15)	−0.0022 (15)	0.0000 (15)
C7	0.0441 (16)	0.0585 (17)	0.0456 (19)	−0.0070 (15)	−0.0024 (14)	−0.0049 (14)
C8	0.069 (2)	0.0521 (17)	0.048 (2)	0.0035 (16)	−0.0021 (18)	0.0009 (16)
C9	0.093 (3)	0.057 (2)	0.055 (2)	−0.008 (2)	0.023 (2)	−0.0044 (17)
C10	0.065 (2)	0.072 (2)	0.077 (3)	−0.009 (2)	0.024 (2)	−0.021 (2)
C11	0.0484 (18)	0.0574 (17)	0.062 (2)	−0.0018 (15)	0.0001 (17)	−0.0149 (17)

Geometric parameters (Å, º)

O1—C1	1.212 (4)	C3—H3	0.9300
O2—C1	1.327 (4)	C4—C5	1.389 (4)
O2—H2	0.8200	C4—H4	0.9300
O3—C11	1.210 (5)	C5—C6	1.388 (4)
O4—C8	1.202 (4)	C6—C7	1.377 (4)
N1—C11	1.394 (4)	C6—H6	0.9300
N1—C8	1.407 (4)	C7—H7	0.9300
N1—C5	1.424 (4)	C8—C9	1.474 (6)
C1—C2	1.480 (5)	C9—C10	1.301 (6)
C2—C3	1.381 (4)	C9—H9	0.9300
C2—C7	1.392 (4)	C10—C11	1.466 (6)
C3—C4	1.373 (4)	C10—H10	0.9300
C1—O2—H2	109.5	C7—C6—C5	119.6 (3)
C11—N1—C8	109.0 (3)	C7—C6—H6	120.2
C11—N1—C5	125.2 (3)	C5—C6—H6	120.2
C8—N1—C5	125.7 (3)	C6—C7—C2	120.3 (3)
O1—C1—O2	122.1 (3)	C6—C7—H7	119.9
O1—C1—C2	125.3 (3)	C2—C7—H7	119.9
O2—C1—C2	112.6 (3)	O4—C8—N1	124.9 (3)
C3—C2—C7	119.4 (3)	O4—C8—C9	129.6 (4)
C3—C2—C1	121.4 (3)	N1—C8—C9	105.5 (3)
C7—C2—C1	119.3 (3)	C10—C9—C8	109.8 (4)
C4—C3—C2	121.0 (3)	C10—C9—H9	125.1
C4—C3—H3	119.5	C8—C9—H9	125.1
C2—C3—H3	119.5	C9—C10—C11	109.1 (4)
C3—C4—C5	119.3 (3)	C9—C10—H10	125.4
C3—C4—H4	120.4	C11—C10—H10	125.4
C5—C4—H4	120.4	O3—C11—N1	124.8 (3)
C6—C5—C4	120.5 (3)	O3—C11—C10	128.5 (4)
C6—C5—N1	119.9 (3)	N1—C11—C10	106.6 (3)
C4—C5—N1	119.6 (3)
O1—C1—C2—C3	161.9 (3)	C3—C2—C7—C6	1.9 (5)
O2—C1—C2—C3	−19.1 (4)	C1—C2—C7—C6	−178.4 (3)
O1—C1—C2—C7	−17.8 (5)	C11—N1—C8—O4	179.9 (3)
O2—C1—C2—C7	161.2 (3)	C5—N1—C8—O4	−4.6 (5)
C7—C2—C3—C4	−0.6 (5)	C11—N1—C8—C9	−0.5 (3)
C1—C2—C3—C4	179.7 (3)	C5—N1—C8—C9	175.0 (3)
C2—C3—C4—C5	−1.2 (5)	O4—C8—C9—C10	178.6 (4)
C3—C4—C5—C6	1.7 (5)	N1—C8—C9—C10	−0.9 (4)
C3—C4—C5—N1	−177.5 (3)	C8—C9—C10—C11	1.9 (4)
C11—N1—C5—C6	43.8 (4)	C8—N1—C11—O3	−175.8 (3)
C8—N1—C5—C6	−131.0 (3)	C5—N1—C11—O3	8.7 (5)
C11—N1—C5—C4	−137.0 (3)	C8—N1—C11—C10	1.6 (3)
C8—N1—C5—C4	48.2 (4)	C5—N1—C11—C10	−174.0 (3)
C4—C5—C6—C7	−0.4 (5)	C9—C10—C11—O3	175.0 (4)
N1—C5—C6—C7	178.8 (3)	C9—C10—C11—N1	−2.2 (4)
C5—C6—C7—C2	−1.4 (5)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O2—H2···O1^i	0.82	1.90	2.672 (3)	156
C3—H3···O3^ii	0.93	2.39	3.103 (4)	134
C6—H6···O4^iii	0.93	2.68	3.392 (4)	134

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