Channel-forming solvate crystals and isostructural solvent-free powder of 5-hy­droxy-6-methyl-2-pyridone

Crystals of 5-hy­droxy-6-methyl-2-pyridone, (I), grown from a variety of solvents, are invariably trigonal (space group R); these are 5-hy­droxy-6-methyl-2-pyridone acetone 0.1667-solvate, C₆H₇NO₂·0.1667C₃H₆O, (Ia), and 6-methyl-5-hy­droxy-2-pyridone propan-2-ol 0.1667-solvate, C₆H₇NO₂·0.1667C₃H₈O, (Ib), and the forms from methanol, (Ic), water, (Id), benzonitrile, (Ie), and benzyl alcohol, (If). They incorporate channels running the length of the c axis that contain extensively disordered solvent mol­ecules. A solvent-free sublimed powder of 5-hy­droxy-6-methyl-2-pyridone micro­crystals is essentially isostructural. Inversion-related host mol­ecules inter­act via pairs of N—H...O hydrogen bonds to form R₂²(8) dimers. Six of these dimers form large R₁₂⁶(42) puckered rings, in which the O atom of each N—H...O hydrogen bond is also the acceptor in an O—H...O hydrogen bond that involves the 5-hy­droxy group. The large R₁₂⁶(42) rings straddle the axes and form stacked columns via π–π inter­actions between inversion-related mol­ecules of (I) [mean inter­planar spacing = 3.254 Å and ring centroid–centroid distance = 3.688 (2) Å]. The channels are lined by methyl groups, which all point inwards to the centre of the channels.

S1. Comment

¹H NMR data obtained from crystals of 6-methyl-5-hydroxy-2-pyridone, (I) (Behrman, 2008, 2009), grown from acetone or propan-2-ol exhibit unusual, and sometimes variable, ratios of pyridone to solvent. A similar observation for the 6-chloro analogue was established as being due to the presence of continuous solvent-accessible channels formed by extensive hydrogen-bonding networks within the crystals (Parkin & Behrman, 2009). The tautomeric equilibrium in the 6-chloro analogue was sensitive to the molecular environment, such that solvate crystals were exclusively the hydroxy tautomer while solvent-free crystals were the pyridone. Studies of related 6-substituted 2-pyridones over many years (summarized by Nichol & Clegg, 2005) show that electron-donating substituents at the 6-position drive the tautomeric equilibrium towards the pyridone, while electron-withdrawing groups favour the hydroxy form. In the present work, we found no evidence of the corresponding 6-methyl-2,5-dihydroxypyridine, (II).

Current work on intrinsic and extrinsic porous organic molecules has been the subject of several recent reviews, most notably by Cooper and coworkers (Holst et al., 2010; Cooper, 2011; Mastalerz et al., 2011; Jones et al., 2011). Given the general interest in hydrogen-bonded assemblies (e.g. Sisson et al., 2005; Glidewell et al., 2005; Hao et al., 2005), and of keto/enol tautomerism in 6-pyridones (Almlöf et al., 1971; Kvick, 1976; Johnson, 1984), we undertook a study of (I) crystallized from a series of solvents. Here, we report the structures of crystals grown from acetone, (Ia), propan-2-ol, (Ib), methanol, (Ic), water, (Id), and benzonitrile, (Ie). A probable structure grown from benzyl alcohol, (If), and a solvent-free crystalline powder obtained by sublimation, (Ig), are also discussed. Data tables are only presented here for structures (Ia) and (Ib); tables for structures (Ic1), (Ic2), (Ic3), (Id) and (Ie) are available in the archived CIF.

In contrast with the 6-chloro analogue, which formed tetragonal crystals (space group I4₁/a) with four channels per unit cell, all crystals of (I) are trigonal, space group R3, and have three channels per unit cell. The host-molecule frameworks in (Ia)–(Ie), and likely also in (If) and (Ig), are isostructural. Given the similarities, the following section concentrates on the structure of (Ia). Unless otherwise noted, the general features (aside from the nature of the solvent) also apply to (Ib)–(Ie), and probably also to (If) and (Ig).

The molecular structure of (I) (Fig. 1) is largely unremarkable. Bond lengths and angles are all within normal ranges and the molecules are flat [the r.m.s. deviation from planarity is 0.0140 (16) Å for non-H atoms]. The 2-hydroxy H atom is oriented away from the 6-methyl group, but is twisted out of the plane of the ring by ca 43° so as to participate in an O2—H2···O1(-y + 4/3, x - y + 2/3, z + 2/3) hydrogen bond to a symmetry-related molecule (Table 2). Inversion-related molecules of (I) interact via pairs of N1—H1···O1 hydrogen bonds to form R₂²(8) dimers (Fig. 2a) (for graph-set notation, see Bernstein et al., 1995). Six of these dimers join to form puckered rings (Fig. 2b) in which atom O1 of each N1—H1···O1 hydrogen bond is also the acceptor in an O2—H2···O1 hydrogen bond. The resulting large R₁₂⁶(42) rings surround the 3 axes and stack into columns via π–π interactions between inversion-related molecules of (I) [the mean π–π spacing is 3.254 (2) Å and the ring centroid-to-centroid is distance 3.688 (2) Å]. The channels are lined with 6-methyl groups which point towards the centre of their respective R₁₂⁶(42) rings. Appropriately sized solvent molecules can occupy the channels, but on average they are severely disordered as a result of the 3 site symmetry within the channels (Fig. 3). In spite of the inherent disorder, it was possible to model the acetone and propan-2-ol molecules in (Ia) and (Ib), albeit with extensive use of restraints (see Refinement section). These models had (in total) one solvent molecule per channel per unit cell. The occupancies of the solvent models were allowed to refine, but in both (Ia) and (Ib) the summed site occupancy of all disorder components was so close to unity that the solvent in the final cycles of refinement was fixed at full occupancy.

Although reasonably sized crystals could be grown from a variety of solvents, satisfactory disorder models for smaller solvents such as methanol in (Ic) and water in (Id) were not readily constructed. Crystals from methanol or water do appear to hold solvent less tightly, so that the solvent content varies depending on the method of drying (i.e. in air, in vacuo or at 373 K), from ca 2.5 molecules per channel per unit cell to less than one. A room-temperature determination of the methanol-containing structure, (Ic2), revealed no substantive differences from the low-temperature model, (Ic1). An attempt to drive the methanol guest molecules from the channels in (Ic) by annealing at 381 K for ca 30 min was also performed. In the resulting structure, (Ic3), the channels remained intact, though they appear to be partially de-populated. The electron count within the channels, as calculated by the SQUEEZE routine in PLATON (Spek, 2009), was reduced from 46 e in (Ic1) to 24 e in (Ic3), but it is worth mentioning that the electron count for the room temperature structure, (Ic2), was only 10 e. This variability is consistent with peak integrations of ¹H NMR spectra for different samples of (Ic). We surmise that some small solvent species are able to vacate the channels to a degree that depends on crystal handling, treatment and environment. Crystallization from benzonitrile produced a similar structure, (Ie), but with shorter and broader channels (as evidenced by the cell dimensions), presumably to accommodate this larger molecule. Crystals grown from benzyl alcohol, (If), were too small for full data collection, but indexing of a miniscule crystal of (If) (ca 0.1 × 0.005 × 0.005 mm) revealed a trigonal unit cell similar to the other crystals.

All attempts to grow solvent-free crystals large enough for single-crystal work by sublimation up to ca 423 K were futile and resulted in a fine white powder, (Ig). Diffraction of Cu Kα X-rays by this sublimed powder was too weak to measure on conventional sealed-tube powder X-ray diffractometers. However, it was possible to collect two-dimensional diffraction images on a rotating-anode based Bruker X8 Proteum single-crystal diffractometer equipped with graded multilayer optics. Diffraction patterns from freshly sublimed (Ig) and from (Ig) that had aged undisturbed for about six months were essentially identical (see Supplementary Material). These two-dimensional images were radially integrated using DATASQUEEZE (Heiney, 2005) and compared with simulated powder patterns based on the single-crystal structures (calculated using Mercury; Macrae et al., 2008), as shown in Fig. 4. Diffraction peak positions from the sublimed powders are in excellent agreement with those in the simulated powder patterns. It is consistent with this that the IR spectrum of the sublimed material is identical to spectra of the solvent-containing crystals. It thus appears that the channel structure is maintained even in the absence of intrinsic solvent, in marked contrast with the 6-chloro crystals, which were found to collapse on solvent loss (Parkin & Behrman, 2009). Holst et al. (2010) regard molecular crystals that retain permanent micropore structures upon desolvation as atypical. We also considered that the channels of the sublimed material might have contained air. Elemental analysis showed no increase in the percentage of nitrogen; even one molecule of N₂ per unit cell would have been easily detectable. The channels in the sublimed powder are substantially empty. ¹H NMR spectra showed solvent:host ratios consistent with the X-ray data. A few other 6-substituted-5-hydroxy-2-pyridones were examined but these did not form channels: 6-H (Behrman, 2008), 6-Br (Eikhoff & Behrman, 2009, Supplementary Material; Smith, 1951; Newkome et al., 1974) and 6-nitroso (Krowicki, 1977).

Related literature

For related literature, see: Almlöf et al. (1971); Behrman (2008, 2009); Bernstein et al. (1995); Cooper (2011); Eikhoff & Behrman (2009); Glidewell et al. (2005); Hao et al. (2005); Heiney (2005); Holst et al. (2010); Johnson (1984); Jones et al. (2011); Krowicki (1977); Kvick (1976); Loth & Hempel (1972); Macrae et al. (2008); Mastalerz et al. (2011); Newkome et al. (1974); Nichol & Clegg (2005); Parkin (2000); Parkin & Behrman (2009); Sheldrick (2008); Sisson et al. (2005); Smith (1951); Spek (2009).

S2. Experimental

The synthesis of 6-methyl-5-hydroxy-2-pyridone has been described in several publications (Behrman, 2008; Loth & Hempel, 1972). Crystals of (Ia) suitable for X-ray diffraction analysis were prepared by dissolving (I) (100 mg) in hot ethanol (6 ml) and then slowly adding acetone (10 ml). The other solvates were prepared as follows (mass of 5-hydroxy-6-methyl-2-pyridone, volume of solvent): (Ib) 50 mg, 5 ml propan-2-ol; (Ic) 50 mg, 3 ml methanol; (Id) 50 mg, 2 ml water; (Ie) 50 mg, 3.5 ml benzonitrile; (If) 20 mg, 0.5 ml benzyl alcohol. Crystals from benzonitrile and benzyl alcohol were washed with diethyl ether. Sublimation was carried out at about 0.5 mm Hg and at a temperature gradually rising from room temperature to about 423 K. ¹H NMR spectra were measured in DMSO-d₆ at 600 MHz. They gave host–solvent ratios consistent with disordered model refinement for the acetone and propan-2-ol solvates, or from a count of the number of electrons present within the channels using SQUEEZE in PLATON (Spek, 2009). Data for the IR, UV and NMR spectra are given by Behrman (2008) and Loth & Hempel (1972).

S3. Refinement

H atoms on the molecules of (I) in each of the structures were found in difference Fourier maps and subsequently placed at idealized positions. For the low-temperature structures, riding models with constrained distances of 0.95 (C_ArH), 0.98 (RCH₃), 0.88 (NH) and 0.84 Å (OH) were used. For the room-temperature structure, (Ic2), the distances were 0.93 (C_ArH), 0.96 (RCH₃), 0.86 (NH) and 0.82 Å (OH). In (Ia) and (Ib), owing to extensive disorder, the H atoms of the solvent molecules were not found in difference maps. They were placed using geometric criteria and refined using riding models, with constrained distances of 0.98 (RCH₃), 0.99 (R₂CH₂) and 0.84 Å (OH). Values for U_iso(H) were set to 1.2U_eq(parent atom), or 1.5U_eq(parent atom) for OH and CH₃. We considered inclusion here of the structures processed using SQUEEZE (Spek, 2009), but there seemed little point as they would have added no additional insight.

In (Ia) and (Ib), the solvent molecules are disordered on sites of 3 point symmetry and required restraints to maintain chemically sensible geometry and physically reasonable displacement parameters. The SHELXL97 (Sheldrick, 2008) commands DFIX, SAME, FLAT and SIMU were used to restrain interatomic distances, maintain geometric similarity and flatness, and keep the displacement parameters of closely proximate atoms similar. In both (Ia) and (Ib), several different disorder models were tried. The best model in each case was chosen by visual inspection and by careful analysis of refinement statistics, including an R tensor (Parkin, 2000), which quantifies the spatial quality of a crystallographic refinement. In (Ic1), (Ic2), (Ic3), (Id) and (Ie), the solvent molecules were also disordered on sites of 3 point symmetry, but suitable disorder models were not constructed.

Computing details

Data collection: APEX2 (Bruker, 2006) for (Ia), (Ib), (Id), (Ie); COLLECT (Nonius, 1998) for Ic1, Ic2, Ic3. Cell refinement: APEX2 (Bruker, 2006) for (Ia), (Ib), (Id), (Ie); SCALEPACK (Otwinowski & Minor, 1997) for Ic1, Ic2, Ic3. Data reduction: APEX2 (Bruker, 2006) for (Ia), (Ib), (Id), (Ie); DENZO-SMN (Otwinowski & Minor, 1997) for Ic1, Ic2, Ic3. For all compounds, program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP in SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008) and local procedures.

Figures

	Fig. 1. The asymmetric unit of the acetone solvate, (Ia), with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. The acetone guest molecule, which was modelled with isotropic displacement parameters, sits on a site of 3 symmetry and is extensively disordered. The structures of the propan-2-ol, methanol, water and benzonitrile solvates, (Ib)–(Ie), are essentially the same, but the guest solvent in each of (Ic)–(Ie) was too badly disordered to model.
	Fig. 2. The hydrogen bonding in (I), showing (a) the molecules forming R2^2(8) inversion-related dimers via pairs of N—H···O hydrogen bonds, and (b) six sets of these hydrogen-bonded dimers forming puckered rings, in which the O atom of each N—H···O interaction is also the acceptor in an O—H···O hydrogen bond involving the 5-hydroxy group as donor. The 6-Me groups all point towards the centre of the large rings. The resulting large R12^6(42) rings straddle the 3 axis and stack to form solvent-accessible channels parallel to the c axis.
	Fig. 3. A packing diagram for (Ia), viewed along c, showing the presence of disordered guest solvent molecules within the channels parallel to c. Crystals of (Ib)–(Ie) exhibit essentially the same packing.
	Fig. 4. Qualitative comparison of powder diffraction patterns of (I). (a) Experimental from sublimed powder, (Ig), at room temperature. Radial integration from two-dimensional diffraction images (see Supplementary material. (b) Simulated, based on the room-temperature single-crystal structure, (Ic2). The thin vertical lines are intended merely to guide the eye.

(Ia) 5-hydroxy-6-methyl-2-pyridone acetone 0.167-solvate

Crystal data

C6H7NO2·0.1667C3H6O	Dx = 1.430 Mg m^−3
Mr = 134.81	Cu Kα radiation, λ = 1.54178 Å
Trigonal, R3	Cell parameters from 3409 reflections
Hall symbol: -R 3	θ = 3.6–68.0°
a = 24.7962 (3) Å	µ = 0.91 mm^−1
c = 5.2924 (1) Å	T = 90 K
V = 2818.08 (7) Å^3	Needle, colourless
Z = 18	0.12 × 0.01 × 0.01 mm
F(000) = 1284

Data collection

Bruker X8 Proteum diffractometer	854 reflections with I > 2σ(I)
Radiation source: fine-focus rotating anode	Rint = 0.077
Graded multilayer optics monochromator	θmax = 68.2°, θmin = 3.6°
Detector resolution: 5.6 pixels mm^-1	h = −29→29
ϕ and ω scans	k = −29→29
14372 measured reflections	l = −4→6
1153 independent reflections

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.044	H-atom parameters constrained
wR(F^2) = 0.130	w = 1/[σ^2(Fo^2) + (0.0629P)^2 + 5.4027P] where P = (Fo^2 + 2Fc^2)/3
S = 1.03	(Δ/σ)max = 0.002
1153 reflections	Δρmax = 0.17 e Å^−3
101 parameters	Δρmin = −0.39 e Å^−3
6 restraints	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.00073 (18)

Special details

Experimental. The Comment section mentions synthesis of three related compounds, namely the 6-H (Behrman, 2008), 6-nitroso (Krowicki, 1977) and 6-Br. Synthesis of the latter is unpublished (Eikhoff & Behrman, 2009), so for the sake of completeness we give it here:

The precursor 6-bromo-2-pyridone was made as described by Newkome et al.(1974). Elbs oxidation of this material yielded 6-bromo-2-pyridone-5-sulfate which was isolated according to the method of Smith (1951). The ester was hydrolyzed at room temperature with 48% HBr as hydrolysis under the usual conditions yields mostly 2,3,6-trihydroxypyridine. Neutralization and sublimation in vacuo gave the title compound which was then crystallized from dichloromethane (m.p. 427–428 K (decomposition)]. Calculated for C₅H₄BrNO₂: Br 42.05%; found: Br 42.06%. UV (water): λ_max 304 nm, 4700 M^-1 cm^-1, sh 334, 225 nm. Ferric chloride color: pink, λ_max 509 nm, sh 544. IR (Nujol): 1660, 1605, 1530, 1456, 1401, 1288, 1267, 1246, 1051, 925, 815 cm^-1. ¹H NMR(DMSO-d₆) 600 MHz: δ 10.58 (s, NH), 9.94 (s, OH), 7.22 (d, H-4, J = 8.5 Hz), 6.50 (d, H-3, J = 8.5 Hz). With drier solvent, NH coupling was observed: δ 7.09 (t, J = 51 Hz).

References Newkome, G. R., Broussard, J., Staires, S. K. & Sauer, J. D. (1974). Synthesis, p. 707.

Smith, J. N. (1951). J. Chem. Soc. pp. 2861–2863.

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 > 2σ(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	Occ. (<1)
N1	0.55395 (8)	0.50854 (8)	0.2534 (3)	0.0290 (5)
H1	0.5336	0.4842	0.1252	0.035*
C2	0.55002 (9)	0.56112 (10)	0.2845 (4)	0.0283 (5)
C3	0.58299 (10)	0.59894 (10)	0.4935 (4)	0.0301 (5)
H3	0.5820	0.6361	0.5267	0.036*
C4	0.61623 (10)	0.58200 (10)	0.6475 (4)	0.0306 (5)
H4	0.6379	0.6077	0.7875	0.037*
C5	0.61921 (10)	0.52778 (10)	0.6048 (4)	0.0301 (5)
C6	0.58679 (10)	0.49035 (10)	0.4044 (4)	0.0303 (5)
O1	0.51734 (7)	0.57242 (7)	0.1304 (3)	0.0311 (4)
O2	0.65110 (7)	0.50989 (7)	0.7627 (3)	0.0368 (5)
H2	0.6853	0.5411	0.8017	0.055*
C7	0.58305 (12)	0.43014 (11)	0.3433 (5)	0.0375 (6)
H7A	0.6167	0.4277	0.4296	0.056*
H7B	0.5871	0.4272	0.1603	0.056*
H7C	0.5428	0.3957	0.3994	0.056*
O1S	0.6492 (7)	0.3252 (11)	0.487 (2)	0.075 (5)*	0.17
C1S	0.6727 (5)	0.3358 (10)	0.716 (2)	0.050 (3)*	0.17
C2S	0.682 (4)	0.3889 (14)	0.831 (5)	0.064 (6)*	0.17
H2S1	0.6589	0.4055	0.7383	0.096*	0.17
H2S2	0.7263	0.4198	0.8307	0.096*	0.17
H2S3	0.6666	0.3796	1.0050	0.096*	0.17
C3S	0.685 (4)	0.292 (3)	0.811 (4)	0.063 (5)*	0.17
H3S1	0.6643	0.2544	0.7070	0.094*	0.17
H3S2	0.6694	0.2820	0.9849	0.094*	0.17
H3S3	0.7300	0.3083	0.8100	0.094*	0.17

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0314 (9)	0.0283 (9)	0.0205 (9)	0.0100 (8)	−0.0001 (7)	−0.0003 (7)
C2	0.0285 (11)	0.0291 (11)	0.0201 (10)	0.0090 (9)	0.0047 (8)	0.0015 (8)
C3	0.0334 (11)	0.0300 (11)	0.0214 (10)	0.0117 (9)	0.0022 (8)	−0.0019 (8)
C4	0.0312 (11)	0.0322 (11)	0.0197 (10)	0.0094 (9)	0.0017 (8)	−0.0007 (8)
C5	0.0296 (11)	0.0333 (11)	0.0218 (10)	0.0116 (9)	0.0025 (8)	0.0042 (8)
C6	0.0305 (11)	0.0315 (11)	0.0226 (10)	0.0108 (9)	0.0037 (8)	0.0029 (8)
O1	0.0344 (8)	0.0325 (8)	0.0224 (8)	0.0137 (7)	−0.0018 (6)	0.0003 (6)
O2	0.0381 (9)	0.0371 (9)	0.0292 (8)	0.0143 (7)	−0.0044 (7)	0.0027 (6)
C7	0.0420 (13)	0.0341 (12)	0.0334 (12)	0.0168 (10)	−0.0018 (10)	0.0001 (10)

Geometric parameters (Å, º)

N1—C2	1.365 (3)	C7—H7A	0.9800
N1—C6	1.368 (3)	C7—H7B	0.9800
N1—H1	0.8800	C7—H7C	0.9800
C2—O1	1.276 (3)	O1S—C1S	1.312 (16)
C2—C3	1.416 (3)	C1S—C2S	1.361 (14)
C3—C4	1.366 (3)	C1S—C3S	1.361 (14)
C3—H3	0.9500	C2S—H2S1	0.9800
C4—C5	1.401 (3)	C2S—H2S2	0.9800
C4—H4	0.9500	C2S—H2S3	0.9800
C5—O2	1.368 (3)	C3S—H3S1	0.9800
C5—C6	1.373 (3)	C3S—H3S2	0.9800
C6—C7	1.485 (3)	C3S—H3S3	0.9800
O2—H2	0.8400
C2—N1—C6	125.66 (18)	C6—C7—H7B	109.5
C2—N1—H1	117.2	H7A—C7—H7B	109.5
C6—N1—H1	117.2	C6—C7—H7C	109.5
O1—C2—N1	119.29 (18)	H7A—C7—H7C	109.5
O1—C2—C3	125.0 (2)	H7B—C7—H7C	109.5
N1—C2—C3	115.68 (19)	O1S—C1S—C2S	116.5 (12)
C4—C3—C2	120.0 (2)	O1S—C1S—C3S	115.8 (12)
C4—C3—H3	120.0	C2S—C1S—C3S	127.7 (16)
C2—C3—H3	120.0	C1S—C2S—H2S1	109.5
C3—C4—C5	121.9 (2)	C1S—C2S—H2S2	109.5
C3—C4—H4	119.1	H2S1—C2S—H2S2	109.5
C5—C4—H4	119.1	C1S—C2S—H2S3	109.5
O2—C5—C6	119.4 (2)	H2S1—C2S—H2S3	109.5
O2—C5—C4	121.95 (19)	H2S2—C2S—H2S3	109.5
C6—C5—C4	118.6 (2)	C1S—C3S—H3S1	109.5
N1—C6—C5	118.2 (2)	C1S—C3S—H3S2	109.5
N1—C6—C7	117.13 (19)	H3S1—C3S—H3S2	109.5
C5—C6—C7	124.7 (2)	C1S—C3S—H3S3	109.5
C5—O2—H2	109.5	H3S1—C3S—H3S3	109.5
C6—C7—H7A	109.5	H3S2—C3S—H3S3	109.5
C6—N1—C2—O1	−179.56 (18)	C2—N1—C6—C5	−0.4 (3)
C6—N1—C2—C3	−0.4 (3)	C2—N1—C6—C7	177.8 (2)
O1—C2—C3—C4	179.5 (2)	O2—C5—C6—N1	178.30 (17)
N1—C2—C3—C4	0.4 (3)	C4—C5—C6—N1	1.1 (3)
C2—C3—C4—C5	0.3 (3)	O2—C5—C6—C7	0.3 (3)
C3—C4—C5—O2	−178.22 (19)	C4—C5—C6—C7	−176.9 (2)
C3—C4—C5—C6	−1.1 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O1^i	0.88	1.90	2.781 (2)	174
O2—H2···O1^ii	0.84	1.81	2.634 (2)	165

Symmetry codes: (i) −x+1, −y+1, −z; (ii) −y+4/3, x−y+2/3, z+2/3.

(Ib) 5-hydroxy-6-methyl-2-pyridone propan-2-ol 0.167-solvate

Crystal data

C6H7NO2·0.1667C3H8O	Dx = 1.424 Mg m^−3
Mr = 135.14	Cu Kα radiation, λ = 1.54178 Å
Trigonal, R3	Cell parameters from 2347 reflections
Hall symbol: -R 3	θ = 3.6–68.0°
a = 24.9208 (5) Å	µ = 0.90 mm^−1
c = 5.2738 (1) Å	T = 90 K
V = 2836.47 (10) Å^3	Needle, colourless
Z = 18	0.13 × 0.01 × 0.01 mm
F(000) = 1290

Data collection

Bruker X8 Proteum diffractometer	908 reflections with I > 2σ(I)
Radiation source: fine-focus rotating anode	Rint = 0.071
Graded multilayer optics monochromator	θmax = 68.3°, θmin = 3.6°
Detector resolution: 5.6 pixels mm^-1	h = −30→30
ϕ and ω scans	k = −23→29
14474 measured reflections	l = −6→6
1163 independent reflections

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.047	H-atom parameters constrained
wR(F^2) = 0.132	w = 1/[σ^2(Fo^2) + (0.0645P)^2 + 5.3911P] where P = (Fo^2 + 2Fc^2)/3
S = 1.07	(Δ/σ)max < 0.001
1163 reflections	Δρmax = 0.27 e Å^−3
101 parameters	Δρmin = −0.30 e Å^−3
11 restraints	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.00069 (19)

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 > 2σ(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	Occ. (<1)
N1	0.55385 (8)	0.50878 (8)	0.2534 (3)	0.0253 (4)
H1	0.5336	0.4846	0.1248	0.030*
C2	0.54990 (9)	0.56108 (9)	0.2850 (4)	0.0248 (5)
C3	0.58313 (9)	0.59890 (10)	0.4940 (4)	0.0260 (5)
H3	0.5822	0.6359	0.5270	0.031*
C4	0.61643 (9)	0.58225 (10)	0.6482 (4)	0.0272 (5)
H4	0.6382	0.6079	0.7883	0.033*
C5	0.61934 (9)	0.52822 (10)	0.6052 (4)	0.0270 (5)
C6	0.58666 (10)	0.49079 (10)	0.4048 (4)	0.0265 (5)
O1	0.51736 (7)	0.57235 (6)	0.1302 (3)	0.0275 (4)
O2	0.65125 (8)	0.51075 (8)	0.7629 (3)	0.0363 (5)
H2	0.6863	0.5414	0.7937	0.054*
C7	0.58304 (11)	0.43091 (10)	0.3429 (5)	0.0338 (6)
H7A	0.6147	0.4272	0.4388	0.051*
H7B	0.5901	0.4293	0.1609	0.051*
H7C	0.5419	0.3967	0.3882	0.051*
O1S	0.680 (3)	0.355 (2)	0.520 (5)	0.232 (17)*	0.17
H1SO	0.6718	0.3820	0.5669	0.348*	0.17
C1S	0.6813 (16)	0.3208 (14)	0.730 (6)	0.182 (15)*	0.17
H1S	0.6875	0.2873	0.6574	0.218*	0.17
C2S	0.620 (2)	0.288 (3)	0.861 (9)	0.131 (13)*	0.17
H2S1	0.5877	0.2648	0.7361	0.197*	0.17
H2S2	0.6125	0.3179	0.9479	0.197*	0.17
H2S3	0.6209	0.2588	0.9853	0.197*	0.17
C3S	0.736 (2)	0.358 (3)	0.893 (9)	0.150 (16)*	0.17
H3S1	0.7730	0.3806	0.7865	0.224*	0.17
H3S2	0.7423	0.3296	1.0053	0.224*	0.17
H3S3	0.7298	0.3866	0.9958	0.224*	0.17

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0245 (9)	0.0224 (9)	0.0241 (8)	0.0080 (7)	0.0000 (7)	−0.0004 (7)
C2	0.0223 (10)	0.0236 (10)	0.0251 (10)	0.0089 (8)	0.0046 (8)	0.0026 (8)
C3	0.0254 (10)	0.0230 (10)	0.0246 (10)	0.0083 (8)	0.0038 (8)	−0.0009 (8)
C4	0.0243 (10)	0.0269 (11)	0.0230 (10)	0.0073 (8)	0.0019 (8)	−0.0012 (8)
C5	0.0224 (10)	0.0279 (11)	0.0260 (10)	0.0091 (9)	0.0030 (8)	0.0046 (8)
C6	0.0228 (10)	0.0239 (10)	0.0278 (10)	0.0078 (8)	0.0032 (8)	0.0027 (8)
O1	0.0282 (8)	0.0261 (8)	0.0262 (8)	0.0120 (6)	−0.0009 (6)	0.0004 (6)
O2	0.0327 (9)	0.0332 (9)	0.0380 (9)	0.0128 (7)	−0.0043 (7)	0.0032 (7)
C7	0.0339 (12)	0.0287 (12)	0.0375 (12)	0.0149 (10)	−0.0035 (10)	−0.0010 (9)

Geometric parameters (Å, º)

N1—C2	1.365 (3)	C7—H7B	0.9800
N1—C6	1.369 (3)	C7—H7C	0.9800
N1—H1	0.8800	O1S—C1S	1.403 (10)
C2—O1	1.277 (3)	O1S—H1SO	0.8400
C2—C3	1.417 (3)	C1S—C3S	1.483 (9)
C3—C4	1.366 (3)	C1S—C2S	1.484 (9)
C3—H3	0.9500	C1S—H1S	1.0000
C4—C5	1.403 (3)	C2S—H2S1	0.9800
C4—H4	0.9500	C2S—H2S2	0.9800
C5—O2	1.364 (3)	C2S—H2S3	0.9800
C5—C6	1.375 (3)	C3S—H3S1	0.9800
C6—C7	1.486 (3)	C3S—H3S2	0.9800
O2—H2	0.8400	C3S—H3S3	0.9800
C7—H7A	0.9800
C2—N1—C6	125.54 (18)	C6—C7—H7C	109.5
C2—N1—H1	117.2	H7A—C7—H7C	109.5
C6—N1—H1	117.2	H7B—C7—H7C	109.5
O1—C2—N1	119.25 (18)	C1S—O1S—H1SO	110.1
O1—C2—C3	125.11 (19)	O1S—C1S—C3S	112.3 (11)
N1—C2—C3	115.65 (18)	O1S—C1S—C2S	112.1 (11)
C4—C3—C2	120.2 (2)	C3S—C1S—C2S	116.5 (11)
C4—C3—H3	119.9	O1S—C1S—H1S	104.9
C2—C3—H3	119.9	C3S—C1S—H1S	104.9
C3—C4—C5	121.7 (2)	C2S—C1S—H1S	104.9
C3—C4—H4	119.1	C1S—C2S—H2S1	109.5
C5—C4—H4	119.1	C1S—C2S—H2S2	109.5
O2—C5—C6	119.6 (2)	H2S1—C2S—H2S2	109.5
O2—C5—C4	121.73 (19)	C1S—C2S—H2S3	109.5
C6—C5—C4	118.6 (2)	H2S1—C2S—H2S3	109.5
N1—C6—C5	118.31 (19)	H2S2—C2S—H2S3	109.5
N1—C6—C7	117.04 (19)	C1S—C3S—H3S1	109.5
C5—C6—C7	124.6 (2)	C1S—C3S—H3S2	109.5
C5—O2—H2	109.5	H3S1—C3S—H3S2	109.5
C6—C7—H7A	109.5	C1S—C3S—H3S3	109.5
C6—C7—H7B	109.5	H3S1—C3S—H3S3	109.5
H7A—C7—H7B	109.5	H3S2—C3S—H3S3	109.5
C6—N1—C2—O1	−179.70 (18)	C2—N1—C6—C5	−0.8 (3)
C6—N1—C2—C3	0.0 (3)	C2—N1—C6—C7	177.83 (19)
O1—C2—C3—C4	179.84 (19)	O2—C5—C6—N1	178.43 (18)
N1—C2—C3—C4	0.2 (3)	C4—C5—C6—N1	1.4 (3)
C2—C3—C4—C5	0.5 (3)	O2—C5—C6—C7	−0.1 (3)
C3—C4—C5—O2	−178.25 (19)	C4—C5—C6—C7	−177.1 (2)
C3—C4—C5—C6	−1.3 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O1^i	0.88	1.91	2.782 (2)	174
O2—H2···O1^ii	0.84	1.81	2.638 (2)	169

Symmetry codes: (i) −x+1, −y+1, −z; (ii) −y+4/3, x−y+2/3, z+2/3.

(Ic1) 5-hydroxy-6-methyl-2-pyridone

Crystal data

C6H7NO2	Dx = 1.326 Mg m^−3
Mr = 125.13	Mo Kα radiation, λ = 0.71073 Å
Trigonal, R3	Cell parameters from 1434 reflections
Hall symbol: -R 3	θ = 1.0–27.5°
a = 24.9131 (11) Å	µ = 0.10 mm^−1
c = 5.2462 (3) Å	T = 90 K
V = 2819.9 (2) Å^3	Block, pale yellow
Z = 18	0.28 × 0.20 × 0.10 mm
F(000) = 1188

Data collection

Nonius KappaCCD area-detector diffractometer	958 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.048
Graphite monochromator	θmax = 27.5°, θmin = 2.8°
Detector resolution: 9.1 pixels mm^-1	h = −32→32
ω scans at fixed χ = 55°	k = −27→27
7559 measured reflections	l = −6→6
1434 independent 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)] = 0.052	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.156	H-atom parameters constrained
S = 1.04	w = 1/[σ^2(Fo^2) + (0.0907P)^2 + 1.2147P] where P = (Fo^2 + 2Fc^2)/3
1434 reflections	(Δ/σ)max < 0.001
84 parameters	Δρmax = 0.43 e Å^−3
0 restraints	Δρmin = −0.24 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 > 2σ(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
N1	0.55416 (7)	0.50846 (7)	0.2548 (3)	0.0204 (4)
H1	0.5337	0.4840	0.1265	0.024*
C2	0.55001 (8)	0.56070 (8)	0.2857 (3)	0.0202 (4)
C3	0.58352 (8)	0.59872 (8)	0.4970 (3)	0.0220 (4)
H3	0.5826	0.6357	0.5303	0.026*
C4	0.61677 (8)	0.58222 (8)	0.6513 (3)	0.0220 (4)
H4	0.6385	0.6079	0.7921	0.026*
C5	0.61978 (8)	0.52811 (9)	0.6076 (3)	0.0217 (5)
C6	0.58743 (8)	0.49090 (8)	0.4061 (3)	0.0210 (4)
O1	0.51731 (6)	0.57186 (6)	0.1321 (2)	0.0229 (4)
O2	0.65202 (6)	0.51054 (6)	0.7664 (3)	0.0276 (4)
H2	0.6881	0.5405	0.7873	0.041*
C7	0.58352 (10)	0.43069 (9)	0.3441 (4)	0.0281 (5)
H7A	0.6115	0.4245	0.4561	0.042*
H7B	0.5956	0.4311	0.1661	0.042*
H7C	0.5409	0.3969	0.3694	0.042*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0208 (8)	0.0188 (8)	0.0175 (8)	0.0069 (6)	−0.0008 (6)	−0.0015 (6)
C2	0.0171 (9)	0.0207 (9)	0.0190 (9)	0.0067 (8)	0.0041 (7)	0.0023 (7)
C3	0.0237 (10)	0.0189 (9)	0.0199 (9)	0.0080 (8)	0.0028 (7)	−0.0008 (7)
C4	0.0216 (10)	0.0220 (10)	0.0166 (9)	0.0066 (8)	0.0010 (7)	−0.0009 (7)
C5	0.0192 (9)	0.0232 (9)	0.0201 (9)	0.0088 (8)	0.0016 (7)	0.0040 (7)
C6	0.0192 (9)	0.0198 (9)	0.0205 (9)	0.0071 (8)	0.0035 (7)	0.0032 (7)
O1	0.0228 (7)	0.0229 (7)	0.0209 (7)	0.0100 (6)	−0.0021 (5)	−0.0005 (5)
O2	0.0254 (8)	0.0266 (8)	0.0280 (8)	0.0109 (6)	−0.0044 (6)	0.0022 (6)
C7	0.0295 (11)	0.0237 (10)	0.0299 (10)	0.0123 (9)	−0.0031 (9)	−0.0019 (8)

Geometric parameters (Å, º)

N1—C2	1.366 (2)	C4—H4	0.9500
N1—C6	1.368 (2)	C5—C6	1.371 (3)
N1—H1	0.8800	C5—O2	1.372 (2)
C2—O1	1.271 (2)	C6—C7	1.490 (3)
C2—C3	1.426 (2)	O2—H2	0.8400
C3—C4	1.360 (3)	C7—H7A	0.9800
C3—H3	0.9500	C7—H7B	0.9800
C4—C5	1.406 (3)	C7—H7C	0.9800
C2—N1—C6	125.63 (15)	C6—C5—C4	118.61 (17)
C2—N1—H1	117.2	O2—C5—C4	121.84 (16)
C6—N1—H1	117.2	N1—C6—C5	118.46 (17)
O1—C2—N1	119.68 (15)	N1—C6—C7	116.76 (16)
O1—C2—C3	125.03 (17)	C5—C6—C7	124.73 (17)
N1—C2—C3	115.28 (16)	C5—O2—H2	109.5
C4—C3—C2	120.31 (18)	C6—C7—H7A	109.5
C4—C3—H3	119.8	C6—C7—H7B	109.5
C2—C3—H3	119.8	H7A—C7—H7B	109.5
C3—C4—C5	121.69 (17)	C6—C7—H7C	109.5
C3—C4—H4	119.2	H7A—C7—H7C	109.5
C5—C4—H4	119.2	H7B—C7—H7C	109.5
C6—C5—O2	119.49 (17)
C6—N1—C2—O1	−179.81 (16)	C2—N1—C6—C5	0.1 (3)
C6—N1—C2—C3	−0.5 (2)	C2—N1—C6—C7	177.63 (16)
O1—C2—C3—C4	179.45 (16)	O2—C5—C6—N1	178.12 (15)
N1—C2—C3—C4	0.2 (2)	C4—C5—C6—N1	0.7 (3)
C2—C3—C4—C5	0.6 (3)	O2—C5—C6—C7	0.8 (3)
C3—C4—C5—C6	−1.0 (3)	C4—C5—C6—C7	−176.70 (17)
C3—C4—C5—O2	−178.37 (16)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O1^i	0.88	1.90	2.7805 (19)	175
O2—H2···O1^ii	0.84	1.81	2.6398 (18)	170

Symmetry codes: (i) −x+1, −y+1, −z; (ii) −y+4/3, x−y+2/3, z+2/3.

(Ic2) 5-hydroxy-6-methyl-2-pyridone

Crystal data

C6H7NO2	Dx = 1.285 Mg m^−3
Mr = 125.13	Mo Kα radiation, λ = 0.71073 Å
Trigonal, R3	Cell parameters from 10421 reflections
Hall symbol: -R 3	θ = 1.0–25.4°
a = 25.2734 (7) Å	µ = 0.10 mm^−1
c = 5.2602 (7) Å	T = 293 K
V = 2909.8 (4) Å^3	Block, pale yellow
Z = 18	0.20 × 0.10 × 0.10 mm
F(000) = 1188

Data collection

Nonius KappaCCD area-detector diffractometer	699 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.089
Graphite monochromator	θmax = 25.3°, θmin = 2.8°
Detector resolution: 9.1 pixels mm^-1	h = −30→30
ω scans at fixed χ = 55°	k = −30→30
10602 measured reflections	l = −6→6
1184 independent 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)] = 0.063	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.198	H-atom parameters constrained
S = 1.02	w = 1/[σ^2(Fo^2) + (0.1252P)^2] where P = (Fo^2 + 2Fc^2)/3
1184 reflections	(Δ/σ)max = 0.002
84 parameters	Δρmax = 0.38 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 > 2σ(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
N1	0.55471 (9)	0.50936 (10)	0.2540 (4)	0.0469 (7)
H1	0.5347	0.4855	0.1299	0.056*
C2	0.55043 (12)	0.56042 (12)	0.2842 (5)	0.0451 (8)
C3	0.58337 (13)	0.59843 (13)	0.4906 (5)	0.0498 (8)
H3	0.5821	0.6340	0.5219	0.060*
C4	0.61702 (12)	0.58290 (12)	0.6440 (5)	0.0503 (8)
H4	0.6381	0.6079	0.7808	0.060*
C5	0.62045 (12)	0.53019 (13)	0.6001 (5)	0.0486 (8)
C6	0.58800 (12)	0.49263 (12)	0.4034 (5)	0.0485 (8)
O1	0.51767 (8)	0.57110 (8)	0.1310 (3)	0.0534 (7)
O2	0.65333 (10)	0.51347 (9)	0.7566 (4)	0.0633 (7)
H2	0.6878	0.5427	0.7770	0.095*
C7	0.58497 (15)	0.43381 (14)	0.3428 (6)	0.0664 (9)
H7A	0.6085	0.4260	0.4651	0.100*
H7B	0.6013	0.4360	0.1758	0.100*
H7C	0.5432	0.4014	0.3483	0.100*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0489 (14)	0.0411 (14)	0.0438 (13)	0.0174 (11)	−0.0034 (11)	−0.0057 (10)
C2	0.0422 (16)	0.0419 (16)	0.0418 (16)	0.0140 (14)	0.0057 (13)	0.0020 (13)
C3	0.0541 (18)	0.0432 (16)	0.0455 (16)	0.0195 (14)	0.0028 (14)	−0.0029 (13)
C4	0.0477 (17)	0.0488 (17)	0.0396 (15)	0.0130 (14)	−0.0014 (13)	−0.0039 (13)
C5	0.0432 (16)	0.0472 (17)	0.0455 (16)	0.0152 (14)	0.0001 (13)	0.0070 (14)
C6	0.0452 (16)	0.0447 (16)	0.0492 (16)	0.0178 (14)	0.0045 (14)	0.0039 (13)
O1	0.0549 (12)	0.0521 (13)	0.0503 (12)	0.0246 (10)	−0.0083 (9)	−0.0017 (9)
O2	0.0576 (14)	0.0575 (13)	0.0651 (14)	0.0215 (11)	−0.0102 (11)	0.0054 (10)
C7	0.071 (2)	0.056 (2)	0.075 (2)	0.0338 (17)	−0.0127 (18)	−0.0051 (17)

Geometric parameters (Å, º)

N1—C2	1.357 (3)	C4—H4	0.9300
N1—C6	1.364 (3)	C5—C6	1.366 (4)
N1—H1	0.8600	C5—O2	1.378 (3)
C2—O1	1.278 (3)	C6—C7	1.484 (4)
C2—C3	1.412 (4)	O2—H2	0.8200
C3—C4	1.365 (4)	C7—H7A	0.9600
C3—H3	0.9300	C7—H7B	0.9600
C4—C5	1.397 (4)	C7—H7C	0.9600
C2—N1—C6	125.6 (2)	C6—C5—C4	119.1 (3)
C2—N1—H1	117.2	O2—C5—C4	121.9 (2)
C6—N1—H1	117.2	N1—C6—C5	118.0 (3)
O1—C2—N1	119.7 (2)	N1—C6—C7	117.1 (2)
O1—C2—C3	124.4 (3)	C5—C6—C7	124.8 (3)
N1—C2—C3	115.9 (3)	C5—O2—H2	109.5
C4—C3—C2	119.9 (3)	C6—C7—H7A	109.5
C4—C3—H3	120.0	C6—C7—H7B	109.5
C2—C3—H3	120.0	H7A—C7—H7B	109.5
C3—C4—C5	121.4 (3)	C6—C7—H7C	109.5
C3—C4—H4	119.3	H7A—C7—H7C	109.5
C5—C4—H4	119.3	H7B—C7—H7C	109.5
C6—C5—O2	119.0 (3)
C6—N1—C2—O1	180.0 (2)	C2—N1—C6—C5	−0.5 (4)
C6—N1—C2—C3	−0.5 (4)	C2—N1—C6—C7	178.1 (2)
O1—C2—C3—C4	179.9 (2)	O2—C5—C6—N1	178.6 (2)
N1—C2—C3—C4	0.3 (4)	C4—C5—C6—N1	1.7 (4)
C2—C3—C4—C5	0.8 (4)	O2—C5—C6—C7	0.1 (4)
C3—C4—C5—C6	−1.9 (4)	C4—C5—C6—C7	−176.8 (3)
C3—C4—C5—O2	−178.7 (2)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O1^i	0.86	1.95	2.804 (3)	174
O2—H2···O1^ii	0.82	1.84	2.653 (3)	173

Symmetry codes: (i) −x+1, −y+1, −z; (ii) −y+4/3, x−y+2/3, z+2/3.

(Ic3) 5-hydroxy-6-methyl-2-pyridone

Crystal data

C6H7NO2	Dx = 1.324 Mg m^−3
Mr = 125.13	Mo Kα radiation, λ = 0.71073 Å
Trigonal, R3	Cell parameters from 1437 reflections
Hall symbol: -R 3	θ = 1.0–27.5°
a = 24.9194 (5) Å	µ = 0.10 mm^−1
c = 5.2541 (10) Å	T = 90 K
V = 2825.6 (5) Å^3	Needle, colourless
Z = 18	0.20 × 0.10 × 0.10 mm
F(000) = 1188

Data collection

Nonius KappaCCD area-detector diffractometer	1085 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.056
Graphite monochromator	θmax = 27.5°, θmin = 1.6°
Detector resolution: 9.1 pixels mm^-1	h = −32→32
ω scans at fixed χ = 55°	k = −27→27
23187 measured reflections	l = −6→6
1437 independent 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)] = 0.045	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.135	H-atom parameters constrained
S = 1.07	w = 1/[σ^2(Fo^2) + (0.0753P)^2 + 2.2624P] where P = (Fo^2 + 2Fc^2)/3
1437 reflections	(Δ/σ)max = 0.001
84 parameters	Δρmax = 0.43 e Å^−3
0 restraints	Δρmin = −0.29 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 > 2σ(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
N1	0.55416 (5)	0.50848 (6)	0.2543 (2)	0.0190 (3)
H1	0.5338	0.4842	0.1257	0.023*
C2	0.55011 (6)	0.56080 (7)	0.2860 (3)	0.0187 (3)
C3	0.58347 (7)	0.59881 (7)	0.4962 (3)	0.0204 (4)
H3	0.5826	0.6359	0.5290	0.024*
C4	0.61670 (7)	0.58224 (7)	0.6507 (3)	0.0208 (4)
H4	0.6384	0.6079	0.7914	0.025*
C5	0.61975 (7)	0.52810 (7)	0.6075 (3)	0.0202 (4)
C6	0.58723 (7)	0.49080 (7)	0.4061 (3)	0.0202 (4)
O1	0.51737 (5)	0.57193 (5)	0.13160 (19)	0.0215 (3)
O2	0.65200 (5)	0.51063 (5)	0.7664 (2)	0.0255 (3)
H2	0.6876	0.5410	0.7918	0.038*
C7	0.58353 (8)	0.43058 (7)	0.3440 (3)	0.0267 (4)
H7A	0.6130	0.4254	0.4500	0.040*
H7B	0.5937	0.4303	0.1640	0.040*
H7C	0.5414	0.3965	0.3770	0.040*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0183 (6)	0.0165 (6)	0.0184 (6)	0.0059 (5)	−0.0008 (5)	−0.0013 (5)
C2	0.0156 (7)	0.0178 (7)	0.0192 (8)	0.0058 (6)	0.0033 (6)	0.0025 (6)
C3	0.0200 (7)	0.0175 (7)	0.0203 (8)	0.0069 (6)	0.0022 (6)	−0.0009 (6)
C4	0.0193 (7)	0.0191 (7)	0.0182 (7)	0.0051 (6)	0.0012 (6)	−0.0007 (6)
C5	0.0166 (7)	0.0204 (7)	0.0201 (8)	0.0066 (6)	0.0014 (6)	0.0037 (6)
C6	0.0165 (7)	0.0187 (7)	0.0223 (8)	0.0065 (6)	0.0034 (6)	0.0028 (6)
O1	0.0205 (6)	0.0205 (6)	0.0217 (6)	0.0089 (4)	−0.0021 (4)	0.0000 (4)
O2	0.0218 (6)	0.0228 (6)	0.0282 (6)	0.0084 (4)	−0.0047 (4)	0.0020 (5)
C7	0.0279 (8)	0.0216 (8)	0.0305 (9)	0.0124 (7)	−0.0038 (7)	−0.0017 (6)

Geometric parameters (Å, º)

N1—C2	1.3671 (18)	C4—H4	0.9500
N1—C6	1.3685 (19)	C5—O2	1.3717 (18)
N1—H1	0.8800	C5—C6	1.374 (2)
C2—O1	1.2755 (17)	C6—C7	1.493 (2)
C2—C3	1.421 (2)	O2—H2	0.8400
C3—C4	1.363 (2)	C7—H7A	0.9800
C3—H3	0.9500	C7—H7B	0.9800
C4—C5	1.407 (2)	C7—H7C	0.9800
C2—N1—C6	125.43 (13)	O2—C5—C4	121.82 (13)
C2—N1—H1	117.3	C6—C5—C4	118.46 (14)
C6—N1—H1	117.3	N1—C6—C5	118.52 (14)
O1—C2—N1	119.36 (13)	N1—C6—C7	116.86 (13)
O1—C2—C3	125.01 (14)	C5—C6—C7	124.59 (14)
N1—C2—C3	115.63 (13)	C5—O2—H2	109.5
C4—C3—C2	120.16 (14)	C6—C7—H7A	109.5
C4—C3—H3	119.9	C6—C7—H7B	109.5
C2—C3—H3	119.9	H7A—C7—H7B	109.5
C3—C4—C5	121.79 (14)	C6—C7—H7C	109.5
C3—C4—H4	119.1	H7A—C7—H7C	109.5
C5—C4—H4	119.1	H7B—C7—H7C	109.5
O2—C5—C6	119.66 (14)
C6—N1—C2—O1	−179.65 (13)	C2—N1—C6—C5	−0.4 (2)
C6—N1—C2—C3	−0.2 (2)	C2—N1—C6—C7	177.74 (13)
O1—C2—C3—C4	179.48 (13)	O2—C5—C6—N1	178.35 (12)
N1—C2—C3—C4	0.0 (2)	C4—C5—C6—N1	1.0 (2)
C2—C3—C4—C5	0.6 (2)	O2—C5—C6—C7	0.4 (2)
C3—C4—C5—O2	−178.45 (13)	C4—C5—C6—C7	−176.95 (14)
C3—C4—C5—C6	−1.2 (2)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O1^i	0.88	1.90	2.7808 (16)	174
O2—H2···O1^ii	0.84	1.81	2.6383 (15)	170

Symmetry codes: (i) −x+1, −y+1, −z; (ii) −y+4/3, x−y+2/3, z+2/3.

(Id) 5-hydroxy-6-methyl-2-pyridone

Crystal data

C6H7NO2	Dx = 1.325 Mg m^−3
Mr = 125.13	Cu Kα radiation, λ = 1.54178 Å
Trigonal, R3	Cell parameters from 8747 reflections
Hall symbol: -R 3	θ = 3.6–68.4°
a = 24.9344 (4) Å	µ = 0.85 mm^−1
c = 5.2415 (1) Å	T = 90 K
V = 2822.17 (8) Å^3	Needle, colourless
Z = 18	0.15 × 0.02 × 0.02 mm
F(000) = 1188

Data collection

Bruker X8 Proteum diffractometer	1077 reflections with I > 2σ(I)
Radiation source: fine-focus rotating anode	Rint = 0.043
Graded multilayer optics monochromator	θmax = 68.4°, θmin = 3.6°
Detector resolution: 5.6 pixels mm^-1	h = −30→26
ϕ and ω scans	k = −30→30
14184 measured reflections	l = −6→6
1161 independent reflections

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.037	H-atom parameters constrained
wR(F^2) = 0.113	w = 1/[σ^2(Fo^2) + (0.0657P)^2 + 2.778P] where P = (Fo^2 + 2Fc^2)/3
S = 1.10	(Δ/σ)max = 0.001
1161 reflections	Δρmax = 0.36 e Å^−3
85 parameters	Δρmin = −0.16 e Å^−3
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.00050 (14)

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 > 2σ(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
N1	0.55416 (5)	0.50869 (5)	0.2548 (2)	0.0215 (3)
H1	0.5338	0.4844	0.1259	0.026*
C2	0.55001 (6)	0.56082 (6)	0.2862 (2)	0.0210 (3)
C3	0.58341 (6)	0.59881 (6)	0.4965 (2)	0.0225 (3)
H3	0.5825	0.6358	0.5295	0.027*
C4	0.61678 (6)	0.58233 (6)	0.6512 (2)	0.0230 (3)
H4	0.6385	0.6081	0.7921	0.028*
C5	0.61991 (6)	0.52825 (6)	0.6079 (2)	0.0227 (3)
C6	0.58723 (6)	0.49097 (6)	0.4062 (2)	0.0224 (3)
O1	0.51731 (4)	0.57183 (4)	0.13173 (16)	0.0235 (3)
O2	0.65212 (4)	0.51098 (4)	0.76609 (18)	0.0272 (3)
H2	0.6874	0.5415	0.7935	0.041*
C7	0.58358 (7)	0.43091 (6)	0.3439 (3)	0.0283 (4)
H7A	0.6133	0.4259	0.4491	0.042*
H7B	0.5934	0.4305	0.1632	0.042*
H7C	0.5416	0.3968	0.3783	0.042*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0213 (6)	0.0197 (6)	0.0195 (5)	0.0073 (4)	−0.0006 (4)	−0.0010 (4)
C2	0.0192 (6)	0.0202 (6)	0.0205 (6)	0.0074 (5)	0.0040 (5)	0.0025 (5)
C3	0.0221 (6)	0.0202 (6)	0.0221 (6)	0.0083 (5)	0.0035 (5)	0.0001 (5)
C4	0.0211 (6)	0.0226 (7)	0.0192 (6)	0.0065 (5)	0.0015 (5)	−0.0008 (5)
C5	0.0205 (6)	0.0229 (7)	0.0212 (6)	0.0083 (5)	0.0024 (5)	0.0043 (5)
C6	0.0198 (6)	0.0212 (7)	0.0226 (6)	0.0077 (5)	0.0033 (5)	0.0031 (5)
O1	0.0242 (5)	0.0222 (5)	0.0225 (5)	0.0105 (4)	−0.0015 (3)	0.0001 (3)
O2	0.0247 (5)	0.0254 (5)	0.0278 (5)	0.0098 (4)	−0.0043 (4)	0.0023 (4)
C7	0.0290 (7)	0.0231 (7)	0.0317 (7)	0.0121 (6)	−0.0030 (5)	−0.0015 (5)

Geometric parameters (Å, º)

N1—C2	1.3644 (17)	C4—H4	0.9500
N1—C6	1.3673 (17)	C5—O2	1.3650 (16)
N1—H1	0.8800	C5—C6	1.3741 (19)
C2—O1	1.2725 (15)	C6—C7	1.4903 (19)
C2—C3	1.4203 (17)	O2—H2	0.8400
C3—C4	1.3643 (19)	C7—H7A	0.9800
C3—H3	0.9500	C7—H7B	0.9800
C4—C5	1.4075 (19)	C7—H7C	0.9800
C2—N1—C6	125.68 (11)	O2—C5—C4	121.83 (12)
C2—N1—H1	117.2	C6—C5—C4	118.29 (12)
C6—N1—H1	117.2	N1—C6—C5	118.52 (12)
O1—C2—N1	119.40 (11)	N1—C6—C7	116.97 (11)
O1—C2—C3	125.11 (12)	C5—C6—C7	124.48 (12)
N1—C2—C3	115.49 (11)	C5—O2—H2	109.5
C4—C3—C2	120.20 (12)	C6—C7—H7A	109.5
C4—C3—H3	119.9	C6—C7—H7B	109.5
C2—C3—H3	119.9	H7A—C7—H7B	109.5
C3—C4—C5	121.81 (12)	C6—C7—H7C	109.5
C3—C4—H4	119.1	H7A—C7—H7C	109.5
C5—C4—H4	119.1	H7B—C7—H7C	109.5
O2—C5—C6	119.82 (12)
C6—N1—C2—O1	−179.71 (11)	C2—N1—C6—C5	−0.46 (19)
C6—N1—C2—C3	−0.15 (18)	C2—N1—C6—C7	177.76 (11)
O1—C2—C3—C4	179.59 (12)	O2—C5—C6—N1	178.39 (10)
N1—C2—C3—C4	0.07 (17)	C4—C5—C6—N1	1.12 (18)
C2—C3—C4—C5	0.63 (19)	O2—C5—C6—C7	0.31 (19)
C3—C4—C5—O2	−178.45 (11)	C4—C5—C6—C7	−176.95 (12)
C3—C4—C5—C6	−1.24 (19)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O1^i	0.88	1.90	2.7809 (14)	174
O2—H2···O1^ii	0.84	1.81	2.6366 (13)	170

Symmetry codes: (i) −x+1, −y+1, −z; (ii) −y+4/3, x−y+2/3, z+2/3.

(Ie) 5-hydroxy-6-methyl-2-pyridone

Crystal data

C6H7NO2	Dx = 1.303 Mg m^−3
Mr = 125.13	Cu Kα radiation, λ = 1.54178 Å
Trigonal, R3	Cell parameters from 2933 reflections
Hall symbol: -R 3	θ = 3.5–67.4°
a = 25.282 (6) Å	µ = 0.83 mm^−1
c = 5.1838 (14) Å	T = 90 K
V = 2869.6 (12) Å^3	Needle, colourless
Z = 18	0.15 × 0.01 × 0.01 mm
F(000) = 1188

Data collection

Bruker X8 Proteum diffractometer	868 reflections with I > 2σ(I)
Radiation source: fine-focus rotating anode	Rint = 0.081
Graded multilayer optics monochromator	θmax = 68.3°, θmin = 3.5°
Detector resolution: 5.6 pixels mm^-1	h = −30→30
ϕ and ω scans	k = −30→29
13477 measured reflections	l = −6→6
1169 independent 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)] = 0.073	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.246	H-atom parameters constrained
S = 1.16	w = 1/[σ^2(Fo^2) + (0.1548P)^2 + 2.6539P] where P = (Fo^2 + 2Fc^2)/3
1169 reflections	(Δ/σ)max = 0.001
84 parameters	Δρmax = 1.13 e Å^−3
0 restraints	Δρmin = −0.20 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 > 2σ(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
N1	0.55380 (12)	0.50951 (12)	0.2552 (5)	0.0336 (7)
H1	0.5330	0.4851	0.1271	0.040*
C2	0.54988 (14)	0.56095 (14)	0.2861 (6)	0.0326 (8)
C3	0.58345 (14)	0.59885 (15)	0.4969 (6)	0.0340 (8)
H3	0.5823	0.6352	0.5308	0.041*
C4	0.61736 (14)	0.58324 (14)	0.6512 (6)	0.0344 (8)
H4	0.6392	0.6089	0.7921	0.041*
C5	0.62074 (15)	0.53023 (15)	0.6068 (6)	0.0350 (8)
C6	0.58736 (15)	0.49258 (14)	0.4067 (6)	0.0347 (8)
O1	0.51708 (10)	0.57130 (10)	0.1316 (4)	0.0358 (7)
O2	0.65331 (11)	0.51356 (11)	0.7642 (5)	0.0415 (7)
H2	0.6891	0.5430	0.7805	0.062*
C7	0.58396 (18)	0.43349 (16)	0.3438 (7)	0.0442 (9)
H7A	0.6083	0.4256	0.4686	0.066*
H7B	0.6000	0.4356	0.1697	0.066*
H7C	0.5413	0.4005	0.3516	0.066*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0320 (14)	0.0284 (13)	0.0315 (13)	0.0084 (11)	0.0016 (11)	−0.0003 (10)
C2	0.0294 (15)	0.0293 (16)	0.0305 (15)	0.0082 (12)	0.0043 (12)	0.0016 (12)
C3	0.0354 (16)	0.0298 (15)	0.0303 (15)	0.0114 (13)	0.0043 (12)	−0.0003 (12)
C4	0.0327 (16)	0.0336 (16)	0.0289 (15)	0.0105 (13)	0.0023 (12)	−0.0007 (12)
C5	0.0313 (16)	0.0345 (16)	0.0323 (16)	0.0114 (13)	0.0045 (12)	0.0056 (13)
C6	0.0325 (16)	0.0317 (16)	0.0334 (15)	0.0112 (13)	0.0060 (12)	0.0047 (12)
O1	0.0351 (12)	0.0343 (12)	0.0336 (12)	0.0141 (10)	−0.0006 (9)	0.0002 (9)
O2	0.0403 (13)	0.0379 (13)	0.0421 (13)	0.0165 (10)	−0.0033 (10)	0.0051 (10)
C7	0.046 (2)	0.0339 (17)	0.0482 (18)	0.0170 (15)	−0.0058 (16)	−0.0045 (15)

Geometric parameters (Å, º)

N1—C2	1.362 (4)	C4—H4	0.9500
N1—C6	1.372 (4)	C5—O2	1.367 (4)
N1—H1	0.8800	C5—C6	1.375 (5)
C2—O1	1.270 (4)	C6—C7	1.489 (5)
C2—C3	1.421 (4)	O2—H2	0.8400
C3—C4	1.367 (5)	C7—H7A	0.9800
C3—H3	0.9500	C7—H7B	0.9800
C4—C5	1.404 (5)	C7—H7C	0.9800
C2—N1—C6	125.6 (3)	O2—C5—C4	122.0 (3)
C2—N1—H1	117.2	C6—C5—C4	118.4 (3)
C6—N1—H1	117.2	N1—C6—C5	118.5 (3)
O1—C2—N1	119.3 (3)	N1—C6—C7	116.9 (3)
O1—C2—C3	125.3 (3)	C5—C6—C7	124.6 (3)
N1—C2—C3	115.5 (3)	C5—O2—H2	109.5
C4—C3—C2	120.3 (3)	C6—C7—H7A	109.5
C4—C3—H3	119.9	C6—C7—H7B	109.5
C2—C3—H3	119.9	H7A—C7—H7B	109.5
C3—C4—C5	121.8 (3)	C6—C7—H7C	109.5
C3—C4—H4	119.1	H7A—C7—H7C	109.5
C5—C4—H4	119.1	H7B—C7—H7C	109.5
O2—C5—C6	119.5 (3)
C6—N1—C2—O1	180.0 (3)	C2—N1—C6—C5	−0.6 (5)
C6—N1—C2—C3	−0.7 (4)	C2—N1—C6—C7	178.3 (3)
O1—C2—C3—C4	−180.0 (3)	O2—C5—C6—N1	178.4 (3)
N1—C2—C3—C4	0.8 (4)	C4—C5—C6—N1	1.9 (4)
C2—C3—C4—C5	0.5 (5)	O2—C5—C6—C7	−0.5 (5)
C3—C4—C5—O2	−178.3 (3)	C4—C5—C6—C7	−177.0 (3)
C3—C4—C5—C6	−1.9 (5)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O1^i	0.88	1.90	2.783 (3)	176
O2—H2···O1^ii	0.84	1.80	2.639 (3)	173

Symmetry codes: (i) −x+1, −y+1, −z; (ii) −y+4/3, x−y+2/3, z+2/3.