Powder study of hydro­chloro­thia­zide–methyl acetate (1/1)

Florence, A.J.; Johnston, A.; Shankland, K.

doi:10.1107/S1600536805025651

organic compounds

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ISSN: 2056-9890

Volume 61| Part 9| September 2005| Pages o2974-o2977

https://doi.org/10.1107/S1600536805025651

Powder study of hydrochlorothiazide–methyl acetate (1/1)

Alastair J. Florence,^a ^* Andrea Johnston ^a and Kenneth Shankland ^b

^aSolid-State Research Group, Department of Pharmaceutical Sciences, University of Strathclyde, 27 Taylor Street, Glasgow G4 0NR, Scotland, and ^bISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon UK OX11 0QX, England
^*Correspondence e-mail: alastair.florence@strath.ac.uk

(Received 22 July 2005; accepted 10 August 2005; online 17 August 2005)

A polycrystalline sample of the title compound, C₇H₈ClN₃O₄S₂·C₃H₆O₂, was produced during an automated parallel crystallization search on hydrochlorothiazide (HCT). The crystal structure was solved by simulated annealing from laboratory X-ray powder diffraction data collected at room temperature to 1.75 Å resolution. Subsequent Rietveld refinement yielded an R_wp value of 0.0182 to 1.54 Å resolution. The compound crystallizes with one molecule of HCT and one of methyl acetate in the asymmetric unit and displays an extensive hydrogen-bonding network.

Comment

Hydrochlorothiazide (HCT) is a thiazide diuretic which is known to crystallize in at least two non-solvated forms; form I (Dupont & Dideberg, 1972 ) and form II (Florence et al., 2005 ). During an automated parallel crystallization search on HCT, multi-sample X-ray powder diffraction analysis (Florence et al., 2003 ) of all recrystallized samples revealed a novel pattern which was identified as the methyl acetate solvate (I).

The crystal structure of (I) was solved by simulated annealing using laboratory X-ray powder diffraction data. The compound crystallizes in the space group P2₁/c with one molecule of hydrochlorothiazide (HCT) and one of methyl acetate in the asymmetric unit (Fig. 1). In (I), the six-membered ring N2/S1/C1/C2/N1/C3 in HCT displays a non-planar conformation, atom N2 having the largest deviation [0.646 (2) Å] from the least-squares plane through the aromatic ring. The sulfonamide side chain displays a torsion angle N3—S2—C5—C6 of 65.1 (4)°, such that atom O1 eclipses H4, and atoms O4 and N3 are staggered with respect to Cl1.

The crystal packing (Fig. 2) is stabilized by intermolecular N—H⋯O hydrogen bonds (Table 2), which form a centrosymmetric R₂²(8) dimer motif between HCT molecules (Fig. 3, top), and an R₄⁴(24) motif interconnecting two molecules of HCT and two molecules of solvent (Fig. 3, bottom). In addition, adjacent HCT molecules are connected by a C—H⋯O interaction (Table 2).

Hydrophobic interactions within the structure of (I) include a C—H⋯π approach between C10—H10A and the centroid of the ring C1/C2/C4–C7 [C10⋯centroid distance of 3.364 (2) Å]. The structure also contains a short O⋯C intermolecular contact of 2.915 (4) Å between atom O1 of the HCT sulfonamide side chain and C9ⁱ [symmetry code: (i) x, $[{3\over 2}]$ − y, − $[{1\over 2}]$ + z], the carbonyl C atom of methyl acetate. This type of contact is not unique, and a search of the Cambridge Structural Database (Version 5.26; Allen, 2002 ) for (O)S=O⋯C=O(ester) intermolecular contacts less than the sum of the van der Waals radii yielded 38 structures comprising 41 contacts within the range 2.83–3.21 Å. It is reasonable to consider this contact to be an attractive dipole–dipole interaction of the type S=O(δ⁻)⋯C(δ⁺)=O, similar to those described elsewhere for carbonyl–carbonyl interactions (Allen et al., 1998 ).

Figure 1
The atomic arrangement in (I)

, showing the contents of the asymmetric unit and the atom-numbering scheme. Isotropic displacement ellipsoids are shown at the 50% probability level.

Figure 2
The crystal structure of (I)

, viewed along the b axis. Dashed lines indicate hydrogen bonds.

Figure 3
The R₂²(8) (top) and R₄⁴(24) (bottom) hydrogen-bonded motifs within the structure of (I)

Figure 4
Final observed (points), calculated (line) and difference [(y_obs-y_calc)/σ(y_obs)] profiles for the Rietveld refinement of the title compound.

Experimental

A polycrystalline sample of (I) was recrystallized by cooling a saturated methyl acetate–acetone (50:50) solution from 313 to 283 K. The sample was lightly ground in a mortar, loaded into a 0.7 mm borosilicate glass capillary and mounted on the diffractometer. Data were collected from a sample in a rotating 0.7 mm borosilicate glass capillary using a variable count time scheme (Shankland et al., 1997 ; Hill & Madsen, 2002 $[Hill, R. J. & Madsen, I. C. (2002). Structure Determination from Powder Diffraction Data, edited by W. I. F. David, K. Shankland, L. B. McCusker and Ch. Baerlocher, pp. 114-116. Oxford University Press.]$ ).

Crystal data

C₇H₈ClN₃O₄S₂·C₃H₆O₂
M_r = 371.83
Monoclinic, P 2₁ /c
a = 9.39703 (16) Å
b = 7.28424 (16) Å
c = 21.9483 (3) Å
β = 95.8020 (11)°
V = 1494.67 (6) Å³
Z = 4
D_x = 1.652 Mg m⁻³
Cu Kα₁ radiation
μ = 5.20 mm⁻¹
T = 298 K
Specimen shape: cylinder
12 × 0.7 × 0.7 mm
Specimen prepared at 298 K
White

Data collection

Bruker AXS D8 Advance diffractometer
Specimen mounting: 0.7 mm borosilicate capillary
Specimen mounted in transmission mode
Scan method: step
430 measured reflections
h = 0 → 6
k = −4 → 4
l = −14 → 14
2θ_min = 5.0, 2θ_max = 60.0°
Increment in 2θ = 0.014°

Refinement

Refinement on I_net
R_p = 0.013
R_wp = 0.018
R_exp = 0.013
R_B = 0.007
S = 1.45
Excluded region(s): 5.0 to 7.5 due to high low angle background and the absence of Bragg reflections.
Wavelength of incident radiation: 1.5406 Å
Profile function: fundamental parameters with axial divergence correction
430 reflections
126 parameters
Only H-atom coordinates refined
w = 1/σ(Y_obs)²
(Δ/σ)_max = 0.004
Δρ_max = 0.6 e Å⁻³
Δρ_min = − 0.7 e Å⁻³
Preferred orientation correction: A spherical harmonics-based preferred orientation correction (Järvinen, 1993 ) was applied with TOPAS during the Rietveld refinement.

Table 1
Selected geometric parameters (Å, °)

Cl1—C6	1.729 (3)
S1—O2	1.426 (3)
S1—O3	1.424 (3)
S1—N2	1.647 (2)
S1—C1	1.770 (2)
S2—O1	1.430 (3)
S2—O4	1.425 (4)
S2—N3	1.635 (2)
S2—C5	1.773 (2)
O5—C9	1.229 (3)
O6—C9	1.379 (3)
O6—C10	1.432 (3)
N1—C2	1.364 (2)
N1—C3	1.395 (2)
N2—C3	1.442 (2)

O2—S1—O3	122.3 (2)
O2—S1—N2	105.1 (2)
O2—S1—C1	108.82 (19)
O3—S1—N2	108.26 (19)
O3—S1—C1	109.26 (19)
N2—S1—C1	100.99 (11)
O1—S2—O4	117.9 (3)
O1—S2—N3	109.7 (3)
O1—S2—C5	106.0 (2)
O4—S2—N3	108.3 (2)
O4—S2—C5	108.99 (19)
N3—S2—C5	105.25 (16)
C9—O6—C10	117.19 (17)
C2—N1—C3	123.80 (15)
S1—N2—C3	114.00 (13)
S1—C1—C4	119.05 (13)
S1—C1—C2	119.79 (11)
N1—C2—C7	120.31 (16)
N1—C2—C1	121.89 (15)
N1—C3—N2	112.9 (2)
S2—C5—C4	117.37 (16)
S2—C5—C6	124.82 (16)
Cl1—C6—C7	116.92 (19)
Cl1—C6—C5	121.60 (16)
O5—C9—O6	117.66 (19)
O5—C9—C8	129.20 (18)
O6—C9—C8	113.14 (14)

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1⋯O6	0.94 (1)	2.48 (1)	3.052 (4)	119 (1)
N2—H2⋯O3ⁱ	0.95 (1)	2.17 (1)	3.086 (3)	161 (1)
N3—H31⋯O1ⁱⁱ	0.95 (1)	2.46 (1)	2.967 (6)	113 (1)
N3—H31⋯O5ⁱⁱⁱ	0.95 (1)	2.26 (1)	3.090 (3)	146 (1)
N3—H32⋯O5^iv	0.95 (1)	2.12 (1)	2.960 (4)	147 (1)
C7—H7⋯O2^v	0.95 (1)	2.41 (1)	3.336 (4)	165 (1)
Symmetry codes: (i) -x+1, -y+2, -z; (ii) $[-x+1, +y-{\script{1\over 2}}, -z-{\script{1\over 2}}]$ ; (iii) -x+1, -y+1, -z; (iv) $[x, -y+{\script{1\over 2}}, +z-{\script{1\over 2}}]$ ; (v) x, y-1, z.

The diffraction pattern indexed to a monoclinic cell [M(20)= 34.0, F(20)= 81.2; DICVOL-91; Boultif & Louer, 1991 ] and the space group P2₁/c was assigned from volume considerations and a statistical consideration of the systematic absences (Markvardsen et al., 2001 ). The data set was background subtracted and truncated to 52.2° 2θ for Pawley fitting (Pawley, 1981 ; χ²_Pawley = 1.64) and the structure solved using the simulated annealing (SA) global optimization procedure, described previously (David et al., 1998 ), that is now implemented in the DASH computer program (David et al., 2001 ). The internal coordinate descriptions (including H atoms) of the molecules were constructed from standard bond lengths, angles and torsions where appropriate. The structure was solved using data to 52.23° 2θ, comprising 291 reflections. The structure was refined against data in the range 7.5 to 60.0° 2θ (430 reflections). The restraints were set such that bonds and angles did not deviate more than 0.01 Å and 1°, respectively, from their initial values during the refinement. Atoms C1, C2, C4, C5, C6, C7, H4, H7, Cl1 and S2 of HCT were restrained to be planar, as were atoms C8, C9, C10, O5 and O6 of the methyl acetate. The SA structure solution involved the optimization of one molecule of HCT plus one molecule of methyl acetate, totaling 13 degrees of freedom (six positional, six orientational and one torsional). All degrees of freedom were assigned random values at the start of the simulated annealing. The best SA solution had a favourable χ²_SA/χ²_Pawley ratio of 5.2, a chemically reasonable packing arrangement and exhibited no significant misfit to the data. Prior to Rietveld refinement, atoms H31 and H32 (attached to N3) were set to positions which satisfied the hydrogen-bonding contacts within the structure. The solved structure was subsequently refined against data in the range 7.5–60.0° 2θ using a restrained Rietveld method (Rietveld, 1969 ) as implemented in TOPAS (Coelho, 2003 ), with the R_wp value falling to 0.0182 during the refinement. All atomic positions (including H atoms) for the structure of (I) were refined, subject to a series of restraints on bond lengths, angles and planarity. A spherical harmonics (8th order) correction of intensities for preferred orientation was applied in the final refinement (Järvinen, 1993). The observed and calculated diffraction patterns for the refined crystal structure are shown in Fig. 4. The atomic coordinates for all atoms are taken from the software, and it is worth noting that the s.u. values derived from the Rietveld refinement are, in common with the majority of Rietveld refinements, significantly underestimated.

Data collection: DIFFRAC plus XRD Commander (Kienle & Jacob, 2003 ); cell refinement: TOPAS (Coelho, 2003); data reduction: DASH (David et al., 2001); program(s) used to solve structure: DASH; program(s) used to refine structure: TOPAS; molecular graphics: PLATON (Spek, 2003 ); software used to prepare material for publication: enCIFer (Cambridge Crystallographic Data Centre, 2004 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: https://doi.org/10.1107/S1600536805025651/cv6560sup1.cif

Rietveld powder data: contains datablock I. DOI: https://doi.org/10.1107/S1600536805025651/cv6560Isup2.rtv

Computing details top

Data collection: DIFFRAC plus XRD Commander (Kienle & Jacob, 2003); cell refinement: TOPAS (Coelho, 2003); data reduction: DASH (David et al., 2001); program(s) used to solve structure: DASH (David et al., 2001); program(s) used to refine structure: TOPAS; molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: enCIFer (Cambridge Crystallographic Data Centre, 2004).

(I) top

Crystal data top

C₇H₈ClN₃O₄S₂·C₃H₆O₂	Z = 4
M_r = 371.83	F(000) = 768.0
Monoclinic, P2₁/c	D_x = 1.652 Mg m⁻³
Hall symbol: -P 2ybc	Cu Kα₁ radiation, λ = 1.54056 Å
a = 9.39703 (16) Å	µ = 5.20 mm⁻¹
b = 7.28424 (16) Å	T = 298 K
c = 21.9483 (3) Å	white
β = 95.8020 (11)°	cylinder, 12 × 0.7 mm
V = 1494.67 (6) Å³	Specimen preparation: Prepared at 298 K

Data collection top

Bruker AXS D8 Advance diffractometer	Data collection mode: transmission
Radiation source: sealed X-ray tube, Bruker AXS D8	Scan method: step
Primary focussing, Ge 111 monochromator	2θ_min = 5.0°, 2θ_max = 60.0°, 2θ_step = 0.014°
Specimen mounting: 0.7 mm borosilicate capillary

Refinement top

Refinement on I_net	126 parameters
Least-squares matrix: selected elements only	72 restraints
R_p = 0.013	1 constraint
R_wp = 0.018	Only H-atom coordinates refined
R_exp = 0.013	Weighting scheme based on measured s.u.'s 1/σ(Y_obs)²
R_Bragg = 0.007	(Δ/σ)_max = 0.004
3929 data points	Background function: Chebyshev polynomial
Excluded region(s): 5.0 to 7.5 due to high low angle background and the absence of Bragg reflections.	Preferred orientation correction: A spherical harmonics-based preferred orientation correction (Järvinen, 1993) was applied with Topas during the Rietveld refinement.
Profile function: Fundamental parameters with axial divergence correction

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Cl1	0.8195 (3)	0.3882 (3)	−0.18148 (9)	0.0329 (5)*
S1	0.73715 (15)	1.05531 (19)	−0.00965 (7)	0.0329 (5)*
S2	0.72621 (16)	0.79646 (19)	−0.24031 (7)	0.0329 (5)*
O1	0.6906 (7)	0.9871 (3)	−0.24511 (19)	0.0329 (5)*
O2	0.8672 (3)	1.1557 (5)	0.00231 (19)	0.0329 (5)*
O3	0.6053 (3)	1.1419 (4)	−0.0305 (2)	0.0329 (5)*
O4	0.8458 (3)	0.7336 (7)	−0.26960 (15)	0.0329 (5)*
N1	0.8265 (6)	0.6705 (2)	0.02849 (8)	0.0329 (5)*
N2	0.71647 (17)	0.9472 (3)	0.05475 (8)	0.0329 (5)*
N3	0.58695 (16)	0.6729 (2)	−0.26508 (15)	0.0329 (5)*
C1	0.7665 (3)	0.8685 (2)	−0.05842 (6)	0.0329 (5)*
C2	0.8055 (5)	0.6976 (2)	−0.03324 (6)	0.0329 (5)*
C3	0.82476 (17)	0.8111 (2)	0.07153 (8)	0.0329 (5)*
C4	0.7449 (4)	0.8932 (2)	−0.12102 (7)	0.0329 (5)*
C5	0.7565 (3)	0.7489 (3)	−0.16085 (8)	0.0329 (5)*
C6	0.7971 (6)	0.5770 (3)	−0.13567 (9)	0.0329 (5)*
C7	0.8207 (4)	0.5514 (2)	−0.07365 (6)	0.0329 (5)*
H3A	0.8089 (12)	0.7606 (14)	0.1100 (5)	0.0443*
H3B	0.9134 (11)	0.8732 (16)	0.0795 (4)	0.0443*
H7	0.8452 (13)	0.4329 (15)	−0.0578 (5)	0.0443*
H4	0.7194 (16)	1.0106 (13)	−0.1369 (6)	0.0443*
H2	0.6190 (12)	0.9181 (15)	0.0575 (5)	0.0443*
H1	0.8462 (12)	0.5493 (16)	0.0418 (5)	0.0443*
H31	0.5006 (13)	0.7193 (15)	−0.2523 (4)	0.0443*
H32	0.6101 (12)	0.5465 (17)	−0.2687 (5)	0.0443*
C8	0.87362 (18)	0.21591 (19)	0.16847 (7)	0.0329 (5)*
C9	0.71849 (18)	0.2591 (2)	0.15411 (8)	0.0329 (5)*
C10	0.54815 (18)	0.4566 (2)	0.09788 (8)	0.0329 (5)*
O5	0.6140 (2)	0.1839 (4)	0.17260 (13)	0.0329 (5)*
O6	0.69391 (19)	0.4044 (3)	0.11414 (10)	0.0329 (5)*
H8A	0.8818 (12)	0.1090 (16)	0.1947 (5)	0.0443*
H8B	0.9172 (12)	0.3172 (16)	0.1893 (5)	0.0443*
H8C	0.9118 (13)	0.1916 (15)	0.1315 (5)	0.0443*
H10A	0.5049 (13)	0.4878 (13)	0.1326 (5)	0.0443*
H10B	0.5005 (13)	0.3589 (16)	0.0758 (5)	0.0443*
H10C	0.5494 (13)	0.5610 (16)	0.0707 (5)	0.0443*

Geometric parameters (Å, º) top

Cl1—C6	1.729 (3)	N3—H31	0.947 (12)
S1—O2	1.426 (3)	C1—C4	1.380 (2)
S1—O3	1.424 (3)	C1—C2	1.396 (2)
S1—N2	1.647 (2)	C2—C7	1.402 (2)
S1—C1	1.770 (2)	C4—C5	1.379 (3)
S2—O1	1.430 (3)	C5—C6	1.406 (3)
S2—O4	1.425 (4)	C6—C7	1.370 (2)
S2—N3	1.635 (2)	C3—H3A	0.947 (11)
S2—C5	1.773 (2)	C3—H3B	0.949 (11)
O5—C9	1.229 (3)	C4—H4	0.945 (10)
O6—C9	1.379 (3)	C7—H7	0.950 (11)
O6—C10	1.432 (3)	C8—C9	1.494 (2)
N1—C2	1.364 (2)	C8—H8A	0.967 (11)
N1—C3	1.395 (2)	C8—H8B	0.940 (12)
N2—C3	1.442 (2)	C8—H8C	0.937 (11)
N1—H1	0.942 (12)	C10—H10A	0.927 (11)
N2—H2	0.948 (11)	C10—H10B	0.948 (12)
N3—H32	0.951 (12)	C10—H10C	0.967 (12)

O2—S1—O3	122.3 (2)	S2—C5—C6	124.82 (16)
O2—S1—N2	105.1 (2)	C4—C5—C6	117.75 (16)
O2—S1—C1	108.82 (19)	Cl1—C6—C7	116.92 (19)
O3—S1—N2	108.26 (19)	C5—C6—C7	121.48 (19)
O3—S1—C1	109.26 (19)	Cl1—C6—C5	121.60 (16)
N2—S1—C1	100.99 (11)	C2—C7—C6	120.57 (17)
O1—S2—O4	117.9 (3)	N1—C3—H3A	109.4 (6)
O1—S2—N3	109.7 (3)	N1—C3—H3B	113.9 (7)
O1—S2—C5	106.0 (2)	N2—C3—H3B	107.7 (7)
O4—S2—N3	108.3 (2)	H3A—C3—H3B	103.6 (9)
O4—S2—C5	108.99 (19)	N2—C3—H3A	108.9 (7)
N3—S2—C5	105.25 (16)	C1—C4—H4	119.4 (8)
C9—O6—C10	117.19 (17)	C5—C4—H4	119.3 (8)
C2—N1—C3	123.80 (15)	C2—C7—H7	119.7 (7)
S1—N2—C3	114.00 (13)	C6—C7—H7	119.8 (7)
C3—N1—H1	119.6 (7)	O5—C9—O6	117.66 (19)
C2—N1—H1	116.6 (7)	O5—C9—C8	129.20 (18)
C3—N2—H2	119.4 (7)	O6—C9—C8	113.14 (14)
S1—N2—H2	111.1 (7)	C9—C8—H8A	108.2 (7)
S2—N3—H31	112.7 (7)	C9—C8—H8B	107.8 (7)
H31—N3—H32	125.5 (10)	C9—C8—H8C	108.0 (7)
S2—N3—H32	112.2 (7)	H8A—C8—H8B	109.8 (10)
C2—C1—C4	121.11 (14)	H8A—C8—H8C	110.4 (10)
S1—C1—C4	119.05 (13)	H8B—C8—H8C	112.6 (10)
S1—C1—C2	119.79 (11)	O6—C10—H10A	110.4 (7)
C1—C2—C7	117.79 (12)	O6—C10—H10B	108.6 (8)
N1—C2—C7	120.31 (16)	O6—C10—H10C	107.0 (7)
N1—C2—C1	121.89 (15)	H10A—C10—H10B	112.4 (10)
N1—C3—N2	112.9 (2)	H10A—C10—H10C	110.4 (9)
C1—C4—C5	121.25 (16)	H10B—C10—H10C	108.0 (10)
S2—C5—C4	117.37 (16)

O2—S1—N2—C3	−65.2 (2)	C2—N1—C3—N2	38.8 (6)
O3—S1—N2—C3	162.64 (19)	S1—N2—C3—N1	−61.7 (3)
C1—S1—N2—C3	47.94 (18)	C2—C1—C4—C5	2.1 (5)
O2—S1—C1—C2	92.7 (3)	S1—C1—C2—N1	−2.1 (6)
O2—S1—C1—C4	−89.8 (3)	S1—C1—C4—C5	−175.4 (3)
O3—S1—C1—C2	−131.6 (3)	C4—C1—C2—C7	−0.6 (6)
O3—S1—C1—C4	46.0 (3)	S1—C1—C2—C7	176.9 (3)
N2—S1—C1—C2	−17.6 (3)	C4—C1—C2—N1	−179.6 (4)
N2—S1—C1—C4	159.9 (2)	C1—C2—C7—C6	−0.3 (6)
O1—S2—C5—C4	−1.5 (4)	N1—C2—C7—C6	178.8 (5)
O1—S2—C5—C6	−178.7 (4)	C1—C4—C5—C6	−2.7 (5)
O4—S2—C5—C4	126.4 (3)	C1—C4—C5—S2	179.9 (3)
O4—S2—C5—C6	−50.9 (4)	S2—C5—C6—Cl1	−1.0 (6)
N3—S2—C5—C4	−117.7 (3)	S2—C5—C6—C7	179.0 (3)
N3—S2—C5—C6	65.1 (4)	C4—C5—C6—Cl1	−178.3 (3)
C10—O6—C9—C8	−179.70 (16)	C4—C5—C6—C7	1.8 (6)
C10—O6—C9—O5	0.5 (3)	Cl1—C6—C7—C2	179.7 (4)
C3—N1—C2—C1	−6.3 (8)	C5—C6—C7—C2	−0.3 (7)
C3—N1—C2—C7	174.7 (4)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O6	0.94 (1)	2.48 (1)	3.052 (4)	119 (1)
N2—H2···O3ⁱ	0.95 (1)	2.18 (1)	3.086 (3)	161 (1)
N3—H31···O1ⁱⁱ	0.95 (1)	2.46 (1)	2.967 (6)	113 (1)
N3—H31···O5ⁱⁱⁱ	0.95 (1)	2.26 (1)	3.090 (3)	146 (1)
N3—H32···O5^iv	0.95 (1)	2.12 (1)	2.960 (4)	147 (1)
C7—H7···O2^v	0.95 (1)	2.41 (1)	3.336 (4)	165 (1)

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

Acknowledgements

The authors thank the Basic Technology programme of the UK Research Councils for funding under the project Control and Prediction of the Organic Solid State (URL: www.cposs.org.uk). They also thank EPSRC for grant GR/N07462/01.

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