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Single-crystal diffuse X-ray scattering from paracetamol polymorphs is successfully calculated with Monte Carlo (MC) models that are used to simulate the crystals. In order to obtain the correct model appropriate force constants are required that describe the interatomic potentials used in the MC algorithm. Coefficients for an empirical `Buckingham'-type formula are used to determine these force constants. These coefficients are subsequently refined using the least-squares method and are found to converge on similar values for both polymorphic forms. An investigation of the correlation space generated from each model provides what would be expected given that strong displacive correlations exist between the molecules comprising the densely hydrogen-bonded layers. More disordered motions between these layers are present in the model for form (II) as opposed to form (I). An investigation into the peculiarities of librational disorder was also conducted, however, correlation values turn out to be so small that any structural information concerning librational correlation is inconclusive. The purpose of this experiment was to identify if the diffuse scattering features could provide further insight into understanding the physical reasoning behind the metastability of form (II). The form (II) → (I) phase transition is also not currently well understood and usually phase transitional information can be obtained from pronounced diffuse scattering features. Since the diffuse scattering is modelled adequately using harmonic potentials it is our conjecture that the `diffuse' is essentially thermal in origin and does not afford any extra information about the form (II) → (I) phase transition.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108768111046295/eb5012sup1.cif
Contains datablocks I, publication_text

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108768111046295/eb5012Isup2.hkl
Contains datablock I

CCDC reference: 866775

Computing details top

Data collection: Collect (Bruker AXS BV, 1997-2004); cell refinement: HKL SCALEPACK (Otwinowski & Minor 1997); data reduction: HKL DENZO and SCALEPACK (Otwinowski & Minor 1997); program(s) used to solve structure: known; program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: Xtal3.7 (Hall et al., 2001); software used to prepare material for publication: WinGX publication routines (Farrugia, 1999).

(I) top
Crystal data top
C8H9NO2F(000) = 640
Mr = 151.16Dx = 1.339 Mg m3
Orthorhombic, PbcaMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2abCell parameters from 10043 reflections
a = 11.8237 (4) Åθ = 2.6–27.5°
b = 7.3971 (3) ŵ = 0.10 mm1
c = 17.1526 (7) ÅT = 293 K
V = 1500.19 (10) Å3Prism, colourless
Z = 80.35 × 0.15 × 0.09 mm
Data collection top
KappaCCD
diffractometer
1704 independent reflections
Radiation source: fine-focus sealed tube1178 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.037
Detector resolution: 9 pixels mm-1θmax = 27.4°, θmin = 2.9°
CCD scansh = 1511
Absorption correction: integration
Gaussian integration (Coppens, 1970)
k = 97
Tmin = 0.967, Tmax = 0.991l = 2217
7284 measured reflections
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.040Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.117All H-atom parameters refined
S = 1.02 w = 1/[σ2(Fo2) + (0.0618P)2 + 0.1916P]
where P = (Fo2 + 2Fc2)/3
1704 reflections(Δ/σ)max < 0.001
136 parametersΔρmax = 0.15 e Å3
0 restraintsΔρmin = 0.18 e Å3
Special details top

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 (Å2) top
xyzUiso*/Ueq
C10.05363 (10)0.29200 (19)0.16106 (7)0.0371 (3)
C20.16057 (11)0.2127 (2)0.16301 (8)0.0399 (4)
C30.22081 (11)0.2076 (2)0.23192 (8)0.0402 (4)
C40.17645 (11)0.2809 (2)0.29949 (8)0.0387 (3)
C50.07201 (11)0.3659 (2)0.29691 (8)0.0406 (4)
C60.01126 (11)0.3705 (2)0.22827 (8)0.0397 (4)
N70.01806 (10)0.29092 (18)0.09458 (7)0.0447 (4)
C80.00639 (12)0.2609 (2)0.01959 (8)0.0465 (4)
O90.10325 (9)0.2285 (2)0.00299 (6)0.0698 (4)
C100.09303 (16)0.2693 (4)0.03459 (11)0.0613 (5)
O110.23691 (9)0.26928 (17)0.36757 (6)0.0545 (3)
H120.1908 (13)0.160 (2)0.1177 (9)0.046 (4)*
H130.2932 (13)0.153 (2)0.2342 (8)0.046 (4)*
H140.0426 (12)0.425 (2)0.3441 (9)0.050 (4)*
H150.0637 (13)0.430 (2)0.2268 (8)0.045 (4)*
H160.0891 (17)0.310 (2)0.1063 (10)0.058 (5)*
H170.126 (3)0.154 (4)0.0426 (19)0.145 (12)*
H180.156 (2)0.338 (4)0.0164 (14)0.111 (8)*
H190.069 (2)0.306 (3)0.0843 (15)0.089 (7)*
H200.188 (2)0.279 (3)0.4098 (14)0.083 (7)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0287 (6)0.0494 (8)0.0332 (7)0.0019 (5)0.0013 (6)0.0049 (6)
C20.0305 (6)0.0535 (9)0.0358 (7)0.0022 (6)0.0049 (6)0.0009 (6)
C30.0264 (6)0.0523 (9)0.0419 (8)0.0026 (5)0.0014 (6)0.0041 (6)
C40.0304 (6)0.0505 (9)0.0353 (7)0.0049 (6)0.0013 (5)0.0038 (6)
C50.0368 (7)0.0480 (9)0.0369 (7)0.0011 (6)0.0046 (6)0.0021 (6)
C60.0288 (6)0.0486 (9)0.0419 (8)0.0050 (6)0.0034 (5)0.0015 (6)
N70.0280 (6)0.0715 (10)0.0347 (6)0.0035 (5)0.0001 (5)0.0027 (5)
C80.0371 (7)0.0651 (10)0.0372 (8)0.0009 (6)0.0011 (6)0.0027 (7)
O90.0405 (6)0.1312 (12)0.0375 (6)0.0133 (6)0.0037 (5)0.0018 (6)
C100.0458 (9)0.0967 (16)0.0414 (9)0.0037 (9)0.0079 (8)0.0008 (9)
O110.0356 (6)0.0923 (9)0.0356 (6)0.0018 (5)0.0037 (5)0.0013 (5)
Geometric parameters (Å, º) top
C1—C61.3847 (19)C5—H140.984 (16)
C1—C21.3941 (18)C6—H150.989 (15)
C1—N71.4209 (18)N7—C81.3369 (19)
C2—C31.381 (2)N7—H160.875 (19)
C2—H120.940 (16)C8—O91.2325 (18)
C3—C41.383 (2)C8—C101.500 (2)
C3—H130.948 (15)C10—H170.95 (3)
C4—O111.3719 (16)C10—H180.96 (3)
C4—C51.3864 (19)C10—H190.94 (3)
C5—C61.3795 (19)O11—H200.93 (3)
C6—C1—C2118.98 (12)C5—C6—H15120.0 (8)
C6—C1—N7117.05 (11)C1—C6—H15119.2 (8)
C2—C1—N7123.91 (12)C8—N7—C1130.10 (12)
C3—C2—C1120.00 (13)C8—N7—H16117.1 (11)
C3—C2—H12120.0 (9)C1—N7—H16112.8 (11)
C1—C2—H12119.9 (9)O9—C8—N7122.38 (13)
C2—C3—C4120.73 (13)O9—C8—C10122.79 (15)
C2—C3—H13120.9 (9)N7—C8—C10114.83 (14)
C4—C3—H13118.4 (9)C8—C10—H17112.0 (19)
O11—C4—C3119.41 (13)C8—C10—H18115.6 (15)
O11—C4—C5121.31 (12)H17—C10—H18102 (2)
C3—C4—C5119.27 (12)C8—C10—H19110.0 (14)
C6—C5—C4120.15 (12)H17—C10—H19104 (2)
C6—C5—H14120.4 (9)H18—C10—H19112 (2)
C4—C5—H14119.4 (9)C4—O11—H20109.5 (13)
C5—C6—C1120.78 (12)
 

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