research communications\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

ISSN: 2056-9890

Threefold helical assembly via hy­dr­oxy hydrogen bonds: the 2:1 co-crystal of bi­cyclo­[3.3.0]octane-endo-3,endo-7-diol and bi­cyclo­[3.3.0]octane-endo-3,exo-7-diol


aSchool of Chemistry, University of New South Wales, UNSW Sydney NSW 2052, Australia, and bMark Wainwright Analytical Centre, University of New South Wales, UNSW Sydney, NSW 2052, Australia
*Correspondence e-mail:

Edited by M. Zeller, Purdue University, USA (Received 27 November 2020; accepted 12 February 2021; online 19 February 2021)

Reduction of bi­cyclo­[3.3.0]octane-3,7-dione yields a mixture of the endo-3,endo-7-diol and endo-3, exo-7-diol (C8H14O2) isomers (5 and 6). These form (5)2·(6) co-crystals in the monoclinic P21/n space group (with Z = 6, Z′ = 1.5) rather than undergoing separation by means of fractional recrystallization or column chromatography. The mol­ecule of 5 occupies a general position, whereas the mol­ecule of 6 is disordered over two orientations across a centre of symmetry with occupancies of 0.463 (2) and 0.037 (2). Individual diol hy­droxy groups associate around a pseudo-threefold screw axis by means of hydrogen bonding. The second hy­droxy group of each diol behaves in a similar manner, generating a three-dimensional hydrogen-bonded network structure. This hydrogen-bond connectivity is identical to that present in three known helical tubuland diol–hydro­quinone co-crystals, and the new crystal structure is even more similar to two homologous aliphatic diol co-crystals.

1. Chemical context

Crystalline binary adducts (Herbstein, 2005[Herbstein, F. H. (2005). Crystalline Molecular Complexes and Compounds: Structures and Principles, Vols. 1 & 2. Oxford University Press.]) have been classified as clathrates, coordinatoclathrates, clathratocomplexes or complexes (Weber & Josel, 1983[Weber, E. & Josel, H.-P. (1983). J. Inclusion Phenom. 1, 79-85.]). At one end of this structural continuum, clathrates have a dominant host structure, host–guest inter­actions are less important, and the guests are spatially caged. Complexes, on the other hand, are mutually coordinated and the importance of three-dimensional enclosure is significantly lessened. Hosts may complex with a liquid guest to yield solvates or hydrates. If the two components are both solids of comparable size, however, then the host–guest distinction vanishes. The latter group of complexes are nowadays generally termed co-crystals (Aakeröy & Chopade, 2012[Aakeröy, C. B. & Chopade, P. D. (2012). Supramolecular Chemistry: From Molecules to Nanomaterials, , Vol. 6, Cocrystals: Synthesis, Structure, and Applications, edited by P. A. Gale & J. W. Steed. pp. 2975-2992. Chichester: Wiley.]).

Research into co-crystals is an area of considerable current significance. Many potentially valuable bioactive mol­ecules have poor aqueous solubility and this restricts their application as pharmaceutical drugs. Combination with a benign partner mol­ecule to produce a co-crystal can result in enhanced properties such as improved drug formulation and greater biological uptake (Almarsson & Zaworotko, 2004[Almarsson, O. & Zaworotko, M. J. (2004). Chem. Commun. pp. 1889-1896.]). Our knowledge of inter­molecular attractive forces often allows a prediction to be made of the complementary partner required for such pharmaceutical co-crystal synthesis (Bis et al., 2006[Bis, J. A., McLaughlin, O. L., Vishweshwar, P. & Zaworotko, M. J. (2006). Cryst. Growth Des. 6, 2648-2650.], 2007[Bis, J. A., Vishweshwar, P., Weyna, D. & Zaworotko, M. J. (2007). Mol. Pharm. 4, 401-416.]).

A second sub-set of co-crystalline substances comprises unexpected combinations of isomers or structurally related compounds (Kelley et al., 2011[Kelley, S. P., Fábián, L. & Brock, C. P. (2011). Acta Cryst. B67, 79-93.]). This is not a new phenomenon. Indeed, the first such material now recognised as being a co-crystal was discovered in 1844 by Friedrich Wöhler. This was the 1:1 combination of p-benzo­quinone 1 and hydro­quinone 2, commonly known as quinhydrone 3 (Fig. 1[link]) (Karagianni et al., 2018[Karagianni, A., Malamatari, M. & Kachrimanis, K. (2018). Pharmaceutics, 10, 18 (30 pp).]; Sakurai, 1968[Sakurai, T. (1968). Acta Cryst. B24, 403-412.]). These novel co-crystalline materials are generally discovered accidentally as a consequence of preparative organic work going wrong, in particular the very few instances where standard purification techniques fail. It is therefore a rare and unpredictable occurrence.

[Figure 1]
Figure 1
1:1 combination of p-benzo­quinone 1 and hydro­quinone 2, commonly known as quinhydrone 3

The present work describes a new example of this phenomenon. Reduction of bi­cyclo­[3.3.0]octane-3,7-dione 4 with lithium aluminium hydride yielded an approximately 2:1 mixture of the diols 5 and 6 (Fig. 2[link]). These isomeric products could not be separated by fractional recrystallization or standard column chromatography using silica or alumina.

[Scheme 1]
[Figure 2]
Figure 2
Synthetic route to formation of title compounds 5 and 6

2. Structural commentary

When the mixture of diols 5 and 6 was recrystallized from toluene, thin plate crystals of composition (5)2·(6) were produced in the monoclinic space group P21/n. The mol­ecules of 5 (atoms labelled with suffix A) are in a general position, whereas mol­ecules of 6 are disordered across the centre of inversion in this space group (thus Z = 6, Z′ = 1.5). There are two sites (atoms labelled with suffixes B and C) of occupancies 0.463 (2) and 0.037 (2), respectively. The minor site C can be described as a position obtained by a twofold rotation about the axis perpendicular to the midpoint of the bond C3B—C7B of the mol­ecule at site B (Fig. 3[link]). However, from here onwards, only the major site B will be used in figures and discussions of inter­molecular inter­actions for the sake of clarity. The bi­cyclo­[3.3.0]octane skeleton comprises two cyclo­pentane rings fused in a cis-manner. Its basic configuration is a flattened V-shape in solution, with the convex face being termed exo- and the concave face endo-. Reduction of the diketone 4 therefore occurs preferentially on the more exposed exo-face to produce the endo-alcohol configuration. The co-crystal formula indicates that this stereoselectivity is around 5:1 using lithium aluminium hydride in tetra­hydro­furan.

[Figure 3]
Figure 3
The isomer 5 (mol­ecule A) (upper), the isomer 6 with its major component (mol­ecule B, centre) and minor components (mol­ecule C, lower) showing their crystallographic atom labelling. Displacement ellipsoids are drawn at the 50% probability level and hydrogen atoms are shown as spheres of arbitrary size.

The cyclo­pentane rings, however, have conformational mobility that can contribute to the optimal crystal packing. In particular, envelope conformations may occur with the envelope flap being orientated syn- to either of the exo- or endo-faces. The isomer 5 has one flap syn to each of these ring faces, while 6 has both its flaps syn to the exo-face of the structure (Fig. 3[link]). Ring twisting can also occur but is relatively minor in (5)2·(6). Qu­anti­tative descriptions of these conformational effects are summarized by the cyclo­pentane ring torsion angle values marked on Fig. 4[link].

[Figure 4]
Figure 4
The bi­cyclo­[3.3.0]octane ring conformations adopted by the isomers 5 (upper) and 6 (lower) in the structure (5)2·(6). Torsion angles are shown with their e.s.d.s.

3. Supra­molecular features

The isomeric diol mol­ecules are connected by hy­droxy hydrogen bonds (Table 1[link]) and a three-dimensional network is formed. Mol­ecules of 5 and 6 form a 2:1 infinite chain with their hydrogen bonds surrounding a pseudo-threefold screw axis along the a-axis direction (Fig. 5[link]). The O⋯O distance between mol­ecules of 5 is 2.743 (2) Å, and those between 5 and 6 are 2.629 (12) and 2.784 (12) Å. Mol­ecules of 6 are not connected directly through hydrogen bonding with each other. Both the second hy­droxy groups of 5 and 6 contribute to further identical screw axis assemblies. Hence the resulting crystal contains alternating zones of 5 and 6 mol­ecules that run along both the a- and c-axis directions (Fig. 6[link]). The only other notable inter­action is a C7A—H7A⋯O2A weak hydrogen bond [D 3.727 (2), d 2.80 Å] that links adjacent mol­ecules of 5.

Table 1
Hydrogen-bond geometry (Å, °)

O1A—H1A⋯O1Bi 0.84 1.89 2.732 (12) 177
O1A—H1A⋯O2Bii 0.84 1.88 2.710 (12) 170
O1A—H1A⋯O1Ci 0.84 2.05 2.83 (6) 154
O1A—H1A⋯O2Cii 0.84 2.04 2.82 (7) 155
C2A—H2AA⋯O1Ci 0.99 2.37 3.18 (5) 139
C2A—H2AA⋯O2Cii 0.99 2.44 3.25 (6) 139
O2A—H2A⋯O1Aiii 0.84 1.91 2.7432 (16) 173
O1B—H1B⋯O2Aiv 0.84 1.98 2.784 (12) 159
O2B—H2B⋯O2Aiii 0.84 1.79 2.629 (12) 173
O1C—H1C⋯O2Aiv 0.84 2.04 2.86 (5) 164
Symmetry codes: (i) [-x+1, -y+1, -z+2]; (ii) x, y, z+1; (iii) [x+{\script{1\over 2}}, -y+{\script{1\over 2}}, z-{\script{1\over 2}}]; (iv) [-x+{\script{1\over 2}}, y+{\script{1\over 2}}, -z+{\script{3\over 2}}].
[Figure 5]
Figure 5
The crystal structure of (5)2·(6) projected on the bc plane and looking down the pseudo-threefold screw axes. Colour code: O atoms red, diol 5 green, and diol 6 major component (light and dark blue). Minor component C and all hydrogen atoms are omitted for clarity and the hy­droxy hydrogen bonds are indicated as solid black lines.
[Figure 6]
Figure 6
The crystal structure of (5)2·(6) projected on the ab plane and showing the pseudo-threefold screw axes running horizontally. The alternating zones of isomers 5 and 6 in the crystal should be noted. Colour code is the same as used in Fig. 5[link].

Viewed down a, the isomer 5 is present as two stacked columns of translated diol mol­ecules. It is therefore probable that diol 6 is stacked similarly. This isomer contains no centre of symmetry, but is situated on a crystallographic inversion site. Mol­ecules of 6 therefore appear in Figs. 5[link] and 6[link] as a superimposition of two disordered forms across a centre of symmetry.

The hy­droxy hydrogen-bonding connectivity present in (5)2·(6) provides a versatile supra­molecular network that occurs in at least five other diol co-crystal structures (Fig. 7[link]). Helical tubuland (HT) diols 79 employ hy­droxy group hydrogen bonding to assemble around threefold screw axes in space group P3121 (Bishop, 2009[Bishop, R. (2009). Acc. Chem. Res. 42, 67-78.]). This creates tubular voids that enclose guest mol­ecules of many structural types. A notable exception is the phenol family, which instead yields hydrogen-bonded co-crystals. This is achieved by one of the three columns of HT diol mol­ecules being replaced by a column of phenols with concomitant formation of pseudo-threefold screw axes. Co-crystals of general formula (HT)2·(2) are produced when hydro­quinone 2 is used as the co-former mol­ecule (Ung et al., 1993[Ung, A. T., Bishop, R., Craig, D. C., Dance, I. G. & Scudder, M. L. (1993). J. Chem. Soc. Chem. Commun. pp. 322-323.], 1994[Ung, A. T., Bishop, R., Craig, D. C., Dance, I. G. & Scudder, M. L. (1994). Chem. Mater. 6, 1269-1281.]; Yue et al., 2002[Yue, W., Bishop, R., Craig, D. C. & Scudder, M. L. (2002). CrystEngComm, 4, 591-595.]). Fig. 8[link] compares the threefold and pseudo-threefold screw axes using the example of HT diol 7. These should be compared to the screw axis observed in (5)2·(6) (Fig. 8[link], right).

[Figure 7]
Figure 7
Mol­ecular structures of diols 710 and 12 that can be used as co-crystal partners to generate the same hydrogen bonding connectivity as that present in (5)2·(6). We predict that cyclo­octane-1,5-diol 11 will behave similarly.
[Figure 8]
Figure 8
Comparison of the threefold screw axis of crystalline 7 (left), and the pseudo-threefold screw axes present in the co-crystals (7)2·(2) (centre) and (5)2·(6) (right).

The hydrogen-bonding networks of 7, (7)2·(2), and (5)2·(6) are compared in Fig. 9[link] (upper, centre, and lower). All are viewed looking down the threefold screw axes. Despite the very different shapes and mol­ecular structures of the building blocks 7/5 and 2/6, their hy­droxy hydrogen-bonding connectivity is identical. The three networks do, however, differ in their crystallographic symmetry. This is a consequence of the presence, or absence, of chirality.

[Figure 9]
Figure 9
Comparison of the hydrogen-bonded networks present in crystals of 7 (upper), (7)2·(2) (centre), and (5)2·(6) (lower) and looking down the threefold screw axes. Only one enanti­omer (dark green) is present in structure 7, but both enanti­omers (light and dark green) are present in compound (7)2·(2). Only achiral mol­ecules are contained in (5)2·(6). The mol­ecules of isomer 5 (light and dark blue) occupy a general position, whereas those of isomer 6 major component (yellow and orange) are equally distributed across a centre of symmetry.

Structure 7 in chiral space group P3121 contains only one enanti­omer (dark green), and the threefold hy­droxy hydrogen bonding coincides with the crystallographic 31 screw axis. Mol­ecules along b surround a 21 screw axis (blue line), but mirror (or glide) symmetry is absent.

Crystallization of the racemic HT diol and hydro­quinone yields the co-crystal (7)2·(2) in space group P21/c. Diol mol­ecules of opposite chirality (light or dark green) are separated in the crystal, with each enanti­omer forming an infinite chain around a 21 screw axis running along b (green lines). Adjacent chains are bridged by achiral hydro­quinone guests (orange), the inversion centre of which coincides with the crystallographic centre of symmetry. The enanti­omeric diol chains are related by a c-glide (magenta lines). Hydro­quinone mol­ecules link the HT diol chains by contributing their hy­droxy groups for completion of the pseudo-threefold hydrogen-bonded helices running along a.

In contrast, both the diol mol­ecules forming compound (5)2·(6) are achiral, but this present case in space group P21/n reveals a further example of threefold helicity involving different symmetry elements. All the mol­ecules of isomer 5 are identical, but here have been coloured light or dark blue to discriminate those related by mirror symmetry operation. The second diol isomer 6 is shown in yellow and orange.

The hy­droxy groups of both isomers associate to produce hydrogen-bonded pseudo-threefold helices down c. Mol­ecules of 5 surround a 21 screw axis running along b (green lines), but are not connected by hydrogen bonds. They are also arranged as chains in the c-axis direction and these chains are related by a c-glide (magenta lines). The isomer 6 performs the same roles as hydro­quinone did in the previous structure. These bridging mol­ecules are located at the crystallographic inversion centre but lack their own centre of symmetry. Hence there is disorder of isomer 6 that creates a statistical centre of symmetry.

4. Database survey

The reduction of dione 4 using sodium borohydride or samarium iodide was earlier investigated by Camps et al., (2001[Camps, P., Lukach, A. E. & Vázquez, S. (2001). Tetrahedron, 57, 2419-2425.]). Small amounts of the pure isomers 5 and 6 were isolated, and these compounds were fully characterized by IR, 1H and 13C NMR, MS, and combustion analysis. No indication of mol­ecular inclusion was evident. X-ray structure determin­ations of these pure isomers are unreported.

Kelley et al. (2011[Kelley, S. P., Fábián, L. & Brock, C. P. (2011). Acta Cryst. B67, 79-93.]) have carried out a comprehensive survey titled Failures of fractional recrystallization: ordered co-crystals of isomers and near isomers. This ground-breaking database search revealed 270 X-ray determinations of ordered co-crystals between isomers or closely related compounds. The phenomenon has therefore been demonstrated to be extremely rare. It will occur where the two partner mol­ecules share structural complementarity and near identical solubility. New examples of this phenomenon cannot usually be predicted.

However, we note that cyclo­hexane-1,4-diol 10 (Loehlin et al., 2008[Loehlin, J. H., Lee, M. & Woo, C. M. (2008). Acta Cryst. B64, 583-588.]) and cyclo­decane-1,6-diol 12 (Ermer et al., 1989[Ermer, O., Vincent, B. R. & Dunitz, J. D. (1989). Isr. J. Chem. 29, 137-142.]) both form 2:1 cis:trans diol co-crystals that are extremely similar to our compound (5)2·(6). These three examples share a simple mol­ecular structure in which two secondary alcohol groups are connected, maintaining net mirror plane symmetry, by means of a cyclic aliphatic linking group. This suggests that other members of this family exist. A probable example is cyclo­octane-1,5-diol 11 but, at present, only the X-ray structure of its cis-isomer has been reported (Miller & McPhail, 1979[Miller, R. W. & McPhail, A. T. (1979). J. Chem. Soc. Perkin Trans. 2, pp. 1527-1531.]).

5. Synthesis and crystallization

A solution of bi­cyclo­[3.3.0]octane-3,7-dione 4 (0.40 g, 2.90 mmol) in dry tetra­hydro­furan (THF, 15 mL) was added dropwise to a stirred ice-cooled solution of lithium aluminium hydride (0.28 g, 7.38 mmol) in dry THF (15 mL). The ice-bath was removed once addition was complete and the mixture stirred overnight at room temperature. Excess LiAlH4 was decomposed by cautious addition of wet diethyl ether. Saturated ammonium chloride solution was then added and the reaction product extracted five times using ethyl acetate. The combined organic extracts were dried (anhydrous Na2SO4), filtered, and the solvents evaporated to yield a 2:1 mixture of the stereoisomers 5 and 6 (0.39 g, 95%). 1H NMR (300 MHz, CDCl3) δ, combined for 5/6: 1.20–1.29 (m, 2H), 1.62–1.71 (m, 4H), 2.01–2.11 (m, 4H), 2.47–2.54 (m, 2H), 4.07–4.12 (m, 1H), 4.18–4.25 (m, 1H); 13C NMR (75.4 MHz, CDCl3) δ, for 5: 41.3 (CH), 43.4 (CH2), 76.3 (CH); for 6: 38.5 (CH), 42.4 (CH2), 42.6 (CH2), 74.6 (C), 75.1 (C). The diol isomers could not be separated by means of column chromatography (silica gel 60 230-400 mesh, neutral or basic aluminium oxide 150 mesh Brockmann activity 1). Attempted crystallization of the diol mixture from benzene, 1,4-dioxane, ethanol, or ethyl acetate did not give crystalline material. Thin needle-like crystals were produced from a cyclo­hexane solution, and thin plates were obtained from di­chloro­methane or toluene. The latter were of sufficient quality for single crystal X-ray structure determ­ination at the Australian Synchrotron facility.

6. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2[link]. The mol­ecule of 6 (suffix B) is located on a crystallographic inversion centre, which is incompatible with the mol­ecular symmetry of the mol­ecule. The mol­ecule was thus refined as 1:1 disordered across this inversion centre. Close inspection of the difference densities revealed additional disorder, by an approximate twofold rotation perpendicular to the C3—C7 bond, and a second minor disordered moiety was added to the refinement model (suffix C). Bond distances and angles of both disordered moieties were restrained to be similar to that of the ordered mol­ecule of 5 (suffix A) using a SHELXL SAME command (the esd used was 0.02 Å). Uij components of ADPs of disordered atoms were restrained to be similar for atoms closer to each other than 2.0 Å using a SHELXL SIMU command (the esd used was 0.01 Å2). The atom O1B and the symmetry equivalent (by inversion) of O2B occupy nearly identical positions, and their ADPs were constrained to be identical (SHELXL command EADP). Subject to these conditions, the occupancy rates refined to two times 0.463 (2) (moiety B and its inversion-created counterpart) and two times 0.037 (2) (moiety C and its inversion-created counterpart).

Table 2
Experimental details

Crystal data
Chemical formula 0.66C8H14O2·0.33C8H14O2
Mr 142.19
Crystal system, space group Monoclinic, P21/n
Temperature (K) 100
a, b, c (Å) 6.2758 (3), 23.6912 (10), 7.776 (4)
β (°) 91.21 (2)
V3) 1155.9 (6)
Z 6
Radiation type Synchrotron, λ = 0.71073 Å
μ (mm−1) 0.09
Crystal size (mm) 0.02 × 0.02 × 0.01
Data collection
Diffractometer Area detector at Australian Synchrotron
No. of measured, independent and observed [I > 2σ(I)] reflections 16006, 2215, 2021
Rint 0.066
(sin θ/λ)max−1) 0.617
R[F2 > 2σ(F2)], wR(F2), S 0.049, 0.127, 1.06
No. of reflections 2215
No. of parameters 272
No. of restraints 399
H-atom treatment H-atom parameters constrained
Δρmax, Δρmin (e Å−3) 0.35, −0.23
Computer programs: XDS (Kabsch, 2010[Kabsch, W. (2010). Acta Cryst. D66, 125-132.]), SHELXT2018/2 (Sheldrick, 2015a[Sheldrick, G. M. (2015a). Acta Cryst. A71, 3-8.]), SHELXL (Sheldrick, 2015b[Sheldrick, G. M. (2015b). Acta Cryst. C71, 3-8.]) and OLEX2 (Dolomanov et al., 2009[Dolomanov, O. V., Bourhis, L. J., Gildea, R. J., Howard, J. A. K. & Puschmann, H. (2009). J. Appl. Cryst. 42, 339-341.]).

The minor moiety hy­droxy atoms (of C) were in addition restrained based on hydrogen-bonding considerations. H2C was restrained to have a distance of 1.90 (2) Å from O2A (at [{1\over 2}] + x, [{1\over 2}] − y, −[{1\over 2}] + z), and H1CA to have a distance of 2.05 (2) Å from O2A (at [{1\over 2}] − x, [{1\over 2}] + y, [{3\over 2}] − z).

Most of the H atoms (except for minor disordered component C) could be located in difference maps and the remaining were fixed at stereochemically reasonable positions using appropriate AFIX commands. In the final structural model, all H atoms were treated as riding atoms in geometrically idealized positions, with C—H distances of 0.99 Å (CH2) and 0.84 Å (OH), and with Uiso(H) = kUeq(C), where k = 1.5 for OH groups, and 1.2 for all other H atoms.

Supporting information

Computing details top

Data collection: XDS (Kabsch, 2010); cell refinement: XDS (Kabsch, 2010); data reduction: XDS (Kabsch, 2010); program(s) used to solve structure: SHELXT2018/2 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL (Sheldrick, 2015b); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).

Bicyclo[3.3.0]octane-endo-3,endo-7-diol–bicyclo[3.3.0]octane-endo-3,exo-7-diol (2/1) top
Crystal data top
0.66C8H14O2·0.33C8H14O2F(000) = 468
Mr = 142.19Dx = 1.226 Mg m3
Monoclinic, P21/nSynchrotron radiation, λ = 0.71073 Å
a = 6.2758 (3) ÅCell parameters from 1189 reflections
b = 23.6912 (10) Åθ = 1–22°
c = 7.776 (4) ŵ = 0.09 mm1
β = 91.21 (2)°T = 100 K
V = 1155.9 (6) Å3Plate, colourless
Z = 60.02 × 0.02 × 0.01 mm
Data collection top
Area detector at Australian Synchrotron
Rint = 0.066
phi scanθmax = 26.0°, θmin = 3.4°
16006 measured reflectionsh = 77
2215 independent reflectionsk = 2929
2021 reflections with I > 2σ(I)l = 99
Refinement top
Refinement on F2Primary atom site location: dual
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.049Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.127H-atom parameters constrained
S = 1.06 w = 1/[σ2(Fo2) + (0.0636P)2 + 0.7974P]
where P = (Fo2 + 2Fc2)/3
2215 reflections(Δ/σ)max = 0.002
272 parametersΔρmax = 0.35 e Å3
399 restraintsΔρmin = 0.23 e Å3
Special details top

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

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
O1A0.06519 (17)0.34885 (4)1.12882 (14)0.0164 (3)
C1A0.0032 (2)0.39024 (6)1.00232 (19)0.0153 (3)
C2A0.1778 (3)0.40019 (6)0.8703 (2)0.0180 (3)
C3A0.1565 (2)0.35136 (6)0.73977 (19)0.0156 (3)
C4A0.3023 (2)0.30022 (6)0.7759 (2)0.0159 (3)
C5A0.1606 (2)0.24957 (6)0.73260 (18)0.0139 (3)
O2A0.23565 (18)0.19773 (4)0.80652 (14)0.0176 (3)
C6A0.0529 (2)0.26608 (6)0.80698 (19)0.0144 (3)
C7A0.0780 (2)0.32858 (6)0.75773 (18)0.0141 (3)
C8A0.1819 (2)0.36634 (6)0.89395 (19)0.0153 (3)
O1B0.5861 (19)0.6170 (5)0.6823 (12)0.0159 (13)0.463 (2)
H1B0.4987530.6429170.6590040.024*0.463 (2)
C1B0.4722 (14)0.5665 (4)0.7261 (9)0.0135 (13)0.463 (2)
H1BA0.4066200.5698820.8416880.016*0.463 (2)
C2B0.3060 (7)0.55080 (17)0.5881 (6)0.0158 (8)0.463 (2)
H2BA0.2230170.5843270.5506560.019*0.463 (2)
H2BB0.2067470.5217990.6309770.019*0.463 (2)
C3B0.4388 (6)0.52750 (15)0.4400 (5)0.0160 (8)0.463 (2)
H3B0.4763450.5585190.3588490.019*0.463 (2)
C4B0.3360 (11)0.4772 (3)0.3397 (8)0.0190 (15)0.463 (2)
H4BA0.2207220.4597030.4064270.023*0.463 (2)
H4BB0.2767870.4897210.2270310.023*0.463 (2)
C5B0.5197 (18)0.4358 (4)0.3161 (10)0.0224 (17)0.463 (2)
H5B0.6099580.4487210.2192220.027*0.463 (2)
O2B0.4395 (19)0.3804 (5)0.2803 (13)0.0159 (13)0.463 (2)
H2B0.5405410.3572040.2831880.024*0.463 (2)
C6B0.6454 (9)0.4400 (3)0.4836 (9)0.0144 (10)0.463 (2)
H6BA0.7924940.4259190.4694320.017*0.463 (2)
H6BB0.5764850.4176810.5745840.017*0.463 (2)
C7B0.6468 (6)0.50277 (15)0.5295 (5)0.0150 (7)0.463 (2)
H7B0.7758560.5213420.4818460.018*0.463 (2)
C8B0.6282 (9)0.5170 (2)0.7203 (7)0.0143 (11)0.463 (2)
H8BA0.7686450.5277980.7704670.017*0.463 (2)
H8BB0.5728150.4842520.7847670.017*0.463 (2)
O1C0.530 (10)0.605 (2)0.791 (7)0.013 (3)0.037 (2)
H1C0.4381060.6303660.7801660.019*0.037 (2)
C1C0.560 (7)0.5784 (17)0.631 (6)0.016 (2)0.037 (2)
H1CA0.6357420.6055840.5548580.019*0.037 (2)
C2C0.359 (8)0.559 (3)0.536 (11)0.016 (3)0.037 (2)
H2CA0.2836220.5910600.4809860.019*0.037 (2)
H2CB0.2607120.5398250.6155030.019*0.037 (2)
C3C0.438 (7)0.5170 (14)0.399 (6)0.016 (2)0.037 (2)
H3C0.4506470.5362640.2848380.020*0.037 (2)
C4C0.302 (6)0.4632 (16)0.380 (7)0.018 (3)0.037 (2)
H4CA0.2048990.4596240.4784600.022*0.037 (2)
H4CB0.2151780.4643960.2724470.022*0.037 (2)
C5C0.457 (7)0.4142 (14)0.377 (6)0.018 (3)0.037 (2)
H5C0.3942940.3844750.4525720.022*0.037 (2)
O2C0.478 (11)0.389 (3)0.215 (8)0.016 (4)0.037 (2)
H2C0.3578480.3779210.1781290.024*0.037 (2)
C6C0.657 (9)0.4329 (17)0.468 (10)0.017 (3)0.037 (2)
H6CA0.7827470.4174840.4083040.020*0.037 (2)
H6CB0.6605530.4187320.5875010.020*0.037 (2)
C7C0.666 (6)0.4971 (16)0.467 (6)0.016 (3)0.037 (2)
H7C0.7789800.5105400.3885750.019*0.037 (2)
C8C0.694 (11)0.525 (2)0.646 (7)0.014 (3)0.037 (2)
H8CA0.6414160.5001030.7375440.017*0.037 (2)
H8CB0.8454990.5342560.6700600.017*0.037 (2)
Atomic displacement parameters (Å2) top
O1A0.0158 (6)0.0160 (5)0.0173 (6)0.0030 (4)0.0062 (4)0.0011 (4)
C1A0.0169 (8)0.0098 (7)0.0189 (7)0.0002 (5)0.0027 (6)0.0011 (5)
C2A0.0200 (8)0.0097 (7)0.0242 (8)0.0038 (6)0.0005 (6)0.0022 (6)
C3A0.0170 (8)0.0143 (7)0.0156 (7)0.0034 (6)0.0009 (5)0.0026 (6)
C4A0.0124 (7)0.0159 (8)0.0193 (7)0.0024 (5)0.0007 (5)0.0022 (6)
C5A0.0144 (7)0.0132 (7)0.0140 (7)0.0007 (5)0.0003 (5)0.0006 (5)
O2A0.0198 (6)0.0121 (5)0.0211 (6)0.0023 (4)0.0014 (4)0.0002 (4)
C6A0.0127 (7)0.0126 (7)0.0179 (7)0.0032 (5)0.0005 (5)0.0019 (6)
C7A0.0145 (7)0.0146 (7)0.0130 (7)0.0007 (5)0.0039 (5)0.0005 (5)
C8A0.0138 (7)0.0132 (7)0.0186 (7)0.0024 (5)0.0038 (6)0.0005 (6)
O1B0.014 (2)0.0119 (10)0.022 (4)0.0030 (13)0.003 (2)0.0091 (19)
C1B0.012 (2)0.009 (2)0.019 (3)0.0011 (15)0.008 (2)0.004 (2)
C2B0.0156 (19)0.0079 (17)0.024 (2)0.0010 (13)0.0016 (15)0.0003 (15)
C3B0.0218 (16)0.0037 (16)0.0220 (18)0.0016 (15)0.0110 (14)0.0005 (14)
C4B0.023 (3)0.014 (2)0.020 (3)0.005 (2)0.009 (2)0.000 (2)
C5B0.029 (3)0.012 (2)0.026 (3)0.0004 (19)0.005 (3)0.006 (2)
O2B0.014 (2)0.0119 (10)0.022 (4)0.0030 (13)0.003 (2)0.0091 (19)
C6B0.0140 (19)0.009 (2)0.020 (2)0.0024 (14)0.0048 (17)0.0043 (18)
C7B0.0167 (16)0.0077 (15)0.0202 (19)0.0013 (13)0.0088 (14)0.0041 (15)
C8B0.020 (2)0.0069 (18)0.016 (2)0.0010 (14)0.0075 (19)0.0003 (18)
O1C0.011 (6)0.010 (6)0.017 (6)0.003 (6)0.000 (6)0.008 (6)
C1C0.016 (4)0.011 (4)0.020 (4)0.001 (4)0.006 (4)0.003 (4)
C2C0.017 (5)0.008 (5)0.022 (5)0.002 (5)0.004 (5)0.001 (5)
C3C0.019 (4)0.008 (4)0.022 (4)0.004 (4)0.006 (4)0.000 (4)
C4C0.021 (5)0.010 (5)0.023 (5)0.002 (5)0.009 (5)0.001 (5)
C5C0.020 (4)0.012 (4)0.023 (5)0.003 (4)0.005 (4)0.005 (4)
O2C0.018 (6)0.010 (6)0.020 (6)0.001 (6)0.001 (6)0.007 (6)
C6C0.020 (5)0.008 (5)0.022 (5)0.004 (5)0.004 (5)0.005 (5)
C7C0.018 (5)0.008 (5)0.021 (5)0.002 (4)0.008 (5)0.003 (5)
C8C0.015 (5)0.008 (5)0.020 (5)0.002 (5)0.008 (5)0.002 (5)
Geometric parameters (Å, º) top
O1A—H1A0.8400C4B—C5B1.527 (11)
O1A—C1A1.4365 (18)C5B—H5B1.0000
C1A—H1AA1.0000C5B—O2B1.431 (12)
C1A—C2A1.535 (2)C5B—C6B1.511 (9)
C1A—C8A1.530 (2)O2B—H2B0.8400
C2A—C3A1.543 (2)C6B—C7B1.529 (6)
C3A—C4A1.540 (2)C7B—C8B1.528 (6)
C3A—C7A1.577 (2)C8B—H8BA0.9900
C4A—C5A1.527 (2)O1C—C1C1.412 (18)
C5A—O2A1.4316 (18)C1C—C2C1.522 (18)
C5A—C6A1.522 (2)C1C—C8C1.521 (18)
C6A—H6AB0.9900C2C—C3C1.547 (18)
C6A—C7A1.537 (2)C3C—H3C1.0000
C7A—H7A1.0000C3C—C4C1.540 (18)
C7A—C8A1.542 (2)C3C—C7C1.585 (16)
O1B—H1B0.8400C4C—C5C1.516 (17)
O1B—C1B1.438 (12)C5C—H5C1.0000
C1B—H1BA1.0000C5C—O2C1.410 (18)
C1B—C2B1.527 (8)C5C—C6C1.496 (17)
C1B—C8B1.530 (9)O2C—H2C0.8400
C2B—C3B1.538 (6)C6C—C7C1.522 (17)
C3B—C4B1.557 (7)C7C—C8C1.542 (18)
C3B—C7B1.579 (4)C8C—H8CA0.9900
O1A—C1A—H1AA110.9O2B—C5B—C4B110.4 (9)
O1A—C1A—C2A112.09 (12)O2B—C5B—H5B109.6
O1A—C1A—C8A108.43 (11)O2B—C5B—C6B113.8 (9)
C2A—C1A—H1AA110.9C6B—C5B—C4B103.7 (5)
C8A—C1A—C2A103.49 (12)C5B—O2B—H2B109.5
C1A—C2A—C3A105.75 (12)C5B—C6B—C7B105.4 (5)
C2A—C3A—C7A105.45 (12)C6B—C7B—C3B104.9 (3)
C4A—C3A—C2A115.28 (12)C6B—C7B—H7B110.0
C4A—C3A—H3A110.1C8B—C7B—C3B105.5 (3)
C4A—C3A—C7A105.45 (11)C8B—C7B—C6B116.1 (4)
H4AA—C4A—H4AB109.0C7B—C8B—C1B105.0 (4)
C5A—C4A—C3A103.72 (12)C7B—C8B—H8BA110.7
O2A—C5A—C4A113.61 (12)O1C—C1C—H1CA108.1
O2A—C5A—H5A109.7O1C—C1C—C2C116 (3)
O2A—C5A—C6A110.66 (12)O1C—C1C—C8C113 (2)
C6A—C5A—C4A103.16 (11)C2C—C1C—H1CA108.1
C5A—O2A—H2A109.5C8C—C1C—C2C104 (2)
C5A—C6A—C7A103.84 (12)C1C—C2C—C3C104.6 (18)
C6A—C7A—C3A105.14 (11)C2C—C3C—C7C105.0 (16)
C6A—C7A—H7A110.1C4C—C3C—C2C114 (3)
C6A—C7A—C8A115.49 (12)C4C—C3C—H3C110.4
C8A—C7A—C3A105.76 (11)C4C—C3C—C7C106.3 (15)
C1A—C8A—C7A105.40 (12)C3C—C4C—H4CA110.5
C7A—C8A—H8AA110.7C5C—C4C—C3C106.2 (16)
O1B—C1B—H1BA111.3O2C—C5C—C4C114 (2)
O1B—C1B—C2B111.9 (8)O2C—C5C—H5C105.7
O1B—C1B—C8B108.1 (8)O2C—C5C—C6C117 (3)
C2B—C1B—H1BA111.3C6C—C5C—C4C107.4 (17)
C2B—C1B—C8B102.7 (5)C6C—C5C—H5C105.7
C1B—C2B—C3B103.9 (4)C5C—C6C—C7C108.9 (17)
C2B—C3B—C4B115.1 (4)C6C—C7C—C3C105.5 (15)
C2B—C3B—C7B105.0 (3)C6C—C7C—H7C110.1
C4B—C3B—H3B110.3C6C—C7C—C8C116 (3)
C4B—C3B—C7B105.5 (3)C8C—C7C—C3C105.1 (16)
C3B—C4B—H4BA110.9C1C—C8C—C7C103.6 (18)
C5B—C4B—C3B104.2 (6)C7C—C8C—H8CA111.0
O1A—C1A—C2A—C3A80.65 (15)C3B—C7B—C8B—C1B21.7 (5)
O1A—C1A—C8A—C7A82.34 (14)C4B—C3B—C7B—C6B2.7 (5)
C1A—C2A—C3A—C4A94.67 (15)C4B—C3B—C7B—C8B125.9 (4)
C1A—C2A—C3A—C7A21.20 (15)C4B—C5B—C6B—C7B40.4 (9)
C2A—C1A—C8A—C7A36.83 (14)C5B—C6B—C7B—C3B26.3 (7)
C2A—C3A—C4A—C5A140.20 (13)C5B—C6B—C7B—C8B142.3 (6)
C2A—C3A—C7A—C6A121.19 (12)O2B—C5B—C6B—C7B160.3 (8)
C2A—C3A—C7A—C8A1.47 (15)C6B—C7B—C8B—C1B137.4 (5)
C3A—C4A—C5A—O2A161.11 (12)C7B—C3B—C4B—C5B21.4 (7)
C3A—C4A—C5A—C6A41.26 (14)C8B—C1B—C2B—C3B41.7 (6)
C3A—C7A—C8A—C1A23.66 (14)O1C—C1C—C2C—C3C163 (4)
C4A—C3A—C7A—C6A1.22 (14)O1C—C1C—C8C—C7C168 (4)
C4A—C3A—C7A—C8A123.88 (12)C1C—C2C—C3C—C4C137 (5)
C4A—C5A—C6A—C7A42.17 (14)C1C—C2C—C3C—C7C21 (5)
C5A—C6A—C7A—C3A26.43 (14)C2C—C1C—C8C—C7C42 (5)
C5A—C6A—C7A—C8A142.58 (12)C2C—C3C—C4C—C5C134 (4)
O2A—C5A—C6A—C7A164.03 (11)C2C—C3C—C7C—C6C127 (5)
C6A—C7A—C8A—C1A92.14 (14)C2C—C3C—C7C—C8C4 (5)
C7A—C3A—C4A—C5A24.33 (14)C3C—C4C—C5C—O2C107 (4)
C8A—C1A—C2A—C3A35.97 (14)C3C—C4C—C5C—C6C24 (5)
O1B—C1B—C2B—C3B74.0 (7)C3C—C7C—C8C—C1C28 (5)
O1B—C1B—C8B—C7B79.0 (7)C4C—C3C—C7C—C6C6 (5)
C1B—C2B—C3B—C4B143.5 (5)C4C—C3C—C7C—C8C117 (5)
C1B—C2B—C3B—C7B28.0 (5)C4C—C5C—C6C—C7C21 (6)
C2B—C1B—C8B—C7B39.4 (6)C5C—C6C—C7C—C3C9 (6)
C2B—C3B—C4B—C5B136.7 (5)C5C—C6C—C7C—C8C125 (5)
C2B—C3B—C7B—C6B119.3 (4)O2C—C5C—C6C—C7C109 (5)
C2B—C3B—C7B—C8B3.9 (4)C6C—C7C—C8C—C1C144 (4)
C3B—C4B—C5B—O2B160.1 (7)C7C—C3C—C4C—C5C18 (4)
C3B—C4B—C5B—C6B38.0 (9)C8C—C1C—C2C—C3C40 (5)
Hydrogen-bond geometry (Å, º) top
O1A—H1A···O1Bi0.841.892.732 (12)177
O1A—H1A···O2Bii0.841.882.710 (12)170
O1A—H1A···O1Ci0.842.052.83 (6)154
O1A—H1A···O2Cii0.842.042.82 (7)155
C2A—H2AA···O1Ci0.992.373.18 (5)139
C2A—H2AA···O2Cii0.992.443.25 (6)139
O2A—H2A···O1Aiii0.841.912.7432 (16)173
O1B—H1B···O2Aiv0.841.982.784 (12)159
O2B—H2B···O2Aiii0.841.792.629 (12)173
O1C—H1C···O2Aiv0.842.042.86 (5)164
Symmetry codes: (i) x+1, y+1, z+2; (ii) x, y, z+1; (iii) x+1/2, y+1/2, z1/2; (iv) x+1/2, y+1/2, z+3/2.


We thank the Australian Synchrotron for the X-ray intensity measurements from the ultra thin crystals of the compound.


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