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A new orthorhombic polymorphic modification of the title compound (alternative name: cis-transoid-cis-2,5,8,15,18,21-hexaoxatri­cyclo­[20.4.0.09,14]­hexa­cosane), C20H36O6, has been found and is compared with the previously known monoclinic modification. In the structures of the two polymorphs, the crown-ether mol­ecules are centrosymmetric and reveal essen­tially the same molecular shape but different packing motifs.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270102018206/av1116sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270102018206/av1116Isup2.hkl
Contains datablock I

CCDC reference: 199442

Comment top

The title compound, (I), is well known as a versatile macrocyclic ligand suitable for the complexation of metals and neutral molecules. A search of the Cambridge Structural Database (CSD, April 2002 release; Allen & Kennard, 1993) produced a list of 90 entries covering a wide range of complexes with 20 different metal ions and 26 neutral molecules. Five stereoisomers are possible for this molecule (Mercer & Truter, 1973). However, the crystallographic information available in the CSD about the pure phases of this macrocyclic ligand is restricted to the unit-cell dimensions for the cis-cisoid-cis (Ref?), cis-transoid-cis (monoclinic setting, R = 0.081; Dalley et al., 1975) and trans-cisoid-trans (Simonov et al., 1985) isomers. Only recently, the atomic coordinates for the known monoclinic polymorph of the cis-transoid-cis isomer became available from a private communication (Nazarenko, 2002, CCDC refcode DCHXCR04). We describe here the solid structure of new orthorhombic polymorph of (1) in comparison with the monoclinic polymorph. \sch

The centrosymmetric formula unit of (I) is shown in Fig. 1. The molecule is elongated in the direction of the cyclohexyl rings. The shape of the centrosymmetric molecule in the structure of the monoclinic polymorph is essentially the same. The superposition of these two polymorph molecules by fitting of all identical non-H atoms gives an r.m.s. deviation of 0.1494 Å. The separations between the trans-annular O atoms in (I) are O1···O1i 7.008 (3) Å, O4···O4i 4.042 (2) Å and O7···O7i 6.928 (2) Å [symmetry code: (i) 1 - x, 1 - y, 1 - z]. There is no evidence of either inter- or intramolecular hydrogen bonding; the shortest potential hydrogen-bond interaction involves atoms C6 and O4i at a separation of 3.376 (2) Å, with the corresponding H···O4i distance being 2.78 (2) Å.

The macrocyclic strand of the molecule in (I) displays a series of anti and gauche torsion angles for C—O and C—C bonds (Fig. 1). The individual O—C—C—O segments are ag+a, aaa, g+g-g-, ag-a, aaa and g-g+g+. Relevant torsion angles are listed in Table 1. A comparison with data available for the pure phases of related 18-membered macrocycles shows similarities in the macrocyclic cavity shape (elliptic in all cases) and in the torsion-angle pattern along the macrocyclic strand, and in the sequences of four linkages in an anti configuration and three (or two) adjacent gauche linkages in the molecule of 18-crown-6 (Maverick et al., 1980) and that of the cis-cisoid-cis (Pears et al., 1988a), cis-transoid-cis (Pears et al., 1988b), trans-cisoid-trans (Pears et al., 1988c) and trans-transoid-trans (Pears et al., 1988 d) isomers of tetraanisyl-18-crown-6. The conformation of the dicyclohexano-18-crown-6 molecule is effectively different in complexes with metals and co-crystals with organic molecules, where the macrocycle cavity adopts a more open shape compared with that reported above. The only exception was found in its co-crystals with 3,5-dichloro-4-amino-benzenesulfamide (Dvorkin et al., 1991), where the conformation of one of the two crystallographically independent crown molecules coincides with that found in the pure phase. This paragraph has been extensively reworded - please check that the sense has not been altered.

The distinctive features of the crystal packing of (I) and of the monoclinic polymorph are noteworthy. In (I), the molecules are aligned along the b axis and form parallel piles in the perpendicular plane (Fig. 2a). The molecules in the piles are arranged in such a way that the polyether chains of neighbouring macrocycles approach the same cavity from both sides. The dihedral angle between the planes of their six O atoms is 62.3°.

In the monoclinic polymorph, the cyclohexano moieties of adjacent molecules approach from the same polyether cavity both sides and the herring-bone packing motif is clearly observed (Fig. 2 b). The dihedral angle between the planes of six O atoms of two neighbouring molecules mutually arranged in the T-shape mode is 61.0°.

Experimental top

Crystals of (I) were obtained serendipitously, as by-products during co-crystallization of the macrocycle with tin tetrafluoride in methanol.

Refinement top

H atoms were found in a difference Fourier synthesis and refined freely.

Computing details top

Data collection: COLLECT (Nonius, 1998); cell refinement: DENZO-SMN (Otwinowski & Minor, 1997); data reduction: maXus (Mackay et al., 1999); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPIII (Farrugia, 1997); software used to prepare material for publication: SHELXL97.

Figures top
[Figure 1] Fig. 1. The structure of (I) projected on the plane of the six O atoms, with the atomic numbering scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small spheres of arbitrary radii.
[Figure 2] Fig. 2. (a) The packing diagram for (I). (b) The packing diagram for the monoclinic polymorph.
cis-transoid-cis 2,5,8,15,18,21-hexaoxatricyclo[20.4.0.09,14]hexacosane top
Crystal data top
C20H36O6? # Insert any comments here.
Mr = 372.49Dx = 1.228 Mg m3
Orthorhombic, PccnMo Kα radiation, λ = 0.71073 Å
a = 9.7563 (3) ÅCell parameters from 2312 reflections
b = 28.5733 (10) Åθ = 1.0–27.9°
c = 7.2263 (2) ŵ = 0.09 mm1
V = 2014.47 (11) Å3T = 293 K
Z = 4Prism, colourless
F(000) = 8160.4 × 0.4 × 0.2 mm
Data collection top
Nonius CCD area-detector
diffractometer
1092 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.054
Graphite monochromatorθmax = 27.9°, θmin = 2.9°
ϕ and ω scansh = 012
4105 measured reflectionsk = 3737
2320 independent reflectionsl = 09
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)] = 0.046Hydrogen site location: difference Fourier map
wR(F2) = 0.102All H-atom parameters refined
S = 0.90 w = 1/[σ2(Fo2) + (0.0485P)2]
where P = (Fo2 + 2Fc2)/3
2320 reflections(Δ/σ)max = 0.001
190 parametersΔρmax = 0.12 e Å3
0 restraintsΔρmin = 0.14 e Å3
Crystal data top
C20H36O6V = 2014.47 (11) Å3
Mr = 372.49Z = 4
Orthorhombic, PccnMo Kα radiation
a = 9.7563 (3) ŵ = 0.09 mm1
b = 28.5733 (10) ÅT = 293 K
c = 7.2263 (2) Å0.4 × 0.4 × 0.2 mm
Data collection top
Nonius CCD area-detector
diffractometer
1092 reflections with I > 2σ(I)
4105 measured reflectionsRint = 0.054
2320 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0460 restraints
wR(F2) = 0.102All H-atom parameters refined
S = 0.90Δρmax = 0.12 e Å3
2320 reflectionsΔρmin = 0.14 e Å3
190 parameters
Special details top

Experimental. ? #Insert any special details here.

Geometry. Mean-plane data from final SHELXL refinement run:-

Least-squares planes (x,y,z in crystal coordinates) and deviations from them (* indicates atom used to define plane)

8.3484 (0.0020) x - 1.5178 (0.0067) y - 3.7198 (0.0025) z = 1.5554 (0.0040)

* -0.2691 (0.0006) O1 * 0.3730 (0.0008) O4 * -0.2250 (0.0005) O7 * 0.2691 (0.0006) O1_$1 * -0.3730 (0.0008) O4_$1 * 0.2250 (0.0005) O7_$1

Rms deviation of fitted atoms = 0.2956

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
O10.39681 (10)0.38825 (4)0.38634 (13)0.0495 (3)
C20.44086 (19)0.39999 (6)0.2044 (2)0.0514 (5)
H2A0.4198 (14)0.3741 (6)0.118 (2)0.061 (5)*
H2B0.5446 (17)0.4048 (5)0.2007 (19)0.057 (5)*
C30.37030 (19)0.44401 (6)0.1469 (2)0.0518 (5)
H3A0.3845 (14)0.4497 (5)0.009 (2)0.062 (5)*
H3B0.2699 (17)0.4423 (5)0.1764 (18)0.060 (5)*
O40.42889 (11)0.48151 (4)0.24767 (14)0.0588 (4)
C50.36632 (19)0.52529 (6)0.2192 (3)0.0492 (4)
H5A0.2655 (19)0.5216 (5)0.2457 (19)0.065 (5)*
H5B0.3794 (14)0.5356 (5)0.088 (2)0.060 (5)*
C60.4323 (2)0.55821 (6)0.3543 (2)0.0530 (5)
H6A0.3972 (15)0.5526 (6)0.481 (3)0.076 (6)*
H6B0.5333 (19)0.5516 (7)0.350 (2)0.081 (6)*
O70.40330 (11)0.60515 (4)0.30056 (14)0.0533 (4)
C80.60506 (16)0.36158 (6)0.5521 (2)0.0474 (4)
H80.6654 (13)0.3746 (5)0.457 (2)0.045 (4)*
C90.46582 (15)0.34924 (6)0.4672 (2)0.0464 (4)
H90.4840 (12)0.3254 (5)0.3659 (18)0.035 (4)*
C100.37042 (18)0.32814 (7)0.6098 (3)0.0546 (5)
H10A0.2828 (18)0.3201 (5)0.548 (2)0.068 (5)*
H10B0.3533 (15)0.3522 (6)0.701 (2)0.060 (5)*
C110.43332 (19)0.28501 (7)0.6992 (3)0.0602 (5)
H11A0.3721 (16)0.2712 (6)0.794 (2)0.068 (5)*
H11B0.4422 (16)0.2605 (6)0.604 (2)0.068 (5)*
C120.5735 (2)0.29566 (7)0.7799 (3)0.0592 (5)
H12A0.6172 (16)0.2659 (7)0.829 (2)0.070 (5)*
H12B0.5648 (16)0.3175 (6)0.888 (2)0.065 (5)*
C130.66721 (18)0.31779 (7)0.6357 (3)0.0549 (5)
H13A0.7620 (19)0.3260 (5)0.686 (2)0.066 (5)*
H13B0.6803 (14)0.2947 (5)0.5333 (19)0.056 (5)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0525 (6)0.0503 (7)0.0455 (7)0.0048 (6)0.0005 (5)0.0008 (5)
C20.0623 (13)0.0466 (12)0.0453 (10)0.0009 (10)0.0002 (9)0.0061 (9)
C30.0607 (11)0.0484 (12)0.0462 (11)0.0067 (10)0.0104 (8)0.0062 (9)
O40.0685 (8)0.0420 (8)0.0659 (8)0.0003 (6)0.0263 (6)0.0072 (6)
C50.0539 (11)0.0407 (11)0.0529 (11)0.0017 (9)0.0076 (8)0.0013 (8)
C60.0617 (12)0.0443 (11)0.0528 (11)0.0008 (10)0.0067 (9)0.0013 (9)
O70.0703 (8)0.0406 (7)0.0489 (7)0.0014 (6)0.0045 (5)0.0030 (5)
C80.0470 (10)0.0483 (11)0.0468 (9)0.0020 (9)0.0035 (8)0.0061 (9)
C90.0502 (10)0.0405 (10)0.0485 (10)0.0019 (8)0.0008 (8)0.0030 (8)
C100.0479 (10)0.0560 (13)0.0598 (12)0.0039 (9)0.0008 (9)0.0028 (10)
C110.0619 (12)0.0545 (13)0.0642 (12)0.0065 (10)0.0039 (10)0.0068 (11)
C120.0635 (12)0.0503 (12)0.0637 (12)0.0065 (10)0.0041 (10)0.0064 (10)
C130.0491 (11)0.0512 (12)0.0646 (12)0.0044 (9)0.0031 (10)0.0039 (9)
Geometric parameters (Å, º) top
O1—C21.4233 (18)C8—C131.516 (2)
O1—C91.4273 (17)C8—C91.532 (2)
C2—C31.493 (2)C8—H80.979 (14)
C2—H2A0.990 (17)C9—C101.514 (2)
C2—H2B1.022 (16)C9—H91.016 (13)
C3—O41.4162 (19)C10—C111.520 (3)
C3—H3A1.018 (15)C10—H10A0.991 (17)
C3—H3B1.004 (16)C10—H10B0.967 (16)
O4—C51.407 (2)C11—C121.518 (3)
C5—C61.501 (2)C11—H11A0.992 (16)
C5—H5A1.008 (18)C11—H11B0.985 (18)
C5—H5B0.999 (15)C12—C131.524 (3)
C6—O71.425 (2)C12—H12A1.014 (18)
C6—H6A0.992 (17)C12—H12B1.001 (16)
C6—H6B1.003 (18)C13—H13A1.021 (18)
O7—C8i1.4297 (18)C13—H13B1.000 (15)
C8—O7i1.4297 (18)
C2—O1—C9114.82 (12)C9—C8—H8109.8 (8)
O1—C2—C3108.46 (14)O1—C9—C10107.45 (13)
O1—C2—H2A110.2 (9)O1—C9—C8113.74 (13)
C3—C2—H2A110.9 (9)C10—C9—C8111.36 (14)
O1—C2—H2B110.8 (8)O1—C9—H9108.2 (7)
C3—C2—H2B109.7 (9)C10—C9—H9109.3 (8)
H2A—C2—H2B106.8 (12)C8—C9—H9106.8 (7)
O4—C3—C2107.94 (14)C9—C10—C11111.33 (15)
O4—C3—H3A109.1 (8)C9—C10—H10A108.4 (9)
C2—C3—H3A110.1 (8)C11—C10—H10A110.6 (9)
O4—C3—H3B108.8 (9)C9—C10—H10B106.6 (10)
C2—C3—H3B110.4 (9)C11—C10—H10B111.0 (10)
H3A—C3—H3B110.4 (11)H10A—C10—H10B108.7 (12)
C5—O4—C3114.98 (12)C12—C11—C10111.38 (16)
O4—C5—C6106.04 (13)C12—C11—H11A110.8 (9)
O4—C5—H5A107.7 (9)C10—C11—H11A111.9 (10)
C6—C5—H5A111.1 (9)C12—C11—H11B109.3 (9)
O4—C5—H5B110.1 (9)C10—C11—H11B108.5 (9)
C6—C5—H5B112.2 (9)H11A—C11—H11B104.7 (14)
H5A—C5—H5B109.6 (11)C11—C12—C13111.15 (15)
O7—C6—C5109.14 (14)C11—C12—H12A110.1 (9)
O7—C6—H6A109.6 (10)C13—C12—H12A109.5 (9)
C5—C6—H6A110.6 (10)C11—C12—H12B110.3 (9)
O7—C6—H6B111.3 (11)C13—C12—H12B108.9 (10)
C5—C6—H6B106.5 (10)H12A—C12—H12B106.8 (13)
H6A—C6—H6B109.7 (14)C8—C13—C12112.04 (15)
C6—O7—C8i115.74 (12)C8—C13—H13A108.3 (9)
O7i—C8—C13105.95 (13)C12—C13—H13A113.3 (8)
O7i—C8—C9113.62 (12)C8—C13—H13B107.5 (8)
C13—C8—C9108.93 (14)C12—C13—H13B108.0 (8)
O7i—C8—H8107.8 (8)H13A—C13—H13B107.4 (12)
C13—C8—H8110.7 (8)
C8—C9—O1—C281.62 (17)O4—C5—C6—O7163.91 (14)
C9—O1—C2—C3174.24 (13)C5—C6—O7—C8i149.65 (14)
O1—C2—C3—O472.42 (18)C6—O7—C8i—C9i72.90 (18)
C2—C3—O4—C5175.48 (14)O7—C8i—C9i—O1i61.32 (17)
C3—O4—C5—C6173.39 (14)
Symmetry code: (i) x+1, y+1, z+1.

Experimental details

Crystal data
Chemical formulaC20H36O6
Mr372.49
Crystal system, space groupOrthorhombic, Pccn
Temperature (K)293
a, b, c (Å)9.7563 (3), 28.5733 (10), 7.2263 (2)
V3)2014.47 (11)
Z4
Radiation typeMo Kα
µ (mm1)0.09
Crystal size (mm)0.4 × 0.4 × 0.2
Data collection
DiffractometerNonius CCD area-detector
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
4105, 2320, 1092
Rint0.054
(sin θ/λ)max1)0.658
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.046, 0.102, 0.90
No. of reflections2320
No. of parameters190
H-atom treatmentAll H-atom parameters refined
Δρmax, Δρmin (e Å3)0.12, 0.14

Computer programs: COLLECT (Nonius, 1998), DENZO-SMN (Otwinowski & Minor, 1997), maXus (Mackay et al., 1999), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), ORTEPIII (Farrugia, 1997), SHELXL97.

Selected torsion angles (º) top
C8—C9—O1—C281.62 (17)O4—C5—C6—O7163.91 (14)
C9—O1—C2—C3174.24 (13)C5—C6—O7—C8i149.65 (14)
O1—C2—C3—O472.42 (18)C6—O7—C8i—C9i72.90 (18)
C2—C3—O4—C5175.48 (14)O7—C8i—C9i—O1i61.32 (17)
C3—O4—C5—C6173.39 (14)
Symmetry code: (i) x+1, y+1, z+1.
 

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