Acta Cryst. (2009). E65, o13 [ doi:10.1107/S1600536808039469 ]
The title compound, C20H16Cl2O2Se2, utilizes the symmetry of the crystallographic inversion center. Molecular chains are formed through symmetric C-H
Cl interactions around inversion centers, mimicking the commonly observed symmetric hydrogen-bonded dimer pattern often found in carboxylic acids.
Crystals suitable for an X-ray diffraction experiment were obtained by slow crystallization from hot toluene.
Hydrogen atoms of (1) were found in the difference Fourier map. All hydrogen atoms were treated as riding atoms with C—H distances of 0.95 for Car and 0.98 for the CMe. Isotropic displacement parameters for all H atoms were constrained to 1.2Ueq of the connected non-hydrogen atom (1.5Ueq for Me groups).
Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994); cell refinement: CAD-4 EXPRESS (Enraf–Nonius, 1994); data reduction: DREAR (Blessing, 1987); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).
![[Figure 1]](./sg2281fig1thm.gif)
| Fig. 1. Thermal elipsoid plot of (1) including labelling of the atoms. The displacement ellipsoids are drawn at the 50% probability level. H atoms are shown as spheres with an arbitrary radii. |
![[Figure 2]](./sg2281fig2thm.gif)
| Fig. 2. A view of the cyclic C—H···Cl interactions linking the molecules into a chain. |
![[Figure 3]](./sg2281fig3thm.gif)
| Fig. 3. Packing diagram of viewed down the b axis. |
| C20H16Cl2O2Se2 | F(000) = 508 |
| Mr = 517.15 | Dx = 1.788 Mg m−3 |
| Monoclinic, P21/n | Melting point: 193 K |
| Hall symbol: -P 2yn | Cu Kα radiation, λ = 1.54184 Å |
| a = 11.7737 (17) Å | Cell parameters from 20 reflections |
| b = 6.6535 (6) Å | θ = 39.3–40.7° |
| c = 13.438 (5) Å | µ = 7.47 mm−1 |
| β = 114.136 (16)° | T = 122 K |
| V = 960.7 (4) Å3 | Block, white |
| Z = 2 | 0.44 × 0.15 × 0.13 mm |
| Enraf–Nonius CAD-4 diffractometer | 1919 reflections with I > 2σ(I) |
| Radiation source: fine-focus sealed tube | Rint = 0.030 |
| graphite | θmax = 74.9°, θmin = 4.2° |
| ω–2θ scans | h = −14→14 |
| Absorption correction: gaussian (DeTitta, 1985). | k = −7→8 |
| Tmin = 0.242, Tmax = 0.796 | l = 0→16 |
| 2641 measured reflections | 5 standard reflections every 166.7 min |
| 1976 independent reflections | intensity decay: 5.7% |
| Refinement on F2 | Secondary atom site location: difference Fourier map |
| Least-squares matrix: full | Hydrogen site location: difference Fourier map |
| R[F2 > 2σ(F2)] = 0.028 | H-atom parameters constrained |
| wR(F2) = 0.076 | w = 1/[σ2(Fo2) + (0.0433P)2 + 0.9774P] where P = (Fo2 + 2Fc2)/3 |
| S = 1.10 | (Δ/σ)max < 0.001 |
| 1976 reflections | Δρmax = 0.60 e Å−3 |
| 119 parameters | Δρmin = −1.20 e Å−3 |
| 0 restraints | Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
| Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.0029 (3) |
| C20H16Cl2O2Se2 | V = 960.7 (4) Å3 |
| Mr = 517.15 | Z = 2 |
| Monoclinic, P21/n | Cu Kα radiation |
| a = 11.7737 (17) Å | µ = 7.47 mm−1 |
| b = 6.6535 (6) Å | T = 122 K |
| c = 13.438 (5) Å | 0.44 × 0.15 × 0.13 mm |
| β = 114.136 (16)° |
| Enraf–Nonius CAD-4 diffractometer | 1919 reflections with I > 2σ(I) |
| Absorption correction: gaussian (DeTitta, 1985). | Rint = 0.030 |
| Tmin = 0.242, Tmax = 0.796 | θmax = 74.9° |
| 2641 measured reflections | 5 standard reflections every 166.7 min |
| 1976 independent reflections | intensity decay: 5.7% |
| R[F2 > 2σ(F2)] = 0.028 | H-atom parameters constrained |
| wR(F2) = 0.076 | Δρmax = 0.60 e Å−3 |
| S = 1.10 | Δρmin = −1.20 e Å−3 |
| 1976 reflections | Absolute structure: ? |
| 119 parameters | Flack parameter: ? |
| 0 restraints | Rogers parameter: ? |
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. |
| x | y | z | Uiso*/Ueq | ||
| Se1 | 0.745362 (19) | 0.19839 (3) | 0.007848 (17) | 0.01812 (12) | |
| Cl | 1.00097 (5) | 0.82041 (8) | 0.40315 (5) | 0.02427 (15) | |
| O1 | 1.23891 (13) | 0.1213 (2) | 0.13084 (12) | 0.0192 (3) | |
| C1 | 1.2567 (2) | 0.2869 (3) | 0.20396 (19) | 0.0232 (5) | |
| H1A | 1.3459 | 0.3140 | 0.2431 | 0.035* | |
| H1B | 1.2213 | 0.2535 | 0.2564 | 0.035* | |
| H1C | 1.2150 | 0.4063 | 0.1623 | 0.035* | |
| C2 | 1.11846 (19) | 0.0668 (3) | 0.06767 (16) | 0.0160 (4) | |
| C3 | 1.0144 (2) | 0.1577 (3) | 0.07253 (17) | 0.0168 (4) | |
| H3 | 1.0245 | 0.2653 | 0.1219 | 0.020* | |
| C4 | 0.89557 (19) | 0.0910 (3) | 0.00514 (16) | 0.0159 (4) | |
| C5 | 0.82080 (19) | 0.3830 (3) | 0.12694 (17) | 0.0172 (4) | |
| C6 | 0.8614 (2) | 0.3181 (3) | 0.23448 (19) | 0.0194 (4) | |
| H6 | 0.8506 | 0.1815 | 0.2493 | 0.023* | |
| C7 | 0.9173 (2) | 0.4513 (3) | 0.32023 (17) | 0.0197 (4) | |
| H7 | 0.9457 | 0.4067 | 0.3936 | 0.024* | |
| C8 | 0.93109 (19) | 0.6504 (3) | 0.29699 (17) | 0.0174 (4) | |
| C9 | 0.8891 (2) | 0.7196 (3) | 0.19057 (19) | 0.0211 (5) | |
| H9 | 0.8985 | 0.8570 | 0.1762 | 0.025* | |
| C10 | 0.8331 (2) | 0.5850 (3) | 0.10537 (17) | 0.0201 (4) | |
| H10 | 0.8030 | 0.6308 | 0.0321 | 0.024* |
| U11 | U22 | U33 | U12 | U13 | U23 | |
| Se1 | 0.01674 (16) | 0.01956 (17) | 0.01817 (16) | 0.00021 (7) | 0.00723 (11) | −0.00363 (7) |
| Cl | 0.0267 (3) | 0.0243 (3) | 0.0206 (3) | −0.0041 (2) | 0.0084 (2) | −0.00601 (18) |
| O1 | 0.0174 (7) | 0.0196 (7) | 0.0194 (7) | −0.0023 (6) | 0.0063 (6) | −0.0059 (6) |
| C1 | 0.0242 (11) | 0.0227 (11) | 0.0217 (11) | −0.0045 (9) | 0.0084 (9) | −0.0084 (8) |
| C2 | 0.0178 (9) | 0.0154 (9) | 0.0145 (9) | −0.0025 (8) | 0.0064 (7) | 0.0012 (7) |
| C3 | 0.0215 (10) | 0.0136 (9) | 0.0164 (9) | −0.0016 (8) | 0.0089 (8) | −0.0014 (7) |
| C4 | 0.0192 (9) | 0.0143 (9) | 0.0156 (9) | 0.0004 (7) | 0.0084 (8) | 0.0013 (7) |
| C5 | 0.0169 (9) | 0.0178 (10) | 0.0196 (10) | 0.0013 (8) | 0.0103 (8) | −0.0016 (8) |
| C6 | 0.0211 (10) | 0.0160 (10) | 0.0216 (11) | 0.0022 (8) | 0.0091 (9) | 0.0024 (8) |
| C7 | 0.0208 (10) | 0.0215 (11) | 0.0170 (9) | 0.0033 (8) | 0.0080 (8) | 0.0037 (8) |
| C8 | 0.0169 (9) | 0.0173 (10) | 0.0189 (10) | 0.0001 (8) | 0.0080 (8) | −0.0038 (8) |
| C9 | 0.0255 (11) | 0.0163 (10) | 0.0213 (11) | −0.0001 (8) | 0.0093 (9) | 0.0018 (8) |
| C10 | 0.0245 (11) | 0.0196 (10) | 0.0170 (10) | 0.0017 (8) | 0.0093 (8) | 0.0031 (8) |
| Se1—C4 | 1.921 (2) | C4—C2i | 1.398 (3) |
| Se1—C5 | 1.923 (2) | C5—C6 | 1.393 (3) |
| Cl—C8 | 1.741 (2) | C5—C10 | 1.395 (3) |
| O1—C2 | 1.371 (2) | C6—C7 | 1.388 (3) |
| O1—C1 | 1.433 (2) | C6—H6 | 0.9500 |
| C1—H1A | 0.9800 | C7—C8 | 1.386 (3) |
| C1—H1B | 0.9800 | C7—H7 | 0.9500 |
| C1—H1C | 0.9800 | C8—C9 | 1.387 (3) |
| C2—C3 | 1.391 (3) | C9—C10 | 1.389 (3) |
| C2—C4i | 1.398 (3) | C9—H9 | 0.9500 |
| C3—C4 | 1.392 (3) | C10—H10 | 0.9500 |
| C3—H3 | 0.9500 | ||
| C4—Se1—C5 | 97.92 (9) | C6—C5—Se1 | 120.74 (16) |
| C2—O1—C1 | 116.88 (17) | C10—C5—Se1 | 119.64 (16) |
| O1—C1—H1A | 109.5 | C7—C6—C5 | 120.6 (2) |
| O1—C1—H1B | 109.5 | C7—C6—H6 | 119.7 |
| H1A—C1—H1B | 109.5 | C5—C6—H6 | 119.7 |
| O1—C1—H1C | 109.5 | C8—C7—C6 | 118.9 (2) |
| H1A—C1—H1C | 109.5 | C8—C7—H7 | 120.6 |
| H1B—C1—H1C | 109.5 | C6—C7—H7 | 120.6 |
| O1—C2—C3 | 124.29 (19) | C7—C8—C9 | 121.7 (2) |
| O1—C2—C4i | 115.37 (18) | C7—C8—Cl | 119.75 (17) |
| C3—C2—C4i | 120.34 (19) | C9—C8—Cl | 118.60 (17) |
| C2—C3—C4 | 120.07 (19) | C8—C9—C10 | 119.0 (2) |
| C2—C3—H3 | 120.0 | C8—C9—H9 | 120.5 |
| C4—C3—H3 | 120.0 | C10—C9—H9 | 120.5 |
| C3—C4—C2i | 119.60 (19) | C9—C10—C5 | 120.3 (2) |
| C3—C4—Se1 | 123.88 (16) | C9—C10—H10 | 119.9 |
| C2i—C4—Se1 | 116.50 (15) | C5—C10—H10 | 119.9 |
| C6—C5—C10 | 119.6 (2) | ||
| C1—O1—C2—C3 | −1.8 (3) | C10—C5—C6—C7 | −2.0 (3) |
| C1—O1—C2—C4i | 178.06 (18) | Se1—C5—C6—C7 | 179.10 (16) |
| O1—C2—C3—C4 | −179.78 (19) | C5—C6—C7—C8 | 0.6 (3) |
| C4i—C2—C3—C4 | 0.4 (3) | C6—C7—C8—C9 | 0.8 (3) |
| C2—C3—C4—C2i | −0.4 (3) | C6—C7—C8—Cl | 179.98 (16) |
| C2—C3—C4—Se1 | 177.83 (15) | C7—C8—C9—C10 | −0.7 (3) |
| C5—Se1—C4—C3 | −3.27 (19) | Cl—C8—C9—C10 | −179.91 (17) |
| C5—Se1—C4—C2i | 174.97 (16) | C8—C9—C10—C5 | −0.8 (3) |
| C4—Se1—C5—C6 | −83.67 (18) | C6—C5—C10—C9 | 2.1 (3) |
| C4—Se1—C5—C10 | 97.46 (18) | Se1—C5—C10—C9 | −179.02 (17) |
| Symmetry codes: (i) −x+2, −y, −z. |
The authors thank Flemming Hansen, Centre of Crystallographic Studies, University of Copenhagen, for obtaining the crystallographic data. The Danish National Research Foundation is acknowledged for supporting the Center for Fundamental Research: Metal Structures in Four Dimensions.
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The structure of the title compound, shown in Fig. 1, crystallized in space group P 21/n utilizing the crystallography inversion center in the molecular symmetry. Generally the molecular geometry of 1 is in close agreement with the related compound 1,3-dimethoxy-4,6-bis(phenylseleno)benzene, hereafter DMPSB. All bond distances and angles are the same within the experimental uncertainty. The molecular conformation of 1 is also very similar to the chloro-unsubstituted compound DMPSB having the planes of phenylseleno groups arranged perpendicular to the plane of the central benzene moiety, but rotated in opposite directions forming a Z like conformation (Fig. 1). Leading to the formation of intramolecular Car—H···π interactions.
The molecular packing arrangement is dominated by molecular chains (see Fig. 2) formed by cyclic Car—H···Cl interactions [H7···Cli = 2.96 Å, C7—H7···Cli = 166.0°; symmetry code: (i) 2 - x,1 - y,1 - z] around an inversion center leading to a pattern, which highly resembles the cyclic hydrogen-bonded dimers frequently observed in carboxylic acids. The Car—H···Cl type of cyclic interaction found in 1 has also been observed in other compounds having a p-chlorosubstituted phenyl group, e.g. in the structure of racemic p-chlorophenoxypropionic acid, where the distance H···Cl is 2.92 Å [C—H···Cl 175°]. The chains are stacked such that the π-π interactions between the phenelseleno groups and between the benzene rings along the diagonal of the b and c-axes, respectively. Due to the chain formation in 1 the packing arrangement is rather different from the pattern found in DMPSB, where interactions with chlorine cannot be formed.