Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270113001790/gz3224sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270113001790/gz3224I_monosup2.hkl | |
Chemdraw file https://doi.org/10.1107/S0108270113001790/gz3224I_monosup3.cdx | |
Chemical Markup Language (CML) file https://doi.org/10.1107/S0108270113001790/gz3224I_monosup4.cml | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270113001790/gz3224I_orthosup5.hkl | |
Chemdraw file https://doi.org/10.1107/S0108270113001790/gz3224I_orthosup6.cdx | |
Chemical Markup Language (CML) file https://doi.org/10.1107/S0108270113001790/gz3224I_orthosup7.cml |
CCDC references: 925781; 925782
For related literature, see: Benites et al. (1996); Collman et al. (1992); Desvergne et al. (1978); Dunitz & Bernstein (1995); Flack (1983); Müller (2009); Macrae et al. (2008); Sheldrick (2008); Tauchert et al. (2010).
For the orthorhombic crystals, compound (I) was prepared according to the procedure of Collman et al. (1992) and crystallized from propan-2-ol by slow evaporation. The crystals used for this study were, without recrystallization, taken from the original 16 year-old bulk sample from which a crystal had been used to derive the orthorhombic structure of (I) by Benites et al. (1996). For the monoclinic crystals, (I) was prepared according to the procedure of Tauchert et al. (2010), chromatographically purified and crystallized by slow evaporation from propan-2-ol in the presence of Pd(PPh3)4 and possible reaction products.
Both structures were refined against F2 on all data by full-matrix least squares using SHELXL97 (Sheldrick, 2008), following established refinement strategies (Müller, 2009). All H atoms were included in the model at geometrically calculated positions, with C—H = 0.95 Å, and refined using a riding model, with Uiso(H) = 1.2Ueq(C).
Four outlier reflections with Fo - Fc/σ > 10 were omitted from refinement of the monoclinic structure, and two low-resolution reflections with Fo << Fc (indicative of obstruction by the beam stop) were omitted from refinement of the orthorhombic structure. The Flack x parameter (Flack, 1983) of the orthorhombic structure was determined to be close to 0.5 and this structure was refined as a racemic twin. The twin ratio was refined freely and converged at 0.42 (3).
Data collection: APEX2 (Bruker, 2011) for I_mono; COLLECT (Nonius, 2000) for I_ortho. Cell refinement: SAINT (Bruker, 2011) for I_mono; SCALEPACK (Otwinowski & Minor 1997) for I_ortho. Data reduction: SAINT (Bruker, 2011) for I_mono; DENZO and SCALEPACK (Otwinowski & Minor 1997) for I_ortho. For both compounds, program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).
C14H8Cl2 | F(000) = 504 |
Mr = 247.10 | Dx = 1.548 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 9433 reflections |
a = 19.0070 (14) Å | θ = 2.7–32.0° |
b = 3.8621 (3) Å | µ = 0.57 mm−1 |
c = 15.1370 (11) Å | T = 100 K |
β = 107.4103 (15)° | Needle, colourless |
V = 1060.25 (14) Å3 | 0.20 × 0.05 × 0.04 mm |
Z = 4 |
Bruker SMART APEX2 CCD area-detector diffractometer | 3700 independent reflections |
Radiation source: IµS micro-focus sealed tube | 3433 reflections with I > 2σ(I) |
Incoatec IµS multilayer optics monochromator | Rint = 0.027 |
Detector resolution: 8.3 pixels mm-1 | θmax = 32.0°, θmin = 2.3° |
ϕ and ω scans | h = −28→28 |
Absorption correction: multi-scan (SADABS; Sheldrick, 2009) | k = −5→5 |
Tmin = 0.894, Tmax = 0.977 | l = −22→22 |
56651 measured reflections |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.028 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.083 | H-atom parameters constrained |
S = 1.15 | w = 1/[σ2(Fo2) + (0.0366P)2 + 0.5831P] where P = (Fo2 + 2Fc2)/3 |
3700 reflections | (Δ/σ)max = 0.001 |
145 parameters | Δρmax = 0.53 e Å−3 |
0 restraints | Δρmin = −0.20 e Å−3 |
C14H8Cl2 | V = 1060.25 (14) Å3 |
Mr = 247.10 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 19.0070 (14) Å | µ = 0.57 mm−1 |
b = 3.8621 (3) Å | T = 100 K |
c = 15.1370 (11) Å | 0.20 × 0.05 × 0.04 mm |
β = 107.4103 (15)° |
Bruker SMART APEX2 CCD area-detector diffractometer | 3700 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 2009) | 3433 reflections with I > 2σ(I) |
Tmin = 0.894, Tmax = 0.977 | Rint = 0.027 |
56651 measured reflections |
R[F2 > 2σ(F2)] = 0.028 | 0 restraints |
wR(F2) = 0.083 | H-atom parameters constrained |
S = 1.15 | Δρmax = 0.53 e Å−3 |
3700 reflections | Δρmin = −0.20 e Å−3 |
145 parameters |
Experimental. Bruker X8 Kappa DUO four-circle diffractometer, Bruker APEX2 CCD. The instrument was purchased with the help of funding from the National Science Foundation (NSF) under Grant Number CHE-0946721. |
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 | ||
Cl2 | 0.382516 (13) | 0.29325 (7) | 0.371481 (17) | 0.01727 (7) | |
Cl1 | 0.130329 (14) | 0.83680 (7) | 0.229521 (17) | 0.01825 (7) | |
C1 | 0.12833 (5) | 0.9344 (3) | 0.34099 (7) | 0.01406 (17) | |
C2 | 0.06746 (6) | 1.0937 (3) | 0.35174 (7) | 0.01650 (18) | |
H2 | 0.0270 | 1.1473 | 0.2991 | 0.020* | |
C3 | 0.06480 (6) | 1.1791 (3) | 0.44184 (8) | 0.01791 (19) | |
H3 | 0.0220 | 1.2864 | 0.4494 | 0.021* | |
C4 | 0.12310 (6) | 1.1087 (3) | 0.51775 (7) | 0.01679 (18) | |
H4 | 0.1209 | 1.1719 | 0.5775 | 0.020* | |
C5 | 0.37151 (6) | 0.6169 (3) | 0.65498 (7) | 0.01720 (19) | |
H5 | 0.3702 | 0.6826 | 0.7150 | 0.021* | |
C6 | 0.43164 (6) | 0.4487 (3) | 0.64500 (7) | 0.01874 (19) | |
H6 | 0.4719 | 0.3980 | 0.6982 | 0.022* | |
C7 | 0.43488 (6) | 0.3484 (3) | 0.55613 (8) | 0.01731 (19) | |
H7 | 0.4771 | 0.2309 | 0.5500 | 0.021* | |
C8 | 0.37733 (5) | 0.4207 (3) | 0.47958 (7) | 0.01412 (17) | |
C9 | 0.25283 (5) | 0.6755 (3) | 0.40811 (7) | 0.01312 (17) | |
H9 | 0.2546 | 0.6121 | 0.3482 | 0.016* | |
C10 | 0.24777 (6) | 0.8657 (3) | 0.58497 (7) | 0.01515 (18) | |
H10 | 0.2463 | 0.9321 | 0.6448 | 0.018* | |
C11 | 0.19057 (5) | 0.8459 (3) | 0.41776 (7) | 0.01298 (17) | |
C12 | 0.18742 (5) | 0.9407 (3) | 0.50812 (7) | 0.01414 (17) | |
C13 | 0.31246 (5) | 0.5974 (3) | 0.48543 (7) | 0.01290 (16) | |
C14 | 0.31032 (6) | 0.6954 (3) | 0.57603 (7) | 0.01411 (17) |
U11 | U22 | U33 | U12 | U13 | U23 | |
Cl2 | 0.01612 (11) | 0.01846 (12) | 0.01843 (12) | 0.00085 (8) | 0.00698 (8) | −0.00174 (8) |
Cl1 | 0.01790 (12) | 0.02263 (13) | 0.01357 (11) | 0.00230 (9) | 0.00371 (8) | −0.00045 (8) |
C1 | 0.0140 (4) | 0.0139 (4) | 0.0146 (4) | −0.0012 (3) | 0.0049 (3) | −0.0002 (3) |
C2 | 0.0145 (4) | 0.0151 (4) | 0.0201 (4) | 0.0000 (3) | 0.0054 (3) | −0.0005 (4) |
C3 | 0.0161 (4) | 0.0167 (5) | 0.0232 (5) | 0.0009 (3) | 0.0093 (4) | −0.0015 (4) |
C4 | 0.0184 (4) | 0.0159 (4) | 0.0190 (4) | −0.0007 (4) | 0.0101 (4) | −0.0019 (4) |
C5 | 0.0195 (4) | 0.0165 (5) | 0.0136 (4) | −0.0032 (4) | 0.0018 (3) | 0.0009 (4) |
C6 | 0.0192 (4) | 0.0163 (5) | 0.0172 (4) | −0.0020 (4) | 0.0001 (3) | 0.0016 (4) |
C7 | 0.0147 (4) | 0.0154 (4) | 0.0201 (4) | −0.0006 (3) | 0.0026 (3) | 0.0011 (4) |
C8 | 0.0136 (4) | 0.0132 (4) | 0.0156 (4) | −0.0012 (3) | 0.0044 (3) | −0.0002 (3) |
C9 | 0.0126 (4) | 0.0138 (4) | 0.0132 (4) | −0.0016 (3) | 0.0042 (3) | −0.0003 (3) |
C10 | 0.0174 (4) | 0.0155 (4) | 0.0134 (4) | −0.0031 (3) | 0.0059 (3) | −0.0009 (3) |
C11 | 0.0134 (4) | 0.0126 (4) | 0.0136 (4) | −0.0020 (3) | 0.0051 (3) | −0.0002 (3) |
C12 | 0.0162 (4) | 0.0130 (4) | 0.0148 (4) | −0.0025 (3) | 0.0071 (3) | −0.0013 (3) |
C13 | 0.0130 (4) | 0.0124 (4) | 0.0135 (4) | −0.0023 (3) | 0.0043 (3) | −0.0001 (3) |
C14 | 0.0161 (4) | 0.0132 (4) | 0.0128 (4) | −0.0035 (3) | 0.0040 (3) | 0.0000 (3) |
Cl2—C8 | 1.7395 (10) | C6—C7 | 1.4190 (16) |
Cl1—C1 | 1.7404 (10) | C6—H6 | 0.9500 |
C1—C2 | 1.3624 (14) | C7—C8 | 1.3633 (14) |
C1—C11 | 1.4297 (14) | C7—H7 | 0.9500 |
C2—C3 | 1.4187 (15) | C8—C13 | 1.4350 (14) |
C2—H2 | 0.9500 | C9—C13 | 1.3970 (13) |
C3—C4 | 1.3638 (16) | C9—C11 | 1.3995 (14) |
C3—H3 | 0.9500 | C9—H9 | 0.9500 |
C4—C12 | 1.4295 (14) | C10—C12 | 1.3980 (14) |
C4—H4 | 0.9500 | C10—C14 | 1.4003 (15) |
C5—C6 | 1.3616 (16) | C10—H10 | 0.9500 |
C5—C14 | 1.4287 (14) | C11—C12 | 1.4343 (14) |
C5—H5 | 0.9500 | C13—C14 | 1.4348 (14) |
C2—C1—C11 | 122.45 (9) | C7—C8—C13 | 122.05 (9) |
C2—C1—Cl1 | 118.64 (8) | C7—C8—Cl2 | 118.99 (8) |
C11—C1—Cl1 | 118.91 (8) | C13—C8—Cl2 | 118.96 (7) |
C1—C2—C3 | 119.71 (10) | C13—C9—C11 | 120.90 (9) |
C1—C2—H2 | 120.1 | C13—C9—H9 | 119.5 |
C3—C2—H2 | 120.1 | C11—C9—H9 | 119.5 |
C4—C3—C2 | 120.66 (10) | C12—C10—C14 | 121.73 (9) |
C4—C3—H3 | 119.7 | C12—C10—H10 | 119.1 |
C2—C3—H3 | 119.7 | C14—C10—H10 | 119.1 |
C3—C4—C12 | 120.57 (10) | C9—C11—C1 | 123.20 (9) |
C3—C4—H4 | 119.7 | C9—C11—C12 | 119.83 (9) |
C12—C4—H4 | 119.7 | C1—C11—C12 | 116.98 (9) |
C6—C5—C14 | 120.57 (10) | C10—C12—C4 | 121.53 (9) |
C6—C5—H5 | 119.7 | C10—C12—C11 | 118.86 (9) |
C14—C5—H5 | 119.7 | C4—C12—C11 | 119.60 (9) |
C5—C6—C7 | 120.76 (10) | C9—C13—C14 | 119.73 (9) |
C5—C6—H6 | 119.6 | C9—C13—C8 | 123.21 (9) |
C7—C6—H6 | 119.6 | C14—C13—C8 | 117.06 (9) |
C8—C7—C6 | 119.89 (10) | C10—C14—C5 | 121.40 (9) |
C8—C7—H7 | 120.1 | C10—C14—C13 | 118.94 (9) |
C6—C7—H7 | 120.1 | C5—C14—C13 | 119.66 (10) |
D—H···A | D—H | H···A | D···A | D—H···A |
C4—H4···Cl1i | 0.95 | 2.95 | 3.8233 (11) | 154 |
Symmetry code: (i) x, −y+5/2, z+1/2. |
C14H8Cl2 | F(000) = 504 |
Mr = 247.10 | Dx = 1.533 Mg m−3 |
Orthorhombic, Pna21 | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: P 2c -2n | Cell parameters from 4800 reflections |
a = 15.331 (2) Å | θ = 2.5–36.5° |
b = 3.8621 (5) Å | µ = 0.57 mm−1 |
c = 18.087 (2) Å | T = 90 K |
V = 1070.9 (2) Å3 | Lath, yellow |
Z = 4 | 0.33 × 0.20 × 0.08 mm |
Nonius KappaCCD area-detector diffractometer | 4919 independent reflections |
Radiation source: fine-focus sealed tube | 4717 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.027 |
ϕ and ω scans | θmax = 36.5°, θmin = 2.9° |
Absorption correction: multi-scan (SCALEPACK; Otwinowski & Minor 1997) | h = −25→24 |
Tmin = 0.835, Tmax = 0.956 | k = −4→6 |
24420 measured reflections | l = −30→29 |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.028 | H-atom parameters constrained |
wR(F2) = 0.072 | w = 1/[σ2(Fo2) + (0.0379P)2 + 0.2409P] where P = (Fo2 + 2Fc2)/3 |
S = 1.06 | (Δ/σ)max = 0.001 |
4919 reflections | Δρmax = 0.37 e Å−3 |
146 parameters | Δρmin = −0.27 e Å−3 |
1 restraint | Absolute structure: Flack (1983), with 2320 Friedel pairs |
Primary atom site location: structure-invariant direct methods | Absolute structure parameter: 0.42 (3) |
C14H8Cl2 | V = 1070.9 (2) Å3 |
Mr = 247.10 | Z = 4 |
Orthorhombic, Pna21 | Mo Kα radiation |
a = 15.331 (2) Å | µ = 0.57 mm−1 |
b = 3.8621 (5) Å | T = 90 K |
c = 18.087 (2) Å | 0.33 × 0.20 × 0.08 mm |
Nonius KappaCCD area-detector diffractometer | 4919 independent reflections |
Absorption correction: multi-scan (SCALEPACK; Otwinowski & Minor 1997) | 4717 reflections with I > 2σ(I) |
Tmin = 0.835, Tmax = 0.956 | Rint = 0.027 |
24420 measured reflections |
R[F2 > 2σ(F2)] = 0.028 | H-atom parameters constrained |
wR(F2) = 0.072 | Δρmax = 0.37 e Å−3 |
S = 1.06 | Δρmin = −0.27 e Å−3 |
4919 reflections | Absolute structure: Flack (1983), with 2320 Friedel pairs |
146 parameters | Absolute structure parameter: 0.42 (3) |
1 restraint |
Experimental. Nonius KappaCCD. The diffractometer was purchased through grant No. LEQSF(1999–2000)-ENH-TR-13, administered by the Louisiana Board of Regents. |
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 | ||
Cl1 | 0.604407 (15) | 0.89356 (7) | 0.499979 (15) | 0.01757 (5) | |
Cl2 | 0.551245 (16) | 0.33625 (6) | 0.248928 (15) | 0.01766 (5) | |
C1 | 0.49318 (6) | 0.9843 (3) | 0.50488 (6) | 0.01308 (15) | |
C2 | 0.46168 (7) | 1.1505 (3) | 0.56601 (6) | 0.01533 (16) | |
H2 | 0.5000 | 1.2154 | 0.6049 | 0.018* | |
C3 | 0.37096 (8) | 1.2256 (3) | 0.57101 (6) | 0.01685 (17) | |
H3 | 0.3488 | 1.3388 | 0.6137 | 0.020* | |
C4 | 0.31555 (7) | 1.1368 (3) | 0.51515 (6) | 0.01620 (17) | |
H4 | 0.2552 | 1.1881 | 0.5194 | 0.019* | |
C5 | 0.26485 (7) | 0.6215 (3) | 0.26894 (6) | 0.01811 (18) | |
H5 | 0.2046 | 0.6772 | 0.2722 | 0.022* | |
C6 | 0.29585 (8) | 0.4562 (3) | 0.20762 (6) | 0.01972 (19) | |
H6 | 0.2570 | 0.3983 | 0.1686 | 0.024* | |
C7 | 0.38568 (8) | 0.3698 (3) | 0.20149 (6) | 0.01817 (18) | |
H7 | 0.4067 | 0.2555 | 0.1585 | 0.022* | |
C8 | 0.44159 (7) | 0.4517 (3) | 0.25761 (6) | 0.01466 (16) | |
C9 | 0.46959 (6) | 0.7135 (3) | 0.38141 (5) | 0.01289 (15) | |
H9 | 0.5298 | 0.6574 | 0.3779 | 0.015* | |
C10 | 0.29172 (7) | 0.8810 (3) | 0.39160 (6) | 0.01500 (16) | |
H10 | 0.2316 | 0.9390 | 0.3949 | 0.018* | |
C11 | 0.43834 (6) | 0.8835 (2) | 0.44444 (5) | 0.01204 (14) | |
C12 | 0.34733 (6) | 0.9675 (3) | 0.45031 (5) | 0.01332 (15) | |
C13 | 0.41335 (7) | 0.6252 (2) | 0.32344 (5) | 0.01301 (15) | |
C14 | 0.32225 (7) | 0.7117 (3) | 0.32837 (5) | 0.01399 (15) |
U11 | U22 | U33 | U12 | U13 | U23 | |
Cl1 | 0.01212 (9) | 0.02056 (10) | 0.02002 (9) | 0.00001 (7) | −0.00155 (8) | −0.00242 (9) |
Cl2 | 0.01851 (10) | 0.01666 (9) | 0.01781 (9) | 0.00126 (8) | 0.00319 (8) | −0.00108 (9) |
C1 | 0.0122 (3) | 0.0125 (3) | 0.0145 (4) | −0.0002 (3) | −0.0002 (3) | 0.0011 (3) |
C2 | 0.0178 (4) | 0.0132 (4) | 0.0149 (4) | −0.0002 (3) | −0.0002 (3) | 0.0000 (3) |
C3 | 0.0204 (4) | 0.0141 (4) | 0.0160 (4) | 0.0017 (3) | 0.0041 (3) | 0.0001 (3) |
C4 | 0.0151 (4) | 0.0146 (4) | 0.0189 (4) | 0.0019 (3) | 0.0042 (3) | 0.0020 (3) |
C5 | 0.0173 (4) | 0.0160 (4) | 0.0210 (4) | −0.0015 (3) | −0.0057 (3) | 0.0034 (3) |
C6 | 0.0242 (5) | 0.0156 (4) | 0.0194 (4) | −0.0016 (4) | −0.0077 (4) | 0.0012 (3) |
C7 | 0.0249 (5) | 0.0149 (4) | 0.0148 (4) | −0.0013 (3) | −0.0030 (3) | 0.0008 (3) |
C8 | 0.0173 (4) | 0.0122 (3) | 0.0146 (4) | −0.0003 (3) | −0.0004 (3) | 0.0010 (3) |
C9 | 0.0127 (4) | 0.0124 (4) | 0.0136 (3) | −0.0003 (3) | 0.0005 (3) | 0.0015 (3) |
C10 | 0.0122 (4) | 0.0145 (4) | 0.0183 (4) | 0.0001 (3) | −0.0004 (3) | 0.0027 (3) |
C11 | 0.0122 (3) | 0.0108 (3) | 0.0131 (3) | −0.0004 (3) | 0.0010 (3) | 0.0015 (3) |
C12 | 0.0125 (3) | 0.0122 (4) | 0.0153 (3) | 0.0003 (3) | 0.0015 (3) | 0.0029 (3) |
C13 | 0.0142 (4) | 0.0112 (4) | 0.0136 (3) | −0.0005 (3) | −0.0007 (3) | 0.0022 (3) |
C14 | 0.0136 (4) | 0.0120 (4) | 0.0164 (4) | −0.0013 (3) | −0.0019 (3) | 0.0030 (3) |
Cl1—C1 | 1.7431 (10) | C6—C7 | 1.4214 (18) |
Cl2—C8 | 1.7463 (11) | C6—H6 | 0.9500 |
C1—C2 | 1.3666 (15) | C7—C8 | 1.3657 (15) |
C1—C11 | 1.4330 (15) | C7—H7 | 0.9500 |
C2—C3 | 1.4237 (17) | C8—C13 | 1.4334 (14) |
C2—H2 | 0.9500 | C9—C13 | 1.3996 (14) |
C3—C4 | 1.3637 (16) | C9—C11 | 1.4001 (14) |
C3—H3 | 0.9500 | C9—H9 | 0.9500 |
C4—C12 | 1.4284 (15) | C10—C14 | 1.3981 (15) |
C4—H4 | 0.9500 | C10—C12 | 1.4022 (15) |
C5—C6 | 1.3650 (17) | C10—H10 | 0.9500 |
C5—C14 | 1.4322 (15) | C11—C12 | 1.4364 (14) |
C5—H5 | 0.9500 | C13—C14 | 1.4388 (15) |
C2—C1—C11 | 122.51 (9) | C7—C8—C13 | 122.42 (10) |
C2—C1—Cl1 | 118.77 (8) | C7—C8—Cl2 | 118.57 (8) |
C11—C1—Cl1 | 118.72 (8) | C13—C8—Cl2 | 119.00 (8) |
C1—C2—C3 | 119.49 (10) | C13—C9—C11 | 120.89 (9) |
C1—C2—H2 | 120.3 | C13—C9—H9 | 119.6 |
C3—C2—H2 | 120.3 | C11—C9—H9 | 119.6 |
C4—C3—C2 | 120.68 (10) | C14—C10—C12 | 121.83 (9) |
C4—C3—H3 | 119.7 | C14—C10—H10 | 119.1 |
C2—C3—H3 | 119.7 | C12—C10—H10 | 119.1 |
C3—C4—C12 | 120.72 (10) | C9—C11—C1 | 123.21 (9) |
C3—C4—H4 | 119.6 | C9—C11—C12 | 119.90 (9) |
C12—C4—H4 | 119.6 | C1—C11—C12 | 116.89 (9) |
C6—C5—C14 | 120.64 (11) | C10—C12—C4 | 121.57 (9) |
C6—C5—H5 | 119.7 | C10—C12—C11 | 118.74 (9) |
C14—C5—H5 | 119.7 | C4—C12—C11 | 119.69 (9) |
C5—C6—C7 | 120.70 (10) | C9—C13—C8 | 123.37 (9) |
C5—C6—H6 | 119.6 | C9—C13—C14 | 119.68 (9) |
C7—C6—H6 | 119.6 | C8—C13—C14 | 116.95 (9) |
C8—C7—C6 | 119.72 (10) | C10—C14—C5 | 121.47 (10) |
C8—C7—H7 | 120.1 | C10—C14—C13 | 118.96 (9) |
C6—C7—H7 | 120.1 | C5—C14—C13 | 119.57 (10) |
D—H···A | D—H | H···A | D···A | D—H···A |
C4—H4···Cl1i | 0.95 | 2.84 | 3.7207 (11) | 154 |
C7—H7···Cl1ii | 0.95 | 2.93 | 3.7870 (12) | 151 |
Symmetry codes: (i) x−1/2, −y+5/2, z; (ii) −x+1, −y+1, z−1/2. |
Experimental details
(I_mono) | (I_ortho) | |
Crystal data | ||
Chemical formula | C14H8Cl2 | C14H8Cl2 |
Mr | 247.10 | 247.10 |
Crystal system, space group | Monoclinic, P21/c | Orthorhombic, Pna21 |
Temperature (K) | 100 | 90 |
a, b, c (Å) | 19.0070 (14), 3.8621 (3), 15.1370 (11) | 15.331 (2), 3.8621 (5), 18.087 (2) |
α, β, γ (°) | 90, 107.4103 (15), 90 | 90, 90, 90 |
V (Å3) | 1060.25 (14) | 1070.9 (2) |
Z | 4 | 4 |
Radiation type | Mo Kα | Mo Kα |
µ (mm−1) | 0.57 | 0.57 |
Crystal size (mm) | 0.20 × 0.05 × 0.04 | 0.33 × 0.20 × 0.08 |
Data collection | ||
Diffractometer | Bruker SMART APEX2 CCD area-detector diffractometer | Nonius KappaCCD area-detector diffractometer |
Absorption correction | Multi-scan (SADABS; Sheldrick, 2009) | Multi-scan (SCALEPACK; Otwinowski & Minor 1997) |
Tmin, Tmax | 0.894, 0.977 | 0.835, 0.956 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 56651, 3700, 3433 | 24420, 4919, 4717 |
Rint | 0.027 | 0.027 |
(sin θ/λ)max (Å−1) | 0.746 | 0.836 |
Refinement | ||
R[F2 > 2σ(F2)], wR(F2), S | 0.028, 0.083, 1.15 | 0.028, 0.072, 1.06 |
No. of reflections | 3700 | 4919 |
No. of parameters | 145 | 146 |
No. of restraints | 0 | 1 |
H-atom treatment | H-atom parameters constrained | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.53, −0.20 | 0.37, −0.27 |
Absolute structure | ? | Flack (1983), with 2320 Friedel pairs |
Absolute structure parameter | ? | 0.42 (3) |
Computer programs: APEX2 (Bruker, 2011), COLLECT (Nonius, 2000), SAINT (Bruker, 2011), DENZO and SCALEPACK (Otwinowski & Minor 1997), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).
D—H···A | D—H | H···A | D···A | D—H···A |
C4—H4···Cl1i | 0.95 | 2.95 | 3.8233 (11) | 154.1 |
Symmetry code: (i) x, −y+5/2, z+1/2. |
D—H···A | D—H | H···A | D···A | D—H···A |
C4—H4···Cl1i | 0.95 | 2.84 | 3.7207 (11) | 154.3 |
C7—H7···Cl1ii | 0.95 | 2.93 | 3.7870 (12) | 150.7 |
Symmetry codes: (i) x−1/2, −y+5/2, z; (ii) −x+1, −y+1, z−1/2. |
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One of the starting materials used in the context of our ongoing research into energy transfer in ternary complexes is the title compound, 1,8-dichloroanthracene, (I). Instead of the desired reaction product, crystals of (I) were obtained and the structure was determined to be a previously undescribed monoclinic polymorph of 1,8-dichloroanthracene.
The orthorhombic structure of (I) had originally been reported without coordinates by Desvergne et al. (1978) and was determined in space group Pnma (with Z = 4) from Weissenberg photographs collected at room temperature. This structure was later corrected by Benites et al. (1996) to space group Pna21 in essentially the same unit cell, determined based on point-detector data collected at room temperature, and refined against F values instead of F2. To better compare the two polymorphs and also to redetermine the structure with current methods, low-temperature data of the orthorhombic form were collected (the original bulk sample was still available) using a modern diffractometer equipped with an area detector. Figs. 1 and 2 show the molecules of the monoclinic and orthorhombic structures, respectively.
Comparison of the two structures shows that the monoclinic polymorph is somewhat denser than the orthorhombic crystal form (1.548 versus 1.533 Mg m-3), despite the fact that the orthorhombic unit cell was determined at a slightly lower temperature than the monoclinic one. To test for the possibility of a temperature-dependent phase transition, the unit cell of the monoclinic form was determined at 290 K from a fresh crystal (data not shown) and was found to be the same monoclinic cell as that reported herein. It also appears that the orthorhombic polymorph does not convert to the denser monoclinic one over time, at least not on a decade timescale, as the orthorhombic crystals used for this study were grown over 16 years ago.
Besides the obvious intramolecular C9—H9···Cl contacts occurring in both molecules, which are based more on molecular geometry than attractive forces between H and Cl, both structures show weak intermolecular C—H···Cl interactions. Using the sum of the van der Waals radii (3.0 Å; Standard reference?) as a cut-off and limiting the search to C—H···Cl angles near a chemically sensible value of 150°, the monoclinic structure has one crystallographically independent van der Waals interaction involving atom Cl1, while the orthorhombic structure has two crystallographically independent interactions of this kind, both involving atom Cl1. These interactions are listed as C—H···Cl hydrogen bonds in Tables 1 and 2.
In the monoclinic polymorph, the C4—H4···Cl1i interactions [symmetry code: (i) x, 5/2 - y, 1/2 + z] link the molecules into infinite zigzag ribbons extending along the c axis, in which neighboring molecules assume an angle of 55.891 (14)° to one another. When seen in projection along the a axis, the zigzag nature of the ribbons is shown (Fig. 3, panel A). A projection along the b axis shows the ribbon from the side (Fig. 3, panel B), while in a view along the axis of propagation, i.e. the c axis, a V-shaped groove presents itself (Fig. 3, panel C).
The C—H···Cl interaction pattern found in the orthorhombic structure is somewhat more complex. The first of the two C—H···Cl interactions [C4—H4···Cl1ii; symmetry code: (ii) -1/2 + x, 5/2 - y, z] links the molecules into infinite zigzag ribbons extending along the a direction (Fig. 4, panel A), with an angle between neighboring molecules of 55.816 (14)°. These ribbons are similar to those described for the monoclinic structure. Most notably, the angle between molecules is almost identical (only five s.u.s apart) and both ribbons are generated by glide planes (a c-glide in the monoclinic structure, corresponding to the propagation of the layer in the c direction, and an a-glide in the orthorhombic one, where the chain extends along a). It should be noted that the a axis in the monoclinic structure is only slightly longer than the c axis in the orthorhombic one [and d100 of the monoclinic form (18.136 Å) is almost identical to the length of the orthorhombic c axis], and the monoclinic c and orthorhombic a axes are also quite similar (as are, as an aside note, the two b axes, making the β angle the only notable difference between the two unit cells).
The second interaction in the orthorhombic structure, C7—H7···Cl1iii [symmetry code: (iii) 1 - x, 1 - y, -1/2 + z], adds an interesting dimension of complexity to the packing of that polymorph. When examined on its own, it connects the molecules into infinite zigzag chains extending along the c direction, perpendicular to the ribbons generated by the first interaction (Fig. 4, panel B). In those chains, the angle between neighboring molecules is 51.494 (13)°. In combination, the two independent C—H···Cl hydrogen bonds give rise to an infinite three-dimensional network (panel C of Fig. 4 shows a packing plot in projection along the b axis). Connection in the third dimension is generated by means of helices extending along the b direction (Fig. 4, panel D). These helices are built using all four symmetry operators of the space group (including x, y, z) and the four symmetry-equivalent molecules contribute to the helix in four different ways. One molecule binds to its neighbors through atoms H4 and H7, a second one through atoms H4 and Cl1, a third through atoms H7 and Cl1, and the fourth only through atom Cl1, which accepts hydrogen bonds from atoms H4 and H7 of neighboring molecules. Panel E of Fig. 4 shows the anatomy of the helix schematically. It is remarkable that, even in the comparatively simple space group Pna21, just two crystallographically independent hydrogen bonds can give rise to two infinite straight chains in two directions and a complex helix in the third, while interconnecting the molecules into a three-dimensional framework.
Fig. 5 shows packing plots of the two structures and the nearest Cl···H distances, in views approximately along the respective b axes. In both structures, both Cl atoms are near five H atoms, and all H atoms, except for atom H9 in both molecules, are involved. The respective Cl···H distances are quite similar in the two polymorphs. This statement does not refer to hydrogen bonds or van der Waals interactions, as most of those Cl···H distances are longer than the sum of the van der Waals radii. Nevertheless, the projections shown in Fig. 5 illustrate well the similarities between the two structures. A comparison of the Cl···H distances in the two structures also reflects the higher density found for the monoclinic structure, as the corresponding distances in the orthorhombic polymorph are significantly longer.
Simulated powder patterns of the two structures calculated using Mercury (Macrae et al., 2008) did not reveal any similarities between the two polymorphs besides those to be expected with such similar unit cells and packings as described in the paragraphs above.
It is interesting to note that the crystals of both polymorphs were derived by the same method and from the same solvent (slow evaporation from propan-2-ol). The presence of other components, namely Pd(PPh3)4 and possible reaction products, during the crystallization of the monoclinic form is the only tangible difference between the two crystallization procedures. However, recrystallization of the 16 year-old orthorhombic sample by slow evaporation from propan-2-ol yielded the monoclinic polymorph (data not shown). Exhaustive additional crystallization experiments should be carried out before a conclusive statement can be made. Nevertheless, it cannot be ruled out that this may be another example of a disappearing polymorph (Dunitz & Bernstein, 1995).