Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270100010337/bm1420sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270100010337/bm1420a-formsup2.hkl | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270100010337/bm1420g-formsup3.hkl |
CCDC references: 152636; 152637
The synthesis of compound (I) is described elsewhere by Grimsdale et al. (1997). The γ-form was obtained as thick yellow plates? green blocks in tables? by slow evaporation of solvent at 278 K from a solution of (I) in CH2Cl2. Fast evaporation of solvent from the same solution at 298 K yielded very thin green plates? needle in tables? of the α-form.
H atoms were placed geometrically, with Csp2—H 0.95 Å and Csp3—H 0.98 Å, and refined riding on their respective carrier atoms with Uiso(H) = 1.2Ueq(C). The program PLATON (Spek, 1990) was used to calculate the hydrogen bonding interactions using C—H distances normalized to the neutron-derived value of 1.08 Å.
For both compounds, data collection: SMART (Bruker, 1998); cell refinement: LSCELL (Clegg, 1995); data reduction: SAINT (Bruker, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SCHAKAL97 (Keller, 1997); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 1990).
C22H20N2O2 | F(000) = 728 |
Mr = 344.40 | Dx = 1.313 Mg m−3 |
Orthorhombic, Pccn | Synchrotron radiation, λ = 0.68910 Å |
Hall symbol: -P 2ab 2ac | Cell parameters from 5802 reflections |
a = 9.124 (1) Å | θ = 3.1–29.3° |
b = 26.061 (3) Å | µ = 0.09 mm−1 |
c = 7.328 (1) Å | T = 150 K |
V = 1742.5 (4) Å3 | Needle, green |
Z = 4 | 0.18 × 0.04 × 0.01 mm |
Bruker SMART CCD diffractometer | 2502 independent reflections |
Radiation source: Daresbury SRS, Station 9.8 (Greaves et al., 1997; Clegg et al., 1998) | 1979 reflections with I > 2σ(I) |
Silicon 111 monochromator | Rint = 0.035 |
Detector resolution: 8.192 pixels mm-1 | θmax = 29.4°, θmin = 2.3° |
thin slice, ω–scans | h = −12→7 |
Absorption correction: multi-scan SADABS (Sheldrick, 1997) | k = −36→36 |
Tmin = 0.985, Tmax = 0.998 | l = −10→10 |
9157 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)] = 0.057 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.138 | H-atom parameters constrained |
S = 1.12 | w = 1/[σ2(Fo2) + (0.0559P)2 + 0.8532P] where P = (Fo2 + 2Fc2)/3 |
2502 reflections | (Δ/σ)max = 0.007 |
119 parameters | Δρmax = 0.34 e Å−3 |
0 restraints | Δρmin = −0.28 e Å−3 |
C22H20N2O2 | V = 1742.5 (4) Å3 |
Mr = 344.40 | Z = 4 |
Orthorhombic, Pccn | Synchrotron radiation, λ = 0.68910 Å |
a = 9.124 (1) Å | µ = 0.09 mm−1 |
b = 26.061 (3) Å | T = 150 K |
c = 7.328 (1) Å | 0.18 × 0.04 × 0.01 mm |
Bruker SMART CCD diffractometer | 2502 independent reflections |
Absorption correction: multi-scan SADABS (Sheldrick, 1997) | 1979 reflections with I > 2σ(I) |
Tmin = 0.985, Tmax = 0.998 | Rint = 0.035 |
9157 measured reflections |
R[F2 > 2σ(F2)] = 0.057 | 0 restraints |
wR(F2) = 0.138 | H-atom parameters constrained |
S = 1.12 | Δρmax = 0.34 e Å−3 |
2502 reflections | Δρmin = −0.28 e Å−3 |
119 parameters |
Experimental. Diffraction intensities for the two polymorphs (α-form and γ-form) were collected at the Daresbury SRS (UK), Station 9.8 (Greaves et al., 1997; Clegg et al., 1998), using a Bruker AXS SMART CCD area-detector diffractometer. Intensities were integrated from several series of exposures. For the α-form, each exposure covered 0.45° in ω, with an exposure time of 1 s; for the γ-form, each exposure covered 0.3° in ω, with an exposure time of 3 s. In both cases, the total data sets were more than a hemisphere. Data were corrected for absorption and incident beam decay (Sheldrick, 1997). The program PLATON (Spek, 1990) was used to calculate the hydrogen-bonding interactions using normalized C—H distances to the neutron derived value (1.08 Å). For all molecular representations, the graphics program SCHAKAL97 (Keller, 1997) was used. |
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 | ||
O1 | −0.03673 (13) | 0.70252 (5) | −0.54373 (16) | 0.0320 (3) | |
N1 | −0.10940 (12) | 0.49301 (5) | 0.63293 (17) | 0.0214 (3) | |
C1 | −0.01382 (16) | 0.66890 (6) | −0.4036 (2) | 0.0229 (3) | |
C2 | 0.09905 (16) | 0.63315 (6) | −0.3974 (2) | 0.0226 (3) | |
H2 | 0.1676 | 0.6308 | −0.4947 | 0.027* | |
C3 | 0.11050 (15) | 0.60076 (6) | −0.24668 (19) | 0.0209 (3) | |
H3 | 0.1874 | 0.5762 | −0.2431 | 0.025* | |
C4 | 0.01271 (15) | 0.60328 (5) | −0.10124 (19) | 0.0188 (3) | |
C5 | −0.09976 (15) | 0.64000 (6) | −0.1111 (2) | 0.0234 (3) | |
H5 | −0.1679 | 0.6427 | −0.0136 | 0.028* | |
C6 | −0.11312 (16) | 0.67216 (6) | −0.2594 (2) | 0.0252 (3) | |
H6 | −0.1902 | 0.6966 | −0.2634 | 0.030* | |
C7 | 0.03328 (15) | 0.56864 (5) | 0.05300 (19) | 0.0200 (3) | |
H7 | 0.1145 | 0.5459 | 0.0464 | 0.024* | |
C8 | −0.05018 (15) | 0.56547 (6) | 0.2031 (2) | 0.0206 (3) | |
H8 | −0.1337 | 0.5871 | 0.2108 | 0.025* | |
C9 | −0.02112 (14) | 0.53096 (5) | 0.35512 (19) | 0.0189 (3) | |
C10 | −0.12769 (15) | 0.52338 (6) | 0.4896 (2) | 0.0215 (3) | |
H10 | −0.2183 | 0.5410 | 0.4776 | 0.026* | |
C11 | 0.0667 (2) | 0.70142 (7) | −0.6900 (2) | 0.0365 (4) | |
H11A | 0.1647 | 0.7092 | −0.6428 | 0.055* | |
H11B | 0.0394 | 0.7270 | −0.7818 | 0.055* | |
H11C | 0.0669 | 0.6672 | −0.7459 | 0.055* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0385 (6) | 0.0306 (6) | 0.0268 (6) | 0.0055 (5) | 0.0029 (5) | 0.0091 (5) |
N1 | 0.0179 (5) | 0.0250 (6) | 0.0212 (6) | −0.0014 (4) | 0.0015 (4) | 0.0011 (5) |
C1 | 0.0262 (7) | 0.0209 (7) | 0.0216 (7) | −0.0023 (5) | −0.0024 (6) | 0.0008 (5) |
C2 | 0.0234 (7) | 0.0250 (7) | 0.0194 (6) | −0.0007 (5) | 0.0011 (5) | −0.0018 (5) |
C3 | 0.0190 (6) | 0.0238 (7) | 0.0200 (7) | 0.0009 (5) | −0.0006 (5) | −0.0011 (5) |
C4 | 0.0169 (6) | 0.0210 (7) | 0.0186 (6) | −0.0022 (5) | −0.0016 (5) | −0.0010 (5) |
C5 | 0.0201 (7) | 0.0276 (7) | 0.0226 (7) | 0.0010 (5) | 0.0033 (5) | −0.0011 (6) |
C6 | 0.0226 (7) | 0.0249 (7) | 0.0280 (7) | 0.0044 (6) | 0.0000 (6) | 0.0010 (6) |
C7 | 0.0182 (6) | 0.0218 (7) | 0.0199 (6) | −0.0012 (5) | −0.0019 (5) | −0.0005 (5) |
C8 | 0.0174 (6) | 0.0231 (7) | 0.0214 (7) | −0.0011 (5) | −0.0010 (5) | 0.0005 (5) |
C9 | 0.0167 (6) | 0.0217 (6) | 0.0184 (6) | −0.0031 (5) | −0.0013 (5) | −0.0010 (5) |
C10 | 0.0163 (6) | 0.0255 (7) | 0.0226 (7) | 0.0003 (5) | 0.0011 (5) | 0.0013 (5) |
C11 | 0.0509 (10) | 0.0314 (8) | 0.0271 (8) | 0.0006 (8) | 0.0069 (8) | 0.0084 (7) |
O1—C1 | 1.3658 (18) | C5—H5 | 0.9500 |
O1—C11 | 1.428 (2) | C6—H6 | 0.9500 |
N1—C10 | 1.3257 (19) | C7—C8 | 1.3406 (19) |
N1—C9i | 1.3477 (17) | C7—H7 | 0.9500 |
C1—C2 | 1.389 (2) | C8—C9 | 1.4558 (19) |
C1—C6 | 1.395 (2) | C8—H8 | 0.9500 |
C2—C3 | 1.394 (2) | C9—N1i | 1.3477 (17) |
C2—H2 | 0.9500 | C9—C10 | 1.3985 (19) |
C3—C4 | 1.3914 (19) | C10—H10 | 0.9500 |
C3—H3 | 0.9500 | C11—H11A | 0.9800 |
C4—C5 | 1.4051 (19) | C11—H11B | 0.9800 |
C4—C7 | 1.4585 (19) | C11—H11C | 0.9800 |
C5—C6 | 1.377 (2) | ||
C1—O1—C11 | 116.75 (13) | C1—C6—H6 | 119.9 |
C10—N1—C9i | 116.08 (12) | C8—C7—C4 | 126.95 (13) |
O1—C1—C2 | 124.63 (14) | C8—C7—H7 | 116.5 |
O1—C1—C6 | 115.55 (13) | C4—C7—H7 | 116.5 |
C2—C1—C6 | 119.82 (14) | C7—C8—C9 | 124.23 (13) |
C1—C2—C3 | 119.18 (13) | C7—C8—H8 | 117.9 |
C1—C2—H2 | 120.4 | C9—C8—H8 | 117.9 |
C3—C2—H2 | 120.4 | N1i—C9—C10 | 120.21 (13) |
C4—C3—C2 | 122.03 (13) | N1i—C9—C8 | 119.80 (12) |
C4—C3—H3 | 119.0 | C10—C9—C8 | 119.98 (12) |
C2—C3—H3 | 119.0 | N1—C10—C9 | 123.72 (13) |
C3—C4—C5 | 117.44 (13) | N1—C10—H10 | 118.1 |
C3—C4—C7 | 118.81 (12) | C9—C10—H10 | 118.1 |
C5—C4—C7 | 123.74 (13) | O1—C11—H11A | 109.5 |
C6—C5—C4 | 121.31 (14) | O1—C11—H11B | 109.5 |
C6—C5—H5 | 119.3 | H11A—C11—H11B | 109.5 |
C4—C5—H5 | 119.3 | O1—C11—H11C | 109.5 |
C5—C6—C1 | 120.22 (14) | H11A—C11—H11C | 109.5 |
C5—C6—H6 | 119.9 | H11B—C11—H11C | 109.5 |
C11—O1—C1—C2 | −2.2 (2) | O1—C1—C6—C5 | −179.95 (14) |
C11—O1—C1—C6 | 177.63 (14) | C2—C1—C6—C5 | −0.1 (2) |
O1—C1—C2—C3 | −179.78 (14) | C3—C4—C7—C8 | −179.51 (14) |
C6—C1—C2—C3 | 0.4 (2) | C5—C4—C7—C8 | 1.5 (2) |
C1—C2—C3—C4 | −0.4 (2) | C4—C7—C8—C9 | −178.12 (13) |
C2—C3—C4—C5 | 0.0 (2) | C7—C8—C9—N1i | 12.8 (2) |
C2—C3—C4—C7 | −179.02 (13) | C7—C8—C9—C10 | −168.16 (14) |
C3—C4—C5—C6 | 0.2 (2) | C9i—N1—C10—C9 | 0.3 (2) |
C7—C4—C5—C6 | 179.27 (14) | N1i—C9—C10—N1 | −0.4 (2) |
C4—C5—C6—C1 | −0.2 (2) | C8—C9—C10—N1 | −179.39 (14) |
Symmetry code: (i) −x, −y+1, −z+1. |
C22H20N2O2 | F(000) = 728 |
Mr = 344.40 | Dx = 1.345 Mg m−3 |
Monoclinic, C2/c | Synchrotron radiation, λ = 0.68910 Å |
a = 32.339 (6) Å | Cell parameters from 4261 reflections |
b = 5.732 (1) Å | θ = 3.6–29.3° |
c = 9.411 (2) Å | µ = 0.09 mm−1 |
β = 102.815 (4)° | T = 150 K |
V = 1701.0 (6) Å3 | Block, yellow |
Z = 4 | 0.14 × 0.12 × 0.10 mm |
Bruker SMART CCD diffractometer | 2384 independent reflections |
Radiation source: Daresbury SRS, Station 9.8 (Greaves et al., 1997; Clegg et al., 1998) | 1937 reflections with I > 2σ(I) |
Silicon 111 monochromator | Rint = 0.032 |
Detector resolution: 8.192 pixels mm-1 | θmax = 29.4°, θmin = 2.5° |
thin slice, ω–scans | h = −43→45 |
Absorption correction: multi-scan SADABS (Sheldrick, 1997) | k = −8→5 |
Tmin = 0.988, Tmax = 0.991 | l = −13→11 |
5705 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)] = 0.049 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.141 | H-atom parameters constrained |
S = 1.09 | w = 1/[σ2(Fo2) + (0.0801P)2 + 0.6111P] where P = (Fo2 + 2Fc2)/3 |
2384 reflections | (Δ/σ)max = 0.009 |
119 parameters | Δρmax = 0.38 e Å−3 |
0 restraints | Δρmin = −0.20 e Å−3 |
C22H20N2O2 | V = 1701.0 (6) Å3 |
Mr = 344.40 | Z = 4 |
Monoclinic, C2/c | Synchrotron radiation, λ = 0.68910 Å |
a = 32.339 (6) Å | µ = 0.09 mm−1 |
b = 5.732 (1) Å | T = 150 K |
c = 9.411 (2) Å | 0.14 × 0.12 × 0.10 mm |
β = 102.815 (4)° |
Bruker SMART CCD diffractometer | 2384 independent reflections |
Absorption correction: multi-scan SADABS (Sheldrick, 1997) | 1937 reflections with I > 2σ(I) |
Tmin = 0.988, Tmax = 0.991 | Rint = 0.032 |
5705 measured reflections |
R[F2 > 2σ(F2)] = 0.049 | 0 restraints |
wR(F2) = 0.141 | H-atom parameters constrained |
S = 1.09 | Δρmax = 0.38 e Å−3 |
2384 reflections | Δρmin = −0.20 e Å−3 |
119 parameters |
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 | ||
O1 | 0.28826 (3) | 0.21068 (16) | 0.67400 (9) | 0.0250 (2) | |
N1 | 0.51819 (3) | 0.71235 (17) | 1.55555 (11) | 0.0191 (2) | |
C1 | 0.32231 (4) | 0.2230 (2) | 0.78949 (12) | 0.0181 (2) | |
C2 | 0.35269 (4) | 0.0489 (2) | 0.82793 (13) | 0.0195 (3) | |
H2 | 0.3512 | −0.0887 | 0.7708 | 0.023* | |
C3 | 0.38526 (4) | 0.07860 (19) | 0.95113 (12) | 0.0187 (2) | |
H3 | 0.4059 | −0.0411 | 0.9775 | 0.022* | |
C4 | 0.38849 (4) | 0.27970 (19) | 1.03710 (12) | 0.0168 (2) | |
C5 | 0.35776 (4) | 0.45371 (19) | 0.99423 (13) | 0.0193 (2) | |
H5 | 0.3593 | 0.5928 | 1.0501 | 0.023* | |
C6 | 0.32530 (4) | 0.4267 (2) | 0.87245 (13) | 0.0207 (3) | |
H6 | 0.3049 | 0.5472 | 0.8450 | 0.025* | |
C7 | 0.42260 (4) | 0.2981 (2) | 1.16777 (12) | 0.0184 (2) | |
H7 | 0.4380 | 0.1594 | 1.1992 | 0.022* | |
C8 | 0.43442 (4) | 0.48976 (19) | 1.24785 (12) | 0.0190 (2) | |
H8 | 0.4200 | 0.6318 | 1.2177 | 0.023* | |
C9 | 0.46837 (4) | 0.49131 (18) | 1.37919 (12) | 0.0169 (2) | |
C10 | 0.48702 (4) | 0.70142 (19) | 1.43708 (13) | 0.0192 (2) | |
H10 | 0.4769 | 0.8429 | 1.3892 | 0.023* | |
C11 | 0.28306 (4) | −0.0003 (2) | 0.59144 (14) | 0.0272 (3) | |
H11A | 0.3084 | −0.0284 | 0.5530 | 0.041* | |
H11B | 0.2582 | 0.0134 | 0.5104 | 0.041* | |
H11C | 0.2790 | −0.1307 | 0.6542 | 0.041* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0246 (5) | 0.0235 (5) | 0.0227 (4) | 0.0019 (3) | −0.0037 (3) | −0.0031 (3) |
N1 | 0.0217 (5) | 0.0134 (4) | 0.0209 (5) | −0.0015 (3) | 0.0022 (4) | −0.0010 (3) |
C1 | 0.0185 (5) | 0.0190 (5) | 0.0163 (5) | −0.0012 (4) | 0.0025 (4) | 0.0006 (4) |
C2 | 0.0199 (5) | 0.0183 (5) | 0.0199 (5) | 0.0002 (4) | 0.0036 (4) | −0.0032 (4) |
C3 | 0.0192 (5) | 0.0153 (5) | 0.0208 (5) | 0.0009 (4) | 0.0029 (4) | −0.0010 (4) |
C4 | 0.0179 (5) | 0.0155 (5) | 0.0171 (5) | −0.0015 (4) | 0.0039 (4) | −0.0007 (4) |
C5 | 0.0219 (6) | 0.0140 (5) | 0.0214 (5) | −0.0005 (4) | 0.0035 (4) | −0.0023 (4) |
C6 | 0.0213 (6) | 0.0158 (5) | 0.0237 (6) | 0.0017 (4) | 0.0020 (4) | 0.0007 (4) |
C7 | 0.0192 (5) | 0.0169 (5) | 0.0184 (5) | −0.0004 (4) | 0.0026 (4) | 0.0002 (4) |
C8 | 0.0194 (5) | 0.0159 (5) | 0.0204 (5) | 0.0004 (4) | 0.0017 (4) | 0.0003 (4) |
C9 | 0.0187 (5) | 0.0136 (5) | 0.0184 (5) | −0.0004 (4) | 0.0039 (4) | −0.0016 (4) |
C10 | 0.0224 (6) | 0.0127 (5) | 0.0211 (5) | 0.0005 (4) | 0.0021 (4) | 0.0003 (4) |
C11 | 0.0265 (6) | 0.0290 (7) | 0.0234 (6) | −0.0002 (5) | −0.0007 (5) | −0.0078 (5) |
O1—C1 | 1.3666 (13) | C5—H5 | 0.9500 |
O1—C11 | 1.4269 (15) | C6—H6 | 0.9500 |
N1—C10 | 1.3283 (14) | C7—C8 | 1.3392 (16) |
N1—C9i | 1.3455 (14) | C7—H7 | 0.9500 |
C1—C2 | 1.3907 (16) | C8—C9 | 1.4599 (15) |
C1—C6 | 1.3960 (16) | C8—H8 | 0.9500 |
C2—C3 | 1.3933 (16) | C9—N1i | 1.3455 (14) |
C2—H2 | 0.9500 | C9—C10 | 1.4018 (15) |
C3—C4 | 1.3988 (15) | C10—H10 | 0.9500 |
C3—H3 | 0.9500 | C11—H11A | 0.9800 |
C4—C5 | 1.4027 (16) | C11—H11B | 0.9800 |
C4—C7 | 1.4622 (15) | C11—H11C | 0.9800 |
C5—C6 | 1.3804 (16) | ||
C1—O1—C11 | 116.98 (9) | C1—C6—H6 | 119.9 |
C10—N1—C9i | 116.76 (10) | C8—C7—C4 | 126.90 (11) |
O1—C1—C2 | 124.60 (10) | C8—C7—H7 | 116.5 |
O1—C1—C6 | 115.58 (10) | C4—C7—H7 | 116.5 |
C2—C1—C6 | 119.82 (10) | C7—C8—C9 | 123.28 (10) |
C1—C2—C3 | 119.28 (10) | C7—C8—H8 | 118.4 |
C1—C2—H2 | 120.4 | C9—C8—H8 | 118.4 |
C3—C2—H2 | 120.4 | N1i—C9—C10 | 120.03 (10) |
C2—C3—C4 | 121.84 (10) | N1i—C9—C8 | 119.16 (10) |
C2—C3—H3 | 119.1 | C10—C9—C8 | 120.81 (10) |
C4—C3—H3 | 119.1 | N1—C10—C9 | 123.21 (10) |
C3—C4—C5 | 117.54 (10) | N1—C10—H10 | 118.4 |
C3—C4—C7 | 119.44 (10) | C9—C10—H10 | 118.4 |
C5—C4—C7 | 123.00 (10) | O1—C11—H11A | 109.5 |
C6—C5—C4 | 121.25 (10) | O1—C11—H11B | 109.5 |
C6—C5—H5 | 119.4 | H11A—C11—H11B | 109.5 |
C4—C5—H5 | 119.4 | O1—C11—H11C | 109.5 |
C5—C6—C1 | 120.25 (10) | H11A—C11—H11C | 109.5 |
C5—C6—H6 | 119.9 | H11B—C11—H11C | 109.5 |
C11—O1—C1—C2 | 2.49 (17) | O1—C1—C6—C5 | 177.97 (11) |
C11—O1—C1—C6 | −176.86 (11) | C2—C1—C6—C5 | −1.41 (18) |
O1—C1—C2—C3 | −177.92 (11) | C3—C4—C7—C8 | 168.23 (12) |
C6—C1—C2—C3 | 1.41 (18) | C5—C4—C7—C8 | −13.20 (19) |
C1—C2—C3—C4 | −0.41 (18) | C4—C7—C8—C9 | 178.58 (11) |
C2—C3—C4—C5 | −0.57 (17) | C7—C8—C9—N1i | −16.69 (18) |
C2—C3—C4—C7 | 178.08 (11) | C7—C8—C9—C10 | 163.10 (12) |
C3—C4—C5—C6 | 0.57 (17) | C9i—N1—C10—C9 | −0.28 (19) |
C7—C4—C5—C6 | −178.03 (11) | N1i—C9—C10—N1 | 0.3 (2) |
C4—C5—C6—C1 | 0.41 (18) | C8—C9—C10—N1 | −179.49 (11) |
Symmetry code: (i) −x+1, −y+1, −z+3. |
Experimental details
(a-form) | (g-form) | |
Crystal data | ||
Chemical formula | C22H20N2O2 | C22H20N2O2 |
Mr | 344.40 | 344.40 |
Crystal system, space group | Orthorhombic, Pccn | Monoclinic, C2/c |
Temperature (K) | 150 | 150 |
a, b, c (Å) | 9.124 (1), 26.061 (3), 7.328 (1) | 32.339 (6), 5.732 (1), 9.411 (2) |
α, β, γ (°) | 90, 90, 90 | 90, 102.815 (4), 90 |
V (Å3) | 1742.5 (4) | 1701.0 (6) |
Z | 4 | 4 |
Radiation type | Synchrotron, λ = 0.68910 Å | Synchrotron, λ = 0.68910 Å |
µ (mm−1) | 0.09 | 0.09 |
Crystal size (mm) | 0.18 × 0.04 × 0.01 | 0.14 × 0.12 × 0.10 |
Data collection | ||
Diffractometer | Bruker SMART CCD diffractometer | Bruker SMART CCD diffractometer |
Absorption correction | Multi-scan SADABS (Sheldrick, 1997) | Multi-scan SADABS (Sheldrick, 1997) |
Tmin, Tmax | 0.985, 0.998 | 0.988, 0.991 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 9157, 2502, 1979 | 5705, 2384, 1937 |
Rint | 0.035 | 0.032 |
(sin θ/λ)max (Å−1) | 0.713 | 0.713 |
Refinement | ||
R[F2 > 2σ(F2)], wR(F2), S | 0.057, 0.138, 1.12 | 0.049, 0.141, 1.09 |
No. of reflections | 2502 | 2384 |
No. of parameters | 119 | 119 |
H-atom treatment | H-atom parameters constrained | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.34, −0.28 | 0.38, −0.20 |
Computer programs: SMART (Bruker, 1998), LSCELL (Clegg, 1995), SAINT (Bruker, 1997), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), SCHAKAL97 (Keller, 1997), SHELXL97 and PLATON (Spek, 1990).
The discovery that semiconducting polymers based on polyphenylenevinylene (PPV) have interesting and useful electroluminescent properties has led to their successful development as components in light-emitting diodes (LEDs) and other semiconducting devices (Burroughes et al., 1990; Braun & Heeger, 1991). The characteristics and efficiencies of these devices have been improved by the introduction of electron-withdrawing substituents on the PPV backbone which lower the barrier to electron injection (Bredas & Heeger, 1994). Another way to achieve high electron affinity is to incorporate electronegative hetero atoms into the polymer backbone. Evidence for this has been found in work on oligomers based on distyrylpyrazine which show promise as emissive and/or charge-transport agents for LED devices. In particular, devices made with the dimethoxy derivative 2,5-bis[2-(4-methoxyphenyl)ethenyl]pyrazine, (I), have been shown to have a higher electron affinity than PPV itself (Nohara et al., 1990; Grimsdale et al., 1997). To understand this effect properly, it is necessary first to obtain a detailed knowledge of the structure of the oligomer in the solid state. The parent compound, 2,5-distyrylpyrazine, has two known polymorphic forms, an orthorhombic α-form (Sasada et al., 1971) and a monoclinic γ-form (Nakanishi et al., 1976); the very similar polymorphic forms found for the title dimethoxy derivative, (I), have accordingly been denoted α and γ. \sch
Preliminary measurements were made on laboratory X-ray diffractometers, but due to the weak diffraction of both forms it was necessary to exploit the high intensity of a synchrotron radiation source to determine the crystal structures accurately. These determinations represent the first reported crystal structures of a substituted 2,5-distyrylpyrazine.
Both forms of (I) have one half molecule in the asymmetric unit and the two rings attached to each double bond are mutually trans. The bond lengths and angles are comparable, but there is a difference in the molecular planarity of the two forms caused by differences in the reciprocal orientation of the aromatic rings. Molecules in the γ-form are slightly more planar, with r.m.s. torsional deviations from planarity of 3.5 (2) and 3.3 (2)° for the lateral and central rings, respectively, compared with 3.6 (2) and 4.2 (2)° in the α-form.
The crystal packing of the two forms is quite different, with a herringbone type of arrangement in the α-form (Fig. 2), and a π-π type of stacking in the γ-form. In the latter, the molecules form a nearly planar network held together by two types of intermolecular hydrogen bonds: C—H···O through the methoxy groups, with H···O 2.49 Å, and C—H···N through the pyrazine rings, with H···N 2.50 Å (Fig. 3). The stacking distance between these pseudoplanes is 3.40 Å, calculated between a pyrazine centroid in one plane and a nearest neighbour C═C bond in the next. In the α-form there are also intermolecular interactions of the type C—H···N (H···N 2.58 Å), in this case linking pyrazine rings to phenyl H atoms. Also in the crystal of (I), the phenyl and pyrazine rings of neighbouring molecules are found aligned face to face, suggesting the possible presence of quadrupole-quadrupole interactions.
The most striking result of this work is the evidence found for intermolecular hydrogen bonding through the pyrazine and methoxy groups, and the different roles it plays in the crystal packing and degree of torsion of the conjugated backbone in the two polymorphs.