γ-Hydroquinone (1) and its tetrafluoro, tetrachloro and tetrabromo derivatives (2), (3) and (4) adopt crystal structures that have an almost invariant system of O—H
O hydrogen bonds. However, within this O—H
O framework, the four structures display variations that are characteristic of the C—H, C—F, C—Cl and C—Br groups. In the parent compound (1) aromatic rings are packed with a herringbone geometry, whilst in the halogenated derivatives (3) and (4), polarization-type halogen
halogen contacts are optimized. The fluoro derivative (2) is exceptional in that neither of the above possibilities is adopted, even though the O—H
O scaffolding does not
per se prohibit either of them geometrically.
Supporting information
| Crystallographic Information File (CIF) Contains datablocks 2, global, 4 |
| Structure factor file (CIF format) Contains datablock 2 |
| Structure factor file (CIF format) Contains datablock 4 |
CCDC references: 138566; 138567
Data collection: XSCANS V.2.10b (Siemens,1994a) for (2); SMART V.4.209 (Siemens, 1995) for (4). Cell refinement: XSCANS V.2.10b (Siemens,1994a) for (2); SAINT V.4.050 (Siemens, 1995) for (4). Data reduction: XSCANS V.2.10b (Siemens,1994a) for (2); SAINT V.4.050 (Siemens, 1995) for (4). For both compounds, program(s) used to solve structure: SHELXTL V.5.03 (Siemens, 1994b); program(s) used to refine structure: SHELXTL V.5.03 (Siemens, 1994b); molecular graphics: SHELXTL V.5.03 (Siemens, 1994b); software used to prepare material for publication: SHELXTL V.5.03 (Siemens, 1994b).
(2) 2,3,5,6-Tetrafluorohydroquinone
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Crystal data top
C_{6}H_{2}F_{4}O_{2} | F(000) = 180 |
M_{r} = 182.08 | D_{x} = 1.957 Mg m^{−}^{3} |
Monoclinic, P2_{1}/n | Melting point: 446 K |
Hall symbol: -P 2yn | Mo Kα radiation, λ = 0.71073 Å |
a = 6.5533 (10) Å | Cell parameters from 50 reflections |
b = 4.8848 (10) Å | θ = 10–12.5° |
c = 10.148 (2) Å | µ = 0.22 mm^{−}^{1} |
β = 107.990 (11)° | T = 298 K |
V = 308.97 (9) Å^{3} | Block, colourless |
Z = 2 | 0.25 × 0.21 × 0.13 mm |
Data collection top
Siemens P4 four circle diffractometer | R_{int} = 0.026 |
Radiation source: fine-focus sealed tube | θ_{max} = 30.0°, θ_{min} = 3.3° |
Graphite monochromator | h = −9→9 |
adaptive ω scans | k = −1→6 |
2177 measured reflections | l = −14→13 |
901 independent reflections | 3 standard reflections every 100 reflections |
664 reflections with I > 2σ(I) | intensity decay: No decay |
Refinement top
Refinement on F^{2} | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F^{2} > 2σ(F^{2})] = 0.041 | All H-atom parameters refined |
wR(F^{2}) = 0.131 | Calculated w = 1/[σ^{2}(F_{o}^{2}) + (0.0709P)^{2} + 0.0239P] where P = (F_{o}^{2} + 2F_{c}^{2})/3 |
S = 1.05 | (Δ/σ)_{max} = 0.001 |
901 reflections | Δρ_{max} = 0.23 e Å^{−}^{3} |
60 parameters | Δρ_{min} = −0.16 e Å^{−}^{3} |
0 restraints | Extinction correction: SHELXL93 (Sheldrick, 1993), Fc^{*}=kFc[1+0.001xFc^{2}λ^{3}/sin(2θ)]^{-1/4} |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.0252 (201) |
Special details top
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 on F^{2} for ALL reflections except for 0 with very negative
F^{2} or flagged by the user for potential systematic errors. Weighted
R-factors wR and all goodnesses of fit S are based on
F^{2}, conventional R-factors R are based on F,
with F set to zero for negative F^{2}. The observed criterion of
F^{2} > σ(F^{2}) is used only for calculating _R_factor_obs
etc. and is not relevant to the choice of reflections for refinement.
R-factors based on F^{2} are statistically about twice as large
as those based on F, and R- factors based on ALL data will be
even larger. |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å^{2}) top | x | y | z | U_{iso}*/U_{eq} | |
O | 0.7357 (2) | 0.0043 (3) | 0.8162 (2) | 0.0636 (4) | |
H | 0.719 (4) | 0.158 (6) | 0.773 (3) | 0.082 (7)* | |
C1 | 0.6196 (3) | 0.0083 (3) | 0.9067 (2) | 0.0469 (4) | |
C2 | 0.6619 (2) | −0.1834 (3) | 1.0113 (2) | 0.0480 (4) | |
C3 | 0.5445 (2) | −0.1912 (3) | 1.10273 (15) | 0.0472 (4) | |
F1 | 0.8189 (2) | −0.3666 (2) | 1.02410 (14) | 0.0700 (4) | |
F2 | 0.5912 (2) | −0.3787 (2) | 1.20450 (12) | 0.0657 (4) | |
Atomic displacement parameters (Å^{2}) top | U^{11} | U^{22} | U^{33} | U^{12} | U^{13} | U^{23} |
O | 0.0844 (9) | 0.0547 (7) | 0.0725 (8) | 0.0039 (6) | 0.0547 (7) | 0.0017 (6) |
C1 | 0.0538 (8) | 0.0449 (8) | 0.0502 (8) | −0.0033 (6) | 0.0281 (6) | −0.0044 (6) |
C2 | 0.0496 (8) | 0.0440 (8) | 0.0561 (8) | 0.0039 (6) | 0.0244 (6) | −0.0020 (6) |
C3 | 0.0541 (8) | 0.0444 (8) | 0.0466 (7) | −0.0013 (6) | 0.0206 (6) | 0.0020 (6) |
F1 | 0.0656 (7) | 0.0608 (7) | 0.0953 (9) | 0.0206 (5) | 0.0422 (6) | 0.0121 (5) |
F2 | 0.0778 (7) | 0.0631 (6) | 0.0623 (6) | 0.0120 (5) | 0.0304 (5) | 0.0199 (5) |
Geometric parameters (Å, º) top
O—C1 | 1.362 (2) | C2—C3 | 1.376 (2) |
C1—C2 | 1.378 (2) | C3—F2 | 1.343 (2) |
C1—C3^{i} | 1.379 (2) | C3—C1^{i} | 1.379 (2) |
C2—F1 | 1.340 (2) | | |
| | | |
O—C1—C2 | 119.27 (14) | C3—C2—C1 | 121.13 (13) |
O—C1—C3^{i} | 123.30 (14) | F2—C3—C2 | 119.66 (14) |
C2—C1—C3^{i} | 117.40 (13) | F2—C3—C1^{i} | 118.87 (13) |
F1—C2—C3 | 119.26 (14) | C2—C3—C1^{i} | 121.46 (14) |
F1—C2—C1 | 119.60 (13) | | |
Symmetry code: (i) −x+1, −y, −z+2. |
(4) 2,3,5,6-Tetrabromohydroquinone
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Crystal data top
C_{6}H_{2}Br_{4}O_{2} | F(000) = 388 |
M_{r} = 425.72 | D_{x} = 3.041 Mg m^{−}^{3} |
Monoclinic, P2_{1}/n | Melting point: 517 K |
Hall symbol: -P 2yn | Mo Kα radiation, λ = 0.71073 Å |
a = 8.8907 (2) Å | Cell parameters from 2859 reflections |
b = 4.7316 (1) Å | θ = 2.9–28.2° |
c = 11.0612 (3) Å | µ = 17.26 mm^{−}^{1} |
β = 92.167 (1)° | T = 303 K |
V = 464.98 (2) Å^{3} | Block, colourless |
Z = 2 | 0.58 × 0.46 × 0.32 mm |
Data collection top
Siemens SMART diffractometer | 1130 independent reflections |
Radiation source: fine-focus sealed tube | 709 reflections with I > 2σ(I) |
Graphite monochromator | R_{int} = 0.150 |
Data collection in ω at 0.3 ° scan width, four runs with
636, 465, 636 and 465 frames, Φ = 0, 88, 180, 270 | θ_{max} = 28.2°, θ_{min} = 2.9° |
Absorption correction: empirical (using intensity measurements) SADABS (blessing, 1995) Siemens SADABS program has been used for the absorption correction | h = −11→11 |
T_{min} = 0.16, T_{max} = 1.00 | k = −6→6 |
4829 measured reflections | l = −14→14 |
Refinement top
Refinement on F^{2} | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F^{2} > 2σ(F^{2})] = 0.067 | Riding |
wR(F^{2}) = 0.146 | Calculated w = 1/[σ^{2}(F_{o}^{2}) + (0.0448P)^{2}] where P = (F_{o}^{2} + 2F_{c}^{2})/3 |
S = 0.93 | (Δ/σ)_{max} = 0.001 |
1130 reflections | Δρ_{max} = 2.04 e Å^{−}^{3} |
56 parameters | Δρ_{min} = −1.92 e Å^{−}^{3} |
0 restraints | Extinction correction: SHELXL93 (Sheldrick, 1993), Fc^{*}=kFc[1+0.001xFc^{2}λ^{3}/sin(2θ)]^{-1/4} |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.0017 (14) |
Special details top
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 on F^{2} for ALL reflections except for 0 with very negative
F^{2} or flagged by the user for potential systematic errors. Weighted
R-factors wR and all goodnesses of fit S are based on
F^{2}, conventional R-factors R are based on F,
with F set to zero for negative F^{2}. The observed criterion of
F^{2} > σ(F^{2}) is used only for calculating _R_factor_obs
etc. and is not relevant to the choice of reflections for refinement.
R-factors based on F^{2} are statistically about twice as large
as those based on F, and R- factors based on ALL data will be
even larger. |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å^{2}) top | x | y | z | U_{iso}*/U_{eq} | |
O | 0.2092 (6) | 0.5559 (14) | −0.1783 (6) | 0.031 (2) | |
H0A | 0.1779 (6) | 0.6640 (14) | −0.2315 (6) | 0.046* | |
Br1 | 0.32011 (10) | 0.1586 (3) | 0.01217 (10) | 0.0367 (4) | |
Br2 | 0.07172 (10) | 0.0776 (2) | 0.22943 (9) | 0.0316 (4) | |
C1 | 0.1052 (9) | 0.5344 (18) | −0.0910 (8) | 0.022 (2) | |
C2 | 0.1356 (8) | 0.354 (2) | 0.0062 (8) | 0.021 (2) | |
C3 | 0.0310 (9) | 0.3210 (19) | 0.0963 (8) | 0.021 (2) | |
Atomic displacement parameters (Å^{2}) top | U^{11} | U^{22} | U^{33} | U^{12} | U^{13} | U^{23} |
O | 0.021 (4) | 0.050 (5) | 0.022 (4) | 0.003 (3) | 0.008 (3) | 0.006 (3) |
Br1 | 0.0203 (5) | 0.0599 (8) | 0.0298 (7) | 0.0126 (4) | 0.0009 (4) | 0.0003 (5) |
Br2 | 0.0276 (6) | 0.0463 (8) | 0.0206 (6) | 0.0010 (4) | −0.0028 (4) | 0.0073 (4) |
C1 | 0.018 (4) | 0.031 (5) | 0.017 (5) | −0.001 (3) | 0.003 (3) | −0.004 (4) |
C2 | 0.012 (4) | 0.036 (6) | 0.014 (5) | 0.000 (3) | −0.001 (3) | 0.001 (4) |
C3 | 0.017 (4) | 0.034 (5) | 0.012 (5) | −0.002 (3) | −0.008 (3) | 0.000 (4) |
Geometric parameters (Å, º) top
O—C1 | 1.366 (9) | C1—C2 | 1.393 (13) |
Br1—C2 | 1.881 (8) | C2—C3 | 1.396 (12) |
Br2—C3 | 1.893 (9) | C3—C1^{i} | 1.390 (11) |
C1—C3^{i} | 1.390 (11) | | |
| | | |
O—C1—C3^{i} | 123.1 (8) | C3—C2—Br1 | 121.6 (7) |
O—C1—C2 | 118.4 (8) | C1^{i}—C3—C2 | 121.2 (8) |
C3^{i}—C1—C2 | 118.5 (8) | C1^{i}—C3—Br2 | 118.2 (6) |
C1—C2—C3 | 120.2 (8) | C2—C3—Br2 | 120.6 (6) |
C1—C2—Br1 | 118.1 (6) | | |
Symmetry code: (i) −x, −y+1, −z. |