Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270103027124/gd1290sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270103027124/gd1290Isup2.hkl |
CCDC reference: 231076
The title compound was obtained by a conventional route, by coupling 1,4-diiodo-2,5-dimethoxybenzene (Ramos et al., 2001) with HC≡ CSiMe3 in the presence of a Pd(PPh3)4/CuI catalyst (Dirk et al., 2001), followed by proto-desilylation of the resulting 1,4-(SiMe3C≡ C)2-2,5-(MeO)2C6H2 (Pelter & James, 2000), and was identified by comparison of the IR and NMR data with literature values. Crystals suitable for X-ray diffraction were obtained from a CDCl3/methanol mixture.
H atoms were located from difference Fourier maps and placed at idealized positions (C—H = 0.95 Å), and their positional and U values were refined.
Alkyne H atoms are frequently described as exhibiting acid characteristics; recent accurate studies of aromatic alkyne derivatives have demonstrated interactions between such H atoms and other electron-rich entities in crystal lattices that might come under the umbrella of 'hydrogen bonding'. Thus low-temperature structure determinations of 1,4-diethynyl- and 1,3,5-triethynyl-benzenes show that interactions between such H atoms and the triple bonds of adjacent molecules may be considerable determinants of crystal packing, while in ethynylbenzene, in addition, interactions with the aromatic π-system are found (Weiss et al., 1997). In systems containing aromatic nitro groups, the interactions are found to take place with the nitro substituents (Robinson et al., 1999). Having on our shelves a crystalline sample of the title compound, we were interested in ascertaining the nature of any such interactions that might occur therein, in view of the frequent association of the methoxy O atoms with putative positive charges, and so have determined its crystal structure.
At ca 150 K, the crystals diffracted nicely, yielding extensive good quality data, with a concomitantly precise result, enabling definitive location of all H atoms in the X-ray sense. The asymmetric unit contains one-half of the centrosymmetric molecule, in space group P21/c. The aromatic ring is a remarkably regular hexagon; the exocyclic angles at the pendant O atom display the usual asymmetry associated with methoxy substituents, the methoxy C atom being approximately coplanar with the sequence C1–C3 [deviation 0.054 (5) Å] and, as usual, enclosing the larger of the exocyclic angles. The C—H distances fall into three classes, viz. (aliphatic) methyl C—H > aromatic > ethynyl. The essentially planar molecules pack in a staggered herringbone fashion as viewed along a; the closest intermolecular contacts are found between the ethynyl H and the methoxy O atoms (Table 1)
In the course of submission of this paper, we were advised of a parallel contemporary study of this compound, among a broader array of related species, the compound in question being the subject of a room-temperature X-ray powder diffraction study using only 243 reflections, giving R = 0.045 (Khan et al., 2003). While the results of the two studies are harmonious, the present low-temperature single-crystal study provides a degree of precision inaccessible in the powder work.
Data collection: SMART (Siemens, 1995); cell refinement: SAINT (Siemens, 1995); data reduction: Xtal3.5 (Hall et al., 1995); program(s) used to solve structure: Xtal3.5; program(s) used to refine structure: CRYLSQ in Xtal3.5; molecular graphics: Xtal3.5; software used to prepare material for publication: BONDLA and CIFIO in Xtal3.5.
C12H10O2 | F(000) = 196 |
Mr = 186.21 | Dx = 1.257 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -p 2ybc | Cell parameters from 3004 reflections |
a = 9.111 (1) Å | θ = 2.8–34.6° |
b = 5.9921 (7) Å | µ = 0.09 mm−1 |
c = 9.408 (1) Å | T = 150 K |
β = 106.710 (2)° | Plate, colourless |
V = 491.93 (9) Å3 | 0.35 × 0.16 × 0.08 mm |
Z = 2 |
Bruker SMART CCD diffractometer | 2574 independent reflections |
Radiation source: sealed tube | 1957 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.025 |
ω scans | θmax = 37.4°, θmin = 2.3° |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | h = −15→14 |
Tmin = 0.77, Tmax = 0.93 | k = −10→10 |
10271 measured reflections | l = −16→16 |
Refinement on F | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.044 | Hydrogen site location: difference Fourier map |
wR(F2) = 0.05 | All H-atom parameters refined |
S = 1.03 | w = 1/[σ2(F) + 0.0003F2] |
1957 reflections | (Δ/σ)max = 0.005 |
84 parameters | Δρmax = 0.53 e Å−3 |
0 restraints | Δρmin = −0.21 e Å−3 |
0 constraints |
C12H10O2 | V = 491.93 (9) Å3 |
Mr = 186.21 | Z = 2 |
Monoclinic, P21/c | Mo Kα radiation |
a = 9.111 (1) Å | µ = 0.09 mm−1 |
b = 5.9921 (7) Å | T = 150 K |
c = 9.408 (1) Å | 0.35 × 0.16 × 0.08 mm |
β = 106.710 (2)° |
Bruker SMART CCD diffractometer | 2574 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | 1957 reflections with I > 2σ(I) |
Tmin = 0.77, Tmax = 0.93 | Rint = 0.025 |
10271 measured reflections |
R[F2 > 2σ(F2)] = 0.044 | 0 restraints |
wR(F2) = 0.05 | All H-atom parameters refined |
S = 1.03 | Δρmax = 0.53 e Å−3 |
1957 reflections | Δρmin = −0.21 e Å−3 |
84 parameters |
x | y | z | Uiso*/Ueq | ||
C1 | 0.12902 (9) | 0.11388 (15) | 0.08619 (9) | 0.0184 (3) | |
C11 | 0.26167 (10) | 0.22987 (15) | 0.17564 (10) | 0.0206 (3) | |
C12 | 0.37230 (11) | 0.32442 (18) | 0.25064 (11) | 0.0253 (4) | |
C2 | 0.14706 (9) | −0.07129 (15) | 0.00091 (9) | 0.0185 (3) | |
O2 | 0.29445 (7) | −0.12925 (12) | 0.01094 (7) | 0.0232 (3) | |
C21 | 0.31587 (11) | −0.30991 (18) | −0.08093 (11) | 0.0251 (4) | |
C3 | 0.01834 (9) | −0.18351 (15) | −0.08506 (9) | 0.0199 (3) | |
H12 | 0.4603 (18) | 0.398 (3) | 0.3090 (17) | 0.043 (4)* | |
H21a | 0.4284 (16) | −0.323 (2) | −0.0608 (15) | 0.032 (3)* | |
H21b | 0.2691 (16) | −0.275 (2) | −0.1866 (15) | 0.030 (3)* | |
H21c | 0.2737 (14) | −0.450 (2) | −0.0564 (14) | 0.028 (3)* | |
H3 | 0.0288 (14) | −0.312 (2) | −0.1451 (14) | 0.025 (3)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1 | 0.0136 (3) | 0.0204 (4) | 0.0185 (3) | −0.0000 (3) | 0.0003 (2) | −0.0007 (3) |
C11 | 0.0168 (3) | 0.0220 (4) | 0.0214 (4) | 0.0011 (3) | 0.0028 (3) | −0.0002 (3) |
C12 | 0.0189 (4) | 0.0276 (4) | 0.0266 (4) | −0.0024 (3) | 0.0020 (3) | −0.0029 (3) |
C2 | 0.0125 (3) | 0.0219 (4) | 0.0190 (3) | 0.0020 (3) | 0.0011 (2) | −0.0000 (3) |
O2 | 0.0132 (2) | 0.0290 (3) | 0.0250 (3) | 0.0036 (2) | 0.0019 (2) | −0.0053 (3) |
C21 | 0.0214 (4) | 0.0273 (4) | 0.0264 (4) | 0.0056 (3) | 0.0068 (3) | −0.0025 (3) |
C3 | 0.0151 (3) | 0.0217 (4) | 0.0205 (3) | 0.0011 (3) | 0.0012 (2) | −0.0034 (3) |
C1—C11 | 1.4377 (11) | C2—C3 | 1.3914 (11) |
C1—C2 | 1.4063 (13) | O2—C21 | 1.4331 (13) |
C1—C3i | 1.4031 (12) | C21—H21a | 0.991 (15) |
C11—C12 | 1.1941 (12) | C21—H21b | 0.985 (13) |
C12—H12 | 0.940 (14) | C21—H21c | 0.979 (14) |
C2—O2 | 1.3638 (11) | C3—H3 | 0.974 (14) |
C11—C1—C2 | 119.93 (8) | O2—C21—H21a | 104.9 (8) |
C11—C1—C3i | 120.15 (8) | O2—C21—H21b | 110.7 (8) |
C2—C1—C3i | 119.92 (7) | O2—C21—H21c | 112.1 (9) |
C1—C11—C12 | 179.39 (11) | H21a—C21—H21b | 109.4 (12) |
C11—C12—H12 | 179.1 (11) | H21a—C21—H21c | 110.0 (11) |
C1—C2—O2 | 115.83 (7) | H21b—C21—H21c | 109.6 (11) |
C1—C2—C3 | 119.71 (8) | C2—C3—H3 | 120.8 (7) |
O2—C2—C3 | 124.45 (8) | C2—C3—C1i | 120.36 (8) |
C2—O2—C21 | 116.92 (7) | H3—C3—C1i | 118.9 (7) |
Symmetry code: (i) −x, −y, −z. |
D—H···A | D—H | H···A | D···A | D—H···A |
C12—H12···O2ii | 0.94 (1) | 2.39 (1) | 3.227 (1) | 148 (1) |
Symmetry code: (ii) −x+1, y+1/2, −z+1/2. |
Experimental details
Crystal data | |
Chemical formula | C12H10O2 |
Mr | 186.21 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 150 |
a, b, c (Å) | 9.111 (1), 5.9921 (7), 9.408 (1) |
β (°) | 106.710 (2) |
V (Å3) | 491.93 (9) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 0.09 |
Crystal size (mm) | 0.35 × 0.16 × 0.08 |
Data collection | |
Diffractometer | Bruker SMART CCD |
Absorption correction | Multi-scan (SADABS; Sheldrick, 1996) |
Tmin, Tmax | 0.77, 0.93 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 10271, 2574, 1957 |
Rint | 0.025 |
(sin θ/λ)max (Å−1) | 0.855 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.044, 0.05, 1.03 |
No. of reflections | 1957 |
No. of parameters | 84 |
H-atom treatment | All H-atom parameters refined |
Δρmax, Δρmin (e Å−3) | 0.53, −0.21 |
Computer programs: SMART (Siemens, 1995), SAINT (Siemens, 1995), Xtal3.5 (Hall et al., 1995), CRYLSQ in Xtal3.5, BONDLA and CIFIO in Xtal3.5.
D—H···A | D—H | H···A | D···A | D—H···A |
C12—H12···O2i | 0.94 (1) | 2.39 (1) | 3.227 (1) | 148 (1) |
Symmetry code: (i) −x+1, y+1/2, −z+1/2. |
Alkyne H atoms are frequently described as exhibiting acid characteristics; recent accurate studies of aromatic alkyne derivatives have demonstrated interactions between such H atoms and other electron-rich entities in crystal lattices that might come under the umbrella of 'hydrogen bonding'. Thus low-temperature structure determinations of 1,4-diethynyl- and 1,3,5-triethynyl-benzenes show that interactions between such H atoms and the triple bonds of adjacent molecules may be considerable determinants of crystal packing, while in ethynylbenzene, in addition, interactions with the aromatic π-system are found (Weiss et al., 1997). In systems containing aromatic nitro groups, the interactions are found to take place with the nitro substituents (Robinson et al., 1999). Having on our shelves a crystalline sample of the title compound, we were interested in ascertaining the nature of any such interactions that might occur therein, in view of the frequent association of the methoxy O atoms with putative positive charges, and so have determined its crystal structure.
At ca 150 K, the crystals diffracted nicely, yielding extensive good quality data, with a concomitantly precise result, enabling definitive location of all H atoms in the X-ray sense. The asymmetric unit contains one-half of the centrosymmetric molecule, in space group P21/c. The aromatic ring is a remarkably regular hexagon; the exocyclic angles at the pendant O atom display the usual asymmetry associated with methoxy substituents, the methoxy C atom being approximately coplanar with the sequence C1–C3 [deviation 0.054 (5) Å] and, as usual, enclosing the larger of the exocyclic angles. The C—H distances fall into three classes, viz. (aliphatic) methyl C—H > aromatic > ethynyl. The essentially planar molecules pack in a staggered herringbone fashion as viewed along a; the closest intermolecular contacts are found between the ethynyl H and the methoxy O atoms (Table 1)
In the course of submission of this paper, we were advised of a parallel contemporary study of this compound, among a broader array of related species, the compound in question being the subject of a room-temperature X-ray powder diffraction study using only 243 reflections, giving R = 0.045 (Khan et al., 2003). While the results of the two studies are harmonious, the present low-temperature single-crystal study provides a degree of precision inaccessible in the powder work.