Redetermination of 1,4-dimethoxy­benzene

Iuliucci, R.; Hoop, C.L.; Arif, A.M.; Harper, J.K.; Pugmire, R.J.; Grant, D.M.

doi:10.1107/S1600536808044231

organic compounds

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Volume 65| Part 2| February 2009| Page o251

doi:10.1107/S1600536808044231

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Redetermination of 1,4-dimethoxybenzene

Robbie Iuliucci,^a ^* Cody L. Hoop,^a Atta M. Arif,^b James K. Harper,^b Ronald J. Pugmire ^b and David M. Grant ^b

^aDepartment of Chemistry, Washington and Jefferson College, 60 South Lincoln Street, Washington, PA 15301, USA, and ^bDepartment of Chemistry, University of Utah, Salt Lake City, UT 84112, USA
^*Correspondence e-mail: riuliucci@washjeff.edu

(Received 9 December 2008; accepted 30 December 2008; online 8 January 2009)

The structure of the centrosymmetric title compound, C₈H₁₀O₂, originally determined by Goodwin et al. [Acta Cryst.(1950), 3, 279–284], has been redetermined to modern standards of precision to aid in its use as a model compound for ¹³C chemical-shift tensor measurements in single-crystal NMR studies. In the crystal structure, a C—H⋯O interaction helps to establish the packing.

Related literature

For previous structural studies of the title compound, see: Goodwin et al. (1950 ); Carter et al. (1988 ).

Experimental

Crystal data

C₈H₁₀O₂
M_r = 138.16
Orthorhombic, P b c a
a = 7.1757 (3) Å
b = 6.2769 (2) Å
c = 16.5573 (7) Å
V = 745.76 (5) Å³
Z = 4
Mo Kα radiation
μ = 0.09 mm⁻¹
T = 150 (1) K
0.33 × 0.30 × 0.23 mm

Data collection

Nonius KappaCCD diffractometer
Absorption correction: multi-scan (DENZO–SMN; Otwinowski & Minor, 1997 ) T_min = 0.972, T_max = 0.980
1510 measured reflections
847 independent reflections
732 reflections with I > 2σ(I)
R_int = 0.013

Refinement

R[F² > 2σ(F²)] = 0.037
wR(F²) = 0.101
S = 1.09
847 reflections
66 parameters
All H-atom parameters refined
Δρ_max = 0.19 e Å⁻³
Δρ_min = −0.16 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C4—H4A⋯O1ⁱ	1.019 (16)	2.552 (15)	3.4381 (15)	145.1 (10)
Symmetry code: (i) $[-x, y+{\script{1\over 2}}, -z+{\script{1\over 2}}]$ .

Data collection: COLLECT (Hooft, 1998 ); cell refinement: DENZO–SMN (Otwinowski & Minor, 1997); data reduction: DENZO–SMN; program(s) used to solve structure: SIR97 (Altomare et al., 1999 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ); molecular graphics: WinGX (Farrugia, 1999 ) and ORTEP-3 (Farrugia, 1997 ); software used to prepare material for publication: publCIF (Westrip, 2009 ).

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808044231/hb2878sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536808044231/hb2878Isup2.hkl

checkCIF report

Comment top

Large single-crystals of organic compounds can be challenging to grow. Substituted methoxybenzenes are one exception and single-crystals on the order of centimeters can be obtained. The ease of crystal growth has enabled substituted methoxybenzenes to be studied by single-crystal NMR experiments. Pioneering work on the development of the two-dimensional single-crystal chemical-shift chemical-shift correlation NMR experiments utilized large crystals of 1,4-dimethoxybenzene (Carter et al., 1988). In 1950 Goodwin et al. obtained the first X-ray diffraction structure for 1,4-dimethoxybenzene. This structure (R-factor = 0.12) is shown in Fig. 1 and reported an unusual H–C–C angle of 75.7°, which prompted the acquisition of a second structure (Carter et al., 1988). More typical H–C–C angles were observed with this new refinement and this structure (R-factor = 0.067) was used to assign tensor orientations in the single-crystal NMR analysis. Inadvertently, the second structure was never submitted to the Cambridge Crystallographic database. Here, the acquisition of a third structure is reported to correct this oversight. The new structure (R-factor = 0.038) is shown in Fig. 2. The unit-cell and space group of the previous studies are confirmed.

Acquisition of this third, more accurate, structure is beneficial to NMR studies because the ¹³C chemical shift tensor data of 1,4-dimethoxybenzene continue to serve as a standard to evaluate new chemical-shift tensor measurement methods as well as to assess electronic structure methods for computing magnetic properties of molecules.

Related literature top

For previous structural studies of the title compound, see: Goodwin et al. (1950); Carter et al. (1988).

Computing details top

Data collection: COLLECT (Hooft, 1998); cell refinement: DENZO–SMN (Otwinowski & Minor, 1997); data reduction: DENZO–SMN (Otwinowski & Minor, 1997); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: WinGX (Farrugia, 1999) and ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: publCIF (Westrip, 2009).

Figures top

	Fig. 1. The structure of (I) according to Goodwin et al. (1950).
	Fig. 2. The redetermined structure of (I) from the present study.

1,4-dimethoxybenzene top

Crystal data top

C₈H₁₀O₂	D_x = 1.231 Mg m⁻³
M_r = 138.16	Melting point: 329 K
Orthorhombic, Pbca	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2ab	Cell parameters from 13221 reflections
a = 7.1757 (3) Å	θ = 1.0–27.5°
b = 6.2769 (2) Å	µ = 0.09 mm⁻¹
c = 16.5573 (7) Å	T = 150 K
V = 745.76 (5) Å³	Prism, colorless
Z = 4	0.33 × 0.30 × 0.23 mm
F(000) = 296

Data collection top

Nonius KappaCCD diffractometer	847 independent reflections
Radiation source: fine-focus sealed tube	732 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.013
ϕ and ω scans	θ_max = 27.5°, θ_min = 3.8°
Absorption correction: multi-scan (DENZO–SMN; Otwinowski & Minor, 1997)	h = −9→9
T_min = 0.972, T_max = 0.980	k = −8→8
1510 measured reflections	l = −21→21

Refinement top

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)] = 0.037	Hydrogen site location: difference Fourier map
wR(F²) = 0.101	All H-atom parameters refined
S = 1.09	w = 1/[σ²(F_o²) + (0.0517P)² + 0.1487P] where P = (F_o² + 2F_c²)/3
847 reflections	(Δ/σ)_max < 0.001
66 parameters	Δρ_max = 0.19 e Å⁻³
0 restraints	Δρ_min = −0.16 e Å⁻³
none constraints

Crystal data top

C₈H₁₀O₂	V = 745.76 (5) Å³
M_r = 138.16	Z = 4
Orthorhombic, Pbca	Mo Kα radiation
a = 7.1757 (3) Å	µ = 0.09 mm⁻¹
b = 6.2769 (2) Å	T = 150 K
c = 16.5573 (7) Å	0.33 × 0.30 × 0.23 mm

Data collection top

Nonius KappaCCD diffractometer	847 independent reflections
Absorption correction: multi-scan (DENZO–SMN; Otwinowski & Minor, 1997)	732 reflections with I > 2σ(I)
T_min = 0.972, T_max = 0.980	R_int = 0.013
1510 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.037	0 restraints
wR(F²) = 0.101	All H-atom parameters refined
S = 1.09	Δρ_max = 0.19 e Å⁻³
847 reflections	Δρ_min = −0.16 e Å⁻³
66 parameters

Special details top

Experimental. The program DENZO-SMN (Otwinowski & Minor, 1997) uses a scaling algorithm (Fox & Holmes, 1966) which effectively corrects for absorption effects. High redundancy data were used in the scaling program hence the 'multi-scan' code word was used. No transmission coefficients are available from the program (only scale factors for each frame). The scale factors in the experimental table are calculated from the 'size' command in the SHELXL97 input file.

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 > 2σ(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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
O1	0.01305 (11)	0.15781 (13)	0.15601 (4)	0.0315 (3)
C2	0.09537 (13)	−0.10269 (16)	0.06126 (6)	0.0257 (3)
C3	−0.09472 (14)	0.18955 (17)	0.01604 (6)	0.0264 (3)
C1	0.00160 (12)	0.08587 (17)	0.07767 (6)	0.0243 (3)
C4	−0.0849 (2)	0.3490 (2)	0.17534 (8)	0.0410 (3)
H2	0.1619 (17)	−0.175 (2)	0.1048 (8)	0.033 (3)*
H3	−0.1604 (18)	0.319 (2)	0.0253 (7)	0.031 (3)*
H4A	−0.061 (2)	0.375 (2)	0.2352 (10)	0.050 (4)*
H4B	−0.221 (3)	0.323 (2)	0.1672 (9)	0.057 (5)*
H4C	−0.036 (2)	0.470 (3)	0.1413 (11)	0.056 (4)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0387 (5)	0.0328 (5)	0.0231 (4)	0.0040 (3)	−0.0018 (3)	−0.0031 (3)
C2	0.0249 (5)	0.0268 (5)	0.0255 (5)	0.0015 (4)	−0.0017 (4)	0.0043 (4)
C3	0.0259 (5)	0.0244 (5)	0.0288 (6)	0.0029 (4)	0.0012 (4)	0.0014 (4)
C1	0.0241 (5)	0.0267 (5)	0.0220 (5)	−0.0028 (4)	0.0012 (3)	0.0007 (4)
C4	0.0534 (8)	0.0377 (7)	0.0321 (6)	0.0092 (6)	−0.0004 (5)	−0.0104 (5)

Geometric parameters (Å, º) top

O1—C1	1.3759 (12)	C3—C1	1.3937 (14)
O1—C4	1.4269 (14)	C3—H3	0.953 (13)
C2—C1	1.3883 (15)	C4—H4A	1.020 (16)
C2—C3ⁱ	1.3912 (15)	C4—H4B	0.998 (18)
C2—H2	0.977 (13)	C4—H4C	1.010 (18)
C3—C2ⁱ	1.3912 (15)

C1—O1—C4	117.26 (9)	O1—C1—C3	124.51 (10)
C1—C2—C3ⁱ	120.83 (9)	C2—C1—C3	119.68 (10)
C1—C2—H2	119.4 (7)	O1—C4—H4A	105.8 (8)
C3ⁱ—C2—H2	119.8 (7)	O1—C4—H4B	108.4 (9)
C2ⁱ—C3—C1	119.48 (10)	H4A—C4—H4B	108.8 (12)
C2ⁱ—C3—H3	118.7 (8)	O1—C4—H4C	109.7 (9)
C1—C3—H3	121.8 (8)	H4A—C4—H4C	111.2 (12)
O1—C1—C2	115.81 (9)	H4B—C4—H4C	112.6 (12)

C4—O1—C1—C2	−178.76 (10)	C3ⁱ—C2—C1—C3	0.10 (16)
C4—O1—C1—C3	1.69 (15)	C2ⁱ—C3—C1—O1	179.44 (9)
C3ⁱ—C2—C1—O1	−179.47 (9)	C2ⁱ—C3—C1—C2	−0.10 (16)

Symmetry code: (i) −x, −y, −z.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C4—H4A···O1ⁱⁱ	1.019 (16)	2.552 (15)	3.4381 (15)	145.1 (10)

Symmetry code: (ii) −x, y+1/2, −z+1/2.

Experimental details

Crystal data
Chemical formula	C₈H₁₀O₂
M_r	138.16
Crystal system, space group	Orthorhombic, Pbca
Temperature (K)	150
a, b, c (Å)	7.1757 (3), 6.2769 (2), 16.5573 (7)
V (Å³)	745.76 (5)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.09
Crystal size (mm)	0.33 × 0.30 × 0.23

Data collection
Diffractometer	Nonius KappaCCD diffractometer
Absorption correction	Multi-scan (DENZO–SMN; Otwinowski & Minor, 1997)
T_min, T_max	0.972, 0.980
No. of measured, independent and observed [I > 2σ(I)] reflections	1510, 847, 732
R_int	0.013
(sin θ/λ)_max (Å⁻¹)	0.649

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.037, 0.101, 1.09
No. of reflections	847
No. of parameters	66
H-atom treatment	All H-atom parameters refined
Δρ_max, Δρ_min (e Å⁻³)	0.19, −0.16

Computer programs: COLLECT (Hooft, 1998), DENZO–SMN (Otwinowski & Minor, 1997), SIR97 (Altomare et al., 1999), SHELXL97 (Sheldrick, 2008), WinGX (Farrugia, 1999) and ORTEP-3 (Farrugia, 1997), publCIF (Westrip, 2009).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C4—H4A···O1ⁱ	1.019 (16)	2.552 (15)	3.4381 (15)	145.1 (10)

Symmetry code: (i) −x, y+1/2, −z+1/2.

Acknowledgements

This work was supported by NSF grant ECC0304433 and NIH grant 5R01GM08521-44. Financial support for CLH was provided by Presidential Discretionary Funds from Washington and Jefferson College.

References

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