Crystal structure of (E)-undec-2-enoic acid

Sonneck, M.; Peppel, T.; Spannenberg, A.; Wohlrab, S.

doi:10.1107/S2056989015009469

organic compounds

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ISSN: 2056-9890

Volume 71| Part 6| June 2015| Pages o426-o427

doi:10.1107/S2056989015009469

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Crystal structure of (E)-undec-2-enoic acid

Marcel Sonneck,^a Tim Peppel,^a ^* Anke Spannenberg ^a and Sebastian Wohlrab ^a

^aLeibniz-Institut für Katalyse e. V. an der Universität Rostock, Albert-Einstein-Strasse 29a, 18059 Rostock, Germany
^*Correspondence e-mail: tim.peppel@catalysis.de

Edited by C. Rizzoli, Universita degli Studi di Parma, Italy (Received 13 May 2015; accepted 18 May 2015; online 28 May 2015)

In the molecule of the title low-melting α,β-unsaturated carboxylic acid, C₁₁H₂₀O₂, the least-squares mean line through the octyl chain forms an angle of 60.10 (13)° with the normal to plane of the acrylic acid fragment (r.m.s. deviation = 0.008 Å). In the crystal, centrosymmetrically related molecules are linked by pairs of O—H⋯O hydrogen bonds into dimers, forming layers parallel to the (041) plane.

Keywords: crystal structure; hydrogen bond; dimer; unsaturated carboxylic acid.

CCDC reference: 1401589

1. Related literature

For an adapted direct synthesis of the title compound following the procedure established by Knoevenagel (1898 ) and Doebner (1902 ), see: Bikulova et al. (1988 ); Kemme et al. (2010 ). For crystal structure determinations of related unsaturated α,β-carboxylic acids, see, for acrylic acid: Higgs & Sass (1963 ); Chatani et al. (1963 ); Boese et al. (1999 ); Oswald & Urquhart (2011 ); see, for crotonic acid: Shimizu et al. (1974 ); see, for (E)-pent-2-enoic acid: Peppel et al. (2015a ); see, for (E)-hex-2-enoic acid: Peppel et al. (2015b ). For structures of co-crystals containing (E)-hex-2-enoic acid, see: Aakeröy et al. (2003 ); Stanton & Bak (2008 ).

2. Experimental

2.1. Crystal data

C₁₁H₂₀O₂
M_r = 184.27
Triclinic, $[P \overline 1]$
a = 4.6346 (4) Å
b = 5.4200 (5) Å
c = 22.7564 (19) Å
α = 88.386 (2)°
β = 88.357 (2)°
γ = 78.340 (2)°
V = 559.46 (8) Å³
Z = 2
Mo Kα radiation
μ = 0.07 mm⁻¹
T = 150 K
0.50 × 0.41 × 0.12 mm

2.2. Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2014 ) T_min = 0.87, T_max = 0.99
13660 measured reflections
2687 independent reflections
2317 reflections with I > 2σ(I)
R_int = 0.022

2.3. Refinement

R[F² > 2σ(F²)] = 0.047
wR(F²) = 0.134
S = 1.10
2687 reflections
122 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.33 e Å⁻³
Δρ_min = −0.24 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1⋯O2ⁱ	0.90 (2)	1.73 (2)	2.6244 (14)	172.2 (19)
Symmetry code: (i) -x+1, -y-1, -z+1.

Data collection: APEX2 (Bruker, 2014); cell refinement: SAINT (Bruker, 2013 ); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015 ); molecular graphics: SHELXL2014; software used to prepare material for publication: SHELXL2014.

Supporting information

CCDC reference: 1401589

Crystal structure: contains datablocks I, New_Global_Publ_Block. DOI: 10.1107/S2056989015009469/rz5160sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S2056989015009469/rz5160Isup2.hkl

Supporting information file. DOI: 10.1107/S2056989015009469/rz5160Isup3.cml

checkCIF report

Synthesis and crystallization top

Malonic acid (25.0g, 240.2 mmol, 1.0 eq) is dissolved in dry pyridine (38.0g, 480.5mmol, 2.0 eq) at room temperature in a three-necked flask equipped with a magnetic stir bar and a reflux condenser under a mild flow of argon. Nonanal (34.2g, 240.2mmol, 1.0 eq) is then added in one portion and the resulting clear solution is further stirred for 72h at room temperature under argon. Afterwards, the resulting light yellow to orange solution is brought to an acidic pH value by adding phosphoric acid at 0 °C (42.5wt. %, 138.5 g, 600.6mmol, 2.5 eq). The resulting two layers are extracted three times with 150mL portions of ethyl acetate and reduced to a volume of ca. 150 mL in vacuo. To remove impurities from aldol condensation the raw acid is converted into the corresponding sodium salt by addition of an aqueous solution of sodium carbonate (20.4 g, 192.2 mmol, 0.8 eq in 200 mL). After stirring for 30 minutes the water phase is separated and extracted three times with 150 mL portions of ethyl acetate. The water phase is then acidified with concentrated hydrochloric acid (37.0wt. %, 35.5 g, 360.4 mmol, 1.5 eq), the organic phase is separated and the water phase is again extracted three times with 150mL portions of ethyl acetate. The combined organic phases are dried over Na₂SO₄ and evaporated to dryness under diminished pressure. The resulting raw product is further purified by distillation in vacuo yielding the product in purity >99% (GC). m.p. 18°C. ¹H NMR (400MHz, CDCl₃): δ = 12.24 (br s, 1H, OH); 7.09 (dt, ³J = 15.6 Hz, ³J = 7.0 Hz, 1H, -CH-); 5.82 (dt, ³J = 15.6 Hz, ⁴J = 1.6 Hz, 1H, -CH-); 2.26-2.19 (m, 2H, -CH₂-); 1.50-1.43 (m, 2H, -CH₂-); 1.33-1.24 (m, 10H, 5x -CH₂-); 0.91-0.85 (m, 3H, -CH₃-). ¹³C NMR (100MHz, CDCl₃): δ = 172.50 (CO); 152.69 (CH); 120.76 (CH); 32.47 (CH₂); 31.98 (CH₂); 29.48 (CH₂), 29.32 (CH₂), 29.29 (CH₂); 28.02 (CH₂); 22.79 (CH₂); 14.22 (CH₃). MS (EI, 70eV): m/z = 184 (M⁺, 0), 99 (15), 97 (12), 96 (11), 95 (11), 86 (17), 84 (17), 83 (17), 82 (17), 81 (16), 73 (36), 70 (17), 69 (25), 68 (20), 67 (19), 57 (37), 56 (20), 55 (46), 54 (12), 53 (23), 45 (22), 43 (60), 42 (20), 41 (100), 40 (14), 39 (57), 29 (62). HRMS (ESI-TOF/MS): calculated for C₁₁H₂₀O₂ ([M—H]^-) 183.13905, found 183.13912. Elemental analysis for C₁₁H₂₀O₂ % (calc.): C 71.67 (71.70); H 10.83 (10.94). Suitable single crystals were grown by slow evaporation of an ethanolic solution at -30 °C over one week.

Refinement top

H1 could be found from the difference Fourier map and was refined with U_iso(H) fixed at 1.5 U_eq(O) . All other H atoms were placed in idealized positions with d(C—H) = 0.95 Å (CH), 0.99 Å (CH₂), 0.98 Å (CH₃) and refined using a riding model with U_iso(H) fixed at 1.2 U_eq(C) for CH and CH₂ and 1.5 U_eq(C) for CH₃.

Comment top

The crystal structure of (E)-undec-2-enoic acid, C₁₁H₂₀O₂, an α,β-unsaturated carboxylic acid with a melting point near room temperature (m. p. 18°C), is characterized by acid dimers. The corresponding dimers are connected via intermolecular hydrogen bonds of the carboxylic groups C=O···H–O. The crystal packing of (E)-undec-2-enoic acid is described by layers of acid dimers parallel to the (0 4 1) plane which are featured by layers of polar headgroups and hydrophobic hydrocarbon chains. The carboxylic group and the following three carbon atoms (C2, C3, C4) of the (E)-undec-2-enoic acid molecule lie in one plane (r.m.s. deviation = 0.008 Å), whereas the atoms of the hydrocarbon chain starting from C4 until C11 adopt a nearly fully staggered conformation.

Related literature top

For an adapted direct synthesis of the title compound following the procedure established by Knoevenagel (1898) and Doebner (1902), see: Bikulova et al. (1988); Kemme et al. (2010). For crystal structure determinations of related unsaturated α,β-carboxylic acids, see, for acrylic acid: Higgs et al. (1963); Chatani et al. (1963); Boese et al. (1999); Oswald et al. (2011); see, for crotonic acid: Shimizu et al. (1974); see, for (E)-pent-2-enoic acid: Peppel et al. (2015a); see, for (E)-hex-2-enoic acid: Peppel et al. (2015b). For structures of co-crystals containing (E)-hex-2-enoic acid, see: Aakeröy et al. (2003); Stanton & Bak (2008).

Computing details top

Data collection: APEX2 (Bruker, 2014); cell refinement: SAINT (Bruker, 2013); data reduction: SAINT (Bruker, 2013); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015); molecular graphics: SHELXL2014 (Sheldrick, 2015); software used to prepare material for publication: SHELXL2014 (Sheldrick, 2015).

Figures top

	Fig. 1. Molecular structure of the title compound with displacement ellipsoids drawn at 30% probability level.
	Fig. 2. Side view of the molecular structure of the title compound (displacement ellipsoids drawn at 30% probability level).
	Fig. 3. Packing diagram showing intermolecular O—H···O hydrogen bonds. Hydrogen atoms not involved in hydrogen bonding are omitted for clarity.

(E)-Undec-2-enoic acid top

Crystal data top

C₁₁H₂₀O₂	Z = 2
M_r = 184.27	F(000) = 204
Triclinic, P1	D_x = 1.094 Mg m⁻³
a = 4.6346 (4) Å	Mo Kα radiation, λ = 0.71073 Å
b = 5.4200 (5) Å	Cell parameters from 7014 reflections
c = 22.7564 (19) Å	θ = 2.7–29.0°
α = 88.386 (2)°	µ = 0.07 mm⁻¹
β = 88.357 (2)°	T = 150 K
γ = 78.340 (2)°	Plate, colourless
V = 559.46 (8) Å³	0.50 × 0.41 × 0.12 mm

Data collection top

Bruker APEXII CCD diffractometer	2687 independent reflections
Radiation source: fine-focus sealed tube	2317 reflections with I > 2σ(I)
Detector resolution: 8.3333 pixels mm^-1	R_int = 0.022
ϕ and ω scans	θ_max = 28.0°, θ_min = 1.8°
Absorption correction: multi-scan (SADABS; Bruker, 2014)	h = −6→6
T_min = 0.87, T_max = 0.99	k = −7→7
13660 measured reflections	l = −30→30

Refinement top

Refinement on F²	0 restraints
Least-squares matrix: full	Hydrogen site location: mixed
R[F² > 2σ(F²)] = 0.047	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.134	w = 1/[σ²(F_o²) + (0.0544P)² + 0.245P] where P = (F_o² + 2F_c²)/3
S = 1.10	(Δ/σ)_max < 0.001
2687 reflections	Δρ_max = 0.33 e Å⁻³
122 parameters	Δρ_min = −0.24 e Å⁻³

Crystal data top

C₁₁H₂₀O₂	γ = 78.340 (2)°
M_r = 184.27	V = 559.46 (8) Å³
Triclinic, P1	Z = 2
a = 4.6346 (4) Å	Mo Kα radiation
b = 5.4200 (5) Å	µ = 0.07 mm⁻¹
c = 22.7564 (19) Å	T = 150 K
α = 88.386 (2)°	0.50 × 0.41 × 0.12 mm
β = 88.357 (2)°

Data collection top

Bruker APEXII CCD diffractometer	2687 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2014)	2317 reflections with I > 2σ(I)
T_min = 0.87, T_max = 0.99	R_int = 0.022
13660 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.047	0 restraints
wR(F²) = 0.134	H atoms treated by a mixture of independent and constrained refinement
S = 1.10	Δρ_max = 0.33 e Å⁻³
2687 reflections	Δρ_min = −0.24 e Å⁻³
122 parameters

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.

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

	x	y	z	U_iso*/U_eq
C1	0.7148 (3)	−0.2848 (2)	0.45696 (6)	0.0231 (3)
C2	0.8753 (3)	−0.1147 (2)	0.42422 (6)	0.0264 (3)
H2	0.9723	−0.0090	0.4457	0.032*
C3	0.8904 (3)	−0.1026 (2)	0.36643 (6)	0.0251 (3)
H3	0.7934	−0.2107	0.3457	0.030*
C4	1.0477 (3)	0.0674 (3)	0.33084 (6)	0.0278 (3)
H4A	1.2051	−0.0358	0.3066	0.033*
H4B	1.1418	0.1667	0.3576	0.033*
C5	0.8388 (3)	0.2471 (2)	0.29077 (6)	0.0247 (3)
H5A	0.7283	0.1481	0.2672	0.030*
H5B	0.6942	0.3622	0.3154	0.030*
C6	0.9983 (3)	0.4033 (2)	0.24928 (6)	0.0248 (3)
H6A	1.1150	0.4972	0.2728	0.030*
H6B	1.1374	0.2884	0.2236	0.030*
C7	0.7898 (3)	0.5893 (2)	0.21098 (6)	0.0249 (3)
H7A	0.6536	0.7060	0.2367	0.030*
H7B	0.6700	0.4953	0.1883	0.030*
C8	0.9460 (3)	0.7429 (2)	0.16835 (6)	0.0263 (3)
H8A	1.0691	0.8340	0.1910	0.032*
H8B	1.0792	0.6263	0.1421	0.032*
C9	0.7376 (3)	0.9326 (2)	0.13091 (6)	0.0267 (3)
H9A	0.6155	0.8415	0.1080	0.032*
H9B	0.6036	1.0487	0.1571	0.032*
C10	0.8949 (3)	1.0861 (3)	0.08881 (6)	0.0329 (3)
H10A	1.0269	0.9703	0.0622	0.039*
H10B	1.0190	1.1756	0.1116	0.039*
C11	0.6854 (4)	1.2777 (3)	0.05206 (7)	0.0392 (4)
H11A	0.5668	1.1901	0.0282	0.059*
H11B	0.7991	1.3723	0.0262	0.059*
H11C	0.5552	1.3943	0.0781	0.059*
O1	0.5924 (2)	−0.43092 (19)	0.42681 (4)	0.0323 (3)
O2	0.7045 (2)	−0.28190 (19)	0.51201 (4)	0.0320 (3)
H1	0.490 (5)	−0.520 (4)	0.4504 (9)	0.048*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.0225 (6)	0.0211 (6)	0.0259 (6)	−0.0050 (5)	−0.0002 (5)	0.0019 (5)
C2	0.0270 (6)	0.0256 (6)	0.0288 (7)	−0.0111 (5)	−0.0007 (5)	0.0023 (5)
C3	0.0239 (6)	0.0227 (6)	0.0294 (7)	−0.0071 (5)	−0.0009 (5)	0.0031 (5)
C4	0.0263 (7)	0.0299 (7)	0.0282 (7)	−0.0093 (5)	0.0012 (5)	0.0064 (5)
C5	0.0245 (6)	0.0253 (6)	0.0255 (6)	−0.0084 (5)	0.0012 (5)	0.0022 (5)
C6	0.0242 (6)	0.0239 (6)	0.0267 (6)	−0.0065 (5)	0.0029 (5)	0.0030 (5)
C7	0.0243 (6)	0.0238 (6)	0.0269 (6)	−0.0065 (5)	0.0012 (5)	0.0023 (5)
C8	0.0255 (6)	0.0239 (6)	0.0292 (7)	−0.0052 (5)	0.0028 (5)	0.0039 (5)
C9	0.0271 (7)	0.0242 (6)	0.0288 (7)	−0.0058 (5)	0.0003 (5)	0.0030 (5)
C10	0.0353 (8)	0.0307 (7)	0.0318 (7)	−0.0059 (6)	0.0037 (6)	0.0064 (6)
C11	0.0485 (9)	0.0335 (8)	0.0338 (8)	−0.0053 (7)	−0.0004 (7)	0.0094 (6)
O1	0.0394 (6)	0.0321 (5)	0.0302 (5)	−0.0195 (4)	−0.0007 (4)	0.0029 (4)
O2	0.0413 (6)	0.0325 (5)	0.0253 (5)	−0.0157 (4)	0.0023 (4)	0.0032 (4)

Geometric parameters (Å, º) top

C1—O2	1.2527 (16)	C7—C8	1.5219 (17)
C1—O1	1.2862 (16)	C7—H7A	0.9900
C1—C2	1.4717 (17)	C7—H7B	0.9900
C2—C3	1.3153 (19)	C8—C9	1.5207 (18)
C2—H2	0.9500	C8—H8A	0.9900
C3—C4	1.4942 (17)	C8—H8B	0.9900
C3—H3	0.9500	C9—C10	1.5173 (19)
C4—C5	1.5289 (18)	C9—H9A	0.9900
C4—H4A	0.9900	C9—H9B	0.9900
C4—H4B	0.9900	C10—C11	1.520 (2)
C5—C6	1.5239 (17)	C10—H10A	0.9900
C5—H5A	0.9900	C10—H10B	0.9900
C5—H5B	0.9900	C11—H11A	0.9800
C6—C7	1.5215 (17)	C11—H11B	0.9800
C6—H6A	0.9900	C11—H11C	0.9800
C6—H6B	0.9900	O1—H1	0.90 (2)

O2—C1—O1	123.41 (12)	C8—C7—H7A	108.8
O2—C1—C2	119.25 (11)	C6—C7—H7B	108.8
O1—C1—C2	117.34 (11)	C8—C7—H7B	108.8
C3—C2—C1	122.85 (12)	H7A—C7—H7B	107.7
C3—C2—H2	118.6	C9—C8—C7	113.76 (11)
C1—C2—H2	118.6	C9—C8—H8A	108.8
C2—C3—C4	125.24 (12)	C7—C8—H8A	108.8
C2—C3—H3	117.4	C9—C8—H8B	108.8
C4—C3—H3	117.4	C7—C8—H8B	108.8
C3—C4—C5	111.88 (11)	H8A—C8—H8B	107.7
C3—C4—H4A	109.2	C10—C9—C8	113.44 (11)
C5—C4—H4A	109.2	C10—C9—H9A	108.9
C3—C4—H4B	109.2	C8—C9—H9A	108.9
C5—C4—H4B	109.2	C10—C9—H9B	108.9
H4A—C4—H4B	107.9	C8—C9—H9B	108.9
C6—C5—C4	112.95 (11)	H9A—C9—H9B	107.7
C6—C5—H5A	109.0	C9—C10—C11	113.21 (13)
C4—C5—H5A	109.0	C9—C10—H10A	108.9
C6—C5—H5B	109.0	C11—C10—H10A	108.9
C4—C5—H5B	109.0	C9—C10—H10B	108.9
H5A—C5—H5B	107.8	C11—C10—H10B	108.9
C7—C6—C5	113.02 (11)	H10A—C10—H10B	107.8
C7—C6—H6A	109.0	C10—C11—H11A	109.5
C5—C6—H6A	109.0	C10—C11—H11B	109.5
C7—C6—H6B	109.0	H11A—C11—H11B	109.5
C5—C6—H6B	109.0	C10—C11—H11C	109.5
H6A—C6—H6B	107.8	H11A—C11—H11C	109.5
C6—C7—C8	113.71 (11)	H11B—C11—H11C	109.5
C6—C7—H7A	108.8	C1—O1—H1	110.8 (13)

O2—C1—C2—C3	−178.40 (13)	C4—C5—C6—C7	−177.83 (11)
O1—C1—C2—C3	1.88 (19)	C5—C6—C7—C8	−178.77 (11)
C1—C2—C3—C4	179.50 (12)	C6—C7—C8—C9	−178.82 (11)
C2—C3—C4—C5	−119.96 (15)	C7—C8—C9—C10	179.63 (11)
C3—C4—C5—C6	−173.87 (11)	C8—C9—C10—C11	−179.27 (12)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···O2ⁱ	0.90 (2)	1.73 (2)	2.6244 (14)	172.2 (19)

Symmetry code: (i) −x+1, −y−1, −z+1.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···O2ⁱ	0.90 (2)	1.73 (2)	2.6244 (14)	172.2 (19)

Symmetry code: (i) −x+1, −y−1, −z+1.

Acknowledgements

The authors thank P. Thiele (University of Rostock) for the DSC measurements and Professor Dr J. G. de Vries (LIKAT) for helpful support.

References

Aakeröy, C. B., Beatty, A. M., Helfrich, B. A. & Nieuwenhuyzen, M. (2003). Cryst. Growth Des. 3, 159–165. Web of Science CSD CrossRef Google Scholar
Bikulova, L. M., Verba, G. G., Kamaev, F. G. & Abduvakhabov, A. A. (1988). Khim. Prir. Soedin. pp. 682–683. Google Scholar
Boese, R., Bläser, D., Steller, I., Latz, R. & Bäumen, A. (1999). Acta Cryst. C55 IUC9900006. Google Scholar
Bruker (2013). SAINT. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Bruker (2014). APEX2 and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Chatani, Y., Sakata, Y. & Nitta, I. (1963). J. Polym. Sci. B Polym. Lett. 1, 419–421. CrossRef Web of Science Google Scholar
Doebner, O. (1902). Ber. Dtsch. Chem. Ges. 35, 1136–1147. CrossRef CAS Google Scholar
Higgs, M. A. & Sass, R. L. (1963). Acta Cryst. 16, 657–661. CSD CrossRef IUCr Journals Web of Science Google Scholar
Kemme, S. T., Šmejkal, T. & Breit, B. (2010). Chem. Eur. J. 16, 3423–3433. CrossRef CAS PubMed Google Scholar
Knoevenagel, E. (1898). Ber. Dtsch. Chem. Ges. 31, 2596–2619. CrossRef CAS Google Scholar
Oswald, I. D. H. & Urquhart, A. J. (2011). CrystEngComm, 13, 4503–4507. Web of Science CSD CrossRef CAS Google Scholar
Peppel, T., Sonneck, M., Spannenberg, A. & Wohlrab, S. (2015a). Acta Cryst. E71, o316. CSD CrossRef IUCr Journals Google Scholar
Peppel, T., Sonneck, M., Spannenberg, A. & Wohlrab, S. (2015b). Acta Cryst. E71, o323. CSD CrossRef IUCr Journals Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Sheldrick, G. M. (2015). Acta Cryst. C71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Shimizu, S., Kekka, S., Kashino, S. & Haisa, M. (1974). Bull. Chem. Soc. Jpn, 47, 1627–1631. CrossRef CAS Web of Science Google Scholar
Stanton, M. K. & Bak, A. (2008). Cryst. Growth Des. 8, 3856–3862. Web of Science CSD CrossRef CAS Google Scholar

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ISSN: 2056-9890

Volume 71| Part 6| June 2015| Pages o426-o427

doi:10.1107/S2056989015009469

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