4-[(2-Hydr­oxy-1-naphth­yl)methyl­idene­amino]benzoic acid

Akkurt, M.; Yıldırım, S.Ö.; Asiri, A.M.; McKee, V.

doi:10.1107/S1600536808006107

organic compounds

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ISSN: 2056-9890

Volume 64| Part 4| April 2008| Page o682

doi:10.1107/S1600536808006107

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4-[(2-Hydroxy-1-naphthyl)methylideneamino]benzoic acid

Mehmet Akkurt,^a ^* Sema Öztürk Yıldırım,^a Abdullah Mohamed Asiri ^b and Vickie McKee ^c

^aDepartment of Physics, Faculty of Arts and Sciences, Erciyes University, 38039 Kayseri, Turkey, ^bChemistry Department, Faculty of Science, King Abdul-Aziz University, P. O. Box 80203, Jeddah 21589, Saudi Arabia, and ^cDepartment of Chemistry, Loughborough University, Leicestershire LE11 3TU, England
^*Correspondence e-mail: akkurt@erciyes.edu.tr

(Received 3 March 2008; accepted 5 March 2008; online 7 March 2008)

The molecule of the title compound, C₁₈H₁₃NO₃, is almost planar, the dihedral angle between the naphthalene and benzene ring systems being 4.04 (6)°. The molecular conformation and packing are stabilized by intramolecular O—H⋯N and intermolecular O—H⋯O and C—H⋯O interactions.

Related literature

For background, see: Asiri & Badahdah (2007 ).

Experimental

Crystal data

C₁₈H₁₃NO₃
M_r = 291.29
Monoclinic, C 2/c
a = 14.7490 (12) Å
b = 4.9850 (4) Å
c = 36.750 (3) Å
β = 91.305 (1)°
V = 2701.3 (4) Å³
Z = 8
Mo Kα radiation
μ = 0.10 mm⁻¹
T = 150 (2) K
0.31 × 0.19 × 0.09 mm

Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2005 ) T_min = 0.970, T_max = 0.991
13445 measured reflections
3520 independent reflections
2761 reflections with I > 2σ(I)
R_int = 0.031

Refinement

R[F² > 2σ(F²)] = 0.050
wR(F²) = 0.145
S = 1.07
3520 reflections
210 parameters
H-atom parameters constrained
Δρ_max = 0.59 e Å⁻³
Δρ_min = −0.33 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—HO1⋯N1	0.82	1.82	2.5572 (16)	148
O2—HO2⋯O3ⁱ	0.82	1.81	2.6281 (14)	171
C14—H14⋯O2ⁱⁱ	0.93	2.56	3.3611 (17)	145
C16—H16⋯O1ⁱⁱⁱ	0.93	2.49	3.1542 (19)	128
Symmetry codes: (i) -x+1, -y-1, -z; (ii) $[-x+{\script{1\over 2}}, -y-{\script{1\over 2}}, -z]$ ; (iii) $[x+{\script{1\over 2}}, y-{\script{1\over 2}}, z]$ .

Data collection: APEX2 (Bruker, 2005); cell refinement: APEX2; data reduction: SAINT (Bruker, 2005); program(s) used to solve structure: SIR97 (Altomare et al., 1999 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 ); software used to prepare material for publication: WinGX (Farrugia, 1999 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808006107/hb2705sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536808006107/hb2705Isup2.hkl

checkCIF report

Comment top

2-Hydroxy Schiff base ligands and their complexes, derived from the reaction of salicylaldehyde and 2-hydroxy-1-naphthaldehyde with amines are of interest due to the existence of (O—H ···N and N—H ···O) type hydrogen bonds and tautomerism between the enol-imine and keto-enamine forms. Tautomerism in 2-hydroxy Schiff bases both in solution and in the solid state was investigated using different spectroscopic techniques (Asiri & Badahdah, 2007).

In the title compound, (I), the molecule is almost planar (Fig. 1). The maximum deviation of the non-H atoms from their mean plane is 0.087 (1) Å for O3. The dihedral angle between the naphthalene ring and the benzene ring is 4.04 (6)°.

The molecular conformation is stabilized by an intramolecular O—H···N hydrogen bond (Table 1). Then, classical inversion dimers are formed by head-to-head O—H···O linkages of the carboxylic acid groups. Finally, C—H ···O interactions link the dimers into sheets (Fig. 2).

Related literature top

For background, see: Asiri & Badahdah (2007).

Experimental top

A solution of 4-aminobenzoic acid (5.0 g, 36.5 mmol) in hot ethanol was mixed with an ethanolic solution of 2-hydroxynaphthaldehyde (7.23 g, 36.5 mmol) and the resulting mixture was refluxed for 3 h. The mxiture was cooled to recover the crude product. Orange laths of (I) were recrystalized from ethanol. IR ν (cm^-1); 1683.3 (C?O), 1588.1 (C?N), 1427.1 (C?C), 1301.4 (C—O) and 1152 (C—N). [M.p.: > 573 K, yield: 54.7%].

Computing details top

Data collection: APEX2 (Bruker, 2005); cell refinement: APEX2 (Bruker, 2005); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures top

	Fig. 1. The molecular structure of (I), with displacement ellipsoids for the non-H atoms are drawn at the 50% probability level.
	Fig. 2. The packing for (I) showing hydrogen bonds as dashed lines.

4-[(2-Hydroxy-1-naphthyl)methylideneamino]benzoic acid top

Crystal data top

C₁₈H₁₃NO₃	F(000) = 1216
M_r = 291.29	D_x = 1.433 Mg m⁻³
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71069 Å
Hall symbol: -C 2yc	Cell parameters from 3973 reflections
a = 14.7490 (12) Å	θ = 2.2–28.8°
b = 4.9850 (4) Å	µ = 0.10 mm⁻¹
c = 36.750 (3) Å	T = 150 K
β = 91.305 (1)°	Lath, orange
V = 2701.3 (4) Å³	0.31 × 0.19 × 0.09 mm
Z = 8

Data collection top

Bruker APEXII CCD diffractometer	3520 independent reflections
Radiation source: sealed tube	2761 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.031
ϕ and ω scans	θ_max = 28.9°, θ_min = 2.2°
Absorption correction: multi-scan (SADABS; Bruker, 2005)	h = −20→19
T_min = 0.970, T_max = 0.991	k = −6→6
13445 measured reflections	l = −49→49

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)] = 0.050	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.145	H-atom parameters constrained
S = 1.07	w = 1/[σ²(F_o²) + (0.0792P)² + 1.0642P] where P = (F_o² + 2F_c²)/3
3520 reflections	(Δ/σ)_max < 0.001
210 parameters	Δρ_max = 0.59 e Å⁻³
0 restraints	Δρ_min = −0.33 e Å⁻³

Crystal data top

C₁₈H₁₃NO₃	V = 2701.3 (4) Å³
M_r = 291.29	Z = 8
Monoclinic, C2/c	Mo Kα radiation
a = 14.7490 (12) Å	µ = 0.10 mm⁻¹
b = 4.9850 (4) Å	T = 150 K
c = 36.750 (3) Å	0.31 × 0.19 × 0.09 mm
β = 91.305 (1)°

Data collection top

Bruker APEXII CCD diffractometer	3520 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2005)	2761 reflections with I > 2σ(I)
T_min = 0.970, T_max = 0.991	R_int = 0.031
13445 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.050	0 restraints
wR(F²) = 0.145	H-atom parameters constrained
S = 1.07	Δρ_max = 0.59 e Å⁻³
3520 reflections	Δρ_min = −0.33 e Å⁻³
210 parameters

Special details top

Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles

Refinement. Refinement on F² for ALL reflections except those flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The observed criterion of F² > σ(F²) is used only for calculating -R-factor-obs 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	0.11588 (7)	0.8430 (3)	0.11623 (4)	0.0398 (4)
O2	0.39188 (7)	−0.3435 (2)	0.00066 (3)	0.0295 (3)
O3	0.52323 (6)	−0.2551 (2)	0.03002 (3)	0.0277 (3)
N1	0.26607 (8)	0.6069 (2)	0.10400 (3)	0.0232 (3)
C1	0.15748 (10)	0.9891 (3)	0.13926 (4)	0.0293 (4)
C2	0.10809 (11)	1.1871 (4)	0.15946 (5)	0.0387 (5)
C3	0.14890 (11)	1.3471 (3)	0.18415 (5)	0.0368 (5)
C4	0.24458 (10)	1.3336 (3)	0.19194 (4)	0.0273 (4)
C5	0.28528 (12)	1.5100 (3)	0.21737 (4)	0.0333 (4)
C6	0.37653 (13)	1.5035 (3)	0.22449 (4)	0.0367 (5)
C7	0.43000 (12)	1.3207 (3)	0.20591 (5)	0.0382 (5)
C8	0.39165 (11)	1.1460 (3)	0.18077 (4)	0.0328 (4)
C9	0.29754 (10)	1.1446 (3)	0.17322 (4)	0.0235 (4)
C10	0.25387 (9)	0.9658 (3)	0.14694 (4)	0.0227 (3)
C11	0.30277 (9)	0.7702 (3)	0.12869 (4)	0.0222 (3)
C12	0.31172 (9)	0.4082 (3)	0.08444 (4)	0.0216 (3)
C13	0.26106 (9)	0.2595 (3)	0.05899 (4)	0.0237 (4)
C14	0.30229 (9)	0.0589 (3)	0.03908 (4)	0.0236 (4)
C15	0.39461 (9)	0.0041 (3)	0.04452 (4)	0.0212 (3)
C16	0.44479 (9)	0.1537 (3)	0.07000 (4)	0.0237 (4)
C17	0.40437 (9)	0.3544 (3)	0.08974 (4)	0.0237 (4)
C18	0.44065 (9)	−0.2106 (3)	0.02406 (4)	0.0224 (3)
HO1	0.15250	0.74990	0.10550	0.0600*
H2	0.04600	1.20430	0.15520	0.053 (6)*
HO2	0.42310	−0.45920	−0.00880	0.0440*
H3	0.11410	1.47080	0.19660	0.046 (5)*
H5	0.24950	1.63300	0.22950	0.041 (5)*
H6	0.40270	1.61950	0.24150	0.045 (5)*
H7	0.49230	1.31630	0.21050	0.058 (6)*
H8	0.42870	1.02670	0.16860	0.037 (5)*
H11	0.36440	0.75340	0.13410	0.0270*
H13	0.19960	0.29500	0.05540	0.0280*
H14	0.26850	−0.03930	0.02210	0.031 (4)*
H16	0.50620	0.11760	0.07370	0.022 (4)*
H17	0.43850	0.45380	0.10650	0.031 (4)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0220 (5)	0.0457 (7)	0.0513 (7)	0.0052 (5)	−0.0055 (5)	−0.0177 (6)
O2	0.0250 (5)	0.0288 (5)	0.0348 (6)	−0.0002 (4)	0.0003 (4)	−0.0125 (4)
O3	0.0212 (5)	0.0280 (5)	0.0340 (5)	0.0019 (4)	0.0017 (4)	−0.0052 (4)
N1	0.0220 (5)	0.0239 (6)	0.0238 (6)	0.0009 (4)	0.0003 (4)	−0.0034 (4)
C1	0.0236 (7)	0.0307 (7)	0.0336 (8)	0.0035 (6)	0.0012 (6)	−0.0026 (6)
C2	0.0244 (7)	0.0432 (9)	0.0485 (10)	0.0085 (7)	0.0031 (7)	−0.0090 (8)
C3	0.0340 (8)	0.0371 (8)	0.0396 (9)	0.0111 (7)	0.0078 (7)	−0.0078 (7)
C4	0.0359 (8)	0.0237 (7)	0.0224 (7)	0.0030 (6)	0.0047 (5)	0.0017 (5)
C5	0.0487 (9)	0.0257 (7)	0.0257 (7)	0.0055 (7)	0.0049 (6)	−0.0032 (6)
C6	0.0533 (10)	0.0281 (7)	0.0285 (8)	−0.0041 (7)	−0.0049 (7)	−0.0053 (6)
C7	0.0379 (9)	0.0361 (8)	0.0402 (9)	−0.0015 (7)	−0.0091 (7)	−0.0079 (7)
C8	0.0319 (8)	0.0295 (7)	0.0368 (8)	0.0039 (6)	−0.0038 (6)	−0.0084 (6)
C9	0.0287 (7)	0.0204 (6)	0.0213 (6)	0.0014 (5)	0.0020 (5)	0.0011 (5)
C10	0.0233 (6)	0.0226 (6)	0.0222 (6)	0.0009 (5)	0.0012 (5)	0.0000 (5)
C11	0.0209 (6)	0.0230 (6)	0.0228 (6)	0.0005 (5)	0.0000 (5)	0.0001 (5)
C12	0.0219 (6)	0.0215 (6)	0.0214 (6)	0.0000 (5)	0.0016 (5)	−0.0002 (5)
C13	0.0182 (6)	0.0264 (7)	0.0264 (7)	0.0009 (5)	−0.0023 (5)	−0.0018 (5)
C14	0.0223 (6)	0.0246 (6)	0.0237 (7)	−0.0021 (5)	−0.0022 (5)	−0.0031 (5)
C15	0.0206 (6)	0.0210 (6)	0.0221 (6)	−0.0017 (5)	0.0018 (5)	−0.0010 (5)
C16	0.0188 (6)	0.0261 (7)	0.0263 (7)	−0.0006 (5)	−0.0001 (5)	−0.0033 (5)
C17	0.0210 (6)	0.0258 (7)	0.0243 (6)	−0.0020 (5)	−0.0016 (5)	−0.0048 (5)
C18	0.0223 (6)	0.0214 (6)	0.0235 (6)	−0.0025 (5)	0.0027 (5)	−0.0013 (5)

Geometric parameters (Å, º) top

O1—C1	1.265 (2)	C12—C17	1.4018 (19)
O2—C18	1.2914 (18)	C12—C13	1.397 (2)
O3—C18	1.2524 (16)	C13—C14	1.388 (2)
O1—HO1	0.8200	C14—C15	1.3987 (19)
O2—HO2	0.8200	C15—C16	1.396 (2)
N1—C12	1.4047 (18)	C15—C18	1.482 (2)
N1—C11	1.3254 (18)	C16—C17	1.379 (2)
C1—C2	1.442 (2)	C2—H2	0.9300
C1—C10	1.448 (2)	C3—H3	0.9300
C2—C3	1.341 (3)	C5—H5	0.9300
C3—C4	1.435 (2)	C6—H6	0.9300
C4—C9	1.413 (2)	C7—H7	0.9300
C4—C5	1.408 (2)	C8—H8	0.9300
C5—C6	1.366 (3)	C11—H11	0.9300
C6—C7	1.394 (2)	C13—H13	0.9300
C7—C8	1.381 (2)	C14—H14	0.9300
C8—C9	1.409 (2)	C16—H16	0.9300
C9—C10	1.454 (2)	C17—H17	0.9300
C10—C11	1.394 (2)

C1—O1—HO1	109.00	C14—C15—C18	121.63 (13)
C18—O2—HO2	109.00	C15—C16—C17	120.76 (13)
C11—N1—C12	126.19 (12)	C12—C17—C16	119.83 (13)
O1—C1—C2	119.70 (14)	O3—C18—C15	119.63 (13)
C2—C1—C10	117.37 (13)	O2—C18—O3	123.39 (13)
O1—C1—C10	122.92 (14)	O2—C18—C15	116.99 (12)
C1—C2—C3	122.09 (15)	C1—C2—H2	119.00
C2—C3—C4	122.11 (15)	C3—C2—H2	119.00
C3—C4—C9	119.09 (14)	C2—C3—H3	119.00
C3—C4—C5	120.38 (14)	C4—C3—H3	119.00
C5—C4—C9	120.52 (14)	C4—C5—H5	119.00
C4—C5—C6	121.06 (14)	C6—C5—H5	119.00
C5—C6—C7	119.19 (15)	C5—C6—H6	120.00
C6—C7—C8	120.81 (16)	C7—C6—H6	120.00
C7—C8—C9	121.42 (14)	C6—C7—H7	120.00
C4—C9—C10	119.40 (13)	C8—C7—H7	120.00
C4—C9—C8	116.99 (13)	C7—C8—H8	119.00
C8—C9—C10	123.59 (13)	C9—C8—H8	119.00
C1—C10—C11	118.61 (13)	N1—C11—H11	118.00
C1—C10—C9	119.90 (13)	C10—C11—H11	118.00
C9—C10—C11	121.48 (12)	C12—C13—H13	120.00
N1—C11—C10	123.46 (12)	C14—C13—H13	120.00
N1—C12—C17	122.74 (13)	C13—C14—H14	120.00
C13—C12—C17	119.77 (13)	C15—C14—H14	120.00
N1—C12—C13	117.49 (12)	C15—C16—H16	120.00
C12—C13—C14	120.09 (12)	C17—C16—H16	120.00
C13—C14—C15	120.15 (13)	C12—C17—H17	120.00
C14—C15—C16	119.41 (13)	C16—C17—H17	120.00
C16—C15—C18	118.96 (12)

C12—N1—C11—C10	179.29 (14)	C7—C8—C9—C10	179.74 (15)
C11—N1—C12—C13	−178.82 (14)	C4—C9—C10—C1	2.2 (2)
C11—N1—C12—C17	1.6 (2)	C4—C9—C10—C11	−177.85 (14)
O1—C1—C2—C3	−179.95 (18)	C8—C9—C10—C1	−176.23 (14)
C10—C1—C2—C3	0.8 (3)	C8—C9—C10—C11	3.8 (2)
O1—C1—C10—C9	178.67 (15)	C1—C10—C11—N1	1.4 (2)
O1—C1—C10—C11	−1.3 (2)	C9—C10—C11—N1	−178.55 (14)
C2—C1—C10—C9	−2.1 (2)	N1—C12—C13—C14	−179.43 (13)
C2—C1—C10—C11	177.93 (15)	C17—C12—C13—C14	0.1 (2)
C1—C2—C3—C4	0.5 (3)	N1—C12—C17—C16	179.04 (13)
C2—C3—C4—C5	178.31 (16)	C13—C12—C17—C16	−0.5 (2)
C2—C3—C4—C9	−0.5 (2)	C12—C13—C14—C15	0.3 (2)
C3—C4—C5—C6	−178.57 (15)	C13—C14—C15—C16	−0.3 (2)
C9—C4—C5—C6	0.2 (2)	C13—C14—C15—C18	179.30 (14)
C3—C4—C9—C8	177.61 (14)	C14—C15—C16—C17	−0.1 (2)
C3—C4—C9—C10	−0.9 (2)	C18—C15—C16—C17	−179.67 (14)
C5—C4—C9—C8	−1.1 (2)	C14—C15—C18—O2	0.7 (2)
C5—C4—C9—C10	−179.65 (14)	C14—C15—C18—O3	−179.25 (14)
C4—C5—C6—C7	0.7 (2)	C16—C15—C18—O2	−179.75 (13)
C5—C6—C7—C8	−0.5 (2)	C16—C15—C18—O3	0.3 (2)
C6—C7—C8—C9	−0.5 (2)	C15—C16—C17—C12	0.5 (2)
C7—C8—C9—C4	1.3 (2)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—HO1···N1	0.82	1.82	2.5572 (16)	148
O2—HO2···O3ⁱ	0.82	1.81	2.6281 (14)	171
C14—H14···O2ⁱⁱ	0.93	2.56	3.3611 (17)	145
C16—H16···O1ⁱⁱⁱ	0.93	2.49	3.1542 (19)	128

Symmetry codes: (i) −x+1, −y−1, −z; (ii) −x+1/2, −y−1/2, −z; (iii) x+1/2, y−1/2, z.

Experimental details

Crystal data
Chemical formula	C₁₈H₁₃NO₃
M_r	291.29
Crystal system, space group	Monoclinic, C2/c
Temperature (K)	150
a, b, c (Å)	14.7490 (12), 4.9850 (4), 36.750 (3)
β (°)	91.305 (1)
V (Å³)	2701.3 (4)
Z	8
Radiation type	Mo Kα
µ (mm⁻¹)	0.10
Crystal size (mm)	0.31 × 0.19 × 0.09

Data collection
Diffractometer	Bruker APEXII CCD diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2005)
T_min, T_max	0.970, 0.991
No. of measured, independent and observed [I > 2σ(I)] reflections	13445, 3520, 2761
R_int	0.031
(sin θ/λ)_max (Å⁻¹)	0.679

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.050, 0.145, 1.07
No. of reflections	3520
No. of parameters	210
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.59, −0.33

Computer programs: APEX2 (Bruker, 2005), SIR97 (Altomare et al., 1999), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 1997), WinGX (Farrugia, 1999).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—HO1···N1	0.82	1.82	2.5572 (16)	148
O2—HO2···O3ⁱ	0.82	1.81	2.6281 (14)	171
C14—H14···O2ⁱⁱ	0.93	2.56	3.3611 (17)	145
C16—H16···O1ⁱⁱⁱ	0.93	2.49	3.1542 (19)	128

Symmetry codes: (i) −x+1, −y−1, −z; (ii) −x+1/2, −y−1/2, −z; (iii) x+1/2, y−1/2, z.

References

Altomare, A., Burla, M. C., Camalli, M., Cascarano, G. L., Giacovazzo, C., Guagliardi, A., Moliterni, A. G. G., Polidori, G. & Spagna, R. (1999). J. Appl. Cryst. 32, 115–119. Web of Science CrossRef CAS IUCr Journals Google Scholar
Asiri, A. M. & Badahdah, K. O. (2007). Molecules, 12, 1796-1804. Web of Science CrossRef PubMed CAS Google Scholar
Bruker (2005). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565. CrossRef IUCr Journals Google Scholar
Farrugia, L. J. (1999). J. Appl. Cryst. 32, 837–838. CrossRef CAS IUCr Journals Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar

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Volume 64| Part 4| April 2008| Page o682

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