2,2′-Dithio­diterephthalic acid

Zhang, L.

doi:10.1107/S1600536809013622

organic compounds

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ISSN: 2056-9890

Volume 65| Part 5| May 2009| Page o1095

doi:10.1107/S1600536809013622

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2,2′-Dithioditerephthalic acid

Ling Zhang ^a ^*

^aDepartment of Chemistry, Lishui University, 323000 Lishui, ZheJiang, People's Republic of China
^*Correspondence e-mail: zhangling2005@126.com

(Received 5 April 2009; accepted 10 April 2009; online 22 April 2009)

In the title molecule, C₁₆H₁₀O₈S₂, the two aromatic rings form a dihedral angle of 87.97 (12)°. In the crystal structure, intermolecular O—H⋯O hydrogen bonds [O⋯O = 2.623 (3)–2.639 (3) Å] link the molecules into layers parallel to the ab plane.

Related literature

For complexes of disulfide derivatives, see Li et al. (2008 ).

Experimental

Crystal data

C₁₆H₁₀O₈S₂
M_r = 394.36
Monoclinic, C 2/c
a = 16.396 (3) Å
b = 9.8462 (15) Å
c = 20.363 (3) Å
β = 98.840 (2)°
V = 3248.2 (9) Å³
Z = 8
Mo Kα radiation
μ = 0.37 mm⁻¹
T = 298 K
0.48 × 0.21 × 0.03 mm

Data collection

Bruker APEXII area-detector diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 2004 ) T_min = 0.831, T_max = 0.988
11095 measured reflections
3027 independent reflections
1992 reflections with I > 2σ(I)
R_int = 0.039

Refinement

R[F² > 2σ(F²)] = 0.047
wR(F²) = 0.140
S = 1.03
3027 reflections
239 parameters
H-atom parameters constrained
Δρ_max = 0.53 e Å⁻³
Δρ_min = −0.32 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O8—H8D⋯O5ⁱ	0.82	1.81	2.632 (3)	174
O6—H6D⋯O7ⁱⁱ	0.82	1.83	2.633 (3)	166
O3—H3D⋯O1ⁱⁱⁱ	0.82	1.81	2.623 (3)	174
O2—H2D⋯O4^iv	0.82	1.82	2.639 (3)	174
Symmetry codes: (i) $[x+{\script{1\over 2}}, y-{\script{1\over 2}}, z]$ ; (ii) $[x-{\script{1\over 2}}, y+{\script{1\over 2}}, z]$ ; (iii) $[x-{\script{1\over 2}}, y-{\script{1\over 2}}, z]$ ; (iv) $[x+{\script{1\over 2}}, y+{\script{1\over 2}}, z]$ .

Data collection: APEX2 (Bruker, 2004 ); cell refinement: SAINT (Bruker, 2004); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEPIII (Burnett & Johnson, 1996 ) and ORTEP-3 for Windows (Farrugia, 1997 ); software used to prepare material for publication: SHELXL97.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809013622/cv2546sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536809013622/cv2546Isup2.hkl

checkCIF report

Comment top

The disulfide derivatives of the nicotinate - dithiodinicotinates - adopt usually a twisted structure with the C—S—S—C torsion of ca 90° in the solid state, that provides a possibility to show the axial chirality with M- and P-forms of the enantiomers (Li et al., 2008). Herewith we present the crystal structure of the title compound (Fig. 1), where torsion angle C—S—S—C is 91.80 (15)°.

In the crystal, intermolecular O—H···O hydrogen bonds (Table 1) link the molecules into layers parallel to ab plane.

Related literature top

For complexes of disulfide derivatives, see Li et al. (2008).

Experimental top

2,2'-Disulfanediylditerephthalic acid (0.40 mg, 0.1 mmol), Mn(CH3COO)2 (0.28 mg, 0.11 mmol), NaOH (25 mg, 0.06 mmol) were added in methanol. The mixture was heated and stirred for six hours under reflux. The resultant was then filtered off to give a pure solution which was treated by diethyl ether in a closed vessel. One week later, single crystals were obtained.

Computing details top

Data collection: APEX2 (Bruker, 2004); cell refinement: SAINT (Bruker, 2004); data reduction: SAINT (Bruker, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEPIII (Burnett & Johnson, 1996) and ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top

Fig. 1. Molecular structure of (I), showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level. H atoms are represented as small spheres of arbitrary radii.

2,2'-Dithioditerephthalic acid top

Crystal data top

C₁₆H₁₀O₈S₂	F(000) = 1616
M_r = 394.36	D_x = 1.613 Mg m⁻³
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 1947 reflections
a = 16.396 (3) Å	θ = 2.4–25.6°
b = 9.8462 (15) Å	µ = 0.37 mm⁻¹
c = 20.363 (3) Å	T = 298 K
β = 98.840 (2)°	Block, colourless
V = 3248.2 (9) Å³	0.48 × 0.21 × 0.03 mm
Z = 8

Data collection top

Bruker APEXII area-detector diffractometer	3027 independent reflections
Radiation source: fine-focus sealed tube	1992 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.039
ϕ and ω scans	θ_max = 25.5°, θ_min = 2.4°
Absorption correction: multi-scan (SADABS; Sheldrick, 2004)	h = −19→19
T_min = 0.831, T_max = 0.988	k = −11→11
11095 measured reflections	l = −24→24

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)] = 0.047	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.140	H-atom parameters constrained
S = 1.03	w = 1/[σ²(F_o²) + (0.0679P)² + 4.4093P] where P = (F_o² + 2F_c²)/3
3027 reflections	(Δ/σ)_max < 0.001
239 parameters	Δρ_max = 0.53 e Å⁻³
0 restraints	Δρ_min = −0.32 e Å⁻³

Crystal data top

C₁₆H₁₀O₈S₂	V = 3248.2 (9) Å³
M_r = 394.36	Z = 8
Monoclinic, C2/c	Mo Kα radiation
a = 16.396 (3) Å	µ = 0.37 mm⁻¹
b = 9.8462 (15) Å	T = 298 K
c = 20.363 (3) Å	0.48 × 0.21 × 0.03 mm
β = 98.840 (2)°

Data collection top

Bruker APEXII area-detector diffractometer	3027 independent reflections
Absorption correction: multi-scan (SADABS; Sheldrick, 2004)	1992 reflections with I > 2σ(I)
T_min = 0.831, T_max = 0.988	R_int = 0.039
11095 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.047	0 restraints
wR(F²) = 0.140	H-atom parameters constrained
S = 1.03	Δρ_max = 0.53 e Å⁻³
3027 reflections	Δρ_min = −0.32 e Å⁻³
239 parameters

Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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
S1	0.26721 (5)	1.00797 (9)	0.25924 (4)	0.0312 (2)
S2	0.15066 (5)	1.01218 (9)	0.20597 (4)	0.0324 (2)
O1	0.41835 (14)	1.0121 (3)	0.32740 (12)	0.0477 (7)
O2	0.46882 (15)	0.9002 (3)	0.41908 (14)	0.0578 (8)
H2D	0.5089	0.9490	0.4171	0.087*
O3	0.05065 (14)	0.6603 (3)	0.32417 (13)	0.0496 (7)
H3D	0.0114	0.6090	0.3250	0.074*
O4	0.10411 (15)	0.5422 (3)	0.41363 (13)	0.0520 (7)
O5	0.00331 (15)	1.0344 (3)	0.13061 (14)	0.0539 (8)
O6	−0.05464 (15)	0.9000 (3)	0.04927 (14)	0.0506 (7)
H6D	−0.0924	0.9549	0.0482	0.076*
O7	0.30978 (15)	0.5421 (3)	0.05144 (13)	0.0442 (7)
O8	0.36843 (15)	0.6784 (3)	0.13228 (15)	0.0591 (8)
H8D	0.4087	0.6302	0.1299	0.089*
C1	0.33165 (18)	0.8542 (3)	0.37059 (15)	0.0254 (7)
C2	0.26309 (18)	0.8786 (3)	0.32073 (15)	0.0256 (7)
C3	0.19173 (18)	0.8031 (3)	0.32198 (15)	0.0267 (7)
H3A	0.1462	0.8166	0.2893	0.032*
C4	0.18767 (18)	0.7073 (3)	0.37180 (15)	0.0267 (7)
C5	0.25458 (19)	0.6852 (3)	0.42111 (15)	0.0292 (7)
H5	0.2514	0.6215	0.4544	0.035*
C6	0.32567 (19)	0.7586 (3)	0.42018 (15)	0.0305 (8)
H6	0.3707	0.7443	0.4532	0.037*
C7	0.41062 (19)	0.9292 (3)	0.37033 (17)	0.0331 (8)
C8	0.11000 (19)	0.6282 (3)	0.37180 (16)	0.0306 (7)
C9	0.15409 (19)	0.8884 (3)	0.14229 (16)	0.0289 (7)
C10	0.08448 (18)	0.8614 (3)	0.09422 (15)	0.0292 (7)
C11	0.0880 (2)	0.7598 (3)	0.04614 (17)	0.0365 (8)
H11	0.0416	0.7418	0.0150	0.044*
C12	0.1597 (2)	0.6863 (3)	0.04463 (17)	0.0344 (8)
H12	0.1616	0.6190	0.0129	0.041*
C13	0.22814 (19)	0.7144 (3)	0.09087 (16)	0.0301 (7)
C14	0.22585 (18)	0.8129 (3)	0.13977 (16)	0.0300 (7)
H14	0.2725	0.8287	0.1710	0.036*
C15	0.0074 (2)	0.9392 (3)	0.09224 (17)	0.0331 (8)
C16	0.30639 (19)	0.6367 (3)	0.08988 (16)	0.0319 (7)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
S1	0.0270 (4)	0.0334 (5)	0.0317 (5)	−0.0071 (3)	−0.0001 (3)	0.0045 (3)
S2	0.0282 (4)	0.0332 (5)	0.0347 (5)	0.0045 (4)	0.0013 (3)	−0.0017 (4)
O1	0.0276 (13)	0.0655 (18)	0.0462 (15)	−0.0226 (12)	−0.0062 (11)	0.0224 (14)
O2	0.0245 (14)	0.075 (2)	0.0660 (18)	−0.0225 (13)	−0.0174 (13)	0.0367 (15)
O3	0.0268 (14)	0.0661 (19)	0.0513 (16)	−0.0234 (12)	−0.0079 (12)	0.0185 (13)
O4	0.0292 (14)	0.0607 (17)	0.0616 (18)	−0.0227 (12)	−0.0072 (12)	0.0274 (14)
O5	0.0308 (14)	0.0606 (18)	0.0651 (18)	0.0206 (13)	−0.0094 (12)	−0.0262 (15)
O6	0.0270 (14)	0.0599 (18)	0.0594 (17)	0.0170 (12)	−0.0105 (12)	−0.0205 (14)
O7	0.0339 (14)	0.0468 (15)	0.0514 (16)	0.0141 (11)	0.0055 (12)	−0.0084 (12)
O8	0.0292 (15)	0.069 (2)	0.075 (2)	0.0203 (13)	−0.0069 (14)	−0.0258 (16)
C1	0.0186 (16)	0.0304 (17)	0.0271 (16)	−0.0088 (13)	0.0029 (12)	−0.0036 (13)
C2	0.0240 (16)	0.0262 (16)	0.0275 (17)	−0.0054 (13)	0.0066 (13)	−0.0019 (13)
C3	0.0200 (16)	0.0313 (17)	0.0277 (17)	−0.0069 (13)	−0.0001 (13)	−0.0014 (13)
C4	0.0213 (16)	0.0305 (17)	0.0289 (17)	−0.0072 (13)	0.0052 (13)	−0.0002 (13)
C5	0.0263 (17)	0.0335 (18)	0.0280 (17)	−0.0079 (14)	0.0050 (13)	0.0047 (13)
C6	0.0203 (17)	0.040 (2)	0.0294 (17)	−0.0068 (14)	−0.0039 (13)	0.0047 (14)
C7	0.0228 (17)	0.039 (2)	0.0361 (19)	−0.0104 (15)	0.0010 (14)	0.0021 (15)
C8	0.0226 (17)	0.0327 (19)	0.0366 (19)	−0.0100 (14)	0.0045 (14)	0.0016 (15)
C9	0.0255 (17)	0.0286 (17)	0.0328 (18)	0.0003 (13)	0.0051 (14)	0.0031 (14)
C10	0.0210 (17)	0.0333 (18)	0.0329 (18)	0.0030 (14)	0.0032 (13)	0.0008 (14)
C11	0.0252 (18)	0.044 (2)	0.038 (2)	0.0059 (15)	−0.0012 (15)	−0.0051 (16)
C12	0.0288 (18)	0.0374 (19)	0.0362 (19)	0.0068 (15)	0.0024 (15)	−0.0066 (15)
C13	0.0262 (18)	0.0309 (18)	0.0333 (18)	0.0062 (14)	0.0048 (14)	0.0025 (14)
C14	0.0186 (16)	0.0340 (18)	0.0361 (18)	0.0037 (13)	−0.0001 (14)	0.0028 (14)
C15	0.0248 (18)	0.0357 (19)	0.0377 (19)	0.0070 (14)	0.0012 (15)	−0.0027 (15)
C16	0.0242 (18)	0.0365 (19)	0.0348 (19)	0.0049 (14)	0.0042 (14)	0.0011 (15)

Geometric parameters (Å, º) top

S1—C2	1.795 (3)	C3—C4	1.394 (4)
S1—S2	2.0476 (11)	C3—H3A	0.9300
S2—C9	1.787 (3)	C4—C5	1.386 (4)
O1—C7	1.217 (4)	C4—C8	1.493 (4)
O2—C7	1.299 (4)	C5—C6	1.374 (4)
O2—H2D	0.8200	C5—H5	0.9300
O3—C8	1.303 (4)	C6—H6	0.9300
O3—H3D	0.8200	C9—C14	1.399 (4)
O4—C8	1.216 (4)	C9—C10	1.410 (4)
O5—C15	1.229 (4)	C10—C11	1.407 (4)
O6—C15	1.295 (4)	C10—C15	1.473 (4)
O6—H6D	0.8200	C11—C12	1.384 (4)
O7—C16	1.223 (4)	C11—H11	0.9300
O8—C16	1.296 (4)	C12—C13	1.378 (4)
O8—H8D	0.8200	C12—H12	0.9300
C1—C6	1.395 (4)	C13—C14	1.395 (4)
C1—C2	1.415 (4)	C13—C16	1.497 (4)
C1—C7	1.491 (4)	C14—H14	0.9300
C2—C3	1.390 (4)

C2—S1—S2	104.58 (10)	O4—C8—O3	124.0 (3)
C9—S2—S1	103.87 (11)	O4—C8—C4	121.5 (3)
C7—O2—H2D	109.5	O3—C8—C4	114.4 (3)
C8—O3—H3D	109.5	C14—C9—C10	118.0 (3)
C15—O6—H6D	109.5	C14—C9—S2	120.6 (2)
C16—O8—H8D	109.5	C10—C9—S2	121.3 (2)
C6—C1—C2	119.9 (3)	C11—C10—C9	120.1 (3)
C6—C1—C7	119.6 (3)	C11—C10—C15	118.5 (3)
C2—C1—C7	120.5 (3)	C9—C10—C15	121.4 (3)
C3—C2—C1	118.3 (3)	C12—C11—C10	120.8 (3)
C3—C2—S1	121.0 (2)	C12—C11—H11	119.6
C1—C2—S1	120.7 (2)	C10—C11—H11	119.6
C2—C3—C4	120.6 (3)	C13—C12—C11	119.0 (3)
C2—C3—H3A	119.7	C13—C12—H12	120.5
C4—C3—H3A	119.7	C11—C12—H12	120.5
C5—C4—C3	120.8 (3)	C12—C13—C14	121.2 (3)
C5—C4—C8	119.9 (3)	C12—C13—C16	119.9 (3)
C3—C4—C8	119.3 (3)	C14—C13—C16	118.8 (3)
C6—C5—C4	119.1 (3)	C13—C14—C9	120.7 (3)
C6—C5—H5	120.5	C13—C14—H14	119.7
C4—C5—H5	120.5	C9—C14—H14	119.7
C5—C6—C1	121.3 (3)	O5—C15—O6	122.9 (3)
C5—C6—H6	119.4	O5—C15—C10	120.7 (3)
C1—C6—H6	119.4	O6—C15—C10	116.4 (3)
O1—C7—O2	123.5 (3)	O7—C16—O8	124.0 (3)
O1—C7—C1	121.4 (3)	O7—C16—C13	121.4 (3)
O2—C7—C1	115.1 (3)	O8—C16—C13	114.6 (3)

C2—S1—S2—C9	−88.20 (15)	S1—S2—C9—C14	1.9 (3)
C6—C1—C2—C3	−1.5 (4)	S1—S2—C9—C10	−179.6 (2)
C7—C1—C2—C3	178.1 (3)	C14—C9—C10—C11	0.9 (5)
C6—C1—C2—S1	176.3 (2)	S2—C9—C10—C11	−177.6 (3)
C7—C1—C2—S1	−4.1 (4)	C14—C9—C10—C15	−178.1 (3)
S2—S1—C2—C3	2.9 (3)	S2—C9—C10—C15	3.4 (4)
S2—S1—C2—C1	−174.9 (2)	C9—C10—C11—C12	−0.9 (5)
C1—C2—C3—C4	1.0 (5)	C15—C10—C11—C12	178.2 (3)
S1—C2—C3—C4	−176.9 (2)	C10—C11—C12—C13	−0.3 (5)
C2—C3—C4—C5	0.0 (5)	C11—C12—C13—C14	1.4 (5)
C2—C3—C4—C8	179.8 (3)	C11—C12—C13—C16	−179.7 (3)
C3—C4—C5—C6	−0.4 (5)	C12—C13—C14—C9	−1.4 (5)
C8—C4—C5—C6	179.8 (3)	C16—C13—C14—C9	179.7 (3)
C4—C5—C6—C1	−0.2 (5)	C10—C9—C14—C13	0.2 (5)
C2—C1—C6—C5	1.2 (5)	S2—C9—C14—C13	178.8 (2)
C7—C1—C6—C5	−178.4 (3)	C11—C10—C15—O5	−175.4 (3)
C6—C1—C7—O1	179.1 (3)	C9—C10—C15—O5	3.6 (5)
C2—C1—C7—O1	−0.5 (5)	C11—C10—C15—O6	5.8 (5)
C6—C1—C7—O2	−1.5 (5)	C9—C10—C15—O6	−175.2 (3)
C2—C1—C7—O2	178.9 (3)	C12—C13—C16—O7	−4.7 (5)
C5—C4—C8—O4	−1.4 (5)	C14—C13—C16—O7	174.2 (3)
C3—C4—C8—O4	178.8 (3)	C12—C13—C16—O8	175.0 (3)
C5—C4—C8—O3	178.2 (3)	C14—C13—C16—O8	−6.1 (5)
C3—C4—C8—O3	−1.6 (5)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O8—H8D···O5ⁱ	0.82	1.81	2.632 (3)	174
O6—H6D···O7ⁱⁱ	0.82	1.83	2.633 (3)	166
O3—H3D···O1ⁱⁱⁱ	0.82	1.81	2.623 (3)	174
O2—H2D···O4^iv	0.82	1.82	2.639 (3)	174

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

Experimental details

Crystal data
Chemical formula	C₁₆H₁₀O₈S₂
M_r	394.36
Crystal system, space group	Monoclinic, C2/c
Temperature (K)	298
a, b, c (Å)	16.396 (3), 9.8462 (15), 20.363 (3)
β (°)	98.840 (2)
V (Å³)	3248.2 (9)
Z	8
Radiation type	Mo Kα
µ (mm⁻¹)	0.37
Crystal size (mm)	0.48 × 0.21 × 0.03

Data collection
Diffractometer	Bruker APEXII area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Sheldrick, 2004)
T_min, T_max	0.831, 0.988
No. of measured, independent and observed [I > 2σ(I)] reflections	11095, 3027, 1992
R_int	0.039
(sin θ/λ)_max (Å⁻¹)	0.606

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.047, 0.140, 1.03
No. of reflections	3027
No. of parameters	239
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.53, −0.32

Computer programs: APEX2 (Bruker, 2004), SAINT (Bruker, 2004), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEPIII (Burnett & Johnson, 1996) and ORTEP-3 for Windows (Farrugia, 1997).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O8—H8D···O5ⁱ	0.82	1.81	2.632 (3)	174.4
O6—H6D···O7ⁱⁱ	0.82	1.83	2.633 (3)	166.3
O3—H3D···O1ⁱⁱⁱ	0.82	1.81	2.623 (3)	173.8
O2—H2D···O4^iv	0.82	1.82	2.639 (3)	174.3

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

Acknowledgements

The author gratefully acknowledges financial support by the Youth Foundation of Lishui University, China (grant No. QN05002).

References

Bruker (2004). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Burnett, M. N. & Johnson, C. K. (1996). ORTEPIII. Report ORNL-6895. Oak Ridge National Laboratory, Tennessee, USA. Google Scholar
Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565. CrossRef IUCr Journals Google Scholar
Li, F., Xu, L., Bi, B., Liu, X. Z. & Fan, L. H. (2008). CrystEngComm, 10, 693–698. Web of Science CrossRef CAS Google Scholar
Sheldrick, G. M. (2004). SADABS. University of Göttingen, Germany. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar