Bis[4-(2-nitro­benzene­sulfonamido)­pyridinium] hexa­fluoro­silicate

Wang, A.-R.

doi:10.1107/S1600536808038191

organic compounds

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Volume 64| Part 12| December 2008| Page o2405

doi:10.1107/S1600536808038191

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Bis[4-(2-nitrobenzenesulfonamido)pyridinium] hexafluorosilicate

Ai-Rong Wang ^a ^*

^aSchool of Chemistry and Chemical Engineering, Henan Institute of Science and Technology, Xinxiang 453003, People's Republic of China
^*Correspondence e-mail: airong_wang@yahoo.cn

(Received 12 November 2008; accepted 17 November 2008; online 22 November 2008)

In the title compound, 2C₁₁H₁₀N₃O₄S⁺·SiF₆²⁻, the short C—N distance [1.386 (2) Å] is indicative of a slight conjugation of N with the π electrons of the pyridinium ring, and with those of the sulfonyl group. The dihedral angle between the benzene and pyridinium rings is 77.48 (7)°. The crystal structure is stabilized by N—H⋯F and C—H⋯F hydrogen bonds. The Si atom of the anion lies on a special position.

Related literature

For zwitterionic forms of N-arylbenzenesulfonamides, see: Li et al. (2007 ); Yu & Li (2007 ). For reference geometric data, see: Allen et al. (1987 ). Damiano et al. (2007 ) describe the use of pyridinium derivatives for the construction of supramolecular architectures.

Experimental

Crystal data

2C₁₁H₁₀N₃O₄S⁺·SiF₆²⁻
M_r = 702.65
Monoclinic, C 2/c
a = 22.691 (5) Å
b = 8.524 (2) Å
c = 14.776 (3) Å
β = 110.95 (3)°
V = 2669 (1) Å³
Z = 4
Mo Kα radiation
μ = 0.35 mm⁻¹
T = 113 (2) K
0.22 × 0.16 × 0.04 mm

Data collection

Rigaku Saturn CCD area-detector diffractometer
Absorption correction: multi-scan (CrystalClear; Rigaku/MSC, 2005 ) T_min = 0.927, T_max = 0.986
10620 measured reflections
3064 independent reflections
2456 reflections with I > 2σ(I)
R_int = 0.053

Refinement

R[F² > 2σ(F²)] = 0.043
wR(F²) = 0.111
S = 1.06
3064 reflections
212 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.38 e Å⁻³
Δρ_min = −0.49 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1N⋯F1ⁱ	0.86 (3)	1.96 (3)	2.789 (2)	162 (3)
N2—H2N⋯F1ⁱⁱ	0.73 (3)	1.97 (3)	2.690 (2)	171 (3)
C4—H4⋯F2ⁱ	0.95	2.35	3.141 (2)	141
C5—H5⋯F3ⁱⁱ	0.95	2.50	3.426 (3)	165
Symmetry codes: (i) $[-x+{\script{3\over 2}}, y+{\script{1\over 2}}, -z+{\script{3\over 2}}]$ ; (ii) $[-x+{\script{3\over 2}}, y-{\script{1\over 2}}, -z+{\script{3\over 2}}]$ .

Data collection: CrystalClear (Rigaku/MSC, 2005); cell refinement: CrystalClear; data reduction: CrystalClear; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL.

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808038191/lx2077sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536808038191/lx2077Isup2.hkl

checkCIF report

Comment top

Organic pyridinium salts have been widely used in the construction of supramolecular architectures (Damiano et al., 2007). As part of our ongoing studies of supramolecular chemistry involving the pyridinium rings (Li et al., 2007), herein we report the crystal structure of the title compound, 4-(2-nitrophenylsulfonylamino)pyridinium hexafluorosilicate (Fig. 1).

In the cations of the title compound the short C—N distance [N2—C1 = 1.386 (2) Å] has a value between those of a typical C═N double and C—N single bond (1.47–1.50 Å and 1.34–1.38 Å, respectively; Allen et al., 1987). This might be indicative of a slight conjugation of N with π electrons of the pyridinium ring, and with those of the sulfonyl group. The dihedral angle between the benzene ring and the pyridinium ring is 77.48 (7)°. The crystal structure is stabilized by N—H···F and C—H···F hydrogen bonds (Table 1).

Related literature top

For zwitterionic forms of N-arylbenzenesulfonamides, see: Li et al. (2007); Yu & Li (2007). For reference geometric data, see: Allen et al. (1987). Damiano et al. (2007) describe the use of pyridinium derivatives for the construction of supramolecular architectures.

Experimental top

A solution of 2-nitrobenzenesulfonyl chloride (2.2 g, 10 mmol) in CH₂Cl₂ (10 ml) was added dropwise to a suspension of 4-aminopyridine (0.9 g, 10 mmol) in CH₂Cl₂ (10 ml) at room temperature with stirring. The reaction mixture was stirred overnight. The yellow solid obtained was washed with warm water to obtain the title compound in a yield of 55.3%. A colorless single crystal suitable for X-ray analysis was obtained by slow evaporation of a fluorosilicic acid (10%) solution at room temperature over a period of a week.

Computing details top

Data collection: CrystalClear (Rigaku/MSC, 2005); cell refinement: CrystalClear (Rigaku/MSC, 2005); data reduction: CrystalClear (Rigaku/MSC, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top

Fig. 1. View of one molecule of the title compound showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 35% probability level (arbitrary spheres for the H atoms). [Symmetry code: (i) -x + 2, y, -z + 3/2.]

Bis[4-(2-nitrobenzenesulfonamido)pyridinium] hexafluorosilicate top

Crystal data top

2C₁₁H₁₀N₃O₄S⁺·SiF₆²⁻	F(000) = 1432
M_r = 702.65	D_x = 1.749 Mg m⁻³
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 3772 reflections
a = 22.691 (5) Å	θ = 1.9–27.5°
b = 8.524 (2) Å	µ = 0.35 mm⁻¹
c = 14.776 (3) Å	T = 113 K
β = 110.95 (3)°	Block, colourless
V = 2669 (1) Å³	0.22 × 0.16 × 0.04 mm
Z = 4

Data collection top

Rigaku Saturn CCD area-detector diffractometer	3064 independent reflections
Radiation source: rotating anode	2456 reflections with I > 2σ(I)
Confocal monochromator	R_int = 0.053
Detector resolution: 7.31 pixels mm^-1	θ_max = 27.5°, θ_min = 1.9°
ω and ϕ scans	h = −22→29
Absorption correction: multi-scan (CrystalClear; Rigaku/MSC, 2005)	k = −10→11
T_min = 0.927, T_max = 0.986	l = −18→19
10620 measured reflections

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)] = 0.043	Hydrogen site location: difference Fourier map
wR(F²) = 0.111	H atoms treated by a mixture of independent and constrained refinement
S = 1.06	w = 1/[σ²(F_o²) + (0.0513P)² + 1.0092P] where P = (F_o² + 2F_c²)/3
3064 reflections	(Δ/σ)_max < 0.001
212 parameters	Δρ_max = 0.38 e Å⁻³
0 restraints	Δρ_min = −0.49 e Å⁻³

Crystal data top

2C₁₁H₁₀N₃O₄S⁺·SiF₆²⁻	V = 2669 (1) Å³
M_r = 702.65	Z = 4
Monoclinic, C2/c	Mo Kα radiation
a = 22.691 (5) Å	µ = 0.35 mm⁻¹
b = 8.524 (2) Å	T = 113 K
c = 14.776 (3) Å	0.22 × 0.16 × 0.04 mm
β = 110.95 (3)°

Data collection top

Rigaku Saturn CCD area-detector diffractometer	3064 independent reflections
Absorption correction: multi-scan (CrystalClear; Rigaku/MSC, 2005)	2456 reflections with I > 2σ(I)
T_min = 0.927, T_max = 0.986	R_int = 0.053
10620 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.043	0 restraints
wR(F²) = 0.111	H atoms treated by a mixture of independent and constrained refinement
S = 1.06	Δρ_max = 0.38 e Å⁻³
3064 reflections	Δρ_min = −0.49 e Å⁻³
212 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
S	0.61983 (2)	0.29097 (5)	0.52758 (4)	0.01969 (15)
O1	0.58452 (8)	0.32136 (18)	0.42794 (11)	0.0273 (4)
O2	0.63133 (8)	0.13308 (16)	0.56235 (12)	0.0282 (4)
O3	0.69576 (9)	0.3188 (2)	0.75056 (13)	0.0473 (5)
O4	0.78705 (10)	0.2230 (3)	0.7737 (2)	0.0843 (10)
N1	0.56160 (8)	0.8430 (2)	0.63088 (13)	0.0192 (4)
H1N	0.5583 (14)	0.942 (3)	0.639 (2)	0.052 (9)*
N2	0.58416 (9)	0.3725 (2)	0.59405 (14)	0.0194 (4)
H2N	0.5795 (14)	0.315 (3)	0.628 (2)	0.043 (9)*
N3	0.74149 (10)	0.3008 (2)	0.72703 (15)	0.0363 (5)
C1	0.57577 (9)	0.5317 (2)	0.60418 (14)	0.0167 (4)
C2	0.57532 (9)	0.6398 (2)	0.53308 (14)	0.0177 (4)
H2	0.5800	0.6058	0.4748	0.021*
C3	0.56798 (9)	0.7955 (2)	0.54852 (15)	0.0193 (4)
H3	0.5674	0.8704	0.5006	0.023*
C4	0.56074 (9)	0.7410 (2)	0.70051 (14)	0.0195 (4)
H4	0.5555	0.7784	0.7577	0.023*
C5	0.56742 (9)	0.5837 (2)	0.68832 (14)	0.0185 (4)
H5	0.5664	0.5109	0.7364	0.022*
C6	0.69299 (10)	0.3905 (2)	0.55358 (15)	0.0192 (4)
C7	0.70103 (11)	0.4743 (2)	0.47788 (16)	0.0258 (5)
H7	0.6675	0.4795	0.4169	0.031*
C8	0.75749 (12)	0.5503 (3)	0.49066 (18)	0.0309 (5)
H8	0.7620	0.6078	0.4385	0.037*
C9	0.80672 (11)	0.5435 (3)	0.57748 (19)	0.0307 (5)
H9	0.8451	0.5965	0.5854	0.037*
C10	0.80059 (10)	0.4591 (3)	0.65379 (18)	0.0295 (5)
H10	0.8347	0.4530	0.7141	0.035*
C11	0.74405 (10)	0.3839 (3)	0.64084 (16)	0.0249 (5)
Si	1.0000	0.65155 (9)	0.7500	0.01731 (19)
F1	0.94232 (7)	0.64561 (14)	0.79977 (10)	0.0303 (3)
F2	0.96119 (6)	0.51233 (14)	0.67115 (9)	0.0265 (3)
F3	0.96052 (7)	0.79039 (14)	0.67359 (9)	0.0333 (3)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
S	0.0207 (3)	0.0158 (3)	0.0229 (3)	−0.0010 (2)	0.0083 (2)	−0.00471 (19)
O1	0.0294 (9)	0.0304 (8)	0.0199 (8)	−0.0032 (7)	0.0060 (6)	−0.0071 (6)
O2	0.0324 (9)	0.0145 (7)	0.0426 (10)	0.0012 (7)	0.0196 (8)	−0.0020 (7)
O3	0.0360 (11)	0.0728 (14)	0.0333 (11)	0.0026 (10)	0.0127 (8)	0.0205 (10)
O4	0.0312 (11)	0.112 (2)	0.104 (2)	0.0222 (13)	0.0172 (12)	0.0855 (17)
N1	0.0217 (9)	0.0125 (8)	0.0228 (10)	0.0012 (7)	0.0073 (7)	−0.0012 (7)
N2	0.0221 (9)	0.0136 (8)	0.0242 (10)	0.0014 (7)	0.0104 (7)	0.0011 (7)
N3	0.0227 (10)	0.0443 (13)	0.0350 (12)	−0.0019 (9)	0.0019 (9)	0.0175 (10)
C1	0.0135 (9)	0.0149 (9)	0.0205 (10)	−0.0005 (8)	0.0045 (7)	−0.0011 (8)
C2	0.0195 (10)	0.0196 (10)	0.0138 (10)	0.0015 (8)	0.0060 (8)	−0.0017 (8)
C3	0.0184 (10)	0.0182 (10)	0.0195 (10)	0.0009 (8)	0.0048 (8)	0.0026 (8)
C4	0.0178 (10)	0.0244 (10)	0.0165 (10)	0.0018 (9)	0.0064 (8)	−0.0008 (8)
C5	0.0177 (10)	0.0195 (10)	0.0182 (10)	−0.0008 (8)	0.0063 (8)	0.0003 (8)
C6	0.0202 (10)	0.0168 (9)	0.0219 (11)	0.0020 (8)	0.0092 (8)	−0.0028 (8)
C7	0.0293 (12)	0.0270 (11)	0.0237 (12)	0.0011 (10)	0.0126 (9)	−0.0029 (9)
C8	0.0367 (14)	0.0297 (12)	0.0359 (14)	−0.0016 (11)	0.0247 (11)	−0.0002 (10)
C9	0.0225 (11)	0.0292 (11)	0.0457 (15)	−0.0018 (10)	0.0184 (10)	−0.0011 (11)
C10	0.0187 (11)	0.0289 (11)	0.0377 (14)	0.0019 (10)	0.0060 (9)	0.0040 (10)
C11	0.0216 (11)	0.0230 (10)	0.0295 (12)	0.0044 (9)	0.0083 (9)	0.0044 (9)
Si	0.0263 (4)	0.0132 (4)	0.0144 (4)	0.000	0.0098 (3)	0.000
F1	0.0431 (8)	0.0202 (6)	0.0393 (8)	0.0036 (6)	0.0292 (7)	0.0010 (5)
F2	0.0306 (7)	0.0222 (6)	0.0233 (7)	−0.0018 (6)	0.0056 (5)	−0.0054 (5)
F3	0.0505 (9)	0.0225 (7)	0.0248 (7)	0.0093 (6)	0.0110 (6)	0.0072 (5)

Geometric parameters (Å, º) top

S—O1	1.426 (2)	C4—H4	0.9500
S—O2	1.431 (2)	C5—H5	0.9500
S—N2	1.634 (2)	C6—C11	1.393 (3)
S—C6	1.779 (2)	C6—C7	1.393 (3)
O3—N3	1.216 (3)	C7—C8	1.387 (3)
O4—N3	1.214 (3)	C7—H7	0.9500
N1—C3	1.338 (3)	C8—C9	1.368 (3)
N1—C4	1.353 (3)	C8—H8	0.9500
N1—H1N	0.86 (3)	C9—C10	1.385 (3)
N2—C1	1.386 (2)	C9—H9	0.9500
N2—H2N	0.73 (3)	C10—C11	1.385 (3)
N3—C11	1.477 (3)	C10—H10	0.9500
C1—C2	1.395 (3)	Si—F3ⁱ	1.6597 (14)
C1—C5	1.395 (3)	Si—F3	1.6597 (14)
C2—C3	1.367 (3)	Si—F2	1.6756 (13)
C2—H2	0.9500	Si—F2ⁱ	1.6756 (13)
C3—H3	0.9500	Si—F1ⁱ	1.7161 (13)
C4—C5	1.368 (3)	Si—F1	1.7161 (13)

O1—S—O2	120.30 (10)	C7—C6—S	116.81 (16)
O1—S—N2	109.10 (10)	C8—C7—C6	120.7 (2)
O2—S—N2	104.47 (10)	C8—C7—H7	119.7
O1—S—C6	105.83 (10)	C6—C7—H7	119.7
O2—S—C6	109.54 (10)	C9—C8—C7	120.8 (2)
N2—S—C6	106.98 (10)	C9—C8—H8	119.6
C3—N1—C4	122.20 (18)	C7—C8—H8	119.6
C3—N1—H1N	118 (2)	C8—C9—C10	119.9 (2)
C4—N1—H1N	120 (2)	C8—C9—H9	120.0
C1—N2—S	126.70 (16)	C10—C9—H9	120.0
C1—N2—H2N	122 (2)	C11—C10—C9	119.0 (2)
S—N2—H2N	110 (2)	C11—C10—H10	120.5
O4—N3—O3	123.2 (2)	C9—C10—H10	120.5
O4—N3—C11	117.7 (2)	C10—C11—C6	122.2 (2)
O3—N3—C11	119.09 (19)	C10—C11—N3	115.0 (2)
N2—C1—C2	122.01 (19)	C6—C11—N3	122.8 (2)
N2—C1—C5	118.34 (18)	F3ⁱ—Si—F3	89.03 (10)
C2—C1—C5	119.64 (18)	F3ⁱ—Si—F2	178.59 (7)
C3—C2—C1	118.97 (19)	F3—Si—F2	90.59 (7)
C3—C2—H2	120.5	F3ⁱ—Si—F2ⁱ	90.59 (7)
C1—C2—H2	120.5	F3—Si—F2ⁱ	178.59 (7)
N1—C3—C2	120.30 (19)	F2—Si—F2ⁱ	89.82 (9)
N1—C3—H3	119.8	F3ⁱ—Si—F1ⁱ	90.21 (7)
C2—C3—H3	119.8	F3—Si—F1ⁱ	92.20 (7)
N1—C4—C5	119.82 (19)	F2—Si—F1ⁱ	88.45 (7)
N1—C4—H4	120.1	F2ⁱ—Si—F1ⁱ	89.16 (7)
C5—C4—H4	120.1	F3ⁱ—Si—F1	92.20 (7)
C4—C5—C1	119.02 (19)	F3—Si—F1	90.21 (7)
C4—C5—H5	120.5	F2—Si—F1	89.16 (7)
C1—C5—H5	120.5	F2ⁱ—Si—F1	88.45 (7)
C11—C6—C7	117.3 (2)	F1ⁱ—Si—F1	176.62 (9)
C11—C6—S	125.73 (17)

O1—S—N2—C1	−65.8 (2)	O2—S—C6—C7	131.78 (16)
O2—S—N2—C1	164.31 (18)	N2—S—C6—C7	−115.54 (17)
C6—S—N2—C1	48.2 (2)	C11—C6—C7—C8	−1.3 (3)
S—N2—C1—C2	24.9 (3)	S—C6—C7—C8	−177.48 (17)
S—N2—C1—C5	−155.30 (16)	C6—C7—C8—C9	0.6 (3)
N2—C1—C2—C3	−178.80 (19)	C7—C8—C9—C10	0.4 (3)
C5—C1—C2—C3	1.4 (3)	C8—C9—C10—C11	−0.6 (3)
C4—N1—C3—C2	−1.5 (3)	C9—C10—C11—C6	−0.1 (3)
C1—C2—C3—N1	0.3 (3)	C9—C10—C11—N3	−178.4 (2)
C3—N1—C4—C5	0.9 (3)	C7—C6—C11—C10	1.0 (3)
N1—C4—C5—C1	0.7 (3)	S—C6—C11—C10	176.86 (17)
N2—C1—C5—C4	178.30 (18)	C7—C6—C11—N3	179.2 (2)
C2—C1—C5—C4	−1.9 (3)	S—C6—C11—N3	−5.0 (3)
O1—S—C6—C11	−175.15 (18)	O4—N3—C11—C10	−43.6 (3)
O2—S—C6—C11	−44.1 (2)	O3—N3—C11—C10	132.9 (2)
N2—S—C6—C11	68.6 (2)	O4—N3—C11—C6	138.1 (3)
O1—S—C6—C7	0.70 (18)	O3—N3—C11—C6	−45.4 (3)

Symmetry code: (i) −x+2, y, −z+3/2.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1N···F1ⁱⁱ	0.86 (3)	1.96 (3)	2.789 (2)	162 (3)
N2—H2N···F1ⁱⁱⁱ	0.73 (3)	1.97 (3)	2.690 (2)	171 (3)
C4—H4···F2ⁱⁱ	0.95	2.35	3.141 (2)	141
C5—H5···F3ⁱⁱⁱ	0.95	2.50	3.426 (3)	165

Symmetry codes: (ii) −x+3/2, y+1/2, −z+3/2; (iii) −x+3/2, y−1/2, −z+3/2.

Experimental details

Crystal data
Chemical formula	2C₁₁H₁₀N₃O₄S⁺·SiF₆²⁻
M_r	702.65
Crystal system, space group	Monoclinic, C2/c
Temperature (K)	113
a, b, c (Å)	22.691 (5), 8.524 (2), 14.776 (3)
β (°)	110.95 (3)
V (Å³)	2669 (1)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.35
Crystal size (mm)	0.22 × 0.16 × 0.04

Data collection
Diffractometer	Rigaku Saturn CCD area-detector diffractometer
Absorption correction	Multi-scan (CrystalClear; Rigaku/MSC, 2005)
T_min, T_max	0.927, 0.986
No. of measured, independent and observed [I > 2σ(I)] reflections	10620, 3064, 2456
R_int	0.053
(sin θ/λ)_max (Å⁻¹)	0.650

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.043, 0.111, 1.06
No. of reflections	3064
No. of parameters	212
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.38, −0.49

Computer programs: CrystalClear (Rigaku/MSC, 2005), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1N···F1ⁱ	0.86 (3)	1.96 (3)	2.789 (2)	162 (3)
N2—H2N···F1ⁱⁱ	0.73 (3)	1.97 (3)	2.690 (2)	171 (3)
C4—H4···F2ⁱ	0.95	2.35	3.141 (2)	140.8
C5—H5···F3ⁱⁱ	0.95	2.50	3.426 (3)	164.7

Symmetry codes: (i) −x+3/2, y+1/2, −z+3/2; (ii) −x+3/2, y−1/2, −z+3/2.

References

Allen, F. H., Kennard, O., Watson, D. G., Brammer, L., Orpen, A. G. & Taylor, R. (1987). J. Chem. Soc. Perkin Trans. 2, pp. S1–19. CrossRef Web of Science Google Scholar
Damiano, T., Morton, D. & Nelson, A. (2007). Org. Biomol. Chem. 5, 2735—2752. Web of Science CrossRef Google Scholar
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Rigaku/MSC (2005). CrystalClear. Rigaku/MSC, The Woodlands, Texas, USA. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Yu, H.-J. & Li, J.-S. (2007). Acta Cryst. E63, o3399. CSD CrossRef IUCr Journals Google Scholar

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Volume 64| Part 12| December 2008| Page o2405

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