Methyl 5-meth­oxy-2-nitro-4-[3-(piperidin-1-yl)prop­oxy]benzoate

Zhang, M.; Lu, R.-Z.; Han, L.-N.; Wei, W.-B.; Wang, H.-B.

doi:10.1107/S1600536809005418

organic compounds

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ISSN: 2056-9890

Volume 65| Part 3| March 2009| Page o558

doi:10.1107/S1600536809005418

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Methyl 5-methoxy-2-nitro-4-[3-(piperidin-1-yl)propoxy]benzoate

Min Zhang,^a Ran-Zhe Lu,^a Lu-Na Han,^a Wen-Bin Wei ^a and Hai-Bo Wang ^a ^*

^aCollege of Science, Nanjing University of Technology, Xinmofan Road No. 5 Nanjing, Nanjing 210009, People's Republic of China
^*Correspondence e-mail: wanghaibo@njut.edu.cn

(Received 13 February 2009; accepted 16 February 2009; online 21 February 2009)

In the molecule of the title compound, C₁₇H₂₄N₂O₆, the dihedral angle between the four coplanar atoms of the piperidine ring and the benzene ring is 39.2 (1)°.

Related literature

For general background, see: Knesl et al. (2006 ). For bond-length data, see: Allen et al. (1987 ).

Experimental

Crystal data

C₁₇H₂₄N₂O₆
M_r = 352.38
Monoclinic, P 2₁ /n
a = 10.073 (2) Å
b = 11.140 (2) Å
c = 16.161 (3) Å
β = 97.23 (3)°
V = 1799.1 (6) Å³
Z = 4
Mo Kα radiation
μ = 0.10 mm⁻¹
T = 293 K
0.30 × 0.20 × 0.20 mm

Data collection

Enraf–Nonius CAD-4 diffractometer
Absorption correction: ψ scan (North et al., 1968 ) T_min = 0.971, T_max = 0.981
3458 measured reflections
3262 independent reflections
1950 reflections with I > 2σ(I)
R_int = 0.042
3 standard reflections every 200 reflections intensity decay: 1%

Refinement

R[F² > 2σ(F²)] = 0.068
wR(F²) = 0.175
S = 1.01
3262 reflections
226 parameters
H-atom parameters constrained
Δρ_max = 0.25 e Å⁻³
Δρ_min = −0.29 e Å⁻³

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994 ); cell refinement: CAD-4 EXPRESS; data reduction: XCAD4 (Harms & Wocadlo, 1995 ); 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: PLATON (Spek, 2009 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809005418/hb2910sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536809005418/hb2910Isup2.hkl

checkCIF report

Comment top

As part of our ongoing studies on quinazoline derivatives (Knesl et al., 2006), we report herein the crystal structure of the title compound, (I).

In the molecule of the title compound (Fig. 1), the bond lengths (Allen et al., 1987) and angles are within normal ranges. Ring A (C4-C9) is, of course, planar.

Related literature top

For general background, see: Knesl et al. (2006). For bond-length data, see: Allen et al. (1987).

Experimental top

A solution of methyl 4-(3-chloropropoxy)-5-methoxy-2-nitrobenzoate (0.013 mol), potassium carbonate (0.052mol), sodium iodide (0.026mol) in acetonitrile (33 mL) was stirred for 5-10 min at room temperature. Piperidine (0.040mol) was added and this mixture heated to reflux for 3 h. Reaction progress was monitored by TLC. Solid material was removed by filtration and washed with acetone. The combined filtrates were evaporated and the dark product obtained dissolved in dichloromethane (30 ml) and extracted with water (4 × 10 ml). The organic phase was dried (Na₂SO₄), decolorized (charcoal), filtered and evaporated to afford the product (yield; 71.2%,) as an amber oil. Yellow blocks of (I) were obtained by slow evaporation of an methanol solution.

Computing details top

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994); cell refinement: CAD-4 EXPRESS (Enraf–Nonius, 1994); data reduction: XCAD4 (Harms & Wocadlo, 1995); 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: PLATON (Spek, 2009).

Figures top

Fig. 1. The molecular structure of (I) showing 50% displacement ellipsoids for the non-hydrogen atoms.

Methyl 5-methoxy-2-nitro-4-[3-(piperidin-1-yl)propoxy]benzoate top

Crystal data top

C₁₇H₂₄N₂O₆	F(000) = 752
M_r = 352.38	D_x = 1.301 Mg m⁻³
Monoclinic, P2₁/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 25 reflections
a = 10.073 (2) Å	θ = 10–13°
b = 11.140 (2) Å	µ = 0.10 mm⁻¹
c = 16.161 (3) Å	T = 293 K
β = 97.23 (3)°	Block, yellow
V = 1799.1 (6) Å³	0.30 × 0.20 × 0.20 mm
Z = 4

Data collection top

Enraf–Nonius CAD-4 diffractometer	1950 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.042
Graphite monochromator	θ_max = 25.3°, θ_min = 2.2°
ω/2θ scans	h = 0→12
Absorption correction: ψ scan (North et al., 1968)	k = 0→13
T_min = 0.971, T_max = 0.981	l = −19→19
3458 measured reflections	3 standard reflections every 200 reflections
3262 independent reflections	intensity decay: 1%

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)] = 0.068	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.175	H-atom parameters constrained
S = 1.01	w = 1/[σ²(F_o²) + (0.06P)² + 2.6P] where P = (F_o² + 2F_c²)/3
3262 reflections	(Δ/σ)_max < 0.001
226 parameters	Δρ_max = 0.25 e Å⁻³
0 restraints	Δρ_min = −0.29 e Å⁻³

Crystal data top

C₁₇H₂₄N₂O₆	V = 1799.1 (6) Å³
M_r = 352.38	Z = 4
Monoclinic, P2₁/n	Mo Kα radiation
a = 10.073 (2) Å	µ = 0.10 mm⁻¹
b = 11.140 (2) Å	T = 293 K
c = 16.161 (3) Å	0.30 × 0.20 × 0.20 mm
β = 97.23 (3)°

Data collection top

Enraf–Nonius CAD-4 diffractometer	1950 reflections with I > 2σ(I)
Absorption correction: ψ scan (North et al., 1968)	R_int = 0.042
T_min = 0.971, T_max = 0.981	3 standard reflections every 200 reflections
3458 measured reflections	intensity decay: 1%
3262 independent reflections

Refinement top

R[F² > 2σ(F²)] = 0.068	0 restraints
wR(F²) = 0.175	H-atom parameters constrained
S = 1.01	Δρ_max = 0.25 e Å⁻³
3262 reflections	Δρ_min = −0.29 e Å⁻³
226 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
O1	1.0523 (2)	0.3714 (2)	0.40317 (15)	0.0487 (7)
O2	1.0082 (3)	0.1757 (2)	0.38640 (16)	0.0563 (7)
O3	0.7178 (3)	0.5462 (3)	0.32890 (18)	0.0746 (10)
O4	0.7681 (3)	0.3835 (3)	0.39767 (17)	0.0627 (8)
O5	0.8037 (2)	0.4291 (2)	0.03763 (13)	0.0404 (6)
O6	0.9697 (2)	0.2550 (2)	0.05972 (14)	0.0408 (6)
N1	0.7693 (3)	0.4455 (3)	0.33404 (18)	0.0445 (8)
N2	0.6436 (2)	0.7187 (2)	−0.17424 (16)	0.0314 (6)
C1	1.1303 (4)	0.3499 (4)	0.4829 (2)	0.0633 (12)
H1A	1.1646	0.4247	0.5061	0.095*
H1B	1.2035	0.2973	0.4756	0.095*
H1C	1.0748	0.3134	0.5199	0.095*
C2	0.9964 (3)	0.2764 (3)	0.3627 (2)	0.0395 (8)
C3	0.9287 (3)	0.3122 (3)	0.27838 (19)	0.0325 (7)
C4	0.9752 (3)	0.2621 (3)	0.20979 (19)	0.0310 (7)
H4A	1.0391	0.2015	0.2174	0.037*
C5	0.9293 (3)	0.2995 (3)	0.13026 (19)	0.0303 (7)
C6	0.8349 (3)	0.3941 (3)	0.1185 (2)	0.0328 (7)
C7	0.7857 (3)	0.4424 (3)	0.18563 (19)	0.0316 (7)
H7A	0.7229	0.5039	0.1782	0.038*
C8	0.8291 (3)	0.4000 (3)	0.26530 (19)	0.0323 (7)
C9	1.0556 (4)	0.1520 (3)	0.0662 (2)	0.0520 (10)
H9A	1.0762	0.1303	0.0118	0.078*
H9B	1.0112	0.0863	0.0896	0.078*
H9C	1.1368	0.1706	0.1016	0.078*
C10	0.7202 (3)	0.5334 (3)	0.0212 (2)	0.0368 (8)
H10A	0.7556	0.5999	0.0560	0.044*
H10B	0.6301	0.5165	0.0332	0.044*
C11	0.7190 (3)	0.5643 (3)	−0.0687 (2)	0.0380 (8)
H11A	0.6879	0.4957	−0.1027	0.046*
H11B	0.8094	0.5827	−0.0796	0.046*
C12	0.6288 (3)	0.6713 (3)	−0.0931 (2)	0.0404 (8)
H12A	0.5364	0.6474	−0.0922	0.048*
H12B	0.6488	0.7343	−0.0519	0.048*
C13	0.5908 (4)	0.6370 (3)	−0.2416 (2)	0.0462 (9)
H13A	0.4957	0.6258	−0.2401	0.055*
H13B	0.6340	0.5595	−0.2326	0.055*
C14	0.6130 (5)	0.6835 (4)	−0.3253 (2)	0.0601 (11)
H14A	0.5713	0.6294	−0.3679	0.072*
H14B	0.7083	0.6848	−0.3293	0.072*
C15	0.5571 (4)	0.8070 (4)	−0.3413 (2)	0.0618 (11)
H15A	0.4602	0.8042	−0.3471	0.074*
H15B	0.5837	0.8382	−0.3928	0.074*
C16	0.6085 (4)	0.8881 (3)	−0.2698 (2)	0.0509 (10)
H16A	0.5661	0.9661	−0.2779	0.061*
H16B	0.7041	0.8991	−0.2691	0.061*
C17	0.5809 (4)	0.8370 (3)	−0.1868 (2)	0.0431 (9)
H17A	0.6163	0.8905	−0.1421	0.052*
H17B	0.4851	0.8299	−0.1860	0.052*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0500 (15)	0.0488 (15)	0.0426 (14)	−0.0022 (12)	−0.0119 (11)	0.0005 (12)
O2	0.0646 (18)	0.0432 (16)	0.0596 (17)	0.0030 (13)	0.0019 (13)	0.0194 (13)
O3	0.077 (2)	0.079 (2)	0.068 (2)	0.0443 (18)	0.0102 (16)	−0.0039 (17)
O4	0.0541 (17)	0.083 (2)	0.0536 (17)	0.0055 (15)	0.0154 (13)	0.0086 (16)
O5	0.0454 (14)	0.0389 (13)	0.0358 (13)	0.0092 (11)	0.0006 (10)	0.0073 (11)
O6	0.0398 (13)	0.0429 (14)	0.0400 (13)	0.0103 (11)	0.0065 (10)	−0.0039 (11)
N1	0.0279 (15)	0.064 (2)	0.0408 (17)	0.0085 (15)	0.0003 (12)	−0.0051 (16)
N2	0.0313 (14)	0.0257 (14)	0.0365 (14)	0.0058 (11)	0.0010 (11)	0.0049 (12)
C1	0.054 (3)	0.085 (3)	0.046 (2)	−0.005 (2)	−0.0129 (18)	0.001 (2)
C2	0.0359 (19)	0.042 (2)	0.0406 (19)	0.0052 (16)	0.0040 (15)	0.0079 (17)
C3	0.0281 (17)	0.0323 (18)	0.0358 (18)	−0.0028 (14)	−0.0015 (13)	0.0014 (14)
C4	0.0257 (16)	0.0305 (17)	0.0369 (18)	0.0034 (13)	0.0052 (13)	−0.0002 (14)
C5	0.0249 (16)	0.0276 (17)	0.0385 (18)	−0.0009 (13)	0.0038 (13)	−0.0059 (14)
C6	0.0273 (17)	0.0325 (18)	0.0369 (18)	−0.0028 (13)	−0.0024 (13)	0.0020 (14)
C7	0.0249 (16)	0.0341 (18)	0.0356 (17)	0.0060 (14)	0.0025 (13)	0.0005 (14)
C8	0.0280 (17)	0.0339 (18)	0.0348 (17)	0.0045 (14)	0.0039 (13)	−0.0040 (14)
C9	0.051 (2)	0.045 (2)	0.060 (2)	0.0147 (18)	0.0097 (18)	−0.0103 (19)
C10	0.0323 (18)	0.0338 (18)	0.044 (2)	0.0052 (14)	0.0025 (14)	0.0066 (15)
C11	0.0389 (19)	0.0320 (18)	0.0419 (19)	0.0012 (15)	0.0009 (15)	0.0072 (15)
C12	0.040 (2)	0.041 (2)	0.0394 (19)	0.0064 (16)	0.0013 (15)	0.0054 (16)
C13	0.051 (2)	0.041 (2)	0.043 (2)	0.0069 (17)	−0.0037 (16)	−0.0023 (17)
C14	0.077 (3)	0.058 (3)	0.043 (2)	0.007 (2)	−0.0016 (19)	−0.004 (2)
C15	0.070 (3)	0.071 (3)	0.043 (2)	0.011 (2)	−0.0005 (19)	0.013 (2)
C16	0.055 (2)	0.045 (2)	0.054 (2)	0.0093 (18)	0.0088 (18)	0.0187 (19)
C17	0.045 (2)	0.0331 (19)	0.051 (2)	0.0104 (16)	0.0081 (16)	0.0028 (17)

Geometric parameters (Å, º) top

O1—C2	1.332 (4)	C9—H9A	0.9600
O1—C1	1.442 (4)	C9—H9B	0.9600
O2—C2	1.187 (4)	C9—H9C	0.9600
O3—N1	1.235 (4)	C10—C11	1.492 (4)
O4—N1	1.240 (4)	C10—H10A	0.9700
O5—C6	1.362 (4)	C10—H10B	0.9700
O5—C10	1.439 (4)	C11—C12	1.521 (4)
O6—C5	1.352 (4)	C11—H11A	0.9700
O6—C9	1.432 (4)	C11—H11B	0.9700
N1—C8	1.422 (4)	C12—H12A	0.9700
N2—C12	1.439 (4)	C12—H12B	0.9700
N2—C17	1.464 (4)	C13—C14	1.492 (5)
N2—C13	1.466 (4)	C13—H13A	0.9700
C1—H1A	0.9600	C13—H13B	0.9700
C1—H1B	0.9600	C14—C15	1.498 (6)
C1—H1C	0.9600	C14—H14A	0.9700
C2—C3	1.499 (4)	C14—H14B	0.9700
C3—C4	1.375 (4)	C15—C16	1.506 (6)
C3—C8	1.398 (4)	C15—H15A	0.9700
C4—C5	1.375 (4)	C15—H15B	0.9700
C4—H4A	0.9300	C16—C17	1.514 (5)
C5—C6	1.416 (4)	C16—H16A	0.9700
C6—C7	1.360 (4)	C16—H16B	0.9700
C7—C8	1.389 (4)	C17—H17A	0.9700
C7—H7A	0.9300	C17—H17B	0.9700

C2—O1—C1	117.1 (3)	O5—C10—H10B	110.2
C6—O5—C10	117.9 (2)	C11—C10—H10B	110.2
C5—O6—C9	118.3 (3)	H10A—C10—H10B	108.5
O3—N1—O4	120.9 (3)	C10—C11—C12	111.3 (3)
O3—N1—C8	119.1 (3)	C10—C11—H11A	109.4
O4—N1—C8	119.9 (3)	C12—C11—H11A	109.4
C12—N2—C17	111.4 (3)	C10—C11—H11B	109.4
C12—N2—C13	112.3 (3)	C12—C11—H11B	109.4
C17—N2—C13	110.2 (3)	H11A—C11—H11B	108.0
O1—C1—H1A	109.5	N2—C12—C11	113.3 (3)
O1—C1—H1B	109.5	N2—C12—H12A	108.9
H1A—C1—H1B	109.5	C11—C12—H12A	108.9
O1—C1—H1C	109.5	N2—C12—H12B	108.9
H1A—C1—H1C	109.5	C11—C12—H12B	108.9
H1B—C1—H1C	109.5	H12A—C12—H12B	107.7
O2—C2—O1	125.0 (3)	N2—C13—C14	112.1 (3)
O2—C2—C3	124.1 (3)	N2—C13—H13A	109.2
O1—C2—C3	110.5 (3)	C14—C13—H13A	109.2
C4—C3—C8	118.2 (3)	N2—C13—H13B	109.2
C4—C3—C2	117.5 (3)	C14—C13—H13B	109.2
C8—C3—C2	124.0 (3)	H13A—C13—H13B	107.9
C5—C4—C3	121.5 (3)	C13—C14—C15	112.3 (3)
C5—C4—H4A	119.3	C13—C14—H14A	109.1
C3—C4—H4A	119.3	C15—C14—H14A	109.1
O6—C5—C4	125.2 (3)	C13—C14—H14B	109.1
O6—C5—C6	115.3 (3)	C15—C14—H14B	109.1
C4—C5—C6	119.5 (3)	H14A—C14—H14B	107.9
C7—C6—O5	126.1 (3)	C14—C15—C16	109.5 (3)
C7—C6—C5	119.6 (3)	C14—C15—H15A	109.8
O5—C6—C5	114.4 (3)	C16—C15—H15A	109.8
C6—C7—C8	120.1 (3)	C14—C15—H15B	109.8
C6—C7—H7A	120.0	C16—C15—H15B	109.8
C8—C7—H7A	120.0	H15A—C15—H15B	108.2
C7—C8—C3	120.9 (3)	C15—C16—C17	111.7 (3)
C7—C8—N1	119.2 (3)	C15—C16—H16A	109.3
C3—C8—N1	119.8 (3)	C17—C16—H16A	109.3
O6—C9—H9A	109.5	C15—C16—H16B	109.3
O6—C9—H9B	109.5	C17—C16—H16B	109.3
H9A—C9—H9B	109.5	H16A—C16—H16B	107.9
O6—C9—H9C	109.5	N2—C17—C16	109.7 (3)
H9A—C9—H9C	109.5	N2—C17—H17A	109.7
H9B—C9—H9C	109.5	C16—C17—H17A	109.7
O5—C10—C11	107.4 (3)	N2—C17—H17B	109.7
O5—C10—H10A	110.2	C16—C17—H17B	109.7
C11—C10—H10A	110.2	H17A—C17—H17B	108.2

C1—O1—C2—O2	−1.6 (5)	C4—C3—C8—C7	−5.0 (5)
C1—O1—C2—C3	−175.4 (3)	C2—C3—C8—C7	169.6 (3)
O2—C2—C3—C4	−55.8 (5)	C4—C3—C8—N1	173.9 (3)
O1—C2—C3—C4	118.1 (3)	C2—C3—C8—N1	−11.5 (5)
O2—C2—C3—C8	129.6 (4)	O3—N1—C8—C7	−25.2 (5)
O1—C2—C3—C8	−56.6 (4)	O4—N1—C8—C7	153.9 (3)
C8—C3—C4—C5	2.3 (5)	O3—N1—C8—C3	155.8 (3)
C2—C3—C4—C5	−172.7 (3)	O4—N1—C8—C3	−25.0 (5)
C9—O6—C5—C4	7.4 (4)	C6—O5—C10—C11	171.1 (3)
C9—O6—C5—C6	−174.4 (3)	O5—C10—C11—C12	177.9 (3)
C3—C4—C5—O6	−180.0 (3)	C17—N2—C12—C11	−166.2 (3)
C3—C4—C5—C6	1.8 (5)	C13—N2—C12—C11	69.6 (4)
C10—O5—C6—C7	5.7 (4)	C10—C11—C12—N2	168.9 (3)
C10—O5—C6—C5	−173.2 (3)	C12—N2—C13—C14	−176.9 (3)
O6—C5—C6—C7	178.3 (3)	C17—N2—C13—C14	58.3 (4)
C4—C5—C6—C7	−3.4 (4)	N2—C13—C14—C15	−55.0 (4)
O6—C5—C6—O5	−2.8 (4)	C13—C14—C15—C16	51.9 (5)
C4—C5—C6—O5	175.6 (3)	C14—C15—C16—C17	−54.0 (5)
O5—C6—C7—C8	−178.2 (3)	C12—N2—C17—C16	175.3 (3)
C5—C6—C7—C8	0.7 (5)	C13—N2—C17—C16	−59.3 (4)
C6—C7—C8—C3	3.5 (5)	C15—C16—C17—N2	58.5 (4)
C6—C7—C8—N1	−175.4 (3)

Experimental details

Crystal data
Chemical formula	C₁₇H₂₄N₂O₆
M_r	352.38
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	293
a, b, c (Å)	10.073 (2), 11.140 (2), 16.161 (3)
β (°)	97.23 (3)
V (Å³)	1799.1 (6)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.10
Crystal size (mm)	0.30 × 0.20 × 0.20

Data collection
Diffractometer	Enraf–Nonius CAD-4 diffractometer
Absorption correction	ψ scan (North et al., 1968)
T_min, T_max	0.971, 0.981
No. of measured, independent and observed [I > 2σ(I)] reflections	3458, 3262, 1950
R_int	0.042
(sin θ/λ)_max (Å⁻¹)	0.601

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.068, 0.175, 1.01
No. of reflections	3262
No. of parameters	226
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.25, −0.29

Computer programs: CAD-4 EXPRESS (Enraf–Nonius, 1994), XCAD4 (Harms & Wocadlo, 1995), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008), PLATON (Spek, 2009).

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
Enraf–Nonius (1994). CAD-4 Software. Enraf–Nonius, Delft, The Netherlands. Google Scholar
Harms, K. & Wocadlo, S. (1995). XCAD4. University of Marburg, Germany. Google Scholar
Knesl, P., Roeseling, D. & Jordis, U. (2006). Molecules, 11, 286–297. Web of Science CrossRef PubMed CAS Google Scholar
North, A. C. T., Phillips, D. C. & Mathews, F. S. (1968). Acta Cryst. A24, 351–359. CrossRef IUCr Journals Web of Science Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Spek, A. L. (2009). Acta Cryst. D65, 148–155. Web of Science CrossRef CAS IUCr Journals Google Scholar