Ethyl 1-(4-meth­oxy­benz­yl)-3-p-tolyl-1H-pyrazole-5-carboxyl­ate

Shi, C.-X.; Xie, Y.-M.

doi:10.1107/S1600536811012311

organic compounds

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 67| Part 5| May 2011| Page o1084

doi:10.1107/S1600536811012311

Open

access

Ethyl 1-(4-methoxybenzyl)-3-p-tolyl-1H-pyrazole-5-carboxylate

Chuan-Xing Shi ^a ^* and Yun-Man Xie ^a

^aHenan Chemical Industry Research Institute Co. Ltd, Zheng Zhou 450052, People's Republic of China
^*Correspondence e-mail: yunman_xie@yahoo.cn

(Received 13 March 2011; accepted 2 April 2011; online 13 April 2011)

In the title compound, C₂₁H₂₂N₂O₃, the pyrazole ring makes dihedral angles of 12.93 (8) and 69.38 (8)°, respectively, with the tolyl and methoxybenzyl rings.

Related literature

For the pharmacological activity of pyrazole compounds, see: Ge et al. (2009 , 2011 ). For the synthesis of the title compound, see: Li et al. (2011 ). For the structure of ethyl 1-benzyl-3-(4-fluorophenyl)-1H-pyrazole-5-carboxylate, see: Han et al. (2011 ). For a related structure, see: Ge et al. (2007 ).

Experimental

Crystal data

C₂₁H₂₂N₂O₃
M_r = 350.41
Monoclinic, P 2₁ /c
a = 7.3272 (6) Å
b = 24.8129 (19) Å
c = 10.4556 (8) Å
β = 97.391 (1)°
V = 1885.1 (3) Å³
Z = 4
Mo Kα radiation
μ = 0.08 mm⁻¹
T = 298 K
0.23 × 0.16 × 0.13 mm

Data collection

Bruker SMART CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 1998 ) T_min = 0.981, T_max = 0.989
9809 measured reflections
3352 independent reflections
2678 reflections with I > 2σ(I)
R_int = 0.022

Refinement

R[F² > 2σ(F²)] = 0.042
wR(F²) = 0.119
S = 1.03
3352 reflections
235 parameters
H-atom parameters constrained
Δρ_max = 0.19 e Å⁻³
Δρ_min = −0.18 e Å⁻³

Data collection: SMART (Bruker, 1998); cell refinement: SAINT (Bruker, 1998); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP in SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXL97.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536811012311/jh2273sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536811012311/jh2273Isup2.hkl

checkCIF report

Comment top

Synthesis of nitrogen-containing heterocyclic compounds has been a subject of great interest due to the wide application in agrochemical and pharmaceutical fields (Ge et al.; 2011, 2009). Some pyrazole derivatives which belong to this category have been of interest for their biological activities. Considerable efforts have been devoted to the development of novel pyrazole compounds. We report here the crystal structure of the title compound, (I) (Fig. 1)

Related literature top

For the pharmacological activity of pyrazole compounds, see: Ge et al. (2009, 2011). For the synthesis of the title compound, see: Li et al. (2011). For the structure of ethyl 1-benzyl-3-(4-fluorophenyl)-1H-pyrazole-5-carboxylate, see: Han et al. (2011). For a related structure, see: Ge et al. (2007).

Experimental top

A mixture of ethyl 3-p-tolyl-1H-pyrazole-5-carboxylate (0.02 mol), 1-(chloromethyl)-4-methoxybenzene (0.0024 mol) and potassium carbonate (0.02 mol) in acetonitrile (100 ml) was heated to reflux for 10 h. The solvent was removed under reduced pressure and an product was isolated by column chromatography on silica gel (yield 85%). Crystals of (I) suitable for X-ray diffraction were obtained by slow cooling of the refluxed solution of the product in ethyl acetate at room temperature for 2 d.

Computing details top

Data collection: SMART (Bruker, 1998); cell refinement: SAINT (Bruker, 1998); data reduction: SAINT (Bruker, 1998); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP in SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top

Fig. 1. The molecular structure of (I), showing displacement ellipsoids drawn at the 50% probability level.

Ethyl 1-(4-methoxybenzyl)-3-p-tolyl-1H-pyrazole-5-carboxylate top

Crystal data top

C₂₁H₂₂N₂O₃	F(000) = 744
M_r = 350.41	D_x = 1.235 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P cd ..2ybc	Cell parameters from 4354 reflections
a = 7.3272 (6) Å	θ = 2.6–27.0°
b = 24.8129 (19) Å	µ = 0.08 mm⁻¹
c = 10.4556 (8) Å	T = 298 K
β = 97.391 (1)°	Block, colorless
V = 1885.1 (3) Å³	0.23 × 0.16 × 0.13 mm
Z = 4

Data collection top

Bruker SMART CCD area-detector diffractometer	3352 independent reflections
Radiation source: fine-focus sealed tube	2678 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.022
ϕ and ω scans	θ_max = 25.1°, θ_min = 2.1°
Absorption correction: multi-scan (SADABS; Bruker, 1998)	h = −8→8
T_min = 0.981, T_max = 0.989	k = −27→29
9809 measured reflections	l = −12→12

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)] = 0.042	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.119	H-atom parameters constrained
S = 1.03	w = 1/[σ²(F_o²) + (0.0599P)² + 0.3339P] where P = (F_o² + 2F_c²)/3
3352 reflections	(Δ/σ)_max = 0.001
235 parameters	Δρ_max = 0.19 e Å⁻³
0 restraints	Δρ_min = −0.18 e Å⁻³

Crystal data top

C₂₁H₂₂N₂O₃	V = 1885.1 (3) Å³
M_r = 350.41	Z = 4
Monoclinic, P2₁/c	Mo Kα radiation
a = 7.3272 (6) Å	µ = 0.08 mm⁻¹
b = 24.8129 (19) Å	T = 298 K
c = 10.4556 (8) Å	0.23 × 0.16 × 0.13 mm
β = 97.391 (1)°

Data collection top

Bruker SMART CCD area-detector diffractometer	3352 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 1998)	2678 reflections with I > 2σ(I)
T_min = 0.981, T_max = 0.989	R_int = 0.022
9809 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.042	0 restraints
wR(F²) = 0.119	H-atom parameters constrained
S = 1.03	Δρ_max = 0.19 e Å⁻³
3352 reflections	Δρ_min = −0.18 e Å⁻³
235 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.

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 > σ(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	0.88269 (19)	0.71616 (5)	1.05256 (13)	0.0819 (4)
O2	1.43164 (19)	0.64241 (7)	0.60151 (14)	0.0970 (5)
O3	1.36112 (17)	0.67333 (5)	0.40045 (14)	0.0775 (4)
N1	1.08187 (17)	0.58456 (5)	0.56329 (12)	0.0554 (3)
N2	0.91743 (17)	0.56391 (5)	0.51579 (12)	0.0538 (3)
C1	0.9991 (4)	0.75363 (9)	1.1249 (2)	0.1030 (8)
H1A	1.0928	0.7346	1.1799	0.155*
H1B	0.9279	0.7751	1.1767	0.155*
H1C	1.0555	0.7766	1.0674	0.155*
C2	0.9582 (2)	0.68359 (6)	0.96740 (15)	0.0576 (4)
C3	0.8353 (2)	0.65104 (7)	0.89121 (16)	0.0600 (4)
H3	0.7105	0.6526	0.8994	0.072*
C4	0.8966 (2)	0.61650 (6)	0.80360 (15)	0.0560 (4)
H4	0.8125	0.5949	0.7528	0.067*
C5	1.0821 (2)	0.61327 (6)	0.78944 (14)	0.0513 (4)
C6	1.2021 (2)	0.64674 (7)	0.86452 (16)	0.0620 (4)
H6	1.3265	0.6458	0.8551	0.074*
C7	1.1422 (2)	0.68166 (7)	0.95353 (16)	0.0641 (4)
H7	1.2258	0.7037	1.0036	0.077*
C8	1.1502 (2)	0.57325 (7)	0.69837 (16)	0.0635 (4)
H8A	1.2837	0.5738	0.7094	0.076*
H8B	1.1114	0.5374	0.7200	0.076*
C9	1.1513 (2)	0.61647 (6)	0.47571 (16)	0.0559 (4)
C10	1.3294 (2)	0.64466 (8)	0.50244 (19)	0.0666 (5)
C11	1.5375 (3)	0.70117 (9)	0.4111 (2)	0.0885 (7)
H11A	1.6373	0.6762	0.4374	0.106*
H11B	1.5415	0.7298	0.4745	0.106*
C12	1.5551 (4)	0.72362 (11)	0.2822 (3)	0.1141 (9)
H12A	1.5448	0.6951	0.2198	0.171*
H12B	1.6728	0.7408	0.2840	0.171*
H12C	1.4592	0.7495	0.2593	0.171*
C13	1.0262 (2)	0.61579 (6)	0.36636 (16)	0.0565 (4)
H13	1.0352	0.6336	0.2891	0.068*
C14	0.8824 (2)	0.58284 (6)	0.39496 (14)	0.0493 (4)
C15	0.7099 (2)	0.56794 (6)	0.31485 (14)	0.0485 (3)
C16	0.6829 (2)	0.57760 (7)	0.18385 (16)	0.0659 (5)
H16	0.7760	0.5936	0.1445	0.079*
C17	0.5193 (3)	0.56376 (8)	0.11051 (17)	0.0725 (5)
H17	0.5047	0.5704	0.0223	0.087*
C18	0.3767 (2)	0.54022 (6)	0.16490 (16)	0.0592 (4)
C19	0.4049 (2)	0.52993 (6)	0.29509 (16)	0.0585 (4)
H19	0.3123	0.5134	0.3341	0.070*
C20	0.5676 (2)	0.54355 (6)	0.36890 (15)	0.0569 (4)
H20	0.5825	0.5363	0.4569	0.068*
C21	0.1957 (3)	0.52677 (9)	0.08541 (19)	0.0802 (6)
H21A	0.1329	0.4998	0.1291	0.120*
H21B	0.2181	0.5133	0.0028	0.120*
H21C	0.1211	0.5586	0.0738	0.120*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0878 (9)	0.0836 (9)	0.0793 (8)	−0.0158 (7)	0.0288 (7)	−0.0257 (7)
O2	0.0658 (8)	0.1384 (13)	0.0840 (10)	−0.0265 (8)	−0.0014 (7)	−0.0224 (9)
O3	0.0556 (7)	0.0793 (8)	0.0982 (10)	−0.0196 (6)	0.0123 (7)	−0.0081 (7)
N1	0.0511 (7)	0.0554 (7)	0.0582 (8)	0.0025 (6)	0.0013 (6)	−0.0091 (6)
N2	0.0500 (7)	0.0516 (7)	0.0588 (8)	−0.0014 (6)	0.0028 (6)	−0.0052 (6)
C1	0.128 (2)	0.0880 (15)	0.1008 (16)	−0.0380 (14)	0.0435 (14)	−0.0397 (13)
C2	0.0673 (10)	0.0547 (9)	0.0516 (9)	−0.0087 (8)	0.0112 (7)	0.0018 (7)
C3	0.0532 (9)	0.0632 (10)	0.0642 (10)	−0.0085 (8)	0.0104 (8)	0.0016 (8)
C4	0.0545 (9)	0.0524 (8)	0.0583 (9)	−0.0097 (7)	−0.0032 (7)	0.0014 (7)
C5	0.0542 (9)	0.0478 (8)	0.0490 (8)	0.0021 (7)	−0.0042 (6)	0.0061 (6)
C6	0.0476 (9)	0.0735 (11)	0.0622 (10)	−0.0030 (8)	−0.0030 (7)	−0.0022 (8)
C7	0.0627 (10)	0.0691 (10)	0.0584 (9)	−0.0155 (8)	−0.0007 (8)	−0.0095 (8)
C8	0.0607 (10)	0.0592 (9)	0.0665 (10)	0.0116 (8)	−0.0080 (8)	−0.0016 (8)
C9	0.0482 (8)	0.0564 (9)	0.0643 (10)	−0.0028 (7)	0.0113 (7)	−0.0149 (7)
C10	0.0503 (9)	0.0732 (11)	0.0767 (12)	−0.0049 (8)	0.0104 (9)	−0.0244 (10)
C11	0.0576 (11)	0.0855 (13)	0.1256 (19)	−0.0235 (10)	0.0243 (11)	−0.0262 (13)
C12	0.0986 (18)	0.1104 (18)	0.142 (2)	−0.0398 (15)	0.0482 (16)	−0.0131 (16)
C13	0.0533 (9)	0.0593 (9)	0.0582 (9)	−0.0068 (7)	0.0120 (7)	−0.0067 (7)
C14	0.0486 (8)	0.0466 (8)	0.0532 (8)	0.0003 (6)	0.0088 (6)	−0.0070 (6)
C15	0.0487 (8)	0.0434 (7)	0.0535 (8)	−0.0011 (6)	0.0072 (6)	−0.0031 (6)
C16	0.0593 (10)	0.0797 (11)	0.0590 (10)	−0.0138 (9)	0.0082 (8)	0.0101 (8)
C17	0.0699 (11)	0.0911 (13)	0.0535 (10)	−0.0144 (10)	−0.0031 (8)	0.0134 (9)
C18	0.0558 (9)	0.0548 (9)	0.0639 (10)	−0.0049 (7)	−0.0034 (8)	0.0031 (8)
C19	0.0534 (9)	0.0594 (9)	0.0623 (10)	−0.0107 (7)	0.0063 (7)	0.0046 (7)
C20	0.0584 (10)	0.0602 (9)	0.0517 (9)	−0.0082 (7)	0.0057 (7)	0.0040 (7)
C21	0.0678 (12)	0.0881 (13)	0.0785 (13)	−0.0158 (10)	−0.0143 (10)	0.0097 (10)

Geometric parameters (Å, º) top

O1—C2	1.371 (2)	C9—C13	1.370 (2)
O1—C1	1.413 (2)	C9—C10	1.475 (2)
O2—C10	1.199 (2)	C11—C12	1.479 (3)
O3—C10	1.327 (2)	C11—H11A	0.9700
O3—C11	1.457 (2)	C11—H11B	0.9700
N1—N2	1.3442 (17)	C12—H12A	0.9600
N1—C9	1.358 (2)	C12—H12B	0.9600
N1—C8	1.464 (2)	C12—H12C	0.9600
N2—C14	1.341 (2)	C13—C14	1.396 (2)
C1—H1A	0.9600	C13—H13	0.9300
C1—H1B	0.9600	C14—C15	1.471 (2)
C1—H1C	0.9600	C15—C16	1.379 (2)
C2—C7	1.375 (2)	C15—C20	1.387 (2)
C2—C3	1.383 (2)	C16—C17	1.381 (2)
C3—C4	1.372 (2)	C16—H16	0.9300
C3—H3	0.9300	C17—C18	1.382 (2)
C4—C5	1.388 (2)	C17—H17	0.9300
C4—H4	0.9300	C18—C19	1.374 (2)
C5—C6	1.379 (2)	C18—C21	1.509 (2)
C5—C8	1.505 (2)	C19—C20	1.377 (2)
C6—C7	1.383 (2)	C19—H19	0.9300
C6—H6	0.9300	C20—H20	0.9300
C7—H7	0.9300	C21—H21A	0.9600
C8—H8A	0.9700	C21—H21B	0.9600
C8—H8B	0.9700	C21—H21C	0.9600

C2—O1—C1	118.00 (15)	O3—C11—C12	106.82 (18)
C10—O3—C11	115.99 (16)	O3—C11—H11A	110.4
N2—N1—C9	111.65 (13)	C12—C11—H11A	110.4
N2—N1—C8	117.54 (14)	O3—C11—H11B	110.4
C9—N1—C8	130.63 (14)	C12—C11—H11B	110.4
C14—N2—N1	105.56 (12)	H11A—C11—H11B	108.6
O1—C1—H1A	109.5	C11—C12—H12A	109.5
O1—C1—H1B	109.5	C11—C12—H12B	109.5
H1A—C1—H1B	109.5	H12A—C12—H12B	109.5
O1—C1—H1C	109.5	C11—C12—H12C	109.5
H1A—C1—H1C	109.5	H12A—C12—H12C	109.5
H1B—C1—H1C	109.5	H12B—C12—H12C	109.5
O1—C2—C7	124.91 (15)	C9—C13—C14	105.70 (14)
O1—C2—C3	115.53 (15)	C9—C13—H13	127.1
C7—C2—C3	119.57 (15)	C14—C13—H13	127.1
C4—C3—C2	120.29 (16)	N2—C14—C13	110.41 (13)
C4—C3—H3	119.9	N2—C14—C15	119.64 (13)
C2—C3—H3	119.9	C13—C14—C15	129.95 (14)
C3—C4—C5	121.11 (14)	C16—C15—C20	117.46 (14)
C3—C4—H4	119.4	C16—C15—C14	121.64 (14)
C5—C4—H4	119.4	C20—C15—C14	120.90 (14)
C6—C5—C4	117.76 (15)	C15—C16—C17	120.77 (16)
C6—C5—C8	121.24 (15)	C15—C16—H16	119.6
C4—C5—C8	120.97 (14)	C17—C16—H16	119.6
C5—C6—C7	121.74 (16)	C16—C17—C18	121.67 (16)
C5—C6—H6	119.1	C16—C17—H17	119.2
C7—C6—H6	119.1	C18—C17—H17	119.2
C2—C7—C6	119.52 (15)	C19—C18—C17	117.44 (15)
C2—C7—H7	120.2	C19—C18—C21	120.94 (16)
C6—C7—H7	120.2	C17—C18—C21	121.62 (16)
N1—C8—C5	112.58 (12)	C18—C19—C20	121.25 (15)
N1—C8—H8A	109.1	C18—C19—H19	119.4
C5—C8—H8A	109.1	C20—C19—H19	119.4
N1—C8—H8B	109.1	C19—C20—C15	121.40 (15)
C5—C8—H8B	109.1	C19—C20—H20	119.3
H8A—C8—H8B	107.8	C15—C20—H20	119.3
N1—C9—C13	106.68 (13)	C18—C21—H21A	109.5
N1—C9—C10	123.21 (15)	C18—C21—H21B	109.5
C13—C9—C10	130.11 (16)	H21A—C21—H21B	109.5
O2—C10—O3	124.36 (17)	C18—C21—H21C	109.5
O2—C10—C9	125.51 (19)	H21A—C21—H21C	109.5
O3—C10—C9	110.13 (15)	H21B—C21—H21C	109.5

C9—N1—N2—C14	0.47 (16)	C13—C9—C10—O2	−179.11 (18)
C8—N1—N2—C14	176.15 (12)	N1—C9—C10—O3	−179.23 (14)
C1—O1—C2—C7	5.1 (3)	C13—C9—C10—O3	1.0 (2)
C1—O1—C2—C3	−174.62 (18)	C10—O3—C11—C12	172.00 (18)
O1—C2—C3—C4	−179.36 (15)	N1—C9—C13—C14	0.54 (17)
C7—C2—C3—C4	0.9 (2)	C10—C9—C13—C14	−179.66 (16)
C2—C3—C4—C5	0.1 (2)	N1—N2—C14—C13	−0.10 (16)
C3—C4—C5—C6	−1.3 (2)	N1—N2—C14—C15	−179.65 (12)
C3—C4—C5—C8	176.70 (14)	C9—C13—C14—N2	−0.28 (17)
C4—C5—C6—C7	1.5 (2)	C9—C13—C14—C15	179.21 (14)
C8—C5—C6—C7	−176.49 (15)	N2—C14—C15—C16	−167.43 (15)
O1—C2—C7—C6	179.58 (16)	C13—C14—C15—C16	13.1 (2)
C3—C2—C7—C6	−0.7 (3)	N2—C14—C15—C20	12.6 (2)
C5—C6—C7—C2	−0.5 (3)	C13—C14—C15—C20	−166.84 (15)
N2—N1—C8—C5	−86.72 (17)	C20—C15—C16—C17	0.5 (3)
C9—N1—C8—C5	88.0 (2)	C14—C15—C16—C17	−179.41 (16)
C6—C5—C8—N1	−116.20 (17)	C15—C16—C17—C18	0.5 (3)
C4—C5—C8—N1	65.9 (2)	C16—C17—C18—C19	−1.4 (3)
N2—N1—C9—C13	−0.65 (17)	C16—C17—C18—C21	177.98 (18)
C8—N1—C9—C13	−175.60 (15)	C17—C18—C19—C20	1.3 (3)
N2—N1—C9—C10	179.54 (14)	C21—C18—C19—C20	−178.05 (17)
C8—N1—C9—C10	4.6 (2)	C18—C19—C20—C15	−0.3 (3)
C11—O3—C10—O2	3.2 (3)	C16—C15—C20—C19	−0.6 (2)
C11—O3—C10—C9	−176.93 (14)	C14—C15—C20—C19	179.35 (14)
N1—C9—C10—O2	0.7 (3)

Experimental details

Crystal data
Chemical formula	C₂₁H₂₂N₂O₃
M_r	350.41
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	298
a, b, c (Å)	7.3272 (6), 24.8129 (19), 10.4556 (8)
β (°)	97.391 (1)
V (Å³)	1885.1 (3)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.08
Crystal size (mm)	0.23 × 0.16 × 0.13

Data collection
Diffractometer	Bruker SMART CCD area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 1998)
T_min, T_max	0.981, 0.989
No. of measured, independent and observed [I > 2σ(I)] reflections	9809, 3352, 2678
R_int	0.022
(sin θ/λ)_max (Å⁻¹)	0.596

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.042, 0.119, 1.03
No. of reflections	3352
No. of parameters	235
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.19, −0.18

Computer programs: SMART (Bruker, 1998), SAINT (Bruker, 1998), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), XP in SHELXTL (Sheldrick, 2008).

References

Bruker (1998). SMART, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Ge, Y.-Q., Dong, W.-L., Xia, Y., Wei, F. & Zhao, B.-X. (2007). Acta Cryst. E63, o1313–o1314. Web of Science CSD CrossRef IUCr Journals Google Scholar
Ge, Y. Q., Jia, J., Li, Y., Yin, L. & Wang, J. W. (2009). Heterocycles, 42, 197–206. Google Scholar
Ge, Y. Q., Jia, J., Yang, H., Tao, X. T. & Wang, J. W. (2011). Dyes Pigments, 88, 344-349. Web of Science CSD CrossRef CAS Google Scholar
Han, Z., Zheng, H.-L. & Tian, X.-L. (2011). Acta Cryst. E67, o511. Web of Science CSD CrossRef IUCr Journals Google Scholar
Li, Y.-Q., Jia, B.-X., Xiao, Y.-L. & Guo, F.-G. (2011). Acta Cryst. E67, o468. Web of Science CSD CrossRef IUCr Journals Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar