4-[4-(Diethyl­amino)benzyl­ideneamino]-4H-1,2,4-triazole

Pan, J.X.; Zhang, J.Z.; Chen, Q.W.

doi:10.1107/S1600536808009100

organic compounds

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 64| Part 6| June 2008| Page o980

doi:10.1107/S1600536808009100

Open

access

4-[4-(Diethylamino)benzylideneamino]-4H-1,2,4-triazole

Jian Xin Pan,^a Ju Zhou Zhang ^a and Qian Wang Chen ^a ^*

^aHefei National Laboratory for Physical Sciences at Microscale, and Department of Materials Science & Engineering, University of Science and Technology of China, Hefei 230026, People's Republic of China
^*Correspondence e-mail: cqw@ustc.edu.cn

(Received 6 March 2008; accepted 3 April 2008; online 3 May 2008)

The title compound, C₁₃H₁₇N₅, is a Schiff base synthesized by the reaction of 4-amino-4H-1,2,4-triazole and 4-(diethylamino)benzaldehyde. The triazole ring forms a dihedral angle of 5.77 (16)° with the benzene ring. The crystal structure is stabilized by an intermolecular C—H⋯N hydrogen bond.

Related literature

For related literature, see: Zhu et al. (2000 ), Atalay et al. (2003 ); Petek et al. (2004 ); Brasselet et al. (1999 ); Cornelissen et al. (1992 ); Demirbs & Ugurluoglu Demirbas (2002 ); Fujigaya et al. (2003 ); Garcia et al. (1997 ); Kahn & Martinez (1998 ); Moliner et al. (2001 ); Tozkoparan et al. (2000 ); Turan-Zitouni et al. (1999 ).

Experimental

Crystal data

C₁₃H₁₇N₅
M_r = 243.32
Orthorhombic, P 2₁ 2₁ 2₁
a = 7.740 (3) Å
b = 9.238 (4) Å
c = 18.497 (7) Å
V = 1322.5 (9) Å³
Z = 4
Mo Kα radiation
μ = 0.08 mm⁻¹
T = 293 (2) K
0.37 × 0.35 × 0.11 mm

Data collection

Bruker APEX2 CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ) T_min = 0.972, T_max = 0.992
6650 measured reflections
1359 independent reflections
895 reflections with I > 2σ(I)
R_int = 0.075

Refinement

R[F² > 2σ(F²)] = 0.059
wR(F²) = 0.131
S = 1.09
1359 reflections
165 parameters
H-atom parameters constrained
Δρ_max = 0.19 e Å⁻³
Δρ_min = −0.17 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C1—H1⋯N1ⁱ	0.93	2.43	3.296 (7)	155
Symmetry code: (i) $[-x+2, y-{\script{1\over 2}}, -z-{\script{1\over 2}}]$ .

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

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808009100/rz2200sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536808009100/rz2200Isup2.hkl

checkCIF report

Comment top

Recent interest in substituted 1,2,4-triazoles has arisen in part from their transition metal complexes with intriguing structures and specific magnetic properties (Garcia et al., 1997; Kahn & Martinez, 1998; Moliner et al., 2001; Fujigaya et al., 2003). In addition, many compounds containing a 1,2,4-triazole unit display a broad range of biological and pharmacological activities, finding application as anti-inflammatory (Tozkoparan et al., 2000), antitumour (Demirbs & Ugurluoglu Demirbas, 2002), analgesic (Turan-Zitouni et al., 1999), antibacterial and antiviral agents (Cornelissen et al., 1992). In a continuation of our interest in the chemical and pharmacological properties of triazole derivatives, we have synthesized the title compound and report here its crystal structure.

The molecular structure and the atom-numbering scheme of the title compound are shown in Fig. 1. In the molecule, all bond lengths and angles are within normal ranges and comparable with the reported values (Atalay et al., 2003; Zhu et al., 2000). In the triazole ring, the N2?C1 and N1?C2 bonds display double-bond character, with bond distances of 1.288 (6) and 1.313 (6) Å, respectively. The 1,2,4-triazole ring is strictly planar (maximum displacement 0.006 (5) Å for C2) and forms a dihedral angle of 5.77 (16) °. The crystal packing is stabilized by an intermolecular C—H···N hydrogen bonding interaction (Table 1).

Related literature top

For related literature, see: Zhu et al. (2000), Atalay et al. (2003); Petek et al. (2004); Brasselet et al. (1999); Cornelissen et al. (1992); Demirbs & Ugurluoglu Demirbas (2002); Fujigaya et al. (2003); Garcia et al. (1997); Kahn & Martinez (1998); Moliner et al. (2001); Tozkoparan et al. (2000); Turan-Zitouni, Kaplancikli, Erol & Killic (1999).

Experimental top

A mixture of 4-amino-l,2,4-triazole (0.88 g, 10 mmol) and 4-(diethylamino)benzaldehyde (1.77 g, 10 mmol), which was prepared by standard procedures (Brasselet et al., 1999), was dissolved in ethanol (180 ml) and stirred for 1 h. Single crystals suitable for X-ray diffraction analysis were obtained by slow evaporation of the ethanol solution.

Computing details top

Data collection: APEX2 (Bruker, 2005); cell refinement: APEX2 (Bruker, 2005); data reduction: 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: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures top

Fig. 1. The molecular structure of the title compound, with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level.

4-[4-(Diethylamino)benzylideneamino]-4H-1,2,4-triazole top

Crystal data top

C₁₃H₁₇N₅	F(000) = 520
M_r = 243.32	D_x = 1.222 Mg m⁻³
Orthorhombic, P2₁2₁2₁	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2ab	Cell parameters from 870 reflections
a = 7.740 (3) Å	θ = 2.5–20.5°
b = 9.238 (4) Å	µ = 0.08 mm⁻¹
c = 18.497 (7) Å	T = 293 K
V = 1322.5 (9) Å³	Block, yellow
Z = 4	0.37 × 0.35 × 0.11 mm

Data collection top

Bruker APEX2 CCD area-detector diffractometer	1359 independent reflections
Radiation source: fine-focus sealed tube	895 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.075
ϕ and ω scans	θ_max = 25.0°, θ_min = 2.5°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −9→9
T_min = 0.972, T_max = 0.992	k = −10→10
6650 measured reflections	l = −21→13

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)] = 0.060	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.131	H-atom parameters constrained
S = 1.09	w = 1/[σ²(F_o²) + (0.0187P)² + 0.429P] where P = (F_o² + 2F_c²)/3
1359 reflections	(Δ/σ)_max < 0.001
165 parameters	Δρ_max = 0.19 e Å⁻³
0 restraints	Δρ_min = −0.17 e Å⁻³

Crystal data top

C₁₃H₁₇N₅	V = 1322.5 (9) Å³
M_r = 243.32	Z = 4
Orthorhombic, P2₁2₁2₁	Mo Kα radiation
a = 7.740 (3) Å	µ = 0.08 mm⁻¹
b = 9.238 (4) Å	T = 293 K
c = 18.497 (7) Å	0.37 × 0.35 × 0.11 mm

Data collection top

Bruker APEX2 CCD area-detector diffractometer	1359 independent reflections
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	895 reflections with I > 2σ(I)
T_min = 0.972, T_max = 0.992	R_int = 0.075
6650 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.060	0 restraints
wR(F²) = 0.131	H-atom parameters constrained
S = 1.09	Δρ_max = 0.19 e Å⁻³
1359 reflections	Δρ_min = −0.17 e Å⁻³
165 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
C1	1.0028 (7)	0.8829 (5)	−0.2061 (3)	0.0777 (15)
H1	1.0615	0.8029	−0.2241	0.093*
C2	0.8502 (7)	1.0221 (5)	−0.1387 (3)	0.0888 (17)
H2	0.7824	1.0569	−0.1010	0.107*
C3	0.9580 (6)	0.6644 (4)	−0.0936 (2)	0.0632 (12)
H3	1.0140	0.6437	−0.1368	0.076*
C4	0.9482 (6)	0.5533 (4)	−0.0388 (2)	0.0562 (11)
C5	0.8680 (7)	0.5730 (4)	0.0283 (2)	0.0667 (13)
H5	0.8150	0.6611	0.0384	0.080*
C6	0.8654 (6)	0.4652 (4)	0.0798 (2)	0.0629 (13)
H6	0.8085	0.4815	0.1234	0.076*
C7	0.9468 (6)	0.3314 (4)	0.0680 (2)	0.0582 (11)
C8	1.0235 (6)	0.3114 (4)	−0.0006 (2)	0.0635 (12)
H8	1.0746	0.2231	−0.0117	0.076*
C9	1.0236 (6)	0.4195 (4)	−0.0505 (2)	0.0642 (12)
H9	1.0770	0.4026	−0.0948	0.077*
C10	1.0615 (7)	0.0993 (4)	0.1119 (2)	0.0684 (13)
H10A	1.1077	0.0746	0.1591	0.082*
H10B	1.1583	0.1240	0.0810	0.082*
C11	0.9734 (7)	−0.0308 (4)	0.0814 (3)	0.0824 (15)
H11A	0.8749	−0.0546	0.1106	0.124*
H11B	1.0523	−0.1110	0.0809	0.124*
H11C	0.9362	−0.0106	0.0329	0.124*
C12	0.8512 (7)	0.2348 (5)	0.1858 (2)	0.0754 (14)
H12A	0.8145	0.1383	0.1997	0.091*
H12B	0.7483	0.2917	0.1765	0.091*
C13	0.9488 (9)	0.3017 (6)	0.2477 (3)	0.112 (2)
H13A	1.0464	0.2421	0.2596	0.168*
H13B	0.8742	0.3094	0.2890	0.168*
H13C	0.9882	0.3964	0.2341	0.168*
N1	0.8934 (7)	1.0979 (5)	−0.1959 (3)	0.1007 (15)
N2	0.9902 (7)	1.0065 (5)	−0.2379 (2)	0.0907 (14)
N3	0.9164 (5)	0.8878 (4)	−0.1417 (2)	0.0651 (10)
N4	0.8933 (5)	0.7886 (4)	−0.08490 (19)	0.0679 (11)
N5	0.9521 (5)	0.2252 (3)	0.11934 (19)	0.0654 (10)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.109 (5)	0.067 (3)	0.057 (3)	−0.009 (3)	−0.003 (3)	−0.004 (2)
C2	0.103 (5)	0.079 (3)	0.084 (4)	0.022 (3)	0.012 (3)	0.010 (3)
C3	0.077 (3)	0.069 (3)	0.044 (3)	−0.002 (3)	0.002 (2)	−0.001 (2)
C4	0.065 (3)	0.057 (2)	0.047 (2)	−0.003 (2)	0.001 (2)	−0.0034 (19)
C5	0.085 (4)	0.056 (2)	0.059 (3)	0.005 (2)	0.006 (2)	−0.008 (2)
C6	0.081 (4)	0.062 (3)	0.045 (3)	0.005 (2)	0.012 (2)	−0.004 (2)
C7	0.064 (3)	0.061 (2)	0.049 (3)	−0.006 (2)	0.002 (2)	−0.005 (2)
C8	0.075 (3)	0.060 (2)	0.056 (3)	0.007 (2)	0.006 (2)	−0.004 (2)
C9	0.068 (3)	0.069 (3)	0.055 (3)	0.001 (2)	0.010 (2)	−0.003 (2)
C10	0.079 (3)	0.069 (3)	0.057 (3)	0.010 (3)	0.001 (2)	0.010 (2)
C11	0.097 (4)	0.073 (3)	0.077 (4)	0.008 (3)	−0.006 (3)	−0.003 (3)
C12	0.092 (4)	0.077 (3)	0.058 (3)	−0.008 (3)	0.011 (3)	−0.001 (2)
C13	0.143 (6)	0.140 (4)	0.053 (3)	−0.027 (5)	0.005 (4)	−0.024 (3)
N1	0.117 (4)	0.082 (3)	0.104 (4)	0.009 (3)	0.003 (3)	0.025 (3)
N2	0.125 (4)	0.078 (3)	0.070 (3)	−0.016 (3)	−0.002 (3)	0.012 (2)
N3	0.081 (3)	0.061 (2)	0.054 (2)	−0.002 (2)	0.000 (2)	0.0043 (18)
N4	0.087 (3)	0.061 (2)	0.056 (2)	0.002 (2)	0.002 (2)	0.0061 (19)
N5	0.081 (3)	0.067 (2)	0.049 (2)	0.005 (2)	0.009 (2)	0.0040 (18)

Geometric parameters (Å, º) top

C1—N2	1.288 (6)	C8—H8	0.9300
C1—N3	1.366 (6)	C9—H9	0.9300
C1—H1	0.9300	C10—N5	1.445 (5)
C2—N1	1.313 (6)	C10—C11	1.493 (6)
C2—N3	1.344 (5)	C10—H10A	0.9700
C2—H2	0.9300	C10—H10B	0.9700
C3—N4	1.262 (5)	C11—H11A	0.9600
C3—C4	1.444 (5)	C11—H11B	0.9600
C3—H3	0.9300	C11—H11C	0.9600
C4—C9	1.384 (6)	C12—N5	1.459 (6)
C4—C5	1.400 (6)	C12—C13	1.505 (7)
C5—C6	1.378 (6)	C12—H12A	0.9700
C5—H5	0.9300	C12—H12B	0.9700
C6—C7	1.405 (5)	C13—H13A	0.9600
C6—H6	0.9300	C13—H13B	0.9600
C7—N5	1.366 (5)	C13—H13C	0.9600
C7—C8	1.412 (6)	N1—N2	1.369 (6)
C8—C9	1.361 (5)	N3—N4	1.406 (4)

N2—C1—N3	109.4 (5)	N5—C10—H10B	108.6
N2—C1—H1	125.3	C11—C10—H10B	108.6
N3—C1—H1	125.3	H10A—C10—H10B	107.6
N1—C2—N3	111.2 (5)	C10—C11—H11A	109.5
N1—C2—H2	124.4	C10—C11—H11B	109.5
N3—C2—H2	124.4	H11A—C11—H11B	109.5
N4—C3—C4	122.4 (4)	C10—C11—H11C	109.5
N4—C3—H3	118.8	H11A—C11—H11C	109.5
C4—C3—H3	118.8	H11B—C11—H11C	109.5
C9—C4—C5	116.2 (4)	N5—C12—C13	113.4 (4)
C9—C4—C3	120.2 (4)	N5—C12—H12A	108.9
C5—C4—C3	123.6 (4)	C13—C12—H12A	108.9
C6—C5—C4	121.7 (4)	N5—C12—H12B	108.9
C6—C5—H5	119.1	C13—C12—H12B	108.9
C4—C5—H5	119.1	H12A—C12—H12B	107.7
C5—C6—C7	121.4 (4)	C12—C13—H13A	109.5
C5—C6—H6	119.3	C12—C13—H13B	109.5
C7—C6—H6	119.3	H13A—C13—H13B	109.5
N5—C7—C6	122.5 (4)	C12—C13—H13C	109.5
N5—C7—C8	121.2 (4)	H13A—C13—H13C	109.5
C6—C7—C8	116.3 (4)	H13B—C13—H13C	109.5
C9—C8—C7	121.0 (4)	C2—N1—N2	105.5 (4)
C9—C8—H8	119.5	C1—N2—N1	109.2 (5)
C7—C8—H8	119.5	C2—N3—C1	104.7 (4)
C8—C9—C4	123.3 (4)	C2—N3—N4	121.5 (4)
C8—C9—H9	118.4	C1—N3—N4	133.8 (4)
C4—C9—H9	118.4	C3—N4—N3	116.6 (4)
N5—C10—C11	114.6 (4)	C7—N5—C10	121.9 (3)
N5—C10—H10A	108.6	C7—N5—C12	121.8 (4)
C11—C10—H10A	108.6	C10—N5—C12	116.3 (3)

N4—C3—C4—C9	−179.0 (5)	N1—C2—N3—C1	−1.1 (6)
N4—C3—C4—C5	−0.4 (7)	N1—C2—N3—N4	177.3 (4)
C9—C4—C5—C6	0.4 (7)	N2—C1—N3—C2	1.0 (6)
C3—C4—C5—C6	−178.3 (4)	N2—C1—N3—N4	−177.2 (4)
C4—C5—C6—C7	1.5 (7)	C4—C3—N4—N3	178.2 (4)
C5—C6—C7—N5	177.2 (4)	C2—N3—N4—C3	178.8 (5)
C5—C6—C7—C8	−3.0 (7)	C1—N3—N4—C3	−3.3 (7)
N5—C7—C8—C9	−177.5 (4)	C6—C7—N5—C10	−168.6 (4)
C6—C7—C8—C9	2.7 (7)	C8—C7—N5—C10	11.6 (6)
C7—C8—C9—C4	−1.0 (7)	C6—C7—N5—C12	9.5 (6)
C5—C4—C9—C8	−0.6 (7)	C8—C7—N5—C12	−170.2 (4)
C3—C4—C9—C8	178.1 (4)	C11—C10—N5—C7	−96.1 (5)
N3—C2—N1—N2	0.8 (7)	C11—C10—N5—C12	85.7 (5)
N3—C1—N2—N1	−0.5 (6)	C13—C12—N5—C7	−92.9 (5)
C2—N1—N2—C1	−0.2 (7)	C13—C12—N5—C10	85.3 (5)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C1—H1···N1ⁱ	0.93	2.43	3.296 (7)	155

Symmetry code: (i) −x+2, y−1/2, −z−1/2.

Experimental details

Crystal data
Chemical formula	C₁₃H₁₇N₅
M_r	243.32
Crystal system, space group	Orthorhombic, P2₁2₁2₁
Temperature (K)	293
a, b, c (Å)	7.740 (3), 9.238 (4), 18.497 (7)
V (Å³)	1322.5 (9)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.08
Crystal size (mm)	0.37 × 0.35 × 0.11

Data collection
Diffractometer	Bruker APEX2 CCD area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Sheldrick, 1996)
T_min, T_max	0.972, 0.992
No. of measured, independent and observed [I > 2σ(I)] reflections	6650, 1359, 895
R_int	0.075
(sin θ/λ)_max (Å⁻¹)	0.595

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.060, 0.131, 1.09
No. of reflections	1359
No. of parameters	165
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.19, −0.17

Computer programs: APEX2 (Bruker, 2005), SIR97 (Altomare et al., 1999), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008), WinGX (Farrugia, 1999).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C1—H1···N1ⁱ	0.93	2.43	3.296 (7)	155.4

Symmetry code: (i) −x+2, y−1/2, −z−1/2.

Acknowledgements

We gratefully acknowledge the financial support of the National Natural Science Foundation of China.

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
Atalay, Ş., Yavuz, M., Bekircan, O., Ağar, A. & Şaşmaz, S. (2003). Acta Cryst. E59, o1528–o1529. Web of Science CSD CrossRef IUCr Journals Google Scholar
Brasselet, S., Cherioux, F., Audebert, P. & Zyss, J. (1999). Chem. Mater. 11, 1915–1920. Web of Science CrossRef CAS Google Scholar
Bruker (2005). APEX2. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Cornelissen, J. P., van Diemen, J. H., Groeneveld, L. R., Haasnoot, J. G., Spek, A. L. & Reedijk, J. (1992). Inorg. Chem. 31, 198–202. CSD CrossRef CAS Web of Science Google Scholar
Demirbs, N. & Ugurluoglu Demirbas, A. (2002). Bioorg. Med. Chem. 10, 3717–3723. Web of Science PubMed Google Scholar
Farrugia, L. J. (1999). J. Appl. Cryst. 32, 837–838. CrossRef CAS IUCr Journals Google Scholar
Fujigaya, T., Jiang, D. L. & Aida, T. (2003). J. Am. Chem. Soc. 125, 14690–14691. Web of Science CrossRef PubMed CAS Google Scholar
Garcia, Y., van Koningsbruggen, P. J., Codjovi, E., Lapouyade, R., Kahn, O. & Rabardel, L. (1997). J. Mater. Chem. 7, 857–858. CrossRef CAS Web of Science Google Scholar
Kahn, O. & Martinez, C. J. (1998). Science, 279, 44–48. Web of Science CrossRef CAS Google Scholar
Moliner, N., Gaspar, A. B., Munoz, M. C., Niel, V., Cano, J. & Real, J. A. (2001). Inorg. Chem. 40, 3986–3991. Web of Science CSD CrossRef PubMed CAS Google Scholar
Petek, H., Şenel, İ., Bekircan, O., Ağar, E. & Şaşmaz, S. (2004). Acta Cryst. E60, o831–o832. Web of Science CSD CrossRef IUCr Journals Google Scholar
Sheldrick, G. M. (1996). 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
Tozkoparan, B., Gökhan, N., Aktay, G., Yesilada, E. & Ertan, M. (2000). Eur. J. Med. Chem. 35, 743–750. Web of Science CrossRef PubMed CAS Google Scholar
Turan-Zitouni, G., Kaplancikli, Z. A., Erol, K. & Killic, F. S. (1999). Farmaco, 54, 218–223. Web of Science CrossRef PubMed CAS Google Scholar
Zhu, D.-R., Xu, Y., Liu, Y.-J., Song, Y., Zhang, Y. & You, X.-Z. (2000). Acta Cryst. C56, 242–243. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar