5-(4-Pyrid­yl)-1,3,4-thia­diazol-2-amine

Wang, Y.; Wan, R.; Han, F.; Wang, P.; Wang, B.

doi:10.1107/S1600536809014470

organic compounds

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ISSN: 2056-9890

Volume 65| Part 5| May 2009| Page o1099

doi:10.1107/S1600536809014470

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5-(4-Pyridyl)-1,3,4-thiadiazol-2-amine

Yao Wang,^a Rong Wan,^a ^* Feng Han,^a Peng Wang ^a and Bin Wang ^a

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

(Received 17 March 2009; accepted 18 April 2009; online 25 April 2009)

The title compound, C₇H₆N₄S, was synthesized by reacting pyridine-4-carboxylic acid and thiosemicarbazide. The asymmetric unit contains two independent molecules, which present different conformations, the dihedral angles between the thiadiazole and pyridine rings being 18.2 (2) and 30.3 (2)°. In the crystal, intermolecular N—H⋯N hydrogen bonds involving the amine groups as donors link molecules into a two-dimensional framework.

Related literature

For the biological activity of 1,3,4-thiadiazoles, see: Nakagawa et al. (1996 ); Wang et al. (1999 ). For the structure of 2-amino-5-phenyl-1,3,4-thiadiazole, see: Öztürk et al. (2004 ).

Experimental

Crystal data

C₇H₆N₄S
M_r = 178.22
Monoclinic, P 2₁ /c
a = 14.794 (3) Å
b = 10.686 (2) Å
c = 10.477 (2) Å
β = 106.52 (3)°
V = 1587.9 (5) Å³
Z = 8
Mo Kα radiation
μ = 0.35 mm⁻¹
T = 293 K
0.20 × 0.10 × 0.10 mm

Data collection

Enraf–Nonius CAD-4 diffractometer
Absorption correction: ψ scan (North et al., 1968 ) T_min = 0.933, T_max = 0.966
3203 measured reflections
3023 independent reflections
1516 reflections with I > 2σ(I)
R_int = 0.042
3 standard reflections every 200 reflections intensity decay: 1%

Refinement

R[F² > 2σ(F²)] = 0.067
wR(F²) = 0.142
S = 1.00
3023 reflections
217 parameters
43 restraints
H-atom parameters constrained
Δρ_max = 0.24 e Å⁻³
Δρ_min = −0.31 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N4A—H4A⋯N1Bⁱ	0.86	2.08	2.940 (5)	177
N4A—H4B⋯N2Aⁱⁱ	0.86	2.21	3.053 (5)	166
N4B—H8A⋯N1Aⁱⁱⁱ	0.86	2.10	2.945 (5)	168
N4B—H8B⋯N2B^iv	0.86	2.13	2.988 (5)	178
Symmetry codes: (i) $[-x, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (ii) $[-x, y+{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (iii) $[-x+1, y+{\script{1\over 2}}, -z-{\script{1\over 2}}]$ ; (iv) $[-x+1, y-{\script{1\over 2}}, -z-{\script{1\over 2}}]$ .

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1989 ); 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: SHELXL97.

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809014470/bh2224sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536809014470/bh2224Isup2.hkl

checkCIF report

Comment top

1,3,4-Thiadiazole derivatives represent an interesting class of compounds possessing a broad spectrum of biological activity (Nakagawa et al., 1996). These compounds are known to exhibit diverse biological effects, such as insecticidal and fungicidal activities (Wang et al., 1999).

The asymmetric unit of the title compound contains two independent molecules (A and B, see Fig. 1), with bond lengths and angles in expected ranges. (Öztürk et al., 2004). Dihedral angles between thiadiazole and pyridine rings are different in each molecule: 18.2 (2)° for molecule A and 30.3 (2)° in molecule B. In the crystal, molecules are linked through N—H···N hydrogen bonds, forming a two-dimensional supramolecular structure.

Related literature top

For the biological activity of 1,3,4-thiadiazoles, see: Nakagawa et al. (1996); Wang et al. (1999). For the structure of 2-amino-5-phenyl-1,3,4-thiadiazole, see: Öztürk et al. (2004).

Experimental top

4-Pyridinecarboxylic acid (2 mmol) and thiosemicarbazide (5 mmol) were mixed in a 25 ml flask, and kept in the oil bath at 363 K for 6 h. After cooling, the crude product precipitated and was filtered. Pure compound was obtained by crystallization from ethanol. Crystals suitable for X-ray diffraction were obtained by slow evaporation of an acetone solution.

Computing details top

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1989); cell refinement: CAD-4 EXPRESS (Enraf–Nonius, 1989); 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: SHELXL97 (Sheldrick, 2008).

Figures top

	Fig. 1. A view of the molecular structure of the title compound. Displacement ellipsoids are drawn at the 50% probability level. The dashed line indicates an intramolecular C—H···S hydrogen bond.
	Fig. 2. Partial packing view showing the hydrogen bonds network. Dashed lines indicate intermolecular N—H···N hydrogen bonds.

5-(4-Pyridyl)-1,3,4-thiadiazol-2-amine top

Crystal data top

C₇H₆N₄S	F(000) = 736
M_r = 178.22	D_x = 1.491 Mg m⁻³
Monoclinic, P2₁/c	Melting point: 543 K
Hall symbol: -P 2ybc	Mo Kα radiation, λ = 0.71073 Å
a = 14.794 (3) Å	Cell parameters from 25 reflections
b = 10.686 (2) Å	θ = 9–12°
c = 10.477 (2) Å	µ = 0.35 mm⁻¹
β = 106.52 (3)°	T = 293 K
V = 1587.9 (5) Å³	Block, colorless
Z = 8	0.20 × 0.10 × 0.10 mm

Data collection top

Enraf–Nonius CAD-4 diffractometer	1516 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.042
Graphite monochromator	θ_max = 26.0°, θ_min = 1.4°
ω/2θ scans	h = −18→17
Absorption correction: ψ scan (North et al., 1968)	k = −13→0
T_min = 0.933, T_max = 0.966	l = 0→12
3203 measured reflections	3 standard reflections every 200 reflections
3023 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)] = 0.067	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.142	H-atom parameters constrained
S = 1.00	w = 1/[σ²(F_o²) + (0.0435P)²] where P = (F_o² + 2F_c²)/3
3023 reflections	(Δ/σ)_max < 0.001
217 parameters	Δρ_max = 0.24 e Å⁻³
43 restraints	Δρ_min = −0.31 e Å⁻³
0 constraints

Crystal data top

C₇H₆N₄S	V = 1587.9 (5) Å³
M_r = 178.22	Z = 8
Monoclinic, P2₁/c	Mo Kα radiation
a = 14.794 (3) Å	µ = 0.35 mm⁻¹
b = 10.686 (2) Å	T = 293 K
c = 10.477 (2) Å	0.20 × 0.10 × 0.10 mm
β = 106.52 (3)°

Data collection top

Enraf–Nonius CAD-4 diffractometer	1516 reflections with I > 2σ(I)
Absorption correction: ψ scan (North et al., 1968)	R_int = 0.042
T_min = 0.933, T_max = 0.966	3 standard reflections every 200 reflections
3203 measured reflections	intensity decay: 1%
3023 independent reflections

Refinement top

R[F² > 2σ(F²)] = 0.067	43 restraints
wR(F²) = 0.142	H-atom parameters constrained
S = 1.00	Δρ_max = 0.24 e Å⁻³
3023 reflections	Δρ_min = −0.31 e Å⁻³
217 parameters

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
SA	0.08251 (8)	0.54450 (10)	0.19829 (12)	0.0483 (4)
N1A	0.3034 (3)	0.3300 (4)	−0.0749 (4)	0.0551 (11)
N2A	0.0328 (3)	0.3203 (3)	0.1338 (4)	0.0513 (10)
N3A	−0.0258 (2)	0.3605 (3)	0.2081 (4)	0.0509 (10)
N4A	−0.0553 (2)	0.5382 (3)	0.3223 (3)	0.0548 (11)
H4A	−0.0999	0.5013	0.3454	0.066*
H4B	−0.0408	0.6143	0.3462	0.066*
C1A	0.2262 (3)	0.2621 (5)	−0.0932 (4)	0.0604 (14)
H1B	0.2192	0.1944	−0.1510	0.073*
C2A	0.3105 (3)	0.4259 (5)	0.0056 (5)	0.0601 (14)
H2B	0.3635	0.4769	0.0204	0.072*
C3A	0.2430 (3)	0.4551 (4)	0.0697 (4)	0.0485 (12)
H3B	0.2515	0.5243	0.1256	0.058*
C4A	0.1643 (3)	0.3827 (4)	0.0511 (4)	0.0393 (11)
C5A	0.1561 (3)	0.2820 (4)	−0.0357 (4)	0.0549 (13)
H5A	0.1038	0.2296	−0.0538	0.066*
C6A	0.0928 (3)	0.4040 (4)	0.1217 (4)	0.0413 (11)
C7A	−0.0070 (3)	0.4754 (4)	0.2470 (4)	0.0396 (11)
SB	0.43176 (9)	0.68957 (10)	−0.17070 (12)	0.0505 (4)
N1B	0.2053 (3)	0.9156 (4)	0.0901 (4)	0.0573 (11)
N2B	0.4342 (3)	0.9258 (3)	−0.1864 (4)	0.0518 (11)
N3B	0.4926 (2)	0.8856 (3)	−0.2569 (4)	0.0489 (10)
N4B	0.5574 (2)	0.7052 (3)	−0.3157 (3)	0.0456 (10)
H8A	0.5907	0.7475	−0.3556	0.055*
H8B	0.5607	0.6249	−0.3136	0.055*
C1B	0.1980 (3)	0.8094 (5)	0.0207 (5)	0.0562 (13)
H8C	0.1499	0.7540	0.0226	0.067*
C2B	0.2762 (3)	0.9914 (4)	0.0858 (4)	0.0577 (13)
H9A	0.2837	1.0650	0.1352	0.069*
C3B	0.3375 (3)	0.9687 (4)	0.0150 (4)	0.0507 (12)
H10A	0.3841	1.0269	0.0141	0.061*
C4B	0.3308 (3)	0.8588 (4)	−0.0563 (4)	0.0362 (10)
C5B	0.2573 (3)	0.7782 (4)	−0.0528 (4)	0.0506 (12)
H12A	0.2489	0.7035	−0.1003	0.061*
C6B	0.3977 (3)	0.8349 (4)	−0.1355 (4)	0.0389 (10)
C7B	0.4998 (3)	0.7650 (4)	−0.2563 (4)	0.0380 (10)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
SA	0.0477 (7)	0.0469 (7)	0.0499 (8)	−0.0047 (6)	0.0134 (6)	−0.0041 (6)
N1A	0.054 (3)	0.071 (3)	0.041 (2)	0.013 (2)	0.015 (2)	−0.002 (2)
N2A	0.045 (2)	0.057 (2)	0.047 (2)	−0.001 (2)	0.005 (2)	−0.003 (2)
N3A	0.046 (2)	0.049 (2)	0.056 (3)	−0.0055 (19)	0.012 (2)	0.003 (2)
N4A	0.058 (3)	0.065 (3)	0.050 (3)	−0.012 (2)	0.028 (2)	0.000 (2)
C1A	0.054 (3)	0.080 (4)	0.043 (3)	−0.004 (3)	0.006 (3)	−0.024 (3)
C2A	0.043 (3)	0.067 (4)	0.071 (4)	0.004 (3)	0.018 (3)	0.011 (3)
C3A	0.046 (3)	0.052 (3)	0.046 (3)	−0.003 (2)	0.011 (2)	−0.004 (2)
C4A	0.029 (2)	0.050 (3)	0.031 (3)	0.003 (2)	−0.006 (2)	0.006 (2)
C5A	0.041 (3)	0.076 (4)	0.041 (3)	−0.001 (3)	0.001 (2)	−0.014 (3)
C6A	0.036 (3)	0.048 (3)	0.037 (3)	−0.004 (2)	0.004 (2)	0.007 (2)
C7A	0.035 (2)	0.046 (3)	0.032 (2)	0.009 (2)	0.002 (2)	0.012 (2)
SB	0.0587 (8)	0.0404 (6)	0.0564 (8)	0.0000 (6)	0.0229 (7)	0.0013 (6)
N1B	0.048 (3)	0.069 (3)	0.055 (3)	0.010 (2)	0.015 (2)	0.007 (2)
N2B	0.056 (3)	0.038 (2)	0.065 (3)	0.0007 (19)	0.022 (2)	0.003 (2)
N3B	0.049 (2)	0.045 (2)	0.055 (3)	0.0003 (19)	0.019 (2)	−0.004 (2)
N4B	0.063 (2)	0.036 (2)	0.047 (2)	0.0107 (18)	0.031 (2)	0.0063 (18)
C1B	0.039 (3)	0.069 (3)	0.060 (3)	−0.009 (3)	0.013 (3)	0.007 (3)
C2B	0.063 (3)	0.058 (3)	0.057 (3)	−0.006 (3)	0.025 (3)	−0.004 (3)
C3B	0.046 (3)	0.055 (3)	0.053 (3)	−0.008 (2)	0.017 (2)	−0.007 (2)
C4B	0.031 (2)	0.039 (2)	0.034 (2)	0.0008 (19)	0.002 (2)	−0.001 (2)
C5B	0.047 (3)	0.046 (3)	0.059 (3)	−0.002 (2)	0.016 (2)	0.001 (2)
C6B	0.035 (2)	0.042 (2)	0.034 (2)	−0.001 (2)	0.001 (2)	0.001 (2)
C7B	0.033 (2)	0.037 (2)	0.036 (2)	0.002 (2)	−0.003 (2)	0.005 (2)

Geometric parameters (Å, º) top

SA—C7A	1.716 (4)	SB—C6B	1.705 (4)
SA—C6A	1.729 (4)	SB—C7B	1.726 (4)
N1A—C2A	1.312 (5)	N1B—C1B	1.335 (5)
N1A—C1A	1.320 (5)	N1B—C2B	1.336 (5)
N2A—C6A	1.292 (5)	N2B—C6B	1.298 (5)
N2A—N3A	1.387 (4)	N2B—N3B	1.356 (4)
N3A—C7A	1.298 (5)	N3B—C7B	1.293 (5)
N4A—C7A	1.380 (5)	N4B—C7B	1.349 (4)
N4A—H4A	0.8600	N4B—H8A	0.8600
N4A—H4B	0.8600	N4B—H8B	0.8600
C1A—C5A	1.356 (6)	C1B—C5B	1.363 (6)
C1A—H1B	0.9300	C1B—H8C	0.9300
C2A—C3A	1.389 (6)	C2B—C3B	1.347 (5)
C2A—H2B	0.9300	C2B—H9A	0.9300
C3A—C4A	1.365 (5)	C3B—C4B	1.380 (5)
C3A—H3B	0.9300	C3B—H10A	0.9300
C4A—C5A	1.392 (5)	C4B—C5B	1.396 (5)
C4A—C6A	1.470 (5)	C4B—C6B	1.483 (5)
C5A—H5A	0.9300	C5B—H12A	0.9300

C7A—SA—C6A	86.7 (2)	C6B—SB—C7B	86.5 (2)
C2A—N1A—C1A	115.6 (4)	C1B—N1B—C2B	116.1 (4)
C6A—N2A—N3A	113.4 (4)	C6B—N2B—N3B	113.0 (3)
C7A—N3A—N2A	110.9 (3)	C7B—N3B—N2B	112.2 (4)
C7A—N4A—H4A	120.0	C7B—N4B—H8A	120.0
C7A—N4A—H4B	120.0	C7B—N4B—H8B	120.0
H4A—N4A—H4B	120.0	H8A—N4B—H8B	120.0
N1A—C1A—C5A	126.0 (5)	N1B—C1B—C5B	123.4 (4)
N1A—C1A—H1B	117.0	N1B—C1B—H8C	118.3
C5A—C1A—H1B	117.0	C5B—C1B—H8C	118.3
N1A—C2A—C3A	123.2 (5)	N1B—C2B—C3B	124.5 (5)
N1A—C2A—H2B	118.4	N1B—C2B—H9A	117.7
C3A—C2A—H2B	118.4	C3B—C2B—H9A	117.7
C4A—C3A—C2A	120.4 (4)	C2B—C3B—C4B	119.7 (4)
C4A—C3A—H3B	119.8	C2B—C3B—H10A	120.2
C2A—C3A—H3B	119.8	C4B—C3B—H10A	120.2
C3A—C4A—C5A	116.3 (4)	C3B—C4B—C5B	116.6 (4)
C3A—C4A—C6A	123.2 (4)	C3B—C4B—C6B	119.5 (4)
C5A—C4A—C6A	120.5 (4)	C5B—C4B—C6B	123.9 (4)
C1A—C5A—C4A	118.5 (5)	C1B—C5B—C4B	119.7 (4)
C1A—C5A—H5A	120.8	C1B—C5B—H12A	120.2
C4A—C5A—H5A	120.8	C4B—C5B—H12A	120.2
N2A—C6A—C4A	123.7 (4)	N2B—C6B—C4B	121.5 (4)
N2A—C6A—SA	113.7 (3)	N2B—C6B—SB	114.2 (3)
C4A—C6A—SA	122.6 (3)	C4B—C6B—SB	124.3 (3)
N3A—C7A—N4A	122.7 (4)	N3B—C7B—N4B	122.1 (4)
N3A—C7A—SA	115.3 (3)	N3B—C7B—SB	114.1 (3)
N4A—C7A—SA	121.9 (3)	N4B—C7B—SB	123.8 (3)

C6A—N2A—N3A—C7A	0.9 (5)	C6B—N2B—N3B—C7B	−0.7 (6)
C2A—N1A—C1A—C5A	−1.0 (7)	C2B—N1B—C1B—C5B	−0.9 (7)
C1A—N1A—C2A—C3A	0.8 (7)	C1B—N1B—C2B—C3B	1.6 (7)
N1A—C2A—C3A—C4A	0.1 (7)	N1B—C2B—C3B—C4B	−2.1 (8)
C2A—C3A—C4A—C5A	−1.0 (6)	C2B—C3B—C4B—C5B	1.7 (6)
C2A—C3A—C4A—C6A	176.4 (4)	C2B—C3B—C4B—C6B	179.3 (4)
N1A—C1A—C5A—C4A	0.1 (8)	N1B—C1B—C5B—C4B	0.7 (7)
C3A—C4A—C5A—C1A	0.9 (6)	C3B—C4B—C5B—C1B	−1.1 (6)
C6A—C4A—C5A—C1A	−176.6 (4)	C6B—C4B—C5B—C1B	−178.6 (4)
N3A—N2A—C6A—C4A	178.1 (4)	N3B—N2B—C6B—C4B	−179.1 (4)
N3A—N2A—C6A—SA	−1.2 (5)	N3B—N2B—C6B—SB	−0.4 (5)
C3A—C4A—C6A—N2A	−160.7 (4)	C3B—C4B—C6B—N2B	−29.4 (6)
C5A—C4A—C6A—N2A	16.7 (6)	C5B—C4B—C6B—N2B	147.9 (4)
C3A—C4A—C6A—SA	18.5 (6)	C3B—C4B—C6B—SB	152.0 (3)
C5A—C4A—C6A—SA	−164.1 (3)	C5B—C4B—C6B—SB	−30.7 (6)
C7A—SA—C6A—N2A	0.9 (3)	C7B—SB—C6B—N2B	1.0 (3)
C7A—SA—C6A—C4A	−178.4 (4)	C7B—SB—C6B—C4B	179.7 (4)
N2A—N3A—C7A—N4A	179.9 (4)	N2B—N3B—C7B—N4B	−177.2 (4)
N2A—N3A—C7A—SA	−0.2 (5)	N2B—N3B—C7B—SB	1.5 (5)
C6A—SA—C7A—N3A	−0.4 (3)	C6B—SB—C7B—N3B	−1.4 (3)
C6A—SA—C7A—N4A	179.6 (4)	C6B—SB—C7B—N4B	177.3 (4)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C3A—H3B···SA	0.93	2.82	3.191 (5)	105
N4A—H4A···N1Bⁱ	0.86	2.08	2.940 (5)	177
N4A—H4B···N2Aⁱⁱ	0.86	2.21	3.053 (5)	166
N4B—H8A···N1Aⁱⁱⁱ	0.86	2.10	2.945 (5)	168
N4B—H8B···N2B^iv	0.86	2.13	2.988 (5)	178

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

Experimental details

Crystal data
Chemical formula	C₇H₆N₄S
M_r	178.22
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	293
a, b, c (Å)	14.794 (3), 10.686 (2), 10.477 (2)
β (°)	106.52 (3)
V (Å³)	1587.9 (5)
Z	8
Radiation type	Mo Kα
µ (mm⁻¹)	0.35
Crystal size (mm)	0.20 × 0.10 × 0.10

Data collection
Diffractometer	Enraf–Nonius CAD-4 diffractometer
Absorption correction	ψ scan (North et al., 1968)
T_min, T_max	0.933, 0.966
No. of measured, independent and observed [I > 2σ(I)] reflections	3203, 3023, 1516
R_int	0.042
(sin θ/λ)_max (Å⁻¹)	0.616

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.067, 0.142, 1.00
No. of reflections	3023
No. of parameters	217
No. of restraints	43
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.24, −0.31

Computer programs: CAD-4 EXPRESS (Enraf–Nonius, 1989), XCAD4 (Harms & Wocadlo,1995), 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
N4A—H4A···N1Bⁱ	0.8600	2.0800	2.940 (5)	177
N4A—H4B···N2Aⁱⁱ	0.8600	2.2100	3.053 (5)	166
N4B—H8A···N1Aⁱⁱⁱ	0.8600	2.1000	2.945 (5)	168
N4B—H8B···N2B^iv	0.8600	2.1300	2.988 (5)	178

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

Acknowledgements

The authors thank Professor Hua-qin Wang of the Analysis Centre, Nanjing University, for providing the Enraf–Nonius CAD-4 diffractometer for this research project.

References

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