Crystal structure of N,N′-[(ethane-1,2-di­yl)bis­(aza­nediylcarbono­thio­yl)]bis­(benzamide)

Samb, I.; Gaye, N.; Sylla-Gueye, R.; Thiam, E.I.; Gaye, M.; Retailleau, P.

doi:10.1107/S205698901900495X

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Volume 75| Part 5| May 2019| Pages 642-645

https://doi.org/10.1107/S205698901900495X

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Crystal structure of N,N′-[(ethane-1,2-diyl)bis(azanediylcarbonothioyl)]bis(benzamide)

Issa Samb,^a Nango Gaye,^b Rokhaya Sylla-Gueye,^b Elhadj Ibrahima Thiam,^b ^* Mohamed Gaye ^b and Pascal Retailleau ^c

^aDépartement de Chimie, UFR SATIC, Université Alioune Diop, Bambey, Senegal, ^bDépartement de Chimie, Faculté des Sciences et Techniques, Université Cheik Anta Diop, Dakar, Senegal, and ^cInstitut de Chimie des Substances Naturelles, CNRS UPR 2301, Université Paris-Sud, Université Paris-Saclay, 1 av. de la Terrasse, 91198 Gif-sur-Yvette, France
^*Correspondence e-mail: i6thiam@yahoo.fr

Edited by L. Van Meervelt, Katholieke Universiteit Leuven, Belgium (Received 28 March 2019; accepted 11 April 2019; online 18 April 2019)

The reaction of benzoyl chloride and ethylendiamine in the presence of potassium thiocyanate yielded a white solid, C₁₈H₁₈N₄O₂S₂, which consists of two benzoylthioureido moieties connected by an ethylene chain. The asymmetric unit consists of one half of the molecule, the complete molecule being generated by crystallographic inversion symmetry. Both thiourea moieties are in a trans conformation. An intramolecular N—H⋯O hydrogen bond occurs. In the crystal, C—H⋯S and C—H⋯O hydrogen bonds link the molecules, forming layers parallel to the ac plane.

Keywords: crystal structure; thiourea; ethylenediamine; benzoylthioureido.

CCDC reference: 1909438

1. Chemical context

Thiourea derivatives have been successfully used in the extraction of some transition metals (i.e. Cu^II, Ni^II and Co^II) from acidic media. Thiourea derivatives have also been shown to possess antibacterial, antifungal, antitubercular, antithyroid and insecticidal properties (Arslan et al., 2004 ; Cunha et al., 2007 ). The structures of several types of thiourea derivatives and its metal complexes have been determined in recent decades. These compounds possess two arms which can act as a tetradentate ligand coordinating through the S atom and the benzoyl O atom of each arm. Urea and thiourea derivatives can behave as catalysts through double interaction by hydrogen bonding with the substrate (Sigman & Jacobsen, 1998 ; Cortes-Clerget et al., 2016 ). Thiourea derivatives with alkyl bridges can adopt diverse conformations (Thiam et al., 2008 ; Pansuriya et al., 2011 ). We have recently begun to examine the coordination behaviour of a series of substituted benzoylthiourea derivatives that possess a number of interesting properties and reported a thioureido ligand in which the two thioureido moieties are bridged by a 1,2-phenylene ring (Thiam et al., 2008). In this paper, we report the synthesis and the characterization of a molecule where the two thioureidos are bridged by an ethane-1,2-diyl group.

2. Structural commentary

The asymmetric unit of the title compound is a half-molecule with the other half being generated by an inversion centre located at the mid-point of the C1—C1a bond [Fig. 1; symmetry code: (a) −x + 2, −y + 1, −z + 1]. The benzoyl groups of each thiourea subunit are trans with respect to the thiono S atoms across the respective C2—N2 bonds. The 1-benzoyl-3-ethylthiourea fragments adopt a cis conformation with respect to the thiono S atom across the respective C2—N1 bonds. The S1—C2 [1.6626 (15) Å] and O1—C3 [1.2209 (16) Å] distances indicate that these correspond to double bonds and are comparable to those observed for 1,2-bis(N-benzoylthioureido)benzene [1.6574 (18) Å for S—C and 1.222 (2) Å for O7—C16] (Thiam et al., 2008). The C—N bond lengths [1.3744 (17)–1.3971 (17) Å] are in the normal range observed for a single C—N bond. The thiourea fragments S1/N1/N2/C1/C2 are planar, with a maximum deviation from the least-squares plane of 0.015 (1) Å for the N1 atom. The dihedral angle between this plane and that of the benzene ring (r.m.s. deviation = 0.006 Å) is 26.97 (5)° versus ca 34° when the benzene ring is chlorinated (Abusaadiya et al., 2016 ). As regularly noticed with carbonylurea derivatives, the molecule also forms intramolecular N1—H1 hydrogen bonds between the carbonyl O and thioamide H atoms producing S(6) rings (N1—H1⋯O1, Table 1).

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—HN1⋯O1	0.86 (2)	1.95 (2)	2.6528 (16)	138 (2)
C5—H5⋯O1ⁱ	0.93	2.58	3.478 (16)	162
C9—H9⋯O1ⁱⁱ	0.93	2.52	3.311 (16)	143
C1—H1A⋯S1ⁱⁱⁱ	0.97	2.97	3.8375 (16)	150
Symmetry codes: (i) $[x, -y+{\script{3\over 2}}, z-{\script{1\over 2}}]$ ; (ii) -x+1, -y+1, -z+1; (iii) $[x, -y+{\script{3\over 2}}, z+{\script{1\over 2}}]$ .

Figure 1
The molecular structure of the title compound, showing the atom-numbering scheme and intramolecular contacts. Displacement ellipsoids are plotted at the 50% probability level. [Symmetry code: (a) −x + 2, −y + 1, −z + 1]

3. Supramolecular features

In the crystal, the molecules, which feature an overall Z-form, have both halves roughly parallel to the ac plane, whereas the mid-point of the C1—C1a bond lies orthogonally parallel to the (100) plane. Molecular layers running almost parallel to the ac plane are formed by intermolecular C—H⋯O and C—H⋯S interactions (Table 1 and Fig. 2). These layers stack along the b direction. Despite the presence of phenyl rings, no π–π interactions are observed in the crystal packing. However, the carbonyl function C3=O1 stacks on phenyl group C4–C9 of a neighbouring layer [O1⋯Cg1^iv = 3.5543 (14) Å; Cg1 is the centroid of ring C4–C9; symmetry code: (iv) −x + 1, y + $[{1\over 2}]$ , −z + $[{1\over 2}]$ ].

Figure 2
Partial crystal packing of the title compound, showing C—H⋯O (red dashed lines) and C—H⋯S (yellow dashed lines) interactions (see Table 1

for details).

4. Database survey

Reflecting the interest in compounds similar to the title compound, no less than 35 associated structures are included in the Cambridge Structural Database (Version 5.38; Groom et al., 2016 ). The match APALEK (Abusaadiya et al., 2016) is the most similar structure to the title compound, the only difference being the substitution of the phenyl ring on the C3 position by a Cl atom. In both cases, the benzoyl functions of each thiourea subunit are trans with respect to the thiono S atom across the C—N bond. The 1-benzoyl-3-ethylthiourea fragment adopts a cis conformation with respect to the thiono S atom across the respective C—N bond. Six structures in which the spacer is different from the spacer in the symmetrical bis(thioureido) molecule studied here appear in the literature. The angles between the phenyl rings are: 63.1° for DAVHOZ (Aydın et al., 2012 ), 10.2° for EGUYAH (Sow et al., 2009 ), 35.4° for NEWJIL (Light, 2018 ), 0.0° for QIXQUK (Ding et al., 2008 ), 3.2° for TIFQAD (Oyeka et al., 2018 ) and 0.0° for XIQPAP (Dong et al., 2007 ). In addition, 23 structures which contain only one arm with a thioureido moiety similar to the studied molecules are reported, while the other arm consists of diverse moieties: CIGDAZ (Karipcin et al., 2013 ), DELMUD (Ngah et al., 2006 ), EYACIQ (Shutalev et al., 2004 ), GIHMIV (Haynes et al., 2014 ), GIHMOB (Haynes et al., 2014), IFUZOZ (Hassan et al., 2008a ,b ), NIQROV (Yamin & Malik, 2007 ), NIQROV01 (Nguyen & Abram, 2008 ), POFKIG (Ngah et al., 2014 ), QEWHUY (Rakhshani et al., 2018 ), RUGKOU (Hassan et al., 2009 ), SAFPAT (Wei, 2016 ), SITKUC (Yamin et al., 2008 ), TADSIB (Zhang et al., 2003 ), TADTEY (Yusof & Yamin, 2003 ), TIBLEW (Khawar Rauf et al., 2007 ). TIHJAW (Yusof et al., 2007 ), UNUBAH (Hassan et al., 2011 ), WOGTUI (Hassan et al., 2008a,b), XEBQOM (Adan et al., 2012 ), YICDEU (Othman et al., 2007 ), YUPYEO (Zheng et al., 2010 ) and YUPYEO01 (Khan et al., 2018 ).

5. Synthesis and crystallization

All purchased chemicals and solvents were of reagent grade and were used without further purification. Melting points were determined with a Büchi 570 melting-point apparatus and were uncorrected. To a mixture of 7.02 g (72 mmol) of potassium thiocyanate and 100 ml of acetone was added dropwise a solution of 10.116 g (72 mmol) of benzoyl chloride in 50 ml of acetone. The resulting mixture was stirred under reflux for 1 h and cooled to room temperature. A solution of 2.2 g (36.6 mmol) of 1,2-ethylenediamine in 20 ml of acetone was added. The yellow solution obtained was stirred at room temperature during 2 h. Hydrochloric acid (0.1 N, 300 ml) was added and a white solid appeared after a few minutes. The compound was filtered off, washed with 3 × 50 ml of water and dried under vacuum. The solid product was washed with water and purified by recrystallization from an ethanol/dichloromethane mixture (1:1 v/v). 12.3 g of the title compound were obtained (yield 88.5%). A small quantity of powder was recrystallized from 5 ml of DMF. Colourless single crystals suitable to XRD grew within six days.

6. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2. Aromatic H atoms were first located by HFIX and other H atoms were located in the difference Fourier map, positioned geometrically and allowed to ride on their respective parent atoms, with C—H = 0.93 (C_arH) or 0.97 Å (CH₂). The NH H atoms were located in a difference Fourier map and freely refined.

Table 2
Experimental details

Crystal data
Chemical formula	C₁₈H₁₈N₄O₂S₂
M_r	386.48
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	293
a, b, c (Å)	11.2250 (6), 7.2547 (5), 11.1397 (6)
β (°)	100.978 (5)
V (Å³)	890.55 (9)
Z	2
Radiation type	Mo Kα
μ (mm⁻¹)	0.32
Crystal size (mm)	0.36 × 0.14 × 0.11

Data collection
Diffractometer	XtaLAB AFC12 (RINC): Kappa single
Absorption correction	Multi-scan CrysAlis PRO (Rigaku OD, 2018 $[Rigaku OD (2018). CrysAlis PRO. Rigaku Oxford Diffraction Ltd, Yarnton, Oxfordshire, England.]$ )
T_min, T_max	0.513, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	7264, 2328, 1942
R_int	0.040
(sin θ/λ)_max (Å⁻¹)	0.704

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.042, 0.121, 1.05
No. of reflections	2325
No. of parameters	124
No. of restraints	2
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.36, −0.31
Computer programs: CrysAlis PRO (Rigaku OD, 2018 $[Rigaku OD (2018). CrysAlis PRO. Rigaku Oxford Diffraction Ltd, Yarnton, Oxfordshire, England.]$ ), SHELXT2014 (Sheldrick, 2015a ) and SHELXL2018 (Sheldrick, 2015b ).

Supporting information

CCDC reference: 1909438

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S205698901900495X/vm2216sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S205698901900495X/vm2216Isup2.hkl

Supporting information file. DOI: https://doi.org/10.1107/S205698901900495X/vm2216Isup3.cml

checkCIF report

Computing details top

Data collection: CrysAlis PRO (Rigaku OD, 2018); cell refinement: CrysAlis PRO (Rigaku OD, 2018); data reduction: CrysAlis PRO (Rigaku OD, 2018); program(s) used to solve structure: SHELXT2014 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2018 (Sheldrick, 2015b); software used to prepare material for publication: SHELXL2018 (Sheldrick, 2015b).

N,N'-[(Ethane-1,2-diyl)bis(azanediylcarbonothioyl)]bis(benzamide) top

Crystal data top

C₁₈H₁₈N₄O₂S₂	F(000) = 404
M_r = 386.48	D_x = 1.441 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
a = 11.2250 (6) Å	Cell parameters from 3377 reflections
b = 7.2547 (5) Å	θ = 4.7–30.2°
c = 11.1397 (6) Å	µ = 0.32 mm⁻¹
β = 100.978 (5)°	T = 293 K
V = 890.55 (9) Å³	Prism, colourless
Z = 2	0.36 × 0.14 × 0.11 mm

Data collection top

XtaLAB AFC12 (RINC): Kappa single diffractometer	2328 independent reflections
Radiation source: micro-focus sealed X-ray tube, Rigaku (Mo)mm03 X-ray Source	1942 reflections with I > 2σ(I)
Rigaku MaxFlux mirror monochromator	R_int = 0.040
ω scans	θ_max = 30.0°, θ_min = 3.7°
Absorption correction: multi-scan CrysAlis PRO (Rigaku OD, 2018)	h = −15→14
T_min = 0.513, T_max = 1.000	k = −10→9
7264 measured reflections	l = −15→15

Refinement top

Refinement on F²	Primary atom site location: dual
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.042	Hydrogen site location: mixed
wR(F²) = 0.121	H atoms treated by a mixture of independent and constrained refinement
S = 1.05	w = 1/[σ²(F_o²) + (0.0683P)² + 0.1222P] where P = (F_o² + 2F_c²)/3
2325 reflections	(Δ/σ)_max < 0.001
124 parameters	Δρ_max = 0.36 e Å⁻³
2 restraints	Δρ_min = −0.31 e Å⁻³

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.

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

	x	y	z	U_iso*/U_eq
N1	0.85736 (10)	0.61198 (19)	0.41958 (11)	0.0399 (3)
HN1	0.8022 (15)	0.636 (3)	0.4606 (15)	0.048*
O1	0.62565 (9)	0.65743 (17)	0.43252 (9)	0.0452 (3)
C1	0.98347 (12)	0.5989 (2)	0.48195 (13)	0.0398 (3)
H1A	0.996007	0.675814	0.554503	0.048*
H1AB	1.035920	0.643780	0.428470	0.048*
S1	0.90847 (3)	0.53047 (7)	0.20190 (4)	0.05100 (17)
N2	0.69512 (10)	0.59494 (18)	0.25797 (10)	0.0372 (3)
HN2	0.6711 (17)	0.573 (2)	0.1826 (14)	0.045*
C2	0.82013 (12)	0.58234 (19)	0.30120 (12)	0.0351 (3)
C3	0.60474 (11)	0.62787 (19)	0.32261 (12)	0.0332 (3)
C4	0.47845 (11)	0.61990 (18)	0.25055 (12)	0.0323 (3)
C5	0.44876 (13)	0.6519 (2)	0.12543 (12)	0.0380 (3)
H5	0.508903	0.681492	0.081672	0.046*
C6	0.32849 (14)	0.6391 (2)	0.06642 (14)	0.0446 (3)
H6	0.308060	0.662390	−0.017073	0.054*
C7	0.23884 (13)	0.5923 (2)	0.13013 (16)	0.0466 (4)
H7	0.158787	0.581443	0.089304	0.056*
C8	0.26809 (14)	0.5617 (2)	0.25436 (16)	0.0469 (4)
H8	0.207621	0.530909	0.297439	0.056*
C9	0.38722 (13)	0.5766 (2)	0.31507 (13)	0.0396 (3)
H9	0.406519	0.557780	0.399116	0.048*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
N1	0.0294 (6)	0.0525 (7)	0.0365 (6)	0.0051 (5)	0.0025 (4)	−0.0034 (5)
O1	0.0362 (5)	0.0667 (7)	0.0327 (5)	0.0038 (5)	0.0061 (4)	−0.0008 (5)
C1	0.0288 (6)	0.0468 (8)	0.0405 (7)	−0.0030 (5)	−0.0013 (5)	−0.0052 (6)
S1	0.0316 (2)	0.0798 (3)	0.0436 (2)	−0.00179 (16)	0.01212 (16)	−0.00785 (18)
N2	0.0274 (5)	0.0518 (7)	0.0316 (5)	0.0025 (5)	0.0039 (4)	−0.0014 (5)
C2	0.0282 (6)	0.0395 (7)	0.0371 (6)	−0.0016 (5)	0.0049 (5)	0.0012 (5)
C3	0.0291 (6)	0.0373 (7)	0.0333 (6)	0.0012 (5)	0.0063 (5)	0.0036 (5)
C4	0.0283 (6)	0.0338 (6)	0.0347 (6)	0.0024 (5)	0.0058 (5)	0.0027 (5)
C5	0.0348 (6)	0.0427 (7)	0.0362 (6)	−0.0003 (5)	0.0063 (5)	0.0053 (5)
C6	0.0410 (7)	0.0497 (8)	0.0390 (7)	0.0026 (6)	−0.0030 (6)	0.0041 (6)
C7	0.0285 (6)	0.0490 (9)	0.0586 (9)	0.0040 (6)	−0.0009 (6)	0.0005 (7)
C8	0.0313 (7)	0.0552 (9)	0.0571 (9)	0.0028 (6)	0.0155 (6)	0.0040 (7)
C9	0.0331 (7)	0.0486 (8)	0.0387 (7)	0.0034 (6)	0.0108 (5)	0.0048 (6)

Geometric parameters (Å, º) top

N1—C2	1.3228 (17)	C4—C5	1.3894 (17)
N1—C1	1.4564 (17)	C4—C9	1.3944 (18)
N1—HN1	0.854 (14)	C5—C6	1.388 (2)
O1—C3	1.2209 (16)	C5—H5	0.9300
C1—C1ⁱ	1.518 (3)	C6—C7	1.380 (2)
C1—H1A	0.9700	C6—H6	0.9300
C1—H1AB	0.9700	C7—C8	1.378 (2)
S1—C2	1.6633 (14)	C7—H7	0.9300
N2—C3	1.3723 (17)	C8—C9	1.383 (2)
N2—C2	1.3971 (16)	C8—H8	0.9300
N2—HN2	0.846 (14)	C9—H9	0.9300
C3—C4	1.4913 (17)

C2—N1—C1	123.98 (12)	C5—C4—C9	119.69 (12)
C2—N1—HN1	116.3 (12)	C5—C4—C3	123.74 (12)
C1—N1—HN1	119.7 (12)	C9—C4—C3	116.58 (12)
N1—C1—C1ⁱ	110.75 (14)	C6—C5—C4	119.34 (13)
N1—C1—H1A	109.5	C6—C5—H5	120.3
C1ⁱ—C1—H1A	109.5	C4—C5—H5	120.3
N1—C1—H1AB	109.5	C7—C6—C5	120.78 (14)
C1ⁱ—C1—H1AB	109.5	C7—C6—H6	119.6
H1A—C1—H1AB	108.1	C5—C6—H6	119.6
C3—N2—C2	128.67 (11)	C8—C7—C6	119.91 (13)
C3—N2—HN2	115.1 (13)	C8—C7—H7	120.0
C2—N2—HN2	116.1 (13)	C6—C7—H7	120.0
N1—C2—N2	116.03 (12)	C7—C8—C9	120.11 (14)
N1—C2—S1	125.77 (10)	C7—C8—H8	119.9
N2—C2—S1	118.19 (10)	C9—C8—H8	119.9
O1—C3—N2	122.46 (12)	C8—C9—C4	120.15 (14)
O1—C3—C4	121.88 (12)	C8—C9—H9	119.9
N2—C3—C4	115.64 (11)	C4—C9—H9	119.9

C2—N1—C1—C1ⁱ	−84.6 (2)	N2—C3—C4—C9	154.33 (13)
C1—N1—C2—N2	177.90 (13)	C9—C4—C5—C6	−0.4 (2)
C1—N1—C2—S1	−1.5 (2)	C3—C4—C5—C6	179.28 (13)
C3—N2—C2—N1	−2.5 (2)	C4—C5—C6—C7	−1.1 (2)
C3—N2—C2—S1	177.01 (12)	C5—C6—C7—C8	1.5 (3)
C2—N2—C3—O1	2.4 (2)	C6—C7—C8—C9	−0.4 (3)
C2—N2—C3—C4	−175.85 (13)	C7—C8—C9—C4	−1.0 (2)
O1—C3—C4—C5	156.36 (14)	C5—C4—C9—C8	1.4 (2)
N2—C3—C4—C5	−25.33 (19)	C3—C4—C9—C8	−178.28 (14)
O1—C3—C4—C9	−23.98 (19)

Symmetry code: (i) −x+2, −y+1, −z+1.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—HN1···O1	0.86 (2)	1.95 (2)	2.6528 (16)	138 (2)
C5—H5···O1ⁱⁱ	0.93	2.58	3.478 (16)	162
C9—H9···O1ⁱⁱⁱ	0.93	2.52	3.311 (16)	143
C1—H1A···S1^iv	0.97	2.97	3.8375 (16)	150

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

Acknowledgements

The authors are grateful to the Sonatel Foundation for financial support.

References

Abusaadiya, S. M., Yamin, B. M., Ngatiman, F. & Hasbullah, S. A. (2016). IUCrData, 1, x160927. Google Scholar
Adan, D., Sapari, S., Halim, S. N. & Yamin, B. M. (2012). Acta Cryst. E68, o2226. CSD CrossRef IUCr Journals Google Scholar
Arslan, H., Ulrich, F. & Külcü, N. (2004). Acta Chim. Slov. 51, 787–792. CAS Google Scholar
Aydın, F., Aykaç, D., Ünver, H. & İskeleli, N. O. (2012). J. Chem. Crystallogr. 42, 381–387. Google Scholar
Cortes-Clerget, M., Gager, O., Monteil, M., Pirat, J.-L., Migianu-Griffoni, E., Deschamp, J. & Lecouvey, M. (2016). Adv. Synth. Catal. 358, 34–40. CAS Google Scholar
Cunha, S., Macedo, F. C. Jr, Costa, G. A. N., Rodrigues, M. T. Jr, Verde, R. B. V., de Souza Neta, L. C., Vencato, I., Lariucci, C. & Sá, F. P. (2007). Monatsh. Chem. 138, 511–516. CSD CrossRef CAS Google Scholar
Ding, Y.-J., Chang, X.-B., Yang, X.-Q. & Dong, W.-K. (2008). Acta Cryst. E64, o658. Web of Science CSD CrossRef IUCr Journals Google Scholar
Dong, W.-K., Yang, X.-Q., Xu, L., Wang, L., Liu, G.-L. & Feng, J.-H. (2007). Z. Kristallogr. New Cryst. Struct. 222, 279–280. CAS Google Scholar
Groom, C. R., Bruno, I. J., Lightfoot, M. P. & Ward, S. C. (2016). Acta Cryst. B72, 171–179. Web of Science CrossRef IUCr Journals Google Scholar
Hassan, I. N., Yamin, B. M. & Kassim, M. B. (2008a). Acta Cryst. E64, o2083. CSD CrossRef IUCr Journals Google Scholar
Hassan, I. N., Yamin, B. M. & Kassim, M. B. (2008b). Acta Cryst. E64, o2167. CSD CrossRef IUCr Journals Google Scholar
Hassan, I. N., Yamin, B. M. & Kassim, M. B. (2009). Acta Cryst. E65, o3078. Web of Science CSD CrossRef IUCr Journals Google Scholar
Hassan, I. N., Yi, C. Y. & Kassim, M. B. (2011). Acta Cryst. E67, o780. Web of Science CSD CrossRef IUCr Journals Google Scholar
Haynes, C. J. E., Busschaert, N., Kirby, I. L., Herniman, J., Light, M. E., Wells, N. J., Marques, I., Félix, V. & Gale, P. A. (2014). Org. Biomol. Chem. 12, 62–72. CSD CrossRef CAS PubMed Google Scholar
Karipcin, F., Atis, M., Sariboga, B., Celik, H. & Tas, M. (2013). J. Mol. Struct. 1048, 69–77. CSD CrossRef CAS Google Scholar
Khan, M. R., Zaib, S., Rauf, M. K., Ebihara, M., Badshah, A., Zahid, M., Nadeem, M. A. & Iqbal, J. (2018). J. Mol. Struct. 1164, 354–362. CSD CrossRef CAS Google Scholar
Khawar Rauf, M., Badshah, A. & Bolte, M. (2007). Acta Cryst. E63, o1679–o1680. CSD CrossRef IUCr Journals Google Scholar
Light, M. E. (2018). CSD Communication, https://doi:10.5517/ccdc.csd.cc1zr8bb. Google Scholar
Ngah, N., Darman, N. & Yamin, B. M. (2006). Acta Cryst. E62, o3369–o3371. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
Ngah, N., Mohamed, N. A., Yamin, B. M. & Mohd Zaki, H. (2014). Acta Cryst. E70, o705. CSD CrossRef IUCr Journals Google Scholar
Nguyen, H. H. & Abram, U. (2008). Inorg. Chem. Commun. 11, 1478–1480. CSD CrossRef CAS Google Scholar
Othman, E. A., Arif, M. A. M. & Yamin, B. M. (2007). Acta Cryst. E63, o2436–o2437. CSD CrossRef IUCr Journals Google Scholar
Oyeka, E. E., Asegbeloyin, J. N., Babahan, I., Eboma, B., Okpareke, O., Lane, J., Ibezim, A., Bıyık, H. H., Törün, B. & Izuogu, D. C. (2018). J. Mol. Struct. 1168, 153–164. CSD CrossRef CAS Google Scholar
Pansuriya, P., Naidu, H., Friedrich, H. B. & Maguire, G. E. M. (2011). Acta Cryst. E67, o2552. CSD CrossRef IUCr Journals Google Scholar
Rakhshani, S., Rezvani, A. R., Dušek, M. & Eigner, V. (2018). Appl. Organomet. Chem. 32, e4342. CSD CrossRef Google Scholar
Rigaku OD (2018). CrysAlis PRO. Rigaku Oxford Diffraction Ltd, Yarnton, Oxfordshire, England. Google Scholar
Sheldrick, G. M. (2015a). Acta Cryst. A71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Sheldrick, G. M. (2015b). Acta Cryst. C71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Shutalev, A. D., Zhukhlistova, N. E. & Gurskaya, G. V. (2004). Mendeleev Commun. 14, 31–33. CSD CrossRef Google Scholar
Sigman, M. S. & Jacobsen, E. N. (1998). J. Am. Chem. Soc. 120, 4901–4902. Web of Science CrossRef CAS Google Scholar
Sow, M. M., Diouf, O., Barry, A. H., Gaye, M. & Sall, A. S. (2009). Acta Cryst. E65, o569. Web of Science CSD CrossRef IUCr Journals Google Scholar
Thiam, E. I., Diop, M., Gaye, M., Sall, A. S. & Barry, A. H. (2008). Acta Cryst. E64, o776. Web of Science CSD CrossRef IUCr Journals Google Scholar
Wei, H. (2016). CSD Communication, https://doi:10.5517/cc1khnrg. Google Scholar
Yamin, B. M., Deris, H., Malik, Z. M. & Yousuf, S. (2008). Acta Cryst. E64, o360. CSD CrossRef IUCr Journals Google Scholar
Yamin, B. M. & Malik, Z. M. (2007). Acta Cryst. E63, o4842. CSD CrossRef IUCr Journals Google Scholar
Yusof, M. S. M., Roslan, R., Kadir, M. A. & Yamin, B. M. (2007). Acta Cryst. E63, o3591. CSD CrossRef IUCr Journals Google Scholar
Yusof, M. S. M. & Yamin, B. M. (2003). Acta Cryst. E59, o828–o829. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
Zhang, Y.-M., Xian, L., Wei, T.-B. & Cai, L.-X. (2003). Acta Cryst. E59, o817–o819. Web of Science CSD CrossRef IUCr Journals Google Scholar
Zheng, X., Li, B., Wang, Q. & Guo, L. (2010). Acta Cryst. E66, o1774. CSD CrossRef IUCr Journals Google Scholar

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