supplementary materials


hb7064 scheme

Acta Cryst. (2013). E69, o684    [ doi:10.1107/S1600536813009252 ]

3-[(4-Phenylpiperazin-1-yl)methyl]-5-(thiophen-2-yl)-2,3-dihydro-1,3,4-oxadiazole-2-thione

A. A. El-Emam, M. A. Al-Omar, A.-R. M. Al-Obaid, S. W. Ng and E. R. T. Tiekink

Abstract top

In the title compound, C17H18N4OS2, the 2-thienyl ring is disordered over two co-planar, opposite orientations in a 0.684 (2): 0.316 ratio. The 1,3,4-oxadiazole ring is almost co-planar with the attached 2-thienyl ring [dihedral angles of 5.34 (19) and 4.8 (5)° for the major and minor components, respectively]. The relative disposition of the thione- and ring-S atoms is anti for the major orientation of the 2-thienyl residue. Overall, the shape of the molecule approximates the letter V. In the crystal, a three-dimensional architecture is consolidated by a combination of weak C-H...S and C-H...[pi] contacts.

Comment top

The title compound, (I), was synthesized among a series of 2-thienyl-1,3,4-oxadiazoles and related derivatives as potential anti-microbial agents (Al-Omar, 2010). Herein, the crystal structure of (I) is reported.

In (I), Fig. 1, the 1,3,4-oxadiazole ring is almost planar (r.m.s. deviation = 0.005 Å) and almost co-planar with the attached 2-thienyl ring, forming a dihedral angle of 5.34 (19)° [the equivalent dihedral for the minor component of the disordered 2-thienyl ring is 4.8 (5)°]. The relative disposition of the two S atoms is anti for the major component of the 2-thienyl residue. The 4-phenylpiperazinyl residue, in which both N-bound substituents occupy equatorial positions in a chair conformation, is linked to the five-membered ring at the methylene-C7 atom so that, overall, the shape of the molecule approximates the letter V. The relative orientations of the 2-thienyl and terminal phenyl rings in (I) are also found in the structure where the 4-phenylpiperazinyl group of (I) is replaced by a N-methylanilino residue (El-Emam et al., 2012).

In the crystal, C—H···S interactions combine with phenyl-C—H···π(thienyl), thienyl-C—H···π(phenyl) and piperazinyl-C—H···π(phenyl) contacts to consolidate a three-dimensional architecture, Table 1 and Fig. 2.

Related literature top

For background to the biological properties of 1,3,4-oxadiazole derivatives, see: Al-Omar (2010). For a related structure, see: El-Emam et al. (2012).

Experimental top

1-Phenylpiperazine (324 mg, 2 mmol) and 37% formaldehyde solution (0.5 ml) were added to a solution of 5-(thiophen-2-yl)-1,3,4-oxadiazole-2-thiol (369 mg, 2 mmol) in ethanol (8 ml), and the mixture was stirred at room temperature for 2 h and allowed to stand overnight. The precipitated crude product was filtered, washed with cold ethanol, dried, and crystallized from ethanol to yield 502 mg (70%) of the title compound (I) as crystals. M.pt: 404–406 K. Light brown prisms were obtained by slow evaporation of its CHCl3:EtOH (1:1; 5 ml) solution at room temperature. 1H NMR (CDCl3, 500.13 MHz): δ 3.0–3.08 (m, 4H, piperazine-H), 3.18–3.26 (m, 4H, piperazine-H), 5.14 (s, 2H, CH2), 6.87–6.96 (m, 3H, Ar—H), 7.18 (t, 1H, thiophene-H, J = 4.3 Hz), 7.22–7.32 (m. 2H, Ar—H), 7.59 (d, 1H, thiophene-H, J = 4.5 Hz), 7.75 (d, 1H, thiophene-H, J = 4.5 Hz). 13C NMR (CDCl3, 125.76 MHz): δ 49.37, 50.30 (piperazine-C), 70.40 (CH2), 116.45, 120.06, 123.67, 128.33, 129.14, 130.77, 130.98, 151.26 (Ar—C & thiophene-C), 155.47 (C N), 177.76 (CS).

Refinement top

The H-atoms were placed in calculated positions [C—H = 0.93 to 0.97 Å, Uiso(H) = 1.2Ueq(C)] and were included in the refinement in the riding model approximation. The thienyl ring is disordered over two positions in a 0.684 (2): 0.316 ratio in respect of four of the five atoms; that connected to the diazoxole ring is ordered. The anisotropic displacement parameters of the primed atoms were set to those of the unprimed ones, and were restrained to be nearly isotropic. Pairs of 1,2-related bond distances were restrained to within 0.01 Å of each other. The thienyl rings were restrained to lie within 0.01 Å of a plane.

Computing details top

Data collection: CrysAlis PRO (Agilent, 2011); cell refinement: CrysAlis PRO (Agilent, 2011); data reduction: CrysAlis PRO (Agilent, 2011); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012) and DIAMOND (Brandenburg, 2006); software used to prepare material for publication: publCIF (Westrip, 2010).

Figures top
[Figure 1] Fig. 1. The molecular structure of (I) showing displacement ellipsoids at the 35% probability level. Only the major component of the disordered 2-thienyl ring is shown for reasons of clarity.
[Figure 2] Fig. 2. A view of the unit contents in projection down the b axis in (I). The C—H···S and C—H···π contacts are shown as orange and purple dashed lines, respectively.
3-[(4-Phenylpiperazin-1-yl)methyl]-5-(thiophen-2-yl)-2,3-dihydro-1,3,4-oxadiazole-2-thione top
Crystal data top
C17H18N4OS2F(000) = 1504
Mr = 358.47Dx = 1.353 Mg m3
Monoclinic, C2/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2ycCell parameters from 2605 reflections
a = 26.1721 (17) Åθ = 3.1–27.5°
b = 5.7253 (3) ŵ = 0.31 mm1
c = 23.7008 (18) ÅT = 295 K
β = 97.802 (6)°Prism, light-brown
V = 3518.5 (4) Å30.40 × 0.30 × 0.20 mm
Z = 8
Data collection top
Agilent SuperNova Dual
diffractometer with Atlas detector
4083 independent reflections
Radiation source: SuperNova (Mo) X-ray Source2797 reflections with I > 2σ(I)
Mirror monochromatorRint = 0.025
Detector resolution: 10.4041 pixels mm-1θmax = 27.6°, θmin = 3.1°
ω scanh = 3234
Absorption correction: multi-scan
(CrysAlis PRO; Agilent, 2011)
k = 75
Tmin = 0.887, Tmax = 1.000l = 1630
9546 measured reflections
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.047Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.123H-atom parameters constrained
S = 1.06 w = 1/[σ2(Fo2) + (0.0496P)2 + 0.9031P]
where P = (Fo2 + 2Fc2)/3
4083 reflections(Δ/σ)max = 0.001
230 parametersΔρmax = 0.25 e Å3
33 restraintsΔρmin = 0.26 e Å3
Crystal data top
C17H18N4OS2V = 3518.5 (4) Å3
Mr = 358.47Z = 8
Monoclinic, C2/cMo Kα radiation
a = 26.1721 (17) ŵ = 0.31 mm1
b = 5.7253 (3) ÅT = 295 K
c = 23.7008 (18) Å0.40 × 0.30 × 0.20 mm
β = 97.802 (6)°
Data collection top
Agilent SuperNova Dual
diffractometer with Atlas detector
4083 independent reflections
Absorption correction: multi-scan
(CrysAlis PRO; Agilent, 2011)
2797 reflections with I > 2σ(I)
Tmin = 0.887, Tmax = 1.000Rint = 0.025
9546 measured reflectionsθmax = 27.6°
Refinement top
R[F2 > 2σ(F2)] = 0.047H-atom parameters constrained
wR(F2) = 0.123Δρmax = 0.25 e Å3
S = 1.06Δρmin = 0.26 e Å3
4083 reflectionsAbsolute structure: ?
230 parametersFlack parameter: ?
33 restraintsRogers parameter: ?
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
xyzUiso*/UeqOcc. (<1)
S10.51012 (6)0.4713 (3)0.35472 (6)0.0619 (3)0.684 (2)
S1'0.51936 (13)0.8668 (6)0.43201 (16)0.0619 (3)0.316
S20.35703 (2)0.65396 (10)0.54603 (3)0.0727 (2)
O10.43151 (5)0.6708 (2)0.47998 (5)0.0534 (3)
N10.41826 (6)0.3583 (3)0.42460 (7)0.0522 (4)
N20.38163 (6)0.3737 (3)0.46156 (7)0.0509 (4)
N30.29660 (6)0.2250 (3)0.41864 (7)0.0556 (4)
N40.22283 (6)0.3760 (2)0.32601 (6)0.0489 (4)
C10.55629 (17)0.6849 (7)0.3488 (3)0.0629 (13)0.684 (2)
H10.57860.67990.32150.076*0.684 (2)
C20.5569 (3)0.8585 (13)0.3874 (2)0.0655 (13)0.684 (2)
H20.57830.98890.38990.079*0.684 (2)
C30.5214 (2)0.8105 (7)0.4216 (2)0.0673 (14)0.684 (2)
H30.51800.90640.45260.081*0.684 (2)
C1'0.5583 (6)0.821 (3)0.3787 (6)0.0629 (13)0.316 (2)
H1'0.58440.92500.37260.076*0.316 (2)
C2'0.5483 (5)0.627 (2)0.3469 (7)0.0655 (13)0.316 (2)
H2'0.56490.58260.31630.079*0.316 (2)
C3'0.5102 (5)0.509 (2)0.3670 (6)0.0673 (14)0.316 (2)
H3'0.49840.36490.35240.081*0.316 (2)
C40.49000 (7)0.6179 (3)0.41049 (8)0.0506 (4)
C50.44667 (7)0.5396 (3)0.43703 (8)0.0481 (4)
C60.38888 (7)0.5603 (3)0.49568 (8)0.0524 (5)
C70.34040 (8)0.1950 (3)0.46076 (10)0.0613 (5)
H7A0.35540.04310.45520.074*
H7B0.32870.19340.49790.074*
C80.26756 (8)0.4377 (4)0.42299 (9)0.0685 (6)
H8A0.28690.56980.41150.082*
H8B0.26190.46160.46220.082*
C90.21648 (8)0.4220 (5)0.38539 (9)0.0721 (6)
H9A0.19610.29800.39910.086*
H9B0.19780.56750.38760.086*
C100.25448 (8)0.1688 (3)0.32178 (10)0.0628 (5)
H10A0.26080.14900.28270.075*
H10B0.23620.03200.33250.075*
C110.30534 (8)0.1901 (4)0.36017 (9)0.0632 (6)
H11A0.32550.04930.35750.076*
H11B0.32470.32090.34800.076*
C120.17704 (7)0.3921 (3)0.28724 (8)0.0473 (4)
C130.14489 (8)0.5860 (3)0.28800 (9)0.0573 (5)
H130.15360.70330.31470.069*
C140.10056 (9)0.6071 (4)0.25001 (10)0.0654 (6)
H140.07990.73840.25150.078*
C150.08620 (9)0.4380 (4)0.20978 (10)0.0670 (6)
H150.05600.45280.18430.080*
C160.11754 (9)0.2471 (4)0.20823 (9)0.0658 (6)
H160.10850.13140.18120.079*
C170.16222 (8)0.2226 (3)0.24588 (9)0.0579 (5)
H170.18280.09130.24370.069*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
S10.0542 (5)0.0638 (7)0.0700 (7)0.0048 (4)0.0171 (5)0.0069 (5)
S1'0.0542 (5)0.0638 (7)0.0700 (7)0.0048 (4)0.0171 (5)0.0069 (5)
S20.0815 (4)0.0786 (4)0.0626 (4)0.0100 (3)0.0265 (3)0.0018 (3)
O10.0542 (8)0.0540 (7)0.0521 (8)0.0023 (6)0.0082 (6)0.0000 (6)
N10.0470 (9)0.0554 (9)0.0546 (10)0.0002 (7)0.0086 (7)0.0011 (7)
N20.0456 (9)0.0535 (8)0.0541 (9)0.0008 (7)0.0089 (7)0.0064 (7)
N30.0471 (9)0.0608 (9)0.0604 (10)0.0044 (8)0.0124 (8)0.0048 (8)
N40.0457 (8)0.0541 (8)0.0491 (9)0.0023 (7)0.0142 (7)0.0106 (7)
C10.052 (2)0.058 (3)0.083 (3)0.0088 (18)0.025 (2)0.003 (2)
C20.061 (2)0.062 (3)0.075 (3)0.0087 (19)0.015 (2)0.0010 (19)
C30.078 (3)0.056 (3)0.068 (3)0.006 (2)0.011 (2)0.0046 (19)
C1'0.052 (2)0.058 (3)0.083 (3)0.0088 (18)0.025 (2)0.003 (2)
C2'0.061 (2)0.062 (3)0.075 (3)0.0087 (19)0.015 (2)0.0010 (19)
C3'0.078 (3)0.056 (3)0.068 (3)0.006 (2)0.011 (2)0.0046 (19)
C40.0448 (10)0.0544 (10)0.0516 (11)0.0005 (8)0.0032 (8)0.0050 (8)
C50.0453 (10)0.0513 (10)0.0464 (10)0.0046 (8)0.0018 (8)0.0041 (8)
C60.0522 (11)0.0542 (10)0.0505 (11)0.0052 (9)0.0065 (9)0.0097 (9)
C70.0594 (13)0.0566 (11)0.0689 (14)0.0061 (10)0.0121 (10)0.0156 (10)
C80.0593 (13)0.0951 (15)0.0518 (12)0.0152 (12)0.0097 (10)0.0165 (11)
C90.0537 (12)0.1097 (17)0.0543 (13)0.0173 (12)0.0127 (10)0.0143 (12)
C100.0535 (12)0.0641 (12)0.0714 (14)0.0021 (10)0.0102 (10)0.0198 (10)
C110.0507 (12)0.0677 (12)0.0729 (15)0.0054 (10)0.0142 (10)0.0162 (10)
C120.0469 (10)0.0488 (9)0.0491 (10)0.0100 (8)0.0165 (8)0.0018 (8)
C130.0612 (12)0.0507 (10)0.0609 (13)0.0047 (10)0.0120 (10)0.0051 (9)
C140.0651 (14)0.0591 (12)0.0713 (15)0.0052 (10)0.0072 (11)0.0040 (11)
C150.0656 (14)0.0697 (13)0.0628 (14)0.0044 (11)0.0026 (11)0.0052 (11)
C160.0708 (14)0.0665 (13)0.0575 (13)0.0078 (11)0.0003 (11)0.0100 (10)
C170.0606 (12)0.0551 (10)0.0585 (12)0.0020 (9)0.0098 (10)0.0077 (9)
Geometric parameters (Å, º) top
S1—C41.708 (2)C3'—C41.371 (9)
S1—C11.738 (3)C3'—H3'0.9300
S1'—C41.666 (3)C4—C51.441 (3)
S1'—C1'1.748 (9)C7—H7A0.9700
S2—C61.636 (2)C7—H7B0.9700
O1—C51.367 (2)C8—C91.505 (3)
O1—C61.377 (2)C8—H8A0.9700
N1—C51.288 (2)C8—H8B0.9700
N1—N21.386 (2)C9—H9A0.9700
N2—C61.338 (2)C9—H9B0.9700
N2—C71.485 (2)C10—C111.512 (3)
N3—C71.425 (3)C10—H10A0.9700
N3—C81.447 (3)C10—H10B0.9700
N3—C111.449 (3)C11—H11A0.9700
N4—C121.411 (2)C11—H11B0.9700
N4—C101.458 (2)C12—C131.395 (3)
N4—C91.463 (2)C12—C171.396 (3)
C1—C21.349 (5)C13—C141.374 (3)
C1—H10.9300C13—H130.9300
C2—C31.342 (7)C14—C151.375 (3)
C2—H20.9300C14—H140.9300
C3—C41.379 (5)C15—C161.370 (3)
C3—H30.9300C15—H150.9300
C1'—C2'1.349 (8)C16—C171.379 (3)
C1'—H1'0.9300C16—H160.9300
C2'—C3'1.344 (10)C17—H170.9300
C2'—H2'0.9300
C4—S1—C190.4 (2)N2—C7—H7A108.3
C4—S1'—C1'86.7 (6)N3—C7—H7B108.3
C5—O1—C6106.05 (14)N2—C7—H7B108.3
C5—N1—N2103.39 (14)H7A—C7—H7B107.4
C6—N2—N1112.28 (15)N3—C8—C9109.90 (18)
C6—N2—C7126.94 (16)N3—C8—H8A109.7
N1—N2—C7120.78 (15)C9—C8—H8A109.7
C7—N3—C8115.60 (17)N3—C8—H8B109.7
C7—N3—C11115.92 (16)C9—C8—H8B109.7
C8—N3—C11109.70 (16)H8A—C8—H8B108.2
C12—N4—C10116.68 (15)N4—C9—C8111.87 (16)
C12—N4—C9114.66 (14)N4—C9—H9A109.2
C10—N4—C9110.64 (17)C8—C9—H9A109.2
C2—C1—S1114.1 (6)N4—C9—H9B109.2
C2—C1—H1122.9C8—C9—H9B109.2
S1—C1—H1122.9H9A—C9—H9B107.9
C3—C2—C1108.2 (7)N4—C10—C11110.80 (16)
C3—C2—H2125.9N4—C10—H10A109.5
C1—C2—H2125.9C11—C10—H10A109.5
C2—C3—C4119.4 (5)N4—C10—H10B109.5
C2—C3—H3120.3C11—C10—H10B109.5
C4—C3—H3120.3H10A—C10—H10B108.1
C2'—C1'—S1'115.9 (14)N3—C11—C10110.26 (16)
C2'—C1'—H1'122.0N3—C11—H11A109.6
S1'—C1'—H1'122.0C10—C11—H11A109.6
C3'—C2'—C1'108.4 (16)N3—C11—H11B109.6
C3'—C2'—H2'125.8C10—C11—H11B109.6
C1'—C2'—H2'125.8H11A—C11—H11B108.1
C2'—C3'—C4114.7 (12)C13—C12—C17116.86 (19)
C2'—C3'—H3'122.7C13—C12—N4120.30 (16)
C4—C3'—H3'122.7C17—C12—N4122.82 (17)
C3'—C4—C3103.2 (6)C14—C13—C12121.24 (19)
C3'—C4—C5126.4 (6)C14—C13—H13119.4
C3—C4—C5130.4 (2)C12—C13—H13119.4
C3'—C4—S1'114.2 (6)C13—C14—C15121.3 (2)
C5—C4—S1'119.33 (17)C13—C14—H14119.3
C3—C4—S1107.6 (2)C15—C14—H14119.3
C5—C4—S1121.91 (15)C16—C15—C14118.2 (2)
S1'—C4—S1118.65 (15)C16—C15—H15120.9
N1—C5—O1113.36 (16)C14—C15—H15120.9
N1—C5—C4127.95 (17)C15—C16—C17121.5 (2)
O1—C5—C4118.66 (16)C15—C16—H16119.3
N2—C6—O1104.91 (15)C17—C16—H16119.3
N2—C6—S2131.15 (15)C16—C17—C12120.94 (19)
O1—C6—S2123.94 (15)C16—C17—H17119.5
N3—C7—N2116.10 (15)C12—C17—H17119.5
N3—C7—H7A108.3
C5—N1—N2—C60.7 (2)S1'—C4—C5—O11.2 (3)
C5—N1—N2—C7179.54 (16)S1—C4—C5—O1177.46 (15)
C4—S1—C1—C20.5 (3)N1—N2—C6—O10.5 (2)
S1—C1—C2—C31.9 (5)C7—N2—C6—O1179.85 (16)
C1—C2—C3—C44.4 (7)N1—N2—C6—S2179.55 (15)
C4—S1'—C1'—C2'0.4 (9)C7—N2—C6—S20.1 (3)
S1'—C1'—C2'—C3'2.3 (13)C5—O1—C6—N20.01 (18)
C1'—C2'—C3'—C43.5 (16)C5—O1—C6—S2179.99 (14)
C2'—C3'—C4—C35.5 (13)C8—N3—C7—N261.8 (2)
C2'—C3'—C4—C5175.2 (9)C11—N3—C7—N268.7 (2)
C2'—C3'—C4—S1'3.4 (17)C6—N2—C7—N397.8 (2)
C2'—C3'—C4—S1152 (10)N1—N2—C7—N382.5 (2)
C2—C3—C4—C3'6.7 (7)C7—N3—C8—C9166.94 (17)
C2—C3—C4—C5174.1 (4)C11—N3—C8—C959.7 (2)
C2—C3—C4—S1'164 (2)C12—N4—C9—C8171.40 (17)
C2—C3—C4—S14.7 (7)C10—N4—C9—C854.1 (2)
C1'—S1'—C4—C3'1.7 (11)N3—C8—C9—N456.9 (3)
C1'—S1'—C4—C312 (2)C12—N4—C10—C11172.40 (16)
C1'—S1'—C4—C5177.1 (6)C9—N4—C10—C1154.1 (2)
C1'—S1'—C4—S10.7 (6)C7—N3—C11—C10166.26 (16)
C1—S1—C4—C3'26 (9)C8—N3—C11—C1060.6 (2)
C1—S1—C4—C32.6 (4)N4—C10—C11—N357.9 (2)
C1—S1—C4—C5176.2 (2)C10—N4—C12—C13179.25 (17)
C1—S1—C4—S1'0.1 (3)C9—N4—C12—C1349.1 (2)
N2—N1—C5—O10.74 (19)C10—N4—C12—C171.0 (2)
N2—N1—C5—C4177.59 (17)C9—N4—C12—C17132.6 (2)
C6—O1—C5—N10.5 (2)C17—C12—C13—C140.5 (3)
C6—O1—C5—C4178.00 (15)N4—C12—C13—C14178.91 (17)
C3'—C4—C5—N11.5 (9)C12—C13—C14—C150.0 (3)
C3—C4—C5—N1179.4 (4)C13—C14—C15—C160.4 (3)
S1'—C4—C5—N1177.1 (2)C14—C15—C16—C170.3 (3)
S1—C4—C5—N10.8 (3)C15—C16—C17—C120.2 (3)
C3'—C4—C5—O1179.8 (9)C13—C12—C17—C160.6 (3)
C3—C4—C5—O11.1 (4)N4—C12—C17—C16178.96 (17)
Hydrogen-bond geometry (Å, º) top
Cg1 is the centroid of the O1,N1,N2,C5,C6 ring
D—H···AD—HH···AD···AD—H···A
C9—H9B···S2i0.972.773.618 (3)146
C1—H1···Cg1ii0.932.723.545 (6)148
C11—H11A···Cg1iii0.972.983.600 (2)123
C15—H15···Cg2iii0.932.953.743 (3)144
Symmetry codes: (i) x+1/2, y+3/2, z+1; (ii) x+1/2, y+1/2, z; (iii) x+1/2, y1/2, z1/2.
Hydrogen-bond geometry (Å, º) top
Cg1 is the centroid of the O1,N1,N2,C5,C6 ring
D—H···AD—HH···AD···AD—H···A
C9—H9B···S2i0.972.773.618 (3)146
C1—H1···Cg1ii0.932.723.545 (6)148
C11—H11A···Cg1iii0.972.983.600 (2)123
C15—H15···Cg2iii0.932.953.743 (3)144
Symmetry codes: (i) x+1/2, y+3/2, z+1; (ii) x+1/2, y+1/2, z; (iii) x+1/2, y1/2, z1/2.
Acknowledgements top

The financial support of the Deanship of Scientific Research and the Research Center of the College of Pharmacy, King Saud University, is greatly appreciated. We also thank the Ministry of Higher Education (Malaysia) for funding structural studies through the High-Impact Research scheme (UM.C/HIR/MOHE/SC/03).

references
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