(E)-2-Cyano-N′-(1,2,3,4-tetra­hydro­naphthalen-1-yl­idene)acetohydrazide

Al-Omar, M.A.; Khalifa, N.M.; Ghabbour, H.A.; Chia, T.S.; Fun, H.-K.

doi:10.1107/S160053681202106X

organic compounds

CRYSTALLOGRAPHIC
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ISSN: 2056-9890

Volume 68| Part 6| June 2012| Page o1740

doi:10.1107/S160053681202106X

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(E)-2-Cyano-N′-(1,2,3,4-tetrahydronaphthalen-1-ylidene)acetohydrazide

Mohamed A. Al-Omar,^a,^b Nagy M. Khalifa,^b,^c Hazem A. Ghabbour,^a Tze Shyang Chia ^d and Hoong-Kun Fun ^d ^*‡

^aDepartment of Pharmaceutical Chemistry, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia, ^bDrug Exploration & Development Chair (DEDC), College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia, ^cDepartment of Therapeutic Chemistry, Pharmaceutical and Drug Industries Division, National Research Centre, Dokki 12622, Cairo, Egypt, and ^dX-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia
^*Correspondence e-mail: hkfun@usm.my

(Received 6 May 2012; accepted 9 May 2012; online 16 May 2012)

In the title compound, C₁₃H₁₃N₃O, the tetrahydrobenzene ring adopts a half-boat (envelope) conformation. The mean plane of the tetrahydronaphthalene ring system forms a dihedral angle of 9.56 (6)° with the mean plane of the cyanoacetohydrazide group. In the crystal, inversion dimers linked by pairs of N—H⋯O hydrogen bonds generate R₂²(8) loops. The dimers are connected by C—H⋯N hydrogen bonds into a chain propagating along [101]. The crystal packing also features C—H⋯π interactions.

Related literature

For background to tetralin, see: Dutta et al. (2002 ); Taddei et al. (2002 ); Zaghary et al. (2005 ); Bahgat & Khalifa (2006 ); El Nezhawy et al. (2009 ); Khalifa et al. (2008 ). For ring puckering parameters, see: Cremer & Pople (1975 ).

Experimental

Crystal data

C₁₃H₁₃N₃O
M_r = 227.26
Triclinic, $[P \overline 1]$
a = 7.6414 (1) Å
b = 7.6748 (1) Å
c = 10.5644 (2) Å
α = 109.589 (1)°
β = 91.405 (1)°
γ = 93.260 (1)°
V = 582.13 (2) Å³
Z = 2
Cu Kα radiation
μ = 0.69 mm⁻¹
T = 296 K
0.59 × 0.51 × 0.40 mm

Data collection

Bruker SMART APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2009 ) T_min = 0.687, T_max = 0.771
5749 measured reflections
1898 independent reflections
1762 reflections with I > 2σ(I)
R_int = 0.017

Refinement

R[F² > 2σ(F²)] = 0.043
wR(F²) = 0.120
S = 1.05
1898 reflections
159 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.18 e Å⁻³
Δρ_min = −0.17 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

Cg1 is the centroid of the C5–C10 ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1N1⋯O1ⁱ	0.91 (2)	1.96 (2)	2.8640 (17)	174.7 (19)
C10—H10A⋯N3ⁱⁱ	0.93	2.58	3.491 (3)	167
C2—H2A⋯Cg1ⁱⁱⁱ	0.97	2.80	3.6775 (17)	152
Symmetry codes: (i) -x, -y+1, -z+1; (ii) x-1, y, z-1; (iii) -x, -y+1, -z.

Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S160053681202106X/hb6781sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S160053681202106X/hb6781Isup2.hkl

Supporting information file. DOI: 10.1107/S160053681202106X/hb6781Isup3.cml

checkCIF report

Comment top

Tetralins (tetrahydronaphthalene derivatives) are of increasing interest since many of these compounds play a vital role in the biological activities because of their biological potentialities, for example, as potent agonists for D2-type receptors (Dutta et al., 2002), a treatment of Alzheimer's disease (Taddei et al., 2002) and as anti-cancer agents (Zaghary et al., 2005). Also, we found that certain substituted tetralin and heterocyclic derivatives show inhibition for cercarial serine protease (Bahgat & Khalifa, 2006), antioxidant (El Nezhawy et al., 2009) and antiinflammatory (Khalifa et al., 2008) activities. Tetralin derivative containing cyanoaceto-hydrazide was prepared as the title compound and its crystal structure is now reported.

The asymmetric unit of the title compound is shown in Fig. 1. The tetrahydrobenzene ring (C1–C6) adopts a half-boat conformation with puckering parameters (Cremer & Pople, 1975), Q = 0.4695 (16) Å, θ = 122.4 (2)° and ϕ = 308.6 (2)°. The flap atom C3 deviates from the mean plane of C1/C2/C4–C6 by -0.6395 (16) Å. In the molecule, the mean plane of tetrahydronaphthalene ring system (C1–C10) forms a dihedral angle of 9.56 (6)° with the mean plane of cyanoacetohydrazide group [O1/N1–N3/C11–C13; maximum deviation = 0.045 (2) Å at atom C12].

In the crystal (Fig. 2), molecules are linked by a pair of N1—H1N1···O1 hydrogen bonds into an inversion dimer with an R₂²(8) ring motif. The dimers are further connected by C10—H10A···N3 hydrogen bonds into an infinite chain along [101]. The crystal packing also features C—H···π interaction (Table 1), involving Cg1 which is the centroid of C5–C10 ring.

Related literature top

For background to tetralin, see: Dutta et al. (2002); Taddei et al. (2002); Zaghary et al. (2005); Bahgat & Khalifa (2006); El Nezhawy et al. (2009); Khalifa et al. (2008). For ring puckering parameters, see: Cremer & Pople (1975).

Experimental top

Equimolar amounts (0.01 mol) of tetralone and 2-cyanoacetohydrazide in dioxane (30 ml) were heated under reflux for 6 h. The mixture was then cooled at room temperature for overnight. The precipitated solid was filtered off, washed with ethanol, dried and crystallized from methanol to afford the title compound as colourless blocks with 73% abundance, m.p.: 183–185 °C.

Computing details top

Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).

Figures top

	Fig. 1. The molecular structure of the title compound with 30% probability displacement ellipsoids.
	Fig. 2. The crystal packing of the title compound. The dashed lines represent the hydrogen bonds. For clarity sake, hydrogen atoms not involved in hydrogen bonding have been omitted.

(E)-2-Cyano-N'-(1,2,3,4-tetrahydronaphthalen-1- ylidene)acetohydrazide top

Crystal data top

C₁₃H₁₃N₃O	Z = 2
M_r = 227.26	F(000) = 240
Triclinic, P1	D_x = 1.297 Mg m⁻³
Hall symbol: -P 1	Cu Kα radiation, λ = 1.54178 Å
a = 7.6414 (1) Å	Cell parameters from 2725 reflections
b = 7.6748 (1) Å	θ = 5.8–70.2°
c = 10.5644 (2) Å	µ = 0.69 mm⁻¹
α = 109.589 (1)°	T = 296 K
β = 91.405 (1)°	Block, colourless
γ = 93.260 (1)°	0.59 × 0.51 × 0.40 mm
V = 582.13 (2) Å³

Data collection top

Bruker SMART APEXII CCD diffractometer	1898 independent reflections
Radiation source: fine-focus sealed tube	1762 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.017
ϕ and ω scans	θ_max = 65.0°, θ_min = 5.8°
Absorption correction: multi-scan (SADABS; Bruker, 2009)	h = −8→8
T_min = 0.687, T_max = 0.771	k = −7→9
5749 measured reflections	l = −12→12

Refinement top

Refinement on F²	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.043	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.120	w = 1/[σ²(F_o²) + (0.0686P)² + 0.0904P] where P = (F_o² + 2F_c²)/3
S = 1.05	(Δ/σ)_max < 0.001
1898 reflections	Δρ_max = 0.18 e Å⁻³
159 parameters	Δρ_min = −0.17 e Å⁻³
0 restraints	Extinction correction: SHELXTL (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.030 (3)

Crystal data top

C₁₃H₁₃N₃O	γ = 93.260 (1)°
M_r = 227.26	V = 582.13 (2) Å³
Triclinic, P1	Z = 2
a = 7.6414 (1) Å	Cu Kα radiation
b = 7.6748 (1) Å	µ = 0.69 mm⁻¹
c = 10.5644 (2) Å	T = 296 K
α = 109.589 (1)°	0.59 × 0.51 × 0.40 mm
β = 91.405 (1)°

Data collection top

Bruker SMART APEXII CCD diffractometer	1898 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2009)	1762 reflections with I > 2σ(I)
T_min = 0.687, T_max = 0.771	R_int = 0.017
5749 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.043	0 restraints
wR(F²) = 0.120	H atoms treated by a mixture of independent and constrained refinement
S = 1.05	Δρ_max = 0.18 e Å⁻³
1898 reflections	Δρ_min = −0.17 e Å⁻³
159 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	0.19129 (16)	0.4167 (2)	0.53245 (10)	0.0798 (4)
N1	0.07938 (15)	0.36666 (18)	0.32370 (11)	0.0530 (3)
N2	0.10531 (14)	0.29801 (15)	0.18782 (10)	0.0456 (3)
N3	0.5764 (3)	0.2338 (4)	0.5360 (2)	0.1264 (9)
C1	−0.02329 (16)	0.29510 (17)	0.10641 (13)	0.0419 (3)
C2	−0.20191 (18)	0.3606 (2)	0.14809 (15)	0.0531 (4)
H2A	−0.1954	0.4950	0.1788	0.064*
H2B	−0.2357	0.3218	0.2230	0.064*
C3	−0.34209 (18)	0.2862 (2)	0.03515 (16)	0.0590 (4)
H3A	−0.3665	0.1544	0.0168	0.071*
H3B	−0.4494	0.3470	0.0632	0.071*
C4	−0.28501 (19)	0.3183 (2)	−0.09133 (16)	0.0583 (4)
H4A	−0.2742	0.4504	−0.0759	0.070*
H4B	−0.3738	0.2621	−0.1629	0.070*
C5	−0.11171 (18)	0.23730 (19)	−0.13436 (14)	0.0491 (4)
C6	0.01244 (16)	0.22607 (16)	−0.03809 (12)	0.0416 (3)
C7	0.17256 (17)	0.15242 (19)	−0.08101 (14)	0.0478 (3)
H7A	0.2555	0.1441	−0.0177	0.057*
C8	0.2098 (2)	0.0923 (2)	−0.21424 (15)	0.0575 (4)
H8A	0.3170	0.0438	−0.2407	0.069*
C9	0.0876 (2)	0.1038 (2)	−0.30948 (15)	0.0636 (4)
H9A	0.1122	0.0629	−0.4001	0.076*
C10	−0.0706 (2)	0.1761 (2)	−0.26907 (15)	0.0613 (4)
H10A	−0.1520	0.1842	−0.3334	0.074*
C11	0.20438 (19)	0.3556 (2)	0.41121 (14)	0.0547 (4)
C12	0.3655 (2)	0.2592 (2)	0.35112 (15)	0.0619 (4)
H12A	0.3304	0.1361	0.2892	0.074*
H12B	0.4251	0.3284	0.3011	0.074*
C13	0.4837 (2)	0.2454 (3)	0.45556 (17)	0.0712 (5)
H1N1	−0.010 (3)	0.434 (3)	0.3642 (19)	0.078 (5)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0795 (8)	0.1259 (11)	0.0388 (6)	0.0515 (7)	0.0104 (5)	0.0263 (6)
N1	0.0473 (7)	0.0739 (8)	0.0390 (6)	0.0203 (6)	0.0055 (5)	0.0178 (5)
N2	0.0432 (6)	0.0558 (7)	0.0378 (6)	0.0092 (5)	0.0022 (4)	0.0148 (5)
N3	0.0968 (14)	0.189 (2)	0.0923 (14)	0.0546 (15)	−0.0274 (11)	0.0414 (14)
C1	0.0377 (7)	0.0438 (7)	0.0456 (7)	0.0036 (5)	0.0000 (5)	0.0167 (5)
C2	0.0420 (7)	0.0643 (9)	0.0538 (8)	0.0104 (6)	0.0054 (6)	0.0195 (7)
C3	0.0374 (7)	0.0665 (9)	0.0744 (10)	0.0053 (6)	−0.0015 (6)	0.0255 (8)
C4	0.0441 (8)	0.0667 (9)	0.0653 (9)	0.0060 (6)	−0.0122 (6)	0.0245 (7)
C5	0.0452 (7)	0.0495 (7)	0.0512 (8)	0.0002 (6)	−0.0089 (6)	0.0164 (6)
C6	0.0395 (7)	0.0401 (6)	0.0429 (7)	0.0007 (5)	−0.0037 (5)	0.0117 (5)
C7	0.0438 (7)	0.0517 (7)	0.0450 (7)	0.0076 (6)	−0.0041 (5)	0.0122 (6)
C8	0.0544 (8)	0.0603 (9)	0.0503 (8)	0.0106 (7)	0.0047 (6)	0.0078 (7)
C9	0.0711 (10)	0.0723 (10)	0.0396 (7)	0.0049 (8)	−0.0002 (7)	0.0089 (7)
C10	0.0632 (9)	0.0711 (10)	0.0466 (8)	0.0019 (7)	−0.0144 (7)	0.0174 (7)
C11	0.0542 (8)	0.0729 (9)	0.0398 (7)	0.0209 (7)	0.0061 (6)	0.0197 (6)
C12	0.0528 (8)	0.0840 (11)	0.0442 (8)	0.0228 (7)	0.0006 (6)	0.0127 (7)
C13	0.0574 (9)	0.0923 (12)	0.0596 (9)	0.0241 (8)	−0.0055 (8)	0.0175 (9)

Geometric parameters (Å, º) top

O1—C11	1.2163 (17)	C4—H4B	0.9700
N1—C11	1.3389 (18)	C5—C10	1.391 (2)
N1—N2	1.3770 (15)	C5—C6	1.4009 (18)
N1—H1N1	0.90 (2)	C6—C7	1.3986 (19)
N2—C1	1.2841 (16)	C7—C8	1.369 (2)
N3—C13	1.122 (2)	C7—H7A	0.9300
C1—C6	1.4766 (18)	C8—C9	1.383 (2)
C1—C2	1.5061 (18)	C8—H8A	0.9300
C2—C3	1.519 (2)	C9—C10	1.376 (2)
C2—H2A	0.9700	C9—H9A	0.9300
C2—H2B	0.9700	C10—H10A	0.9300
C3—C4	1.508 (2)	C11—C12	1.5140 (19)
C3—H3A	0.9700	C12—C13	1.444 (2)
C3—H3B	0.9700	C12—H12A	0.9700
C4—C5	1.510 (2)	C12—H12B	0.9700
C4—H4A	0.9700

C11—N1—N2	119.64 (11)	C6—C5—C4	120.20 (13)
C11—N1—H1N1	112.9 (12)	C7—C6—C5	118.82 (12)
N2—N1—H1N1	127.0 (12)	C7—C6—C1	120.57 (11)
C1—N2—N1	117.97 (11)	C5—C6—C1	120.59 (11)
N2—C1—C6	116.02 (11)	C8—C7—C6	121.36 (12)
N2—C1—C2	124.94 (12)	C8—C7—H7A	119.3
C6—C1—C2	119.01 (11)	C6—C7—H7A	119.3
C1—C2—C3	112.97 (12)	C7—C8—C9	119.94 (13)
C1—C2—H2A	109.0	C7—C8—H8A	120.0
C3—C2—H2A	109.0	C9—C8—H8A	120.0
C1—C2—H2B	109.0	C10—C9—C8	119.50 (14)
C3—C2—H2B	109.0	C10—C9—H9A	120.3
H2A—C2—H2B	107.8	C8—C9—H9A	120.3
C4—C3—C2	111.41 (12)	C9—C10—C5	121.62 (13)
C4—C3—H3A	109.3	C9—C10—H10A	119.2
C2—C3—H3A	109.3	C5—C10—H10A	119.2
C4—C3—H3B	109.3	O1—C11—N1	122.97 (13)
C2—C3—H3B	109.3	O1—C11—C12	120.79 (13)
H3A—C3—H3B	108.0	N1—C11—C12	116.23 (12)
C3—C4—C5	111.56 (12)	C13—C12—C11	110.54 (13)
C3—C4—H4A	109.3	C13—C12—H12A	109.5
C5—C4—H4A	109.3	C11—C12—H12A	109.5
C3—C4—H4B	109.3	C13—C12—H12B	109.5
C5—C4—H4B	109.3	C11—C12—H12B	109.5
H4A—C4—H4B	108.0	H12A—C12—H12B	108.1
C10—C5—C6	118.76 (13)	N3—C13—C12	179.4 (2)
C10—C5—C4	121.04 (12)

C11—N1—N2—C1	173.62 (13)	C2—C1—C6—C7	−175.60 (12)
N1—N2—C1—C6	178.06 (11)	N2—C1—C6—C5	−172.51 (11)
N1—N2—C1—C2	−0.3 (2)	C2—C1—C6—C5	5.95 (18)
N2—C1—C2—C3	−161.63 (13)	C5—C6—C7—C8	0.2 (2)
C6—C1—C2—C3	20.06 (18)	C1—C6—C7—C8	−178.26 (12)
C1—C2—C3—C4	−50.51 (17)	C6—C7—C8—C9	0.0 (2)
C2—C3—C4—C5	55.23 (17)	C7—C8—C9—C10	0.1 (2)
C3—C4—C5—C10	151.26 (14)	C8—C9—C10—C5	−0.4 (3)
C3—C4—C5—C6	−30.03 (18)	C6—C5—C10—C9	0.6 (2)
C10—C5—C6—C7	−0.5 (2)	C4—C5—C10—C9	179.32 (15)
C4—C5—C6—C7	−179.24 (12)	N2—N1—C11—O1	178.53 (15)
C10—C5—C6—C1	177.98 (12)	N2—N1—C11—C12	−2.2 (2)
C4—C5—C6—C1	−0.76 (19)	O1—C11—C12—C13	3.3 (2)
N2—C1—C6—C7	5.94 (18)	N1—C11—C12—C13	−175.97 (15)

Hydrogen-bond geometry (Å, º) top

Cg1 is the centroid of the C5–C10 ring.

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1N1···O1ⁱ	0.91 (2)	1.96 (2)	2.8640 (17)	174.7 (19)
C10—H10A···N3ⁱⁱ	0.93	2.58	3.491 (3)	167
C2—H2A···Cg1ⁱⁱⁱ	0.97	2.80	3.6775 (17)	152

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

Experimental details

Crystal data
Chemical formula	C₁₃H₁₃N₃O
M_r	227.26
Crystal system, space group	Triclinic, P1
Temperature (K)	296
a, b, c (Å)	7.6414 (1), 7.6748 (1), 10.5644 (2)
α, β, γ (°)	109.589 (1), 91.405 (1), 93.260 (1)
V (Å³)	582.13 (2)
Z	2
Radiation type	Cu Kα
µ (mm⁻¹)	0.69
Crystal size (mm)	0.59 × 0.51 × 0.40

Data collection
Diffractometer	Bruker SMART APEXII CCD diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2009)
T_min, T_max	0.687, 0.771
No. of measured, independent and observed [I > 2σ(I)] reflections	5749, 1898, 1762
R_int	0.017
(sin θ/λ)_max (Å⁻¹)	0.588

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.043, 0.120, 1.05
No. of reflections	1898
No. of parameters	159
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.18, −0.17

Computer programs: APEX2 (Bruker, 2009), SAINT (Bruker, 2009), SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).

Hydrogen-bond geometry (Å, º) top

Cg1 is the centroid of the C5–C10 ring.

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1N1···O1ⁱ	0.91 (2)	1.96 (2)	2.8640 (17)	174.7 (19)
C10—H10A···N3ⁱⁱ	0.93	2.58	3.491 (3)	167
C2—H2A···Cg1ⁱⁱⁱ	0.97	2.80	3.6775 (17)	152

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

Footnotes

‡Thomson Reuters ResearcherID: A-3561-2009.

Acknowledgements

MAO, NMK and HAG thank the Deanship of Scientific Research at King Saud University for funding through the research group project No. RGP-VPP-099. HKF and TSC thank Universiti Sains Malaysia (USM) for the Research University Grant (1001/PFIZIK/811160). TSC also thanks the Malaysian Government and USM for the award of a research fellowship.

References

Bahgat, M. M. & Khalifa, N. M. (2006). Acta Pol. Pharm. 63, 181–188. CAS PubMed Google Scholar
Bruker (2009). SADABS, APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Cremer, D. & Pople, J. A. (1975). J. Am. Chem. Soc. 97, 1354–1358. CrossRef CAS Web of Science Google Scholar
Dutta, A. K., Fei, X.-S. & Reith, M. E. A. (2002). Bioorg. Med. Chem. Lett. 12, 619–622. Web of Science CrossRef PubMed CAS Google Scholar
El Nezhawy, A. O. H., Ramla, M. M., Khalifa, N. M. & Abdulla, M. M. (2009). Monatsh. Chem. 140, 531–539. Web of Science CrossRef CAS Google Scholar
Khalifa, N. M., Ramla, M. M., Amr, A. E.-G. E. & Abdulla, M. M. (2008). Phosphorus Sulfur Silicon Relat. Elem. 183, 3046–3062. Web of Science CrossRef CAS Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Spek, A. L. (2009). Acta Cryst. D65, 148–155. Web of Science CrossRef CAS IUCr Journals Google Scholar
Taddei, P., Torreggiani, A. & Fini, G. (2002). Biopolymers, 67, 289–293. Web of Science CrossRef PubMed Google Scholar
Zaghary, W. A., Heiba, M. E., Anwar, M. M. & Hassan, S. A. (2005). Egypt. Pharm. J. (NRC), 4, 145–149. Google Scholar

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