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Acta Cryst. (2008). E64, o729    [ doi:10.1107/S160053680800706X ]

Diethyl 2-[(4-nitrophenyl)(4-phenyl-1,2,3-selenadiazol-5-yl)methyl]malonate

A. Marx, S. Saravanan, S. Muthusubramanian, V. Manivannan and N. P. Rath

Abstract top

In the title compound, C22H21N3O6Se, the heterocyclic ring makes dihedral angles of 50.03 (11) and 67.75 (11)°, respectively, with the benzene and phenyl rings. The terminal C atoms of the ester groups are disordered over two positions: the site occupancies for the C atoms are 0.62 (3)/0.38 (3) and 0.48 (3)/0.52 (3). In the crystal structure, weak intra- and intermolecular C-H...O interactions are observed.

Comment top

Selenium containing compounds like 1,2,3-selenadiazole possess various beneficial activities like antibacterial (El-Kashef et al., 1986), antimicrobial (El-Bahaie et al., 1990) activities. The geometric parameters in the compound, (I) (Fig. 1), agree with the reported values of similar structures (Bertini et al., 1984; Gunasekaran et al., 2007).

The heterocyclic ring makes the dihedral angles of 50.03 (11) and 67.75 (11)° with the benzene and phenyl rings. The terminal C atoms of the ester groups are disordered over two positions; the site occupancies for the C atoms are 0.62/0.38 and 0.48/0.52. The molecular structure is stabilized by weak intramolecular C—H···O interactions and the crystal packing of (I) is stabilized by weak intermolecular C—H···O contacts (Table 1 and Fig. 2).

Related literature top

For biological activities, see: El-Kashef et al. (1986); El-Bahaie et al. (1990). For closely relaed compounds, see: Bertini et al. (1984); Gunasekaran et al. (2007).

Experimental top

2.22 g (0.02 mol) of powdered selenium dioxide was dissolved in glacial acetic acid by gentle warming. To this warm solution, 0.002 mol of diethyl 2-{3-[2-(aminocarbonyl)hydrazono]-1-(4-nitrophenyl)-3-phenylpropyl} malonate was added at once and the mixture was gently heated on a water bath until gas evolution ceased. The selenium deposited on cooling was removed by filtration and the filtrate poured into crushed ice, extracted with chloroform and purified by column chromatography, using silica gel (60–120 mesh) to yield diethyl 2-[(4-nitrophenyl) (4-phenyl-1,2,3-selenadiazol-5-yl)methyl]malonate. Solvent used for crystallization is ethanol.

Refinement top

The site occupancy factors were refined as C19 = 0.62 (3), C19A = 0.38 (3), C22 = 0.48 (3) and C22A = 0.52 (3) during anisotropic refinement. The C21—C22A, C21—C22, C18—C19 and C18—C19A bond distances were restrained to be 1.5 (1) Å. H atoms were positioned geometrically and refined using riding model with C—H = 0.93 Å and Uiso(H) = 1.2Ueq(C) for aromatic C—H, C—H = 0.98 Å and Uiso(H) = 1.2Ueq(C) for CH, C—H = 0.97 Å and Uiso(H) = 1.2Ueq(C) for CH2, and C—H = 0.96 Å and Uiso(H) = 1.5Ueq(C) for CH3.

Computing details top

Data collection: APEX2 (Bruker, 2004); cell refinement: APEX2 (Bruker, 2004); data reduction: APEX2 (Bruker, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. The molecular structure of (I), with atom labels and 50% probability displacement ellipsoids for non-H atoms.
[Figure 2] Fig. 2. The packing of (I), viewed down the a axis. Hydrogen bonds are shown as dashed lines. H atoms not involved in hydrogen bonds have been omitted.
Diethyl 2-[(4-nitrophenyl)(4-phenyl-1,2,3-selenadiazol-5-yl)methyl]malonate top
Crystal data top
C22H21N3O6SeZ = 2
Mr = 502.38F000 = 512
Triclinic, P1Dx = 1.467 Mg m−3
Hall symbol: -P 1Mo Kα radiation
λ = 0.71073 Å
a = 9.9530 (6) ÅCell parameters from 8446 reflections
b = 10.5220 (6) Åθ = 1.7–26º
c = 12.2305 (7) ŵ = 1.69 mm−1
α = 79.350 (3)ºT = 295 (2) K
β = 74.632 (3)ºBlock, colourless
γ = 67.632 (3)º0.23 × 0.17 × 0.16 mm
V = 1137.05 (11) Å3
Data collection top
Bruker SMART APEX area-detector
diffractometer		4477 independent reflections
Radiation source: fine-focus sealed tube3053 reflections with I > 2σ(I)
Monochromator: graphiteRint = 0.028
T = 295(2) Kθmax = 26.1º
ω and φ scansθmin = 1.7º
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)		h = −12→12
Tmin = 0.697, Tmax = 0.773k = −12→12
30194 measured reflectionsl = −15→15
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.054H-atom parameters constrained
wR(F2) = 0.161  w = 1/[σ2(Fo2) + (0.0776P)2 + 0.9842P]
where P = (Fo2 + 2Fc2)/3
S = 1.04(Δ/σ)max < 0.001
4477 reflectionsΔρmax = 0.93 e Å−3
313 parametersΔρmin = −0.80 e Å−3
4 restraintsExtinction correction: none
Primary atom site location: structure-invariant direct methods
Crystal data top
C22H21N3O6Seγ = 67.632 (3)º
Mr = 502.38V = 1137.05 (11) Å3
Triclinic, P1Z = 2
a = 9.9530 (6) ÅMo Kα
b = 10.5220 (6) ŵ = 1.69 mm−1
c = 12.2305 (7) ÅT = 295 (2) K
α = 79.350 (3)º0.23 × 0.17 × 0.16 mm
β = 74.632 (3)º
Data collection top
Bruker SMART APEX area-detector
diffractometer		4477 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)		3053 reflections with I > 2σ(I)
Tmin = 0.697, Tmax = 0.773Rint = 0.028
30194 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0544 restraints
wR(F2) = 0.161H-atom parameters constrained
S = 1.04Δρmax = 0.93 e Å−3
4477 reflectionsΔρmin = −0.80 e Å−3
313 parameters
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
Se11.00900 (5)0.21345 (6)0.44996 (4)0.0888 (3)
O11.5749 (5)0.1019 (4)−0.0847 (4)0.1160 (15)
O21.6666 (5)0.0959 (5)0.0564 (5)0.1327 (17)
O40.7916 (3)0.6035 (4)0.4808 (2)0.0859 (10)
O61.0425 (4)0.6499 (3)0.1149 (2)0.0859 (10)
N10.8397 (5)0.1628 (5)0.5006 (4)0.0939 (13)
N20.7447 (4)0.2286 (4)0.4410 (3)0.0753 (10)
N31.5628 (6)0.1283 (4)0.0109 (5)0.0929 (14)
C10.7808 (4)0.3215 (4)0.3527 (3)0.0558 (9)
C20.9155 (4)0.3332 (4)0.3410 (3)0.0521 (8)
C30.6670 (4)0.4007 (4)0.2854 (3)0.0542 (9)
C40.5213 (5)0.4674 (5)0.3410 (4)0.0686 (11)
H40.49520.45630.42010.082*
C50.4156 (5)0.5494 (5)0.2804 (5)0.0807 (13)
H50.31930.59530.31870.097*
C60.4514 (6)0.5637 (5)0.1641 (5)0.0837 (14)
H60.38010.61980.12310.100*
C70.5930 (6)0.4949 (5)0.1085 (4)0.0796 (13)
H70.61680.50310.02930.095*
C80.7013 (5)0.4133 (5)0.1679 (3)0.0640 (10)
H80.79700.36710.12880.077*
C90.9818 (4)0.4288 (4)0.2556 (3)0.0495 (8)
H90.91990.46610.19870.059*
C101.1371 (4)0.3504 (4)0.1923 (3)0.0509 (8)
C111.1559 (5)0.3109 (4)0.0853 (3)0.0627 (10)
H111.07390.33460.05290.075*
C121.2940 (5)0.2375 (5)0.0274 (4)0.0738 (12)
H121.30630.2109−0.04410.089*
C131.4136 (5)0.2034 (4)0.0754 (4)0.0696 (12)
C141.4005 (5)0.2414 (4)0.1802 (4)0.0677 (11)
H141.48370.21820.21100.081*
C151.2595 (4)0.3154 (4)0.2393 (3)0.0592 (9)
H151.24770.34130.31090.071*
C160.9754 (4)0.5531 (4)0.3084 (3)0.0529 (9)
H161.04740.52050.35770.064*
C170.8230 (4)0.6224 (4)0.3794 (3)0.0574 (9)
O30.7304 (3)0.7037 (3)0.3154 (3)0.0766 (8)
C180.5803 (5)0.7789 (5)0.3722 (6)0.110 (2)
H18A0.56020.74130.45100.132*0.62 (3)
H18B0.50880.77320.33450.132*0.62 (3)
H18C0.58340.79120.44810.132*0.38 (3)
H18D0.52130.72100.38110.132*0.38 (3)
C190.571 (2)0.9256 (10)0.366 (2)0.150 (8)0.62 (3)
H19A0.62970.93170.41390.226*0.62 (3)
H19B0.46900.98300.39070.226*0.62 (3)
H19C0.60740.95610.28860.226*0.62 (3)
C19A0.500 (3)0.917 (2)0.318 (2)0.140 (12)0.38 (3)
H19D0.57040.95730.27110.209*0.38 (3)
H19E0.43600.97690.37600.209*0.38 (3)
H19F0.44070.90710.27170.209*0.38 (3)
C201.0180 (4)0.6576 (4)0.2149 (3)0.0580 (10)
O51.0258 (4)0.7581 (3)0.2602 (3)0.0796 (9)
C211.0583 (9)0.8667 (6)0.1809 (6)0.131 (3)
H21A1.00110.88950.12240.157*0.48 (3)
H21B1.16290.83460.14420.157*0.48 (3)
H21C1.06770.84800.10400.157*0.52 (3)
H21D1.15210.87050.18640.157*0.52 (3)
C221.022 (4)0.9937 (15)0.2377 (14)0.109 (8)0.48 (3)
H22A0.92621.01380.28800.164*0.48 (3)
H22B1.02211.07020.18100.164*0.48 (3)
H22C1.09610.97860.28060.164*0.48 (3)
C22A0.937 (2)1.0027 (12)0.205 (2)0.152 (8)0.52 (3)
H22D0.85331.01010.17650.228*0.52 (3)
H22E0.97271.07630.16940.228*0.52 (3)
H22F0.90721.00870.28620.228*0.52 (3)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Se10.0812 (4)0.1012 (4)0.0863 (4)−0.0446 (3)−0.0377 (3)0.0424 (3)
O10.116 (3)0.095 (3)0.110 (3)−0.042 (2)0.047 (3)−0.035 (2)
O20.067 (2)0.126 (4)0.170 (5)−0.014 (2)0.018 (3)−0.035 (3)
O40.0721 (19)0.109 (2)0.0520 (17)−0.0186 (18)0.0079 (14)−0.0072 (16)
O60.125 (3)0.082 (2)0.0519 (18)−0.051 (2)−0.0073 (17)0.0087 (14)
N10.091 (3)0.103 (3)0.085 (3)−0.051 (2)−0.023 (2)0.041 (2)
N20.070 (2)0.082 (2)0.070 (2)−0.039 (2)−0.0106 (18)0.0203 (19)
N30.076 (3)0.067 (3)0.115 (4)−0.029 (2)0.025 (3)−0.014 (3)
C10.059 (2)0.060 (2)0.049 (2)−0.0287 (18)−0.0026 (16)−0.0018 (16)
C20.056 (2)0.054 (2)0.0456 (19)−0.0232 (17)−0.0087 (16)0.0014 (15)
C30.054 (2)0.058 (2)0.055 (2)−0.0286 (18)−0.0118 (17)0.0014 (17)
C40.061 (3)0.082 (3)0.066 (3)−0.033 (2)−0.004 (2)−0.011 (2)
C50.055 (3)0.082 (3)0.109 (4)−0.022 (2)−0.021 (3)−0.018 (3)
C60.080 (3)0.076 (3)0.108 (4)−0.035 (3)−0.047 (3)0.015 (3)
C70.087 (3)0.100 (3)0.068 (3)−0.052 (3)−0.032 (2)0.017 (2)
C80.060 (2)0.080 (3)0.059 (2)−0.037 (2)−0.0125 (19)0.002 (2)
C90.0473 (19)0.054 (2)0.0480 (19)−0.0215 (16)−0.0091 (15)0.0014 (15)
C100.052 (2)0.0492 (19)0.049 (2)−0.0221 (17)−0.0031 (16)−0.0016 (15)
C110.065 (2)0.071 (3)0.053 (2)−0.030 (2)−0.0024 (19)−0.0099 (19)
C120.083 (3)0.077 (3)0.061 (2)−0.038 (3)0.010 (2)−0.018 (2)
C130.064 (3)0.051 (2)0.080 (3)−0.025 (2)0.020 (2)−0.016 (2)
C140.053 (2)0.057 (2)0.087 (3)−0.0197 (19)−0.009 (2)0.000 (2)
C150.054 (2)0.057 (2)0.061 (2)−0.0173 (18)−0.0054 (18)−0.0079 (18)
C160.052 (2)0.051 (2)0.051 (2)−0.0203 (17)−0.0052 (16)0.0026 (16)
C170.054 (2)0.052 (2)0.061 (2)−0.0203 (18)−0.0008 (18)−0.0071 (18)
O30.0510 (16)0.0754 (19)0.0778 (19)−0.0092 (14)−0.0015 (14)0.0076 (15)
C180.054 (3)0.088 (4)0.148 (5)−0.004 (3)0.004 (3)0.003 (4)
C190.089 (11)0.096 (9)0.207 (18)0.014 (7)0.010 (11)−0.036 (9)
C19A0.083 (14)0.159 (19)0.119 (16)−0.017 (14)−0.001 (11)0.041 (13)
C200.050 (2)0.053 (2)0.060 (2)−0.0169 (17)−0.0017 (17)0.0025 (18)
O50.096 (2)0.0653 (18)0.0764 (19)−0.0450 (17)0.0138 (16)−0.0137 (15)
C210.165 (6)0.074 (4)0.132 (5)−0.070 (4)0.049 (5)−0.015 (3)
C220.134 (18)0.069 (8)0.116 (11)−0.042 (9)−0.006 (10)0.000 (7)
C22A0.168 (17)0.117 (12)0.181 (18)−0.080 (13)−0.056 (15)0.053 (11)
Geometric parameters (Å, °) top
Se1—C21.836 (4)C14—H140.9300
Se1—N11.875 (4)C15—H150.9300
O1—N31.216 (6)C16—C171.510 (5)
O2—N31.208 (7)C16—C201.525 (5)
O4—C171.195 (5)C16—H160.9800
O6—C201.195 (5)C17—O31.315 (5)
N1—N21.260 (5)O3—C181.447 (5)
N2—C11.386 (5)C18—C191.4991 (10)
N3—C131.472 (6)C18—C19A1.4992 (10)
C1—C21.361 (5)C18—H18A0.9700
C1—C31.476 (5)C18—H18B0.9700
C2—C91.514 (5)C18—H18C0.9700
C3—C81.379 (5)C18—H18D0.9700
C3—C41.392 (5)C19—H19A0.9600
C4—C51.374 (6)C19—H19B0.9600
C4—H40.9300C19—H19C0.9600
C5—C61.366 (7)C19A—H19D0.9600
C5—H50.9300C19A—H19E0.9600
C6—C71.368 (7)C19A—H19F0.9600
C6—H60.9300C20—O51.316 (5)
C7—C81.380 (6)O5—C211.434 (6)
C7—H70.9300C21—C221.4989 (10)
C8—H80.9300C21—C22A1.4990 (10)
C9—C101.517 (5)C21—H21A0.9700
C9—C161.535 (5)C21—H21B0.9700
C9—H90.9800C21—H21C0.9700
C10—C151.378 (5)C21—H21D0.9700
C10—C111.391 (5)C22—H22A0.9600
C11—C121.366 (6)C22—H22B0.9600
C11—H110.9300C22—H22C0.9600
C12—C131.363 (7)C22A—H22D0.9600
C12—H120.9300C22A—H22E0.9600
C13—C141.371 (6)C22A—H22F0.9600
C14—C151.392 (5)
C2—Se1—N187.20 (17)C17—C16—C9111.8 (3)
N2—N1—Se1110.9 (3)C20—C16—C9110.1 (3)
N1—N2—C1117.2 (4)C17—C16—H16108.4
O2—N3—O1123.6 (5)C20—C16—H16108.4
O2—N3—C13117.9 (6)C9—C16—H16108.4
O1—N3—C13118.5 (6)O4—C17—O3124.9 (4)
C2—C1—N2115.9 (4)O4—C17—C16123.6 (4)
C2—C1—C3127.3 (3)O3—C17—C16111.5 (3)
N2—C1—C3116.7 (3)C17—O3—C18117.6 (4)
C1—C2—C9127.6 (3)O3—C18—C19106.1 (6)
C1—C2—Se1108.8 (3)O3—C18—C19A118.2 (9)
C9—C2—Se1123.7 (3)O3—C18—H18A110.5
C8—C3—C4118.5 (4)C19—C18—H18A110.5
C8—C3—C1121.9 (3)O3—C18—H18B110.5
C4—C3—C1119.6 (3)C19—C18—H18B110.5
C5—C4—C3120.7 (4)H18A—C18—H18B108.7
C5—C4—H4119.6O3—C18—H18C107.7
C3—C4—H4119.6C19A—C18—H18C107.7
C6—C5—C4120.2 (4)O3—C18—H18D107.7
C6—C5—H5119.9C19A—C18—H18D107.7
C4—C5—H5119.9H18C—C18—H18D107.1
C5—C6—C7119.5 (5)C18—C19—H19A109.5
C5—C6—H6120.3C18—C19—H19B109.5
C7—C6—H6120.3C18—C19—H19C109.5
C6—C7—C8121.1 (4)C18—C19A—H19D109.5
C6—C7—H7119.4C18—C19A—H19E109.5
C8—C7—H7119.4H19D—C19A—H19E109.5
C3—C8—C7119.8 (4)C18—C19A—H19F109.5
C3—C8—H8120.1H19D—C19A—H19F109.5
C7—C8—H8120.1H19E—C19A—H19F109.5
C2—C9—C10111.3 (3)O6—C20—O5124.2 (4)
C2—C9—C16112.8 (3)O6—C20—C16125.6 (4)
C10—C9—C16112.6 (3)O5—C20—C16110.2 (3)
C2—C9—H9106.5C20—O5—C21115.6 (4)
C10—C9—H9106.5O5—C21—C22112.0 (7)
C16—C9—H9106.5O5—C21—C22A110.3 (8)
C15—C10—C11119.3 (3)O5—C21—H21A109.2
C15—C10—C9121.5 (3)C22—C21—H21A109.2
C11—C10—C9119.1 (3)O5—C21—H21B109.2
C12—C11—C10120.4 (4)C22—C21—H21B109.2
C12—C11—H11119.8H21A—C21—H21B107.9
C10—C11—H11119.8O5—C21—H21C109.6
C13—C12—C11119.4 (4)C22A—C21—H21C109.6
C13—C12—H12120.3O5—C21—H21D109.6
C11—C12—H12120.3C22A—C21—H21D109.6
C12—C13—C14122.2 (4)H21C—C21—H21D108.1
C12—C13—N3119.1 (5)C21—C22—H22A109.5
C14—C13—N3118.7 (5)C21—C22—H22B109.5
C13—C14—C15118.3 (4)C21—C22—H22C109.5
C13—C14—H14120.9C21—C22A—H22D109.5
C15—C14—H14120.9C21—C22A—H22E109.5
C10—C15—C14120.4 (4)H22D—C22A—H22E109.5
C10—C15—H15119.8C21—C22A—H22F109.5
C14—C15—H15119.8H22D—C22A—H22F109.5
C17—C16—C20109.6 (3)H22E—C22A—H22F109.5
C2—Se1—N1—N20.3 (4)C10—C11—C12—C13−0.2 (6)
Se1—N1—N2—C10.3 (6)C11—C12—C13—C14−0.5 (6)
N1—N2—C1—C2−1.0 (6)C11—C12—C13—N3−178.0 (4)
N1—N2—C1—C3−178.4 (4)O2—N3—C13—C12−178.0 (5)
N2—C1—C2—C9−177.9 (4)O1—N3—C13—C121.8 (6)
C3—C1—C2—C9−0.8 (6)O2—N3—C13—C144.4 (6)
N2—C1—C2—Se11.1 (4)O1—N3—C13—C14−175.8 (4)
C3—C1—C2—Se1178.2 (3)C12—C13—C14—C150.9 (6)
N1—Se1—C2—C1−0.8 (3)N3—C13—C14—C15178.4 (4)
N1—Se1—C2—C9178.3 (3)C11—C10—C15—C140.1 (5)
C2—C1—C3—C850.7 (6)C9—C10—C15—C14178.9 (3)
N2—C1—C3—C8−132.2 (4)C13—C14—C15—C10−0.7 (6)
C2—C1—C3—C4−127.9 (4)C2—C9—C16—C17−48.0 (4)
N2—C1—C3—C449.2 (5)C10—C9—C16—C17−175.1 (3)
C8—C3—C4—C5−3.1 (6)C2—C9—C16—C20−170.0 (3)
C1—C3—C4—C5175.6 (4)C10—C9—C16—C2062.9 (4)
C3—C4—C5—C61.7 (7)C20—C16—C17—O4−138.2 (4)
C4—C5—C6—C70.5 (7)C9—C16—C17—O499.5 (5)
C5—C6—C7—C8−1.3 (7)C20—C16—C17—O342.6 (4)
C4—C3—C8—C72.3 (6)C9—C16—C17—O3−79.7 (4)
C1—C3—C8—C7−176.4 (4)O4—C17—O3—C181.7 (6)
C6—C7—C8—C3−0.1 (7)C16—C17—O3—C18−179.0 (4)
C1—C2—C9—C10−128.4 (4)C17—O3—C18—C19105.5 (15)
Se1—C2—C9—C1052.8 (4)C17—O3—C18—C19A149 (2)
C1—C2—C9—C16103.8 (4)C17—C16—C20—O6−118.3 (4)
Se1—C2—C9—C16−75.0 (4)C9—C16—C20—O65.1 (6)
C2—C9—C10—C15−81.3 (4)C17—C16—C20—O562.4 (4)
C16—C9—C10—C1546.6 (4)C9—C16—C20—O5−174.3 (3)
C2—C9—C10—C1197.5 (4)O6—C20—O5—C213.5 (7)
C16—C9—C10—C11−134.6 (3)C16—C20—O5—C21−177.2 (5)
C15—C10—C11—C120.3 (6)C20—O5—C21—C22163.5 (15)
C9—C10—C11—C12−178.5 (4)C20—O5—C21—C22A121.8 (17)
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
C22A—H22D···O2i0.962.473.38 (4)159
C11—H11···O6ii0.932.563.410 (6)152
C18—H18A···O40.972.292.686 (7)103
C21—H21C···O60.972.172.627 (6)107
Symmetry codes: (i) x−1, y+1, z; (ii) −x+2, −y+1, −z.
Table 1
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
C22A—H22D···O2i0.962.473.38 (4)159
C11—H11···O6ii0.932.563.410 (6)152
C18—H18A···O40.972.292.686 (7)103
C21—H21C···O60.972.172.627 (6)107
Symmetry codes: (i) x−1, y+1, z; (ii) −x+2, −y+1, −z.
references
References top

Bertini, V., Dapporto, P., Lucchesini, F., Sega, A. & De Munno, A. (1984). Acta Cryst. C40, 653–655.

Bruker (2004). APEX2. Bruker AXS Inc., Madison, Wisconsin, USA.

El-Bahaie, S., Assy, M. G. & Hassanien, M. M. (1990). Pharmazie, 45, 791–793.

El-Kashef, H. S., E-Bayoumy, B. & Aly, T. I. (1986). Egypt. J. Pharm. Sci. 27, 27–30.

Gunasekaran, B., Manivannan, V., Saravanan, S., Muthusubramanian, S. & Nethaji, M. (2007). Acta Cryst. E63, o4024–?.

Sheldrick, G. M. (1996). SADABS. University of Göttingen, Germany.

Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122.

Spek, A. L. (2003). J. Appl. Cryst. 36, 7–13.