N2-[1-(2-Hydroxy­phen­yl)ethyl­idene]-N2′-(1H-indol-3-ylmethyl­ene)carbonic dihydrazide

Saharin, S.M.; Mohd Ali, H.; Robinson, W.T.; Mahmood, A.A.

doi:10.1107/S1600536808035757

organic compounds

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ISSN: 2056-9890

Volume 64| Part 12| December 2008| Page o2357

doi:10.1107/S1600536808035757

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N²-[1-(2-Hydroxyphenyl)ethylidene]-N^2′-(1H-indol-3-ylmethylene)carbonic dihydrazide

Siti Munirah Saharin,^a Hapipah Mohd Ali,^a ^* Ward T. Robinson ^a and A. A. Mahmood ^b

^aDepartment of Chemistry, University of Malaya, 50603 Kuala Lumpur, Malaysia, and ^bDepartment of Molecular Medicine, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia
^*Correspondence e-mail: hapipah@um.edu.my

(Received 23 October 2008; accepted 31 October 2008; online 13 November 2008)

In the crystal structure of the title compound {alternative name: 1-[1-(2-hydroxyphenyl)ethylideneamino]-3-(1H-indol-3-ylmethyleneamino)urea}, C₁₈H₁₇N₅O₂, the planar indole component is twisted at an angle of 63.7 (10)° with respect to the rest of the molecule. This compound is one of a series being studied for biological activity. The hydroxy groups are involved in both intramolecular (O—H⋯N) and intermolecular (N—H⋯O) hydrogen bonds.

Related literature

For a related compound, see: Dan et al. (1987 ).

Experimental

Crystal data

C₁₈H₁₇N₅O₂
M_r = 335.37
Monoclinic, P 2₁ /n
a = 7.0802 (8) Å
b = 9.5335 (11) Å
c = 25.110 (3) Å
β = 97.295 (2)°
V = 1681.2 (3) Å³
Z = 4
Mo Kα radiation
μ = 0.09 mm⁻¹
T = 100 (2) K
0.42 × 0.42 × 0.16 mm

Data collection

Bruker APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ) T_min = 0.821, T_max = 0.986
11912 measured reflections
4740 independent reflections
4145 reflections with I > 2σ(I)
R_int = 0.014

Refinement

R[F² > 2σ(F²)] = 0.043
wR(F²) = 0.122
S = 1.03
4740 reflections
228 parameters
H-atom parameters constrained
Δρ_max = 0.43 e Å⁻³
Δρ_min = −0.32 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1A⋯N5	0.84	1.78	2.5121 (11)	145
N3—H3B⋯O2ⁱ	0.88	1.99	2.8481 (13)	166
N1—H1B⋯O1ⁱⁱ	0.88	2.14	2.8803 (13)	142
Symmetry codes: (i) -x+1, -y, -z; (ii) $[x+{\script{1\over 2}}, -y+{\script{1\over 2}}, z+{\script{1\over 2}}]$ .

Data collection: APEX2 (Bruker, 2007 ); cell refinement: SAINT (Bruker, 2007); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: X-SEED (Barbour, 2001 ); software used to prepare material for publication: publCIF (Westrip, 2008 ).

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808035757/hg2434sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536808035757/hg2434Isup2.hkl

checkCIF report

Comment top

X-ray structures, of Schiff bases derived from condensation of indole-3-carboxaldehyde and 2-hydroxyacetophenone, have not been investigated. The title compound (Fig. 1) appears to be the first example with the planar indole component is twisted at an angle of 116.3 (10)° with respect to the rest of the molecule. However, compound bis(salicylidene)carbonohydrazide (Dan et al.1987), which was reported previously shows planarity for the whole molecule.

Related literature top

For a related compound, see: Dan et al. (1987).

Experimental top

Indole-3-carboxaldehyde (0.30 g, 2.07 mmol), carbohydrazide (0.187 g, 2.07 mmol), and 2-Hydroxyacetophenone (0.24 ml, 2.07 mmol) were heated in acidified ethanol (20 ml) for 2 h. The solvent was removed and the product recrystallized from DMSO.

Computing details top

Data collection: APEX2 (Bruker, 2007); cell refinement: APEX2 (Bruker, 2007); data reduction: SAINT (Bruker, 2007); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: X-SEED (Barbour, 2001); software used to prepare material for publication: publCIF (Westrip, 2008).

Figures top

Fig. 1. Thermal ellipsoid plot (Barbour, 2001) of C₁₈H₁₇N₅O₂at 70% probability level. Hydrogen atoms are drawn as spheres of arbitrary radius

1-[1-(2-hydroxyphenyl)ethylideneamino]-3-(1H-indol-3- ylmethyleneamino)urea top

Crystal data top

C₁₈H₁₇N₅O₂	F(000) = 704
M_r = 335.37	D_x = 1.325 Mg m⁻³
Monoclinic, P2₁/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 6889 reflections
a = 7.0802 (8) Å	θ = 2.3–30.5°
b = 9.5335 (11) Å	µ = 0.09 mm⁻¹
c = 25.110 (3) Å	T = 100 K
β = 97.295 (2)°	Irregular, colourless
V = 1681.2 (3) Å³	0.42 × 0.42 × 0.16 mm
Z = 4

Data collection top

Bruker APEXII CCD area-detector diffractometer	4740 independent reflections
Radiation source: fine-focus sealed tube	4145 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.014
ω scans	θ_max = 30.6°, θ_min = 2.3°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −10→4
T_min = 0.821, T_max = 0.986	k = −13→12
11912 measured reflections	l = −34→35

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)] = 0.044	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.122	H-atom parameters constrained
S = 1.03	w = 1/[σ²(F_o²) + (0.0656P)² + 0.7125P] where P = (F_o² + 2F_c²)/3
4740 reflections	(Δ/σ)_max < 0.001
228 parameters	Δρ_max = 0.43 e Å⁻³
0 restraints	Δρ_min = −0.32 e Å⁻³

Crystal data top

C₁₈H₁₇N₅O₂	V = 1681.2 (3) Å³
M_r = 335.37	Z = 4
Monoclinic, P2₁/n	Mo Kα radiation
a = 7.0802 (8) Å	µ = 0.09 mm⁻¹
b = 9.5335 (11) Å	T = 100 K
c = 25.110 (3) Å	0.42 × 0.42 × 0.16 mm
β = 97.295 (2)°

Data collection top

Bruker APEXII CCD area-detector diffractometer	4740 independent reflections
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	4145 reflections with I > 2σ(I)
T_min = 0.821, T_max = 0.986	R_int = 0.014
11912 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.044	0 restraints
wR(F²) = 0.122	H-atom parameters constrained
S = 1.03	Δρ_max = 0.43 e Å⁻³
4740 reflections	Δρ_min = −0.32 e Å⁻³
228 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
N2	0.47231 (13)	0.13948 (10)	0.11232 (3)	0.01593 (18)
O2	0.38944 (12)	0.16315 (8)	−0.02799 (3)	0.01958 (18)
O1	0.22435 (14)	0.47449 (9)	−0.09575 (3)	0.0246 (2)
H1A	0.2598	0.4252	−0.0686	0.037*
N5	0.28865 (13)	0.41919 (9)	0.00270 (3)	0.01540 (18)
N3	0.45872 (14)	0.09630 (10)	0.05941 (4)	0.01774 (19)
H3B	0.4878	0.0099	0.0513	0.021*
C13	0.17966 (15)	0.64221 (11)	−0.02541 (4)	0.0159 (2)
N4	0.35380 (14)	0.31965 (9)	0.03933 (3)	0.01631 (19)
H4B	0.3663	0.3374	0.0740	0.020*
C11	0.25266 (15)	0.54484 (11)	0.01820 (4)	0.0150 (2)
C10	0.39925 (15)	0.19077 (11)	0.02031 (4)	0.0155 (2)
C9	0.57339 (15)	0.06194 (11)	0.14689 (4)	0.0160 (2)
H9	0.6346	−0.0193	0.1354	0.019*
C8	0.59385 (15)	0.09842 (11)	0.20307 (4)	0.0153 (2)
N1	0.69458 (15)	0.09189 (10)	0.29159 (4)	0.0203 (2)
H1B	0.7590	0.0676	0.3225	0.024*
C12	0.28004 (18)	0.59167 (13)	0.07571 (5)	0.0224 (2)
H12A	0.1593	0.5833	0.0907	0.034*
H12B	0.3223	0.6896	0.0777	0.034*
H12C	0.3764	0.5326	0.0963	0.034*
C14	0.16631 (16)	0.60243 (11)	−0.07989 (4)	0.0180 (2)
C15	0.09241 (18)	0.69504 (13)	−0.12025 (5)	0.0237 (2)
H15	0.0813	0.6664	−0.1568	0.028*
C7	0.71448 (17)	0.03294 (12)	0.24298 (4)	0.0192 (2)
H7	0.7986	−0.0418	0.2375	0.023*
C5	0.49227 (15)	0.20425 (11)	0.22913 (4)	0.0147 (2)
C18	0.12097 (18)	0.77799 (12)	−0.01393 (5)	0.0240 (2)
H18	0.1294	0.8076	0.0224	0.029*
C3	0.48431 (17)	0.27906 (12)	0.32274 (5)	0.0208 (2)
H3	0.5303	0.2721	0.3599	0.025*
C1	0.27606 (18)	0.38481 (13)	0.24917 (5)	0.0255 (3)
H1	0.1791	0.4509	0.2376	0.031*
C4	0.55764 (16)	0.19532 (11)	0.28456 (4)	0.0164 (2)
C2	0.34160 (18)	0.37266 (13)	0.30407 (5)	0.0247 (2)
H2	0.2868	0.4299	0.3290	0.030*
C17	0.05073 (19)	0.87046 (13)	−0.05440 (6)	0.0283 (3)
H17	0.0134	0.9625	−0.0457	0.034*
C6	0.35025 (16)	0.30202 (12)	0.21144 (5)	0.0200 (2)
H6	0.3056	0.3114	0.1743	0.024*
C16	0.03524 (18)	0.82812 (13)	−0.10749 (5)	0.0264 (3)
H16	−0.0148	0.8907	−0.1352	0.032*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
N2	0.0201 (4)	0.0163 (4)	0.0114 (4)	0.0015 (3)	0.0021 (3)	−0.0005 (3)
O2	0.0286 (4)	0.0170 (4)	0.0127 (3)	0.0047 (3)	0.0009 (3)	−0.0006 (3)
O1	0.0389 (5)	0.0196 (4)	0.0140 (4)	0.0084 (4)	−0.0020 (3)	−0.0002 (3)
N5	0.0172 (4)	0.0140 (4)	0.0148 (4)	0.0021 (3)	0.0012 (3)	0.0020 (3)
N3	0.0264 (5)	0.0145 (4)	0.0121 (4)	0.0054 (3)	0.0016 (3)	−0.0001 (3)
C13	0.0141 (4)	0.0142 (4)	0.0192 (5)	0.0006 (4)	0.0015 (4)	0.0011 (4)
N4	0.0228 (5)	0.0140 (4)	0.0118 (4)	0.0046 (3)	0.0008 (3)	0.0009 (3)
C11	0.0144 (4)	0.0146 (4)	0.0162 (4)	0.0004 (4)	0.0027 (3)	−0.0004 (4)
C10	0.0175 (5)	0.0144 (4)	0.0143 (4)	0.0017 (4)	0.0013 (4)	0.0002 (3)
C9	0.0180 (5)	0.0149 (4)	0.0153 (4)	0.0021 (4)	0.0033 (4)	0.0004 (4)
C8	0.0172 (5)	0.0148 (4)	0.0139 (4)	0.0013 (4)	0.0024 (4)	0.0012 (3)
N1	0.0262 (5)	0.0209 (5)	0.0128 (4)	0.0031 (4)	−0.0008 (3)	0.0018 (3)
C12	0.0300 (6)	0.0201 (5)	0.0173 (5)	0.0019 (4)	0.0036 (4)	−0.0036 (4)
C14	0.0173 (5)	0.0162 (5)	0.0197 (5)	0.0010 (4)	−0.0007 (4)	0.0018 (4)
C15	0.0235 (6)	0.0242 (6)	0.0221 (5)	0.0013 (4)	−0.0028 (4)	0.0061 (4)
C7	0.0232 (5)	0.0187 (5)	0.0157 (5)	0.0044 (4)	0.0016 (4)	0.0015 (4)
C5	0.0161 (5)	0.0138 (4)	0.0143 (4)	−0.0022 (4)	0.0027 (3)	−0.0007 (3)
C18	0.0265 (6)	0.0172 (5)	0.0281 (6)	0.0045 (4)	0.0033 (5)	−0.0003 (4)
C3	0.0244 (6)	0.0212 (5)	0.0176 (5)	−0.0058 (4)	0.0052 (4)	−0.0048 (4)
C1	0.0210 (6)	0.0239 (6)	0.0310 (6)	0.0058 (4)	0.0013 (5)	−0.0083 (5)
C4	0.0188 (5)	0.0151 (5)	0.0156 (5)	−0.0030 (4)	0.0030 (4)	−0.0003 (4)
C2	0.0240 (6)	0.0244 (6)	0.0269 (6)	−0.0022 (5)	0.0076 (5)	−0.0108 (5)
C17	0.0284 (6)	0.0161 (5)	0.0402 (7)	0.0068 (4)	0.0034 (5)	0.0046 (5)
C6	0.0189 (5)	0.0199 (5)	0.0208 (5)	0.0031 (4)	0.0002 (4)	−0.0029 (4)
C16	0.0219 (6)	0.0218 (6)	0.0343 (6)	0.0021 (4)	−0.0013 (5)	0.0116 (5)

Geometric parameters (Å, º) top

N2—C9	1.2862 (14)	C12—H12A	0.9800
N2—N3	1.3824 (12)	C12—H12B	0.9800
O2—C10	1.2344 (13)	C12—H12C	0.9800
O1—C14	1.3626 (13)	C14—C15	1.3949 (15)
O1—H1A	0.8400	C15—C16	1.3816 (18)
N5—C11	1.2948 (13)	C15—H15	0.9500
N5—N4	1.3608 (12)	C7—H7	0.9500
N3—C10	1.3591 (13)	C5—C6	1.4013 (15)
N3—H3B	0.8800	C5—C4	1.4125 (14)
C13—C18	1.4007 (15)	C18—C17	1.3887 (17)
C13—C14	1.4111 (15)	C18—H18	0.9500
C13—C11	1.4779 (14)	C3—C2	1.3844 (18)
N4—C10	1.3712 (13)	C3—C4	1.3973 (15)
N4—H4B	0.8800	C3—H3	0.9500
C11—C12	1.5003 (15)	C1—C6	1.3866 (16)
C9—C8	1.4424 (14)	C1—C2	1.4024 (18)
C9—H9	0.9500	C1—H1	0.9500
C8—C7	1.3807 (14)	C2—H2	0.9500
C8—C5	1.4431 (14)	C17—C16	1.384 (2)
N1—C7	1.3672 (14)	C17—H17	0.9500
N1—C4	1.3784 (14)	C6—H6	0.9500
N1—H1B	0.8800	C16—H16	0.9500

C9—N2—N3	116.25 (9)	C15—C14—C13	120.46 (10)
C14—O1—H1A	109.5	C16—C15—C14	120.45 (11)
C11—N5—N4	120.31 (9)	C16—C15—H15	119.8
C10—N3—N2	118.31 (9)	C14—C15—H15	119.8
C10—N3—H3B	120.8	N1—C7—C8	109.75 (10)
N2—N3—H3B	120.8	N1—C7—H7	125.1
C18—C13—C14	117.56 (10)	C8—C7—H7	125.1
C18—C13—C11	120.87 (10)	C6—C5—C4	118.98 (10)
C14—C13—C11	121.57 (9)	C6—C5—C8	134.45 (10)
N5—N4—C10	117.64 (9)	C4—C5—C8	106.55 (9)
N5—N4—H4B	121.2	C17—C18—C13	121.61 (12)
C10—N4—H4B	121.2	C17—C18—H18	119.2
N5—C11—C13	114.95 (9)	C13—C18—H18	119.2
N5—C11—C12	123.94 (10)	C2—C3—C4	117.05 (10)
C13—C11—C12	121.10 (9)	C2—C3—H3	121.5
O2—C10—N3	122.82 (10)	C4—C3—H3	121.5
O2—C10—N4	123.15 (9)	C6—C1—C2	121.18 (11)
N3—C10—N4	114.02 (9)	C6—C1—H1	119.4
N2—C9—C8	119.98 (10)	C2—C1—H1	119.4
N2—C9—H9	120.0	N1—C4—C3	129.59 (10)
C8—C9—H9	120.0	N1—C4—C5	107.85 (9)
C7—C8—C9	125.24 (10)	C3—C4—C5	122.54 (10)
C7—C8—C5	106.56 (9)	C3—C2—C1	121.48 (11)
C9—C8—C5	128.18 (9)	C3—C2—H2	119.3
C7—N1—C4	109.28 (9)	C1—C2—H2	119.3
C7—N1—H1B	125.4	C16—C17—C18	119.80 (11)
C4—N1—H1B	125.4	C16—C17—H17	120.1
C11—C12—H12A	109.5	C18—C17—H17	120.1
C11—C12—H12B	109.5	C1—C6—C5	118.75 (11)
H12A—C12—H12B	109.5	C1—C6—H6	120.6
C11—C12—H12C	109.5	C5—C6—H6	120.6
H12A—C12—H12C	109.5	C15—C16—C17	120.09 (11)
H12B—C12—H12C	109.5	C15—C16—H16	120.0
O1—C14—C15	116.97 (10)	C17—C16—H16	120.0
O1—C14—C13	122.57 (9)

C9—N2—N3—C10	−162.57 (10)	C5—C8—C7—N1	−0.35 (13)
C11—N5—N4—C10	−176.52 (10)	C7—C8—C5—C6	−178.47 (12)
N4—N5—C11—C13	−179.00 (9)	C9—C8—C5—C6	−0.3 (2)
N4—N5—C11—C12	0.64 (16)	C7—C8—C5—C4	−0.58 (12)
C18—C13—C11—N5	174.99 (10)	C9—C8—C5—C4	177.62 (10)
C14—C13—C11—N5	−5.00 (15)	C14—C13—C18—C17	0.46 (18)
C18—C13—C11—C12	−4.66 (16)	C11—C13—C18—C17	−179.52 (11)
C14—C13—C11—C12	175.35 (10)	C7—N1—C4—C3	177.00 (11)
N2—N3—C10—O2	177.29 (10)	C7—N1—C4—C5	−1.54 (13)
N2—N3—C10—N4	−1.86 (15)	C2—C3—C4—N1	−178.03 (11)
N5—N4—C10—O2	2.37 (16)	C2—C3—C4—C5	0.33 (17)
N5—N4—C10—N3	−178.48 (9)	C6—C5—C4—N1	179.57 (10)
N3—N2—C9—C8	−179.42 (9)	C8—C5—C4—N1	1.29 (12)
N2—C9—C8—C7	−172.45 (11)	C6—C5—C4—C3	0.90 (16)
N2—C9—C8—C5	9.66 (17)	C8—C5—C4—C3	−177.38 (10)
C18—C13—C14—O1	178.09 (11)	C4—C3—C2—C1	−1.19 (18)
C11—C13—C14—O1	−1.93 (17)	C6—C1—C2—C3	0.8 (2)
C18—C13—C14—C15	−1.62 (16)	C13—C18—C17—C16	0.9 (2)
C11—C13—C14—C15	178.37 (10)	C2—C1—C6—C5	0.44 (18)
O1—C14—C15—C16	−178.26 (11)	C4—C5—C6—C1	−1.26 (16)
C13—C14—C15—C16	1.46 (18)	C8—C5—C6—C1	176.42 (12)
C4—N1—C7—C8	1.19 (13)	C14—C15—C16—C17	−0.10 (19)
C9—C8—C7—N1	−178.62 (10)	C18—C17—C16—C15	−1.1 (2)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1A···N5	0.84	1.78	2.5121 (11)	145
N3—H3B···O2ⁱ	0.88	1.99	2.8481 (13)	166
N1—H1B···O1ⁱⁱ	0.88	2.14	2.8803 (13)	142

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

Experimental details

Crystal data
Chemical formula	C₁₈H₁₇N₅O₂
M_r	335.37
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	100
a, b, c (Å)	7.0802 (8), 9.5335 (11), 25.110 (3)
β (°)	97.295 (2)
V (Å³)	1681.2 (3)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.09
Crystal size (mm)	0.42 × 0.42 × 0.16

Data collection
Diffractometer	Bruker APEXII CCD area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Sheldrick, 1996)
T_min, T_max	0.821, 0.986
No. of measured, independent and observed [I > 2σ(I)] reflections	11912, 4740, 4145
R_int	0.014
(sin θ/λ)_max (Å⁻¹)	0.715

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.044, 0.122, 1.03
No. of reflections	4740
No. of parameters	228
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.43, −0.32

Computer programs: APEX2 (Bruker, 2007), SAINT (Bruker, 2007), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), X-SEED (Barbour, 2001), publCIF (Westrip, 2008).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1A···N5	0.84	1.78	2.5121 (11)	145
N3—H3B···O2ⁱ	0.88	1.99	2.8481 (13)	166
N1—H1B···O1ⁱⁱ	0.88	2.14	2.8803 (13)	142

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

Acknowledgements

The authors thank the University of Malaya for funding this study (Science Fund Grants 12–02-03–2031, 12–02-03–2051 and PJP FS350–2008 A).

References

Barbour, L. J. (2001). J. Supramol. Chem. 1, 189–191. CrossRef CAS Google Scholar
Bruker (2007). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Dan, J., Seth, S. & Chakraborty, S. (1987). Acta Cryst. C43, 1114–1116. CSD CrossRef CAS Web of Science IUCr Journals Google Scholar
Sheldrick, G. M. (1996). SADABS. University of Göttingen, Germany. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Westrip, S. P. (2008). publCIF. In preparation. Google Scholar

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