N′-[(E)-(1-Methyl-1H-pyrrol-2-yl)methyl­idene]pyridine-4-carbohydrazide

Hussain, A.; Tahir, M.N.; Shafiq, Z.; Yaqub, M.; Mazhar, M.

doi:10.1107/S1600536810025341

organic compounds

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ISSN: 2056-9890

Volume 66| Part 7| July 2010| Page o1881

doi:10.1107/S1600536810025341

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ADDENDA AND ERRATA

A correction has been published for this article. To view the correction, click here.

N′-[(E)-(1-Methyl-1H-pyrrol-2-yl)methylidene]pyridine-4-carbohydrazide

Abid Hussain,^a M. Nawaz Tahir,^b ^* Zahid Shafiq,^a Muhammad Yaqub ^a and Muhammad Mazhar ^c

^aDepartment of Chemistry, Bahauddin Zakariya University, Multan 60800, Pakistan, ^bDepartment of Physics, University of Sargodha, Sargodha, Pakistan, and ^cBahauddin Zakariya University, Department of Chemistry, Multan 60800, Pakistan
^*Correspondence e-mail: dmntahir_uos@yahoo.com

(Received 27 June 2010; accepted 28 June 2010; online 30 June 2010)

In the title compound, C₁₂H₁₂N₄O, the pyridine and pyrrole rings are inclined at an angle of 29.22 (8)° and an intramolecular C—H⋯N interaction geneates an S(6) ring. In the crystal, molecules are linked by N—H⋯N hydrogen bonds, forming (010) C(7) chains. The chains are cross-linked by weak C—H⋯O interactions, which generate R₂²(18) ring motifs within an infinite sheet. Finally, two C—H⋯π interactions are present, where the C—H groups are from the pyridine ring and π is the pyrrole ring.

Related literature

For background information on Schiff bases containing heterocyclic rings and for related structures, see: Shafiq et al.,(2009a ,b ); Hussain et al. (2010 ) For graph-set notation, see: Bernstein et al. (1995 ).

Experimental

Crystal data

C₁₂H₁₂N₄O
M_r = 228.26
Monoclinic, P 2₁ /n
a = 8.2134 (3) Å
b = 10.6740 (4) Å
c = 13.1332 (4) Å
β = 96.938 (2)°
V = 1142.95 (7) Å³
Z = 4
Mo Kα radiation
μ = 0.09 mm⁻¹
T = 296 K
0.24 × 0.18 × 0.15 mm

Data collection

Bruker Kappa APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2005 ) T_min = 0.980, T_max = 0.985
12030 measured reflections
2803 independent reflections
2023 reflections with I > 2σ(I)
R_int = 0.029

Refinement

R[F² > 2σ(F²)] = 0.045
wR(F²) = 0.127
S = 1.04
2803 reflections
155 parameters
H-atom parameters constrained
Δρ_max = 0.28 e Å⁻³
Δρ_min = −0.21 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

Cg1 is the centroid of the C8—C11/N4 ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N2—H2⋯N1ⁱ	0.86	2.19	3.0205 (18)	163
C4—H4⋯O1ⁱⁱ	0.93	2.54	3.3821 (19)	150
C12—H12B⋯O1ⁱⁱⁱ	0.96	2.55	3.450 (2)	156
C12—H12C⋯N3	0.96	2.36	3.025 (2)	126
C2—H2A⋯Cg1^iv	0.93	2.83	3.3258 (16)	114
C5—H5⋯Cg1^v	0.93	2.71	3.4669 (17)	139
Symmetry codes: (i) $[-x+{\script{1\over 2}}, y+{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (ii) $[x-{\script{1\over 2}}, -y+{\script{1\over 2}}, z-{\script{1\over 2}}]$ ; (iii) -x+2, -y+1, -z+1; (iv) -x+1, -y+1, -z+1; (v) $[-x+{\script{3\over 2}}, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ .

Data collection: APEX2 (Bruker, 2009 ); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT; 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, 1997 ) and PLATON (Spek, 2009 ); software used to prepare material for publication: WinGX (Farrugia, 1999 ) and PLATON.

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810025341/hb5530sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536810025341/hb5530Isup2.hkl

checkCIF report

Comment top

We have reported crystal structures of Schiff bases with N-containing aromatic ring (Shafiq et al., 2009a, 2009b), (Hussain et al., 2010) and as a part of this project, we report herein the structure and synthesis of the title compound (I, Fig. 1).

In (I) the pyridine ring A (C1–C5/N1), the central moiety B (O1/C6/N2/N3/C7) and the pyrrol moiety C (C8—C11/N4/C12) are planar with r. m. s. deviations of 0.0345, 0.0285 and 0.0276 Å, respectively. The dihedral angle between A/B, A/C and B/C is 38.32 (8)°, 29.22 (8)° and 9.44 (13)°, respectively. In title molecule, there exist intra as well inter-molecular H-bondings (Table 1). The molecules form infinite one dimensional polymeric chains extending along the b axis (Fig. 2), if only strong H-bondings are considered. If the strong as well as weak H-bondings are considered then the molecules form two-dimensional polymeric chains with R₂²(18) (Bernstein et al., 1995) ring motifs (Fig. 3). The C—H···π interactions (Table 1) also play important role in stabilizing the molecules.

Related literature top

For background information on Schiff bases containing heterocyclic rings and for related structures, see: Shafiq et al.,(2009a,b); Hussain et al. (2010) For graph-set notation, see: Bernstein et al. (1995).

Experimental top

To a hot stirred solution of isoniazid (1.37 g, 0.01 mole) in ethanol 15 ml was added N-methylpyrrol-2-carboxaldehyde (1.1 ml, 0.01 mol). The resultant mixture was then heated under reflux. The reaction was monitored through TLC. After an hour, the precipitate were formed. The reaction mixture was further heated for 30 min. The resultant crude material was recrystalized in 1,4-dioxane:ethanol (1:4) to affoard red prisms of (I).

Computing details top

Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); 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, 1997) and PLATON (Spek, 2009); software used to prepare material for publication: WinGX (Farrugia, 1999) and PLATON (Spek, 2009).

Figures top

	Fig. 1. View of (I) with displacement ellipsoids drawn at the 50% probability level. H-atoms are shown by small circles of arbitrary radius.
	Fig. 2. The partial packing of (I), which shows that molecules form infinite one dimensional polymeric chains extending along b axis.
	Fig. 3. The partial packing (PLATON; Spek, 2009) which shows that molecules form R₂²(18) ring motifs in the infinite polymeric chains.

N'-[(E)-(1-Methyl-1H-pyrrol-2-yl)methylidene]pyridine- 4-carbohydrazide top

Crystal data top

C₁₂H₁₂N₄O	F(000) = 480
M_r = 228.26	D_x = 1.326 Mg m⁻³
Monoclinic, P2₁/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 1770 reflections
a = 8.2134 (3) Å	θ = 2.6–28.4°
b = 10.6740 (4) Å	µ = 0.09 mm⁻¹
c = 13.1332 (4) Å	T = 296 K
β = 96.938 (2)°	Prism, red
V = 1142.95 (7) Å³	0.24 × 0.18 × 0.15 mm
Z = 4

Data collection top

Bruker Kappa APEXII CCD diffractometer	2803 independent reflections
Radiation source: fine-focus sealed tube	2023 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.029
Detector resolution: 7.50 pixels mm^-1	θ_max = 28.3°, θ_min = 2.5°
ω scans	h = −10→10
Absorption correction: multi-scan (SADABS; Bruker, 2005)	k = −14→14
T_min = 0.980, T_max = 0.985	l = −17→17
12030 measured reflections

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)] = 0.045	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.127	H-atom parameters constrained
S = 1.04	w = 1/[σ²(F_o²) + (0.0618P)² + 0.235P] where P = (F_o² + 2F_c²)/3
2803 reflections	(Δ/σ)_max < 0.001
155 parameters	Δρ_max = 0.28 e Å⁻³
0 restraints	Δρ_min = −0.21 e Å⁻³

Crystal data top

C₁₂H₁₂N₄O	V = 1142.95 (7) Å³
M_r = 228.26	Z = 4
Monoclinic, P2₁/n	Mo Kα radiation
a = 8.2134 (3) Å	µ = 0.09 mm⁻¹
b = 10.6740 (4) Å	T = 296 K
c = 13.1332 (4) Å	0.24 × 0.18 × 0.15 mm
β = 96.938 (2)°

Data collection top

Bruker Kappa APEXII CCD diffractometer	2803 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2005)	2023 reflections with I > 2σ(I)
T_min = 0.980, T_max = 0.985	R_int = 0.029
12030 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.045	0 restraints
wR(F²) = 0.127	H-atom parameters constrained
S = 1.04	Δρ_max = 0.28 e Å⁻³
2803 reflections	Δρ_min = −0.21 e Å⁻³
155 parameters

Special details top

Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles

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	0.68517 (16)	0.25900 (11)	0.46989 (10)	0.0596 (4)
N1	0.25031 (16)	0.01556 (12)	0.25463 (10)	0.0424 (4)
N2	0.55170 (15)	0.41010 (11)	0.37015 (10)	0.0388 (4)
N3	0.65784 (16)	0.50489 (12)	0.40795 (10)	0.0417 (4)
N4	0.85194 (16)	0.74061 (12)	0.46127 (10)	0.0411 (4)
C1	0.46019 (16)	0.19827 (12)	0.34909 (10)	0.0315 (4)
C2	0.40449 (19)	0.10059 (13)	0.40461 (11)	0.0374 (4)
C3	0.30152 (19)	0.01259 (14)	0.35500 (12)	0.0414 (5)
C4	0.3056 (2)	0.11012 (14)	0.20128 (11)	0.0421 (5)
C5	0.40918 (19)	0.20229 (14)	0.24441 (11)	0.0378 (4)
C6	0.57736 (18)	0.29160 (14)	0.40312 (11)	0.0371 (4)
C7	0.62947 (19)	0.61063 (14)	0.36395 (12)	0.0416 (5)
C8	0.72195 (19)	0.72388 (14)	0.38651 (12)	0.0404 (5)
C9	0.6991 (2)	0.83500 (15)	0.33312 (13)	0.0497 (5)
C10	0.8163 (2)	0.92006 (16)	0.37628 (13)	0.0539 (6)
C11	0.9081 (2)	0.85957 (15)	0.45424 (13)	0.0496 (6)
C12	0.9127 (2)	0.65484 (17)	0.54194 (14)	0.0574 (6)
H2	0.46924	0.42717	0.32551	0.0466*
H2A	0.43635	0.09445	0.47482	0.0449*
H3	0.26551	−0.05268	0.39352	0.0497*
H4	0.27213	0.11375	0.13112	0.0505*
H5	0.44438	0.26614	0.20412	0.0454*
H7	0.54104	0.61488	0.31268	0.0500*
H9	0.61937	0.85044	0.27801	0.0597*
H10	0.82924	1.00246	0.35569	0.0646*
H11	0.99575	0.89429	0.49628	0.0595*
H12A	0.86108	0.67234	0.60217	0.0860*
H12B	1.02928	0.66469	0.55737	0.0860*
H12C	0.88828	0.57043	0.51995	0.0860*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0566 (8)	0.0471 (7)	0.0666 (8)	−0.0071 (6)	−0.0275 (6)	0.0054 (6)
N1	0.0438 (8)	0.0334 (7)	0.0475 (7)	−0.0070 (6)	−0.0048 (5)	−0.0019 (5)
N2	0.0359 (7)	0.0296 (6)	0.0480 (7)	−0.0057 (5)	−0.0070 (5)	−0.0040 (5)
N3	0.0389 (7)	0.0336 (7)	0.0511 (7)	−0.0081 (5)	−0.0010 (5)	−0.0087 (5)
N4	0.0427 (7)	0.0335 (7)	0.0474 (7)	−0.0083 (5)	0.0062 (6)	−0.0074 (5)
C1	0.0297 (7)	0.0266 (7)	0.0374 (7)	0.0006 (5)	0.0003 (5)	−0.0018 (5)
C2	0.0437 (8)	0.0331 (8)	0.0340 (7)	−0.0001 (6)	−0.0012 (6)	0.0025 (6)
C3	0.0458 (9)	0.0331 (8)	0.0449 (8)	−0.0071 (7)	0.0035 (6)	0.0052 (6)
C4	0.0509 (9)	0.0385 (8)	0.0341 (7)	−0.0045 (7)	−0.0061 (6)	−0.0011 (6)
C5	0.0453 (9)	0.0318 (7)	0.0359 (7)	−0.0047 (6)	0.0030 (6)	0.0032 (6)
C6	0.0348 (8)	0.0343 (8)	0.0406 (7)	−0.0037 (6)	−0.0022 (6)	−0.0022 (6)
C7	0.0380 (8)	0.0344 (8)	0.0509 (9)	−0.0047 (7)	−0.0012 (7)	−0.0074 (7)
C8	0.0396 (8)	0.0351 (8)	0.0470 (8)	−0.0051 (6)	0.0069 (7)	−0.0087 (6)
C9	0.0580 (10)	0.0381 (9)	0.0529 (9)	−0.0047 (8)	0.0064 (8)	−0.0029 (7)
C10	0.0729 (12)	0.0331 (8)	0.0580 (10)	−0.0118 (8)	0.0178 (9)	−0.0040 (7)
C11	0.0560 (10)	0.0380 (9)	0.0570 (10)	−0.0198 (8)	0.0162 (8)	−0.0155 (8)
C12	0.0538 (11)	0.0461 (10)	0.0680 (11)	−0.0058 (8)	−0.0098 (8)	0.0025 (9)

Geometric parameters (Å, º) top

O1—C6	1.219 (2)	C7—C8	1.439 (2)
N1—C3	1.335 (2)	C8—C9	1.379 (2)
N1—C4	1.339 (2)	C9—C10	1.393 (2)
N2—N3	1.3877 (18)	C10—C11	1.359 (2)
N2—C6	1.3453 (19)	C2—H2A	0.9300
N3—C7	1.277 (2)	C3—H3	0.9300
N4—C8	1.372 (2)	C4—H4	0.9300
N4—C11	1.358 (2)	C5—H5	0.9300
N4—C12	1.443 (2)	C7—H7	0.9300
N2—H2	0.8600	C9—H9	0.9300
C1—C2	1.3815 (19)	C10—H10	0.9300
C1—C5	1.3886 (19)	C11—H11	0.9300
C1—C6	1.502 (2)	C12—H12A	0.9600
C2—C3	1.374 (2)	C12—H12B	0.9600
C4—C5	1.377 (2)	C12—H12C	0.9600

C3—N1—C4	116.64 (13)	N4—C11—C10	109.47 (15)
N3—N2—C6	120.21 (12)	C1—C2—H2A	120.00
N2—N3—C7	114.22 (13)	C3—C2—H2A	120.00
C8—N4—C11	108.33 (13)	N1—C3—H3	118.00
C8—N4—C12	127.81 (13)	C2—C3—H3	118.00
C11—N4—C12	123.58 (14)	N1—C4—H4	118.00
C6—N2—H2	120.00	C5—C4—H4	118.00
N3—N2—H2	120.00	C1—C5—H5	121.00
C2—C1—C6	119.03 (12)	C4—C5—H5	121.00
C2—C1—C5	117.80 (13)	N3—C7—H7	117.00
C5—C1—C6	123.13 (12)	C8—C7—H7	117.00
C1—C2—C3	119.32 (13)	C8—C9—H9	126.00
N1—C3—C2	123.67 (14)	C10—C9—H9	126.00
N1—C4—C5	123.72 (14)	C9—C10—H10	127.00
C1—C5—C4	118.86 (13)	C11—C10—H10	127.00
N2—C6—C1	113.89 (12)	N4—C11—H11	125.00
O1—C6—N2	124.87 (14)	C10—C11—H11	125.00
O1—C6—C1	121.24 (13)	N4—C12—H12A	109.00
N3—C7—C8	125.91 (15)	N4—C12—H12B	109.00
N4—C8—C9	107.35 (13)	N4—C12—H12C	109.00
C7—C8—C9	125.57 (15)	H12A—C12—H12B	109.00
N4—C8—C7	127.04 (14)	H12A—C12—H12C	109.00
C8—C9—C10	107.99 (15)	H12B—C12—H12C	109.00
C9—C10—C11	106.87 (15)

C4—N1—C3—C2	0.6 (2)	C2—C1—C5—C4	0.4 (2)
C3—N1—C4—C5	−0.5 (2)	C6—C1—C5—C4	177.90 (14)
C6—N2—N3—C7	173.81 (14)	C2—C1—C6—O1	38.1 (2)
N3—N2—C6—O1	4.1 (2)	C2—C1—C6—N2	−142.47 (14)
N3—N2—C6—C1	−175.38 (12)	C5—C1—C6—O1	−139.38 (16)
N2—N3—C7—C8	−178.82 (14)	C5—C1—C6—N2	40.08 (19)
C11—N4—C8—C7	177.64 (15)	C1—C2—C3—N1	−0.2 (2)
C11—N4—C8—C9	0.04 (17)	N1—C4—C5—C1	0.0 (2)
C12—N4—C8—C7	−8.4 (3)	N3—C7—C8—N4	−2.9 (3)
C12—N4—C8—C9	174.00 (15)	N3—C7—C8—C9	174.33 (16)
C8—N4—C11—C10	0.12 (19)	N4—C8—C9—C10	−0.18 (18)
C12—N4—C11—C10	−174.15 (15)	C7—C8—C9—C10	−177.82 (15)
C5—C1—C2—C3	−0.3 (2)	C8—C9—C10—C11	0.25 (19)
C6—C1—C2—C3	−177.89 (14)	C9—C10—C11—N4	−0.23 (19)

Hydrogen-bond geometry (Å, º) top

Cg1 is the centroid of the C8—C11/N4 ring.

D—H···A	D—H	H···A	D···A	D—H···A
N2—H2···N1ⁱ	0.86	2.19	3.0205 (18)	163
C4—H4···O1ⁱⁱ	0.93	2.54	3.3821 (19)	150
C12—H12B···O1ⁱⁱⁱ	0.96	2.55	3.450 (2)	156
C12—H12C···N3	0.96	2.36	3.025 (2)	126
C2—H2A···Cg1^iv	0.93	2.83	3.3258 (16)	114
C5—H5···Cg1^v	0.93	2.71	3.4669 (17)	139

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

Experimental details

Crystal data
Chemical formula	C₁₂H₁₂N₄O
M_r	228.26
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	296
a, b, c (Å)	8.2134 (3), 10.6740 (4), 13.1332 (4)
β (°)	96.938 (2)
V (Å³)	1142.95 (7)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.09
Crystal size (mm)	0.24 × 0.18 × 0.15

Data collection
Diffractometer	Bruker Kappa APEXII CCD diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2005)
T_min, T_max	0.980, 0.985
No. of measured, independent and observed [I > 2σ(I)] reflections	12030, 2803, 2023
R_int	0.029
(sin θ/λ)_max (Å⁻¹)	0.666

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.045, 0.127, 1.04
No. of reflections	2803
No. of parameters	155
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.28, −0.21

Computer programs: APEX2 (Bruker, 2009), SAINT (Bruker, 2009), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 1997) and PLATON (Spek, 2009), WinGX (Farrugia, 1999) and PLATON (Spek, 2009).

Hydrogen-bond geometry (Å, º) top

Cg1 is the centroid of the C8—C11/N4 ring.

D—H···A	D—H	H···A	D···A	D—H···A
N2—H2···N1ⁱ	0.86	2.19	3.0205 (18)	163
C4—H4···O1ⁱⁱ	0.93	2.54	3.3821 (19)	150
C12—H12B···O1ⁱⁱⁱ	0.96	2.55	3.450 (2)	156
C12—H12C···N3	0.96	2.36	3.025 (2)	126
C2—H2A···Cg1^iv	0.93	2.83	3.3258 (16)	114
C5—H5···Cg1^v	0.93	2.71	3.4669 (17)	139

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

Acknowledgements

The authors acknowledge the provision of funds for the purchase of diffractometer and encouragement by Dr Muhammad Akram Chaudhary, Vice Chancellor, University of Sargodha, Pakistan.

References

Bernstein, J., Davis, R. E., Shimoni, L. & Chang, N.-L. (1995). Angew. Chem. Int. Ed. Engl. 34, 1555–1573. CrossRef CAS Web of Science Google Scholar
Bruker (2005). SADABS. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Bruker (2009). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565. CrossRef IUCr Journals Google Scholar
Farrugia, L. J. (1999). J. Appl. Cryst. 32, 837–838. CrossRef CAS IUCr Journals Google Scholar
Hussain, A., Shafiq, Z., Tahir, M. N. & Yaqub, M. (2010). Acta. Cryst. E66, o1880. Web of Science CSD CrossRef IUCr Journals Google Scholar
Shafiq, Z., Yaqub, M., Tahir, M. N., Hussain, A. & Iqbal, M. S. (2009a). Acta Cryst. E65, o2496. Web of Science CSD CrossRef IUCr Journals Google Scholar
Shafiq, Z., Yaqub, M., Tahir, M. N., Hussain, A. & Iqbal, M. S. (2009b). Acta Cryst. E65, o2899. Web of Science CrossRef IUCr Journals 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

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Volume 66| Part 7| July 2010| Page o1881

doi:10.1107/S1600536810025341

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