N-[(E)-2,4-Dichloro­benzyl­idene]-4-methyl­aniline

Tahir, M.N.; Shad, H.A.; Tariq, M.I.; Tariq, R.H.

doi:10.1107/S1600536810036640

organic compounds

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 66| Part 10| October 2010| Page o2583

doi:10.1107/S1600536810036640

Open

access

N-[(E)-2,4-Dichlorobenzylidene]-4-methylaniline

M. Nawaz Tahir,^a ^* Hazoor Ahmad Shad,^b Muhammad Ilyas Tariq ^c and Riaz H. Tariq ^d

^aDepartment of Physics, University of Sargodha, Sargodha, Pakistan, ^bDepartment of Chemistry, Govt. M. D. College, Toba Tek Singh, Punjab, Pakistan, ^cDepartment of Chemistry, University of Sargodha, Sargodha, Pakistan, and ^dInstitute of Chemical and Pharmaceutical Sciences, The University of Faisalabad, Faisalabad, Pakistan
^*Correspondence e-mail: dmntahir_uos@yahoo.com

(Received 12 September 2010; accepted 13 September 2010; online 18 September 2010)

In the title compound, C₁₄H₁₁Cl₂N, the dihedral angle between the 4-methylanilinic and 2,4-dichlorobenzaldehyde moieties is 7.37 (8)°. In the crystal, C—H⋯π interactions between the terminal methyl group and a symmetry-related ring of the anilinic group help to establish the packing.

Related literature

For background to our project to synthesize various Schiff bases of 2,4-dichlorobenzaldehyde as possible ligands for complexing metals, see: Hayat et al. (2010 ). For related structures, see: Hayat et al. (2010); Bernstein (1972 ). For graph-set notation, see: Bernstein et al. (1995 ).

Experimental

Crystal data

C₁₄H₁₁Cl₂N
M_r = 264.14
Monoclinic, P 2₁
a = 10.1069 (3) Å
b = 4.7469 (2) Å
c = 12.9922 (4) Å
β = 95.668 (2)°
V = 620.27 (4) Å³
Z = 2
Mo Kα radiation
μ = 0.50 mm⁻¹
T = 296 K
0.32 × 0.20 × 0.18 mm

Data collection

Bruker Kappa APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2005 ) T_min = 0.886, T_max = 0.916
5221 measured reflections
2082 independent reflections
1937 reflections with I > 2σ(I)
R_int = 0.022

Refinement

R[F² > 2σ(F²)] = 0.030
wR(F²) = 0.079
S = 1.06
2082 reflections
155 parameters
1 restraint
H-atom parameters constrained
Δρ_max = 0.16 e Å⁻³
Δρ_min = −0.15 e Å⁻³
Absolute structure: Flack (1983 ), 807 Friedel pairs
Flack parameter: 0.10 (7)

Table 1
Hydrogen-bond geometry (Å, °)

Cg1 is the centroid of the C1–C6 ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C7—H7C⋯Cg1ⁱ	0.96	2.71	3.565 (2)	148
Symmetry code: (i) x, y-1, z.

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 ); software used to prepare material for publication: WinGX (Farrugia, 1999 ) and PLATON (Spek, 2009 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810036640/dn2602sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536810036640/dn2602Isup2.hkl

checkCIF report

Comment top

As a part of our on going project related to synthesize various Schiff bases of 2,4-dichlorobenzaldehyde as possible ligands for complexing metals (Hayat et al., 2010), we report here the title compound.

In the title compound, the 4-methylanilinic group A (C1—C7/N1) and 2,4-dichlorobenzaldehyde moiety B (C8—C14/CL1/CL2) are planar with r. m. s. deviation of 0.0114 and 0.0209 Å, respectively. The dihedral angle between A/B is 7.37 (8)°. The title compound essentially consists of monomers (Fig. 1). There exist weak intramolecular C—H···Cl hydrogen bonds (Table 1, Fig. 1) forming an S(5) ring motif (Bernstein et al., 1995). There also exists a C—H···π interaction (Table 1) which helps in consolidating the crystal packing. Bond distances and bond angles agree with related compounds already published as the 4-chloro-N-[(E)-2,4-dichlorobenzylidene]aniline (Hayat et al., 2010) and the N-(2,4-dichlorobenzylidene)aniline (Bernstein, 1972).

Related literature top

For background to our project to synthesize various Schiff bases of 2,4-dichlorobenzaldehyde as possible ligands for complexing metals, see: Hayat et al. (2010). For related structures, see: Hayat et al. (2010); Bernstein (1972). For graph-set notation, see: Bernstein et al. (1995).

Experimental top

Equimolar quantities of 4-methylaniline and 2,4-dichlorobanzaldehyde were refluxed in methanol for 30 min resulting in yellow solution. The solution was kept at room temperature which affoarded light yellow needles after 72 h.

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); software used to prepare material for publication: WinGX (Farrugia, 1999) and PLATON (Spek, 2009).

Figures top

Fig. 1. View of the title compound with the atom numbering scheme. The thermal ellipsoids are drawn at the 50% probability level. H-atoms are shown as small circles of arbitrary radii. The dotted line represents the intramolecular H-bonding.

N-[(E)-2,4-Dichlorobenzylidene]-4-methylaniline top

Crystal data top

C₁₄H₁₁Cl₂N	F(000) = 272
M_r = 264.14	D_x = 1.414 Mg m⁻³
Monoclinic, P2₁	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2yb	Cell parameters from 1937 reflections
a = 10.1069 (3) Å	θ = 1.6–25.2°
b = 4.7469 (2) Å	µ = 0.50 mm⁻¹
c = 12.9922 (4) Å	T = 296 K
β = 95.668 (2)°	Needles, colorless
V = 620.27 (4) Å³	0.32 × 0.20 × 0.18 mm
Z = 2

Data collection top

Bruker Kappa APEXII CCD diffractometer	2082 independent reflections
Radiation source: fine-focus sealed tube	1937 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.022
Detector resolution: 8.20 pixels mm^-1	θ_max = 25.2°, θ_min = 1.6°
ω scans	h = −12→12
Absorption correction: multi-scan (SADABS; Bruker, 2005)	k = −5→4
T_min = 0.886, T_max = 0.916	l = −15→15
5221 measured reflections

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)] = 0.030	H-atom parameters constrained
wR(F²) = 0.079	w = 1/[σ²(F_o²) + (0.0434P)² + 0.0661P] where P = (F_o² + 2F_c²)/3
S = 1.06	(Δ/σ)_max < 0.001
2082 reflections	Δρ_max = 0.16 e Å⁻³
155 parameters	Δρ_min = −0.15 e Å⁻³
1 restraint	Absolute structure: Flack (1983), 807 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.10 (7)

Crystal data top

C₁₄H₁₁Cl₂N	V = 620.27 (4) Å³
M_r = 264.14	Z = 2
Monoclinic, P2₁	Mo Kα radiation
a = 10.1069 (3) Å	µ = 0.50 mm⁻¹
b = 4.7469 (2) Å	T = 296 K
c = 12.9922 (4) Å	0.32 × 0.20 × 0.18 mm
β = 95.668 (2)°

Data collection top

Bruker Kappa APEXII CCD diffractometer	2082 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2005)	1937 reflections with I > 2σ(I)
T_min = 0.886, T_max = 0.916	R_int = 0.022
5221 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.030	H-atom parameters constrained
wR(F²) = 0.079	Δρ_max = 0.16 e Å⁻³
S = 1.06	Δρ_min = −0.15 e Å⁻³
2082 reflections	Absolute structure: Flack (1983), 807 Friedel pairs
155 parameters	Absolute structure parameter: 0.10 (7)
1 restraint

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
Cl1	−0.16693 (6)	0.51040 (18)	0.89821 (4)	0.0670 (3)
Cl2	−0.39799 (5)	1.07125 (13)	0.57256 (4)	0.0492 (2)
N1	0.08154 (17)	0.0949 (5)	0.69281 (13)	0.0393 (6)
C1	0.1724 (2)	−0.1021 (5)	0.74152 (15)	0.0359 (7)
C2	0.2670 (2)	−0.2162 (5)	0.68218 (17)	0.0436 (8)
C3	0.3592 (2)	−0.4089 (6)	0.72278 (18)	0.0488 (8)
C4	0.3619 (2)	−0.4993 (5)	0.82462 (16)	0.0422 (8)
C5	0.2663 (2)	−0.3948 (6)	0.88216 (16)	0.0478 (8)
C6	0.1728 (2)	−0.1997 (6)	0.84251 (16)	0.0450 (8)
C7	0.4635 (3)	−0.7104 (6)	0.8693 (2)	0.0601 (10)
C8	0.0090 (2)	0.2361 (5)	0.74719 (16)	0.0396 (7)
C9	−0.08867 (19)	0.4437 (5)	0.70395 (15)	0.0354 (6)
C10	−0.17493 (19)	0.5787 (6)	0.76574 (14)	0.0394 (6)
C11	−0.2697 (2)	0.7695 (5)	0.72713 (16)	0.0408 (7)
C12	−0.2778 (2)	0.8341 (5)	0.62295 (16)	0.0359 (7)
C13	−0.1920 (2)	0.7130 (5)	0.55900 (15)	0.0376 (7)
C14	−0.10045 (19)	0.5191 (5)	0.59983 (14)	0.0378 (7)
H2	0.26757	−0.16057	0.61359	0.0523*
H3	0.42111	−0.48034	0.68121	0.0586*
H5	0.26408	−0.45686	0.94987	0.0574*
H6	0.10958	−0.13313	0.88390	0.0540*
H7A	0.45868	−0.72613	0.94246	0.0901*
H7B	0.55083	−0.64872	0.85642	0.0901*
H7C	0.44563	−0.89053	0.83730	0.0901*
H8	0.01785	0.20723	0.81833	0.0475*
H11	−0.32689	0.85279	0.77004	0.0490*
H13	−0.19621	0.76212	0.48946	0.0452*
H14	−0.04426	0.43496	0.55632	0.0453*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Cl1	0.0692 (4)	0.0965 (7)	0.0371 (3)	0.0234 (4)	0.0140 (3)	0.0138 (3)
Cl2	0.0445 (3)	0.0449 (4)	0.0571 (3)	0.0089 (3)	−0.0002 (2)	0.0058 (3)
N1	0.0421 (9)	0.0365 (12)	0.0392 (8)	0.0048 (9)	0.0034 (7)	0.0005 (9)
C1	0.0374 (11)	0.0300 (13)	0.0394 (11)	0.0005 (9)	−0.0007 (8)	−0.0031 (9)
C2	0.0509 (13)	0.0423 (15)	0.0388 (11)	0.0090 (12)	0.0108 (10)	0.0015 (10)
C3	0.0487 (12)	0.0460 (15)	0.0524 (12)	0.0099 (14)	0.0083 (10)	−0.0053 (13)
C4	0.0413 (12)	0.0301 (15)	0.0529 (12)	−0.0007 (10)	−0.0063 (9)	−0.0033 (11)
C5	0.0565 (13)	0.0481 (17)	0.0373 (10)	0.0021 (13)	−0.0029 (9)	0.0031 (11)
C6	0.0497 (13)	0.0473 (15)	0.0384 (11)	0.0087 (12)	0.0062 (9)	−0.0025 (10)
C7	0.0529 (15)	0.0483 (17)	0.0748 (18)	0.0085 (13)	−0.0145 (12)	0.0017 (14)
C8	0.0419 (12)	0.0385 (14)	0.0380 (10)	0.0012 (10)	0.0026 (9)	0.0012 (10)
C9	0.0330 (10)	0.0335 (12)	0.0394 (10)	−0.0025 (10)	0.0016 (8)	−0.0012 (10)
C10	0.0415 (10)	0.0443 (14)	0.0328 (9)	−0.0009 (12)	0.0057 (8)	0.0030 (11)
C11	0.0399 (11)	0.0410 (15)	0.0424 (11)	0.0039 (10)	0.0089 (9)	−0.0022 (10)
C12	0.0352 (11)	0.0290 (12)	0.0426 (11)	−0.0022 (9)	−0.0004 (8)	0.0011 (9)
C13	0.0419 (12)	0.0360 (13)	0.0348 (10)	−0.0011 (10)	0.0027 (9)	−0.0014 (10)
C14	0.0370 (10)	0.0388 (15)	0.0378 (10)	0.0020 (10)	0.0055 (8)	−0.0060 (11)

Geometric parameters (Å, º) top

Cl1—C10	1.7454 (19)	C11—C12	1.382 (3)
Cl2—C12	1.736 (2)	C12—C13	1.384 (3)
N1—C1	1.415 (3)	C13—C14	1.374 (3)
N1—C8	1.260 (3)	C2—H2	0.9300
C1—C2	1.396 (3)	C3—H3	0.9300
C1—C6	1.391 (3)	C5—H5	0.9300
C2—C3	1.373 (3)	C6—H6	0.9300
C3—C4	1.389 (3)	C7—H7A	0.9600
C4—C5	1.372 (3)	C7—H7B	0.9600
C4—C7	1.509 (4)	C7—H7C	0.9600
C5—C6	1.386 (3)	C8—H8	0.9300
C8—C9	1.467 (3)	C11—H11	0.9300
C9—C10	1.398 (3)	C13—H13	0.9300
C9—C14	1.393 (3)	C14—H14	0.9300
C10—C11	1.376 (3)

Cl1···C6ⁱ	3.519 (2)	C1···H7C^viii	3.0800
Cl2···Cl2ⁱⁱ	3.5598 (8)	C2···H7C^viii	3.0000
Cl2···Cl2ⁱⁱⁱ	3.5598 (8)	C3···H7C^viii	2.9600
Cl1···H7B^iv	2.9500	C4···H7C^viii	3.0100
Cl1···H6ⁱ	2.9100	C5···H7C^viii	3.0900
Cl1···H8	2.6500	C6···H8	2.4900
Cl2···H2^v	3.1400	C8···H6	2.6300
N1···C14^vi	3.446 (3)	C13···H2^x	2.9000
N1···H14	2.6300	H2···Cl2^xi	3.1400
N1···H13^vii	2.8500	H2···C13^vii	2.9000
C1···C4^viii	3.552 (3)	H2···H13^vii	2.4800
C1···C8^vi	3.553 (3)	H5···H7A	2.3600
C1···C9^vi	3.405 (3)	H6···C8	2.6300
C4···C1^vi	3.552 (3)	H6···H8	2.0100
C5···C8^vi	3.465 (3)	H6···Cl1^ix	2.9100
C6···C9^vi	3.486 (3)	H7A···H5	2.3600
C6···C8^vi	3.323 (3)	H7B···Cl1^xii	2.9500
C6···Cl1^ix	3.519 (2)	H7C···C1^vi	3.0800
C8···C6^viii	3.323 (3)	H7C···C2^vi	3.0000
C8···C1^viii	3.553 (3)	H7C···C3^vi	2.9600
C8···C5^viii	3.465 (3)	H7C···C4^vi	3.0100
C8···C11^vi	3.573 (3)	H7C···C5^vi	3.0900
C9···C6^viii	3.486 (3)	H8···Cl1	2.6500
C9···C1^viii	3.405 (3)	H8···C6	2.4900
C9···C12^vi	3.569 (3)	H8···H6	2.0100
C11···C8^viii	3.573 (3)	H13···N1^x	2.8500
C12···C9^viii	3.569 (3)	H13···H2^x	2.4800
C14···N1^viii	3.446 (3)	H14···N1	2.6300

C1—N1—C8	119.23 (18)	C9—C14—C13	122.46 (19)
N1—C1—C2	117.33 (18)	C1—C2—H2	119.00
N1—C1—C6	125.67 (19)	C3—C2—H2	119.00
C2—C1—C6	117.0 (2)	C2—C3—H3	119.00
C1—C2—C3	121.5 (2)	C4—C3—H3	119.00
C2—C3—C4	121.4 (2)	C4—C5—H5	119.00
C3—C4—C5	117.3 (2)	C6—C5—H5	119.00
C3—C4—C7	121.4 (2)	C1—C6—H6	120.00
C5—C4—C7	121.3 (2)	C5—C6—H6	120.00
C4—C5—C6	122.0 (2)	C4—C7—H7A	109.00
C1—C6—C5	120.8 (2)	C4—C7—H7B	109.00
N1—C8—C9	123.32 (19)	C4—C7—H7C	109.00
C8—C9—C10	121.49 (18)	H7A—C7—H7B	110.00
C8—C9—C14	122.30 (19)	H7A—C7—H7C	110.00
C10—C9—C14	116.21 (19)	H7B—C7—H7C	109.00
Cl1—C10—C9	120.69 (17)	N1—C8—H8	118.00
Cl1—C10—C11	116.39 (16)	C9—C8—H8	118.00
C9—C10—C11	122.92 (18)	C10—C11—H11	121.00
C10—C11—C12	118.33 (19)	C12—C11—H11	121.00
Cl2—C12—C11	118.99 (16)	C12—C13—H13	121.00
Cl2—C12—C13	119.97 (16)	C14—C13—H13	120.00
C11—C12—C13	121.0 (2)	C9—C14—H14	119.00
C12—C13—C14	118.98 (18)	C13—C14—H14	119.00

C8—N1—C1—C2	−168.7 (2)	N1—C8—C9—C14	−5.9 (4)
C8—N1—C1—C6	13.7 (4)	C8—C9—C10—Cl1	1.5 (3)
C1—N1—C8—C9	−179.6 (2)	C8—C9—C10—C11	−178.5 (2)
N1—C1—C2—C3	−180.0 (2)	C14—C9—C10—Cl1	−178.14 (17)
C6—C1—C2—C3	−2.2 (3)	C14—C9—C10—C11	2.0 (3)
N1—C1—C6—C5	179.6 (2)	C8—C9—C14—C13	179.9 (2)
C2—C1—C6—C5	2.0 (3)	C10—C9—C14—C13	−0.6 (3)
C1—C2—C3—C4	0.2 (4)	Cl1—C10—C11—C12	178.75 (18)
C2—C3—C4—C5	1.9 (4)	C9—C10—C11—C12	−1.3 (4)
C2—C3—C4—C7	−179.8 (2)	C10—C11—C12—Cl2	179.26 (18)
C3—C4—C5—C6	−2.1 (4)	C10—C11—C12—C13	−0.7 (3)
C7—C4—C5—C6	179.6 (2)	Cl2—C12—C13—C14	−177.94 (17)
C4—C5—C6—C1	0.2 (4)	C11—C12—C13—C14	2.1 (3)
N1—C8—C9—C10	174.6 (2)	C12—C13—C14—C9	−1.4 (3)

Symmetry codes: (i) −x, y+1/2, −z+2; (ii) −x−1, y−1/2, −z+1; (iii) −x−1, y+1/2, −z+1; (iv) x−1, y+1, z; (v) −x, y+3/2, −z+1; (vi) x, y−1, z; (vii) −x, y−1/2, −z+1; (viii) x, y+1, z; (ix) −x, y−1/2, −z+2; (x) −x, y+1/2, −z+1; (xi) −x, y−3/2, −z+1; (xii) x+1, y−1, z.

Hydrogen-bond geometry (Å, º) top

Cg1 is the centroid of the C1–C6 phenyl ring.

D—H···A	D—H	H···A	D···A	D—H···A
C8—H8···Cl1	0.93	2.65	3.065 (2)	108
C7—H7C···Cg1^vi	0.96	2.71	3.565 (2)	148

Symmetry code: (vi) x, y−1, z.

Experimental details

Crystal data
Chemical formula	C₁₄H₁₁Cl₂N
M_r	264.14
Crystal system, space group	Monoclinic, P2₁
Temperature (K)	296
a, b, c (Å)	10.1069 (3), 4.7469 (2), 12.9922 (4)
β (°)	95.668 (2)
V (Å³)	620.27 (4)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	0.50
Crystal size (mm)	0.32 × 0.20 × 0.18

Data collection
Diffractometer	Bruker Kappa APEXII CCD diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2005)
T_min, T_max	0.886, 0.916
No. of measured, independent and observed [I > 2σ(I)] reflections	5221, 2082, 1937
R_int	0.022
(sin θ/λ)_max (Å⁻¹)	0.600

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.030, 0.079, 1.06
No. of reflections	2082
No. of parameters	155
No. of restraints	1
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.16, −0.15
Absolute structure	Flack (1983), 807 Friedel pairs
Absolute structure parameter	0.10 (7)

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

Hydrogen-bond geometry (Å, º) top

Cg1 is the centroid of the C1–C6 phenyl ring.

D—H···A	D—H	H···A	D···A	D—H···A
C8—H8···Cl1	0.93	2.65	3.065 (2)	108
C7—H7C···Cg1ⁱ	0.96	2.71	3.565 (2)	148

Symmetry code: (i) x, y−1, z.

Acknowledgements

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

References

Bernstein, J. (1972). J. Chem. Soc. Perkin Trans. 2, pp. 946–950. CrossRef Google Scholar
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
Flack, H. D. (1983). Acta Cryst. A39, 876–881. CrossRef CAS Web of Science IUCr Journals Google Scholar
Hayat, U., Siddiqui, W. A., Tahir, M. N. & Hussain, G. (2010). Acta Cryst. E66, o2523. Web of Science CSD 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