2,5-Dimethyl-1-phenyl­sulfonyl-1H-pyrrole-3,4-dicarbaldehyde

Seshadri, P.R.; Balakrishnan, B.; Ilangovan, K.; Sureshbabu, R.; Mohanakrishnan, A.K.

doi:10.1107/S1600536809004425

organic compounds

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 65| Part 3| March 2009| Page o531

doi:10.1107/S1600536809004425

Open

access

2,5-Dimethyl-1-phenylsulfonyl-1H-pyrrole-3,4-dicarbaldehyde

P. R. Seshadri,^a ^* B. Balakrishnan,^b K. Ilangovan,^c R. Sureshbabu ^d and A. K. Mohanakrishnan ^d

^aPostgraduate and Research Department of Physics, Agurchand Manmull Jain College, Chennai 600 114, India, ^bDepartment of Physics, P. T. Lee Chengalvaraya Naicker College of Engineering and Technology, Kancheepuram 631 502, India, ^cPostgraduate and Research Department of Physics, RKM Vivekananda College, Chennai 600 004, India, and ^dDepartment of Organic Chemistry, University of Madras, Guindy Campus, Chennai 600 025, India
^*Correspondence e-mail: seshadri_pr@yahoo.com

(Received 20 January 2009; accepted 6 February 2009; online 18 February 2009)

In the title compound, C₁₄H₁₃NO₄S, the mean planes of the pyrrole and phenyl rings form a dihedral angle of 88.7 (1)°. The aldehyde groups are slightly twisted from the pyrrole plane. In the crystal structure, molecules are linked into a three-dimensional framework by C—H⋯O hydrogen bonds.

Related literature

For general background, see: Ali et al. (1989 ); Amal Raj et al. (2003 ). For bond-length data, see: Allen et al. (1987 ). For N-atom hybridization details, see: Beddoes et al. (1986 ).

Experimental

Crystal data

C₁₄H₁₃NO₄S
M_r = 291.31
Monoclinic, P 2₁ /n
a = 9.0257 (3) Å
b = 12.6240 (5) Å
c = 11.9914 (5) Å
β = 97.700 (2)°
V = 1353.99 (9) Å³
Z = 4
Mo Kα radiation
μ = 0.25 mm⁻¹
T = 293 K
0.25 × 0.20 × 0.20 mm

Data collection

Bruker Kappa APEXII area-detector diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 2001 ) T_min = 0.940, T_max = 0.952
19609 measured reflections
4736 independent reflections
3164 reflections with I > 2σ(I)
R_int = 0.032

Refinement

R[F² > 2σ(F²)] = 0.048
wR(F²) = 0.154
S = 1.00
4736 reflections
183 parameters
H-atom parameters constrained
Δρ_max = 0.19 e Å⁻³
Δρ_min = −0.42 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C6—H6⋯O3	0.93	2.46	3.077 (2)	124
C7—H7A⋯O4	0.96	2.33	3.021 (3)	128
C11—H11⋯O4ⁱ	0.93	2.53	3.456 (2)	174
C13—H13⋯O2	0.93	2.52	3.304 (2)	143
C14—H14⋯O3ⁱⁱ	0.93	2.57	3.383 (2)	146
Symmetry codes: (i) x, y, z-1; (ii) -x+1, -y+1, -z+1.

Data collection: APEX2 (Bruker, 2004 ); cell refinement: SAINT (Bruker, 2004); 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 (Farrugia, 1997 ) and PLATON (Spek, 2009 ); software used to prepare material for publication: PARST (Nardelli, 1995 ).

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809004425/wn2307sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536809004425/wn2307Isup2.hkl

checkCIF report

Comment top

Heterocyclic compounds, especially five-membered rings, have occupied an important place among organic compounds because of their biological activities. The fungicidal activity of novel heterocycles has been reported by Ali et al. (1989). These are crucial intermediates for various pyrrole natural products possessing antitumour properties. They are found to have antifungal activity against various pathogens (Amal Raj et al., 2003). Against this background and in order to obtain detailed information on molecular conformation in the solid state, an X-ray crystallographic study of the title compound has been carried out and the results are presented here.

The geometric parameters are normal (Allen et al., 1987). The mean planes of the pyrrole and phenyl rings form a dihedral angle of 88.7 (1)°. The aldehyde groups are slightly twisted from the pyrrole plane, with O3 towards C2 and O4 towards C1, as evidenced by the torsion angles C2—C3—C5—O3 = 2.1 (3)° and C1—C2—C6—O4 = 5.9 (3)° (Fig. 1). The sum of the angles at N is 360.0, which is an indication of sp² hybridization (Beddoes et al., 1986). In the crystal structure, the molecules are linked into a three-dimensional framework by C—H···O hydrogen bonds (Fig. 2 and Table 1).

Related literature top

For general background, see: Ali et al. (1989); Amal Raj et al. (2003). For bond-length data, see: Allen et al. (1987). For N-atom hybridization details, see: Beddoes et al. (1986). [Please check amended text]

Experimental top

To a suspension of 3°-butoxide (4.4 g, 39.7 mmol) in dry THF (20 ml), 18-crown-6 (catalyst) and 2,5-dimethyl-1H-pyrrole-3,4-dicarbaldehyde (4 g, 26.5 mmol) in dry THF were added slowly at room temperature and the reaction mixture was stirred for 15 min. To this, PhSO₂Cl (6.1 g, 34.4 mmol) in dry THF (15 ml) was added and stirred for another 4 h. The mixture was then poured over ice–water (500 ml) and the solid obtained was filtered. The product, 2,5-dimethyl-1-(phenyl sulfonyl)-1H-pyrrole-3,4-dicarbaldehyde, was recrystallized from methanol. Yield 4.9 g (64%). M.p = 395 K.

Computing details top

Data collection: APEXII (Bruker, 2004); cell refinement: SAINT (Bruker, 2004); data reduction: SAINT (Bruker, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997) and PLATON (Spek, 2009); software used to prepare material for publication: PARST (Nardelli, 1995).

Figures top

	Fig. 1. Molecular structure of the title compound showing 30% probability displacement ellipsoids. Hydrogen atoms are represented by spheres of arbitrary radius.
	Fig. 2. Crystal packing of the title compound. Hydrogen bonds are shown as dashed lines.

2,5-Dimethyl-1-phenylsulfonyl-1H-pyrrole-3,4-dicarbaldehyde top

Crystal data top

C₁₄H₁₃NO₄S	F(000) = 608
M_r = 291.31	D_x = 1.429 Mg m⁻³
Monoclinic, P2₁/n	Mo Kα radiation, λ = 0.71073 Å
a = 9.0257 (3) Å	Cell parameters from 6814 reflections
b = 12.6240 (5) Å	θ = 2.4–32.2°
c = 11.9914 (5) Å	µ = 0.25 mm⁻¹
β = 97.700 (2)°	T = 293 K
V = 1353.99 (9) Å³	Block, colourless
Z = 4	0.25 × 0.20 × 0.20 mm

Data collection top

Bruker Kappa-APEXII area-detector diffractometer	4736 independent reflections
Radiation source: fine-focus sealed tube	3164 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.032
ω scans	θ_max = 32.2°, θ_min = 2.4°
Absorption correction: multi-scan (SADABS; Sheldrick, 2001)	h = −13→10
T_min = 0.940, T_max = 0.952	k = −18→18
19609 measured reflections	l = −16→17

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)] = 0.048	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.154	H-atom parameters constrained
S = 1.00	w = 1/[σ²(F_o²) + (0.0787P)² + 0.2246P] where P = (F_o² + 2F_c²)/3
4736 reflections	(Δ/σ)_max < 0.001
183 parameters	Δρ_max = 0.19 e Å⁻³
0 restraints	Δρ_min = −0.42 e Å⁻³

Crystal data top

C₁₄H₁₃NO₄S	V = 1353.99 (9) Å³
M_r = 291.31	Z = 4
Monoclinic, P2₁/n	Mo Kα radiation
a = 9.0257 (3) Å	µ = 0.25 mm⁻¹
b = 12.6240 (5) Å	T = 293 K
c = 11.9914 (5) Å	0.25 × 0.20 × 0.20 mm
β = 97.700 (2)°

Data collection top

Bruker Kappa-APEXII area-detector diffractometer	4736 independent reflections
Absorption correction: multi-scan (SADABS; Sheldrick, 2001)	3164 reflections with I > 2σ(I)
T_min = 0.940, T_max = 0.952	R_int = 0.032
19609 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.048	0 restraints
wR(F²) = 0.154	H-atom parameters constrained
S = 1.00	Δρ_max = 0.19 e Å⁻³
4736 reflections	Δρ_min = −0.42 e Å⁻³
183 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
S1	0.51190 (5)	0.21083 (3)	0.25629 (3)	0.05026 (14)
N	0.56878 (14)	0.29263 (9)	0.36572 (10)	0.0417 (3)
O1	0.64275 (15)	0.17150 (11)	0.21659 (11)	0.0704 (4)
O3	0.82639 (16)	0.54763 (12)	0.58440 (12)	0.0777 (4)
O2	0.40939 (17)	0.13956 (10)	0.29555 (12)	0.0743 (4)
O4	0.49857 (19)	0.36086 (17)	0.70677 (12)	0.1023 (6)
C1	0.51247 (15)	0.29778 (11)	0.46937 (11)	0.0422 (3)
C2	0.59280 (15)	0.37280 (11)	0.53213 (11)	0.0404 (3)
C3	0.69918 (14)	0.41747 (11)	0.46621 (11)	0.0383 (3)
C4	0.68371 (15)	0.36717 (11)	0.36473 (11)	0.0412 (3)
C5	0.80621 (18)	0.50177 (13)	0.49571 (14)	0.0524 (4)
H5	0.8646	0.5223	0.4412	0.063*
C6	0.57651 (19)	0.40278 (16)	0.64774 (13)	0.0579 (4)
H6	0.6327	0.4602	0.6779	0.069*
C7	0.3863 (2)	0.23246 (17)	0.50008 (16)	0.0661 (5)
H7A	0.3587	0.2571	0.5702	0.099*
H7B	0.4168	0.1597	0.5075	0.099*
H7C	0.3022	0.2386	0.4423	0.099*
C8	0.7684 (2)	0.38292 (17)	0.26769 (14)	0.0662 (5)
H8A	0.8349	0.4421	0.2825	0.099*
H8B	0.6997	0.3965	0.2009	0.099*
H8C	0.8253	0.3203	0.2571	0.099*
C9	0.41822 (17)	0.29562 (12)	0.15557 (12)	0.0455 (3)
C10	0.4612 (2)	0.29939 (16)	0.04944 (14)	0.0604 (4)
H10	0.5403	0.2583	0.0315	0.072*
C11	0.3837 (3)	0.3659 (2)	−0.02973 (16)	0.0767 (6)
H11	0.4104	0.3696	−0.1019	0.092*
C12	0.2683 (3)	0.42608 (17)	−0.00229 (17)	0.0780 (6)
H12	0.2176	0.4707	−0.0561	0.094*
C13	0.2260 (3)	0.42188 (16)	0.10310 (18)	0.0744 (6)
H13	0.1476	0.4638	0.1207	0.089*
C14	0.3000 (2)	0.35534 (13)	0.18281 (14)	0.0579 (4)
H14	0.2708	0.3507	0.2541	0.069*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
S1	0.0664 (3)	0.0385 (2)	0.0462 (2)	−0.00334 (15)	0.00855 (17)	−0.00739 (14)
N	0.0513 (6)	0.0408 (6)	0.0347 (5)	−0.0058 (5)	0.0120 (5)	−0.0013 (4)
O1	0.0800 (8)	0.0655 (8)	0.0655 (8)	0.0209 (7)	0.0084 (6)	−0.0213 (6)
O3	0.0858 (9)	0.0823 (10)	0.0652 (8)	−0.0240 (7)	0.0105 (7)	−0.0272 (7)
O2	0.1039 (10)	0.0500 (7)	0.0681 (8)	−0.0305 (7)	0.0080 (7)	0.0000 (6)
O4	0.1016 (12)	0.1637 (17)	0.0496 (8)	−0.0353 (11)	0.0398 (8)	−0.0136 (9)
C1	0.0459 (7)	0.0463 (7)	0.0362 (6)	−0.0003 (5)	0.0121 (5)	0.0061 (5)
C2	0.0429 (6)	0.0467 (7)	0.0333 (6)	0.0049 (5)	0.0115 (5)	0.0032 (5)
C3	0.0418 (6)	0.0389 (7)	0.0347 (6)	0.0024 (5)	0.0074 (5)	0.0024 (5)
C4	0.0465 (7)	0.0430 (7)	0.0358 (6)	−0.0019 (5)	0.0123 (5)	0.0015 (5)
C5	0.0560 (8)	0.0535 (9)	0.0480 (8)	−0.0081 (7)	0.0078 (6)	−0.0012 (7)
C6	0.0595 (9)	0.0796 (12)	0.0366 (7)	0.0025 (8)	0.0143 (6)	−0.0055 (7)
C7	0.0662 (10)	0.0772 (12)	0.0595 (10)	−0.0208 (9)	0.0248 (8)	0.0053 (9)
C8	0.0784 (12)	0.0817 (13)	0.0445 (9)	−0.0255 (10)	0.0295 (8)	−0.0068 (8)
C9	0.0551 (8)	0.0435 (7)	0.0379 (7)	−0.0089 (6)	0.0067 (6)	−0.0098 (5)
C10	0.0643 (10)	0.0774 (12)	0.0411 (8)	−0.0095 (8)	0.0134 (7)	−0.0091 (8)
C11	0.0942 (15)	0.0952 (16)	0.0402 (9)	−0.0202 (12)	0.0072 (9)	0.0005 (9)
C12	0.1054 (16)	0.0665 (12)	0.0567 (11)	−0.0007 (11)	−0.0086 (11)	0.0022 (9)
C13	0.0900 (14)	0.0586 (11)	0.0710 (12)	0.0162 (10)	−0.0029 (10)	−0.0134 (9)
C14	0.0742 (11)	0.0527 (9)	0.0472 (9)	0.0036 (8)	0.0099 (8)	−0.0136 (7)

Geometric parameters (Å, º) top

S1—O2	1.4155 (13)	C7—H7A	0.9600
S1—O1	1.4209 (13)	C7—H7B	0.9600
S1—N	1.6945 (12)	C7—H7C	0.9600
S1—C9	1.7452 (17)	C8—H8A	0.9600
N—C4	1.4018 (17)	C8—H8B	0.9600
N—C1	1.4060 (17)	C8—H8C	0.9600
O3—C5	1.203 (2)	C9—C10	1.380 (2)
O4—C6	1.187 (2)	C9—C14	1.381 (2)
C1—C2	1.358 (2)	C10—C11	1.385 (3)
C1—C7	1.492 (2)	C10—H10	0.9300
C2—C3	1.4382 (18)	C11—C12	1.364 (3)
C2—C6	1.463 (2)	C11—H11	0.9300
C3—C4	1.3631 (19)	C12—C13	1.370 (3)
C3—C5	1.449 (2)	C12—H12	0.9300
C4—C8	1.4890 (19)	C13—C14	1.376 (3)
C5—H5	0.9300	C13—H13	0.9300
C6—H6	0.9300	C14—H14	0.9300

O2—S1—O1	119.94 (9)	H7A—C7—H7B	109.5
O2—S1—N	105.88 (7)	C1—C7—H7C	109.5
O1—S1—N	107.05 (7)	H7A—C7—H7C	109.5
O2—S1—C9	110.02 (8)	H7B—C7—H7C	109.5
O1—S1—C9	109.26 (8)	C4—C8—H8A	109.5
N—S1—C9	103.33 (7)	C4—C8—H8B	109.5
C4—N—C1	109.39 (11)	H8A—C8—H8B	109.5
C4—N—S1	123.39 (9)	C4—C8—H8C	109.5
C1—N—S1	127.22 (10)	H8A—C8—H8C	109.5
C2—C1—N	107.03 (11)	H8B—C8—H8C	109.5
C2—C1—C7	128.14 (13)	C10—C9—C14	121.40 (16)
N—C1—C7	124.83 (14)	C10—C9—S1	119.29 (14)
C1—C2—C3	108.37 (12)	C14—C9—S1	119.29 (12)
C1—C2—C6	126.27 (13)	C9—C10—C11	118.31 (18)
C3—C2—C6	125.35 (14)	C9—C10—H10	120.8
C4—C3—C2	108.18 (12)	C11—C10—H10	120.8
C4—C3—C5	123.06 (13)	C12—C11—C10	120.27 (18)
C2—C3—C5	128.76 (13)	C12—C11—H11	119.9
C3—C4—N	107.02 (11)	C10—C11—H11	119.9
C3—C4—C8	129.31 (14)	C11—C12—C13	121.2 (2)
N—C4—C8	123.67 (13)	C11—C12—H12	119.4
O3—C5—C3	125.90 (15)	C13—C12—H12	119.4
O3—C5—H5	117.1	C12—C13—C14	119.66 (19)
C3—C5—H5	117.1	C12—C13—H13	120.2
O4—C6—C2	126.33 (18)	C14—C13—H13	120.2
O4—C6—H6	116.8	C13—C14—C9	119.18 (16)
C2—C6—H6	116.8	C13—C14—H14	120.4
C1—C7—H7A	109.5	C9—C14—H14	120.4
C1—C7—H7B	109.5

O2—S1—N—C4	172.55 (12)	C1—N—C4—C3	0.29 (16)
O1—S1—N—C4	43.51 (14)	S1—N—C4—C3	−179.53 (10)
C9—S1—N—C4	−71.78 (13)	C1—N—C4—C8	179.88 (15)
O2—S1—N—C1	−7.23 (15)	S1—N—C4—C8	0.1 (2)
O1—S1—N—C1	−136.28 (13)	C4—C3—C5—O3	−178.68 (17)
C9—S1—N—C1	108.43 (13)	C2—C3—C5—O3	2.1 (3)
C4—N—C1—C2	−1.03 (16)	C1—C2—C6—O4	5.9 (3)
S1—N—C1—C2	178.78 (10)	C3—C2—C6—O4	−173.12 (19)
C4—N—C1—C7	178.16 (15)	O2—S1—C9—C10	−122.33 (14)
S1—N—C1—C7	−2.0 (2)	O1—S1—C9—C10	11.30 (15)
N—C1—C2—C3	1.33 (16)	N—S1—C9—C10	125.00 (13)
C7—C1—C2—C3	−177.83 (16)	O2—S1—C9—C14	55.92 (14)
N—C1—C2—C6	−177.86 (14)	O1—S1—C9—C14	−170.46 (12)
C7—C1—C2—C6	3.0 (3)	N—S1—C9—C14	−56.75 (13)
C1—C2—C3—C4	−1.18 (16)	C14—C9—C10—C11	0.7 (3)
C6—C2—C3—C4	178.02 (14)	S1—C9—C10—C11	178.93 (14)
C1—C2—C3—C5	178.14 (14)	C9—C10—C11—C12	0.3 (3)
C6—C2—C3—C5	−2.7 (2)	C10—C11—C12—C13	−0.4 (3)
C2—C3—C4—N	0.53 (15)	C11—C12—C13—C14	−0.5 (3)
C5—C3—C4—N	−178.84 (13)	C12—C13—C14—C9	1.4 (3)
C2—C3—C4—C8	−179.04 (17)	C10—C9—C14—C13	−1.6 (2)
C5—C3—C4—C8	1.6 (3)	S1—C9—C14—C13	−179.77 (14)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C6—H6···O3	0.93	2.46	3.077 (2)	124
C7—H7A···O4	0.96	2.33	3.021 (3)	128
C11—H11···O4ⁱ	0.93	2.53	3.456 (2)	174
C13—H13···O2	0.93	2.52	3.304 (2)	143
C14—H14···O3ⁱⁱ	0.93	2.57	3.383 (2)	146

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

Experimental details

Crystal data
Chemical formula	C₁₄H₁₃NO₄S
M_r	291.31
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	293
a, b, c (Å)	9.0257 (3), 12.6240 (5), 11.9914 (5)
β (°)	97.700 (2)
V (Å³)	1353.99 (9)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.25
Crystal size (mm)	0.25 × 0.20 × 0.20

Data collection
Diffractometer	Bruker Kappa-APEXII area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Sheldrick, 2001)
T_min, T_max	0.940, 0.952
No. of measured, independent and observed [I > 2σ(I)] reflections	19609, 4736, 3164
R_int	0.032
(sin θ/λ)_max (Å⁻¹)	0.750

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.048, 0.154, 1.00
No. of reflections	4736
No. of parameters	183
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.19, −0.42

Computer programs: APEXII (Bruker, 2004), SAINT (Bruker, 2004), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 (Farrugia, 1997) and PLATON (Spek, 2009), PARST (Nardelli, 1995).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C6—H6···O3	0.93	2.46	3.077 (2)	124.0
C7—H7A···O4	0.96	2.33	3.021 (3)	128.0
C11—H11···O4ⁱ	0.93	2.53	3.456 (2)	174.0
C13—H13···O2	0.93	2.52	3.304 (2)	143.0
C14—H14···O3ⁱⁱ	0.93	2.57	3.383 (2)	146.0

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

Acknowledgements

BB and RS thank Dr Babu Varghese, SAIF, IIT Madras, India, for his help with the data collection.

References

Ali, R., Misra, B. & Nizamuddin (1989). Indian J. Chem. Sect. B, 28, 526–528. Google Scholar
Allen, F. H., Kennard, O., Watson, D. G., Brammer, L., Orpen, A. G. & Taylor, R. (1987). J. Chem. Soc. Perkin Trans. 2, pp. S1–19. CrossRef Web of Science Google Scholar
Amal Raj, A., Raghunathan, R., Sridevikumari, M. R. & Raman, N. (2003). Bioorg. Med. Chem. 11, 407–419. Web of Science PubMed Google Scholar
Beddoes, R. L., Dalton, L., Joule, J. A., Mills, O. S., Street, J. O. & Watt, C. I. F. (1986). J. Chem. Soc. Perkin Trans. 2, pp. 787–797. CSD CrossRef Google Scholar
Bruker (2004). 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
Nardelli, M. (1995). J. Appl. Cryst. 28, 659. CrossRef IUCr Journals Google Scholar
Sheldrick, G. M. (2001). 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
Spek, A. L. (2009). Acta Cryst. D65, 148–155. Web of Science CrossRef CAS IUCr Journals Google Scholar