2-(4-Methoxy­phenyl­sulfin­yl)cyclo­hexan-1-one

Zukerman-Schpector, J.; Vinhato, E.; Cerqueira Jr, C.R.; Rodrigues, A.; Olivato, P.R.

doi:10.1107/S1600536809013695

organic compounds

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ISSN: 2056-9890

Volume 65| Part 5| May 2009| Page o1075

doi:10.1107/S1600536809013695

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2-(4-Methoxyphenylsulfinyl)cyclohexan-1-one

Julio Zukerman-Schpector,^a ^* Elisângela Vinhato,^b Carlos R. Cerqueira Jr,^b Alessandro Rodrigues ^b and Paulo R. Olivato ^b

^aUniversidade Federal de São Carlos, Laboratório de Cristalografia, Estereodinâmica e Modelagem Molecular, Departamento de Química, São Carlos, SP, Brazil, and ^bUniversidade de São Paulo, Conformational Analysis and Electronic Interactions Laboratory, Instituto de Química, São Paulo, SP, Brazil
^*Correspondence e-mail: julio@power.ufscar.br

(Received 8 April 2009; accepted 11 April 2009; online 18 April 2009)

The cyclohexanone ring in the title compound, C₁₃H₁₆O₃S, is in a distorted chair conformation. The intramolecular S⋯O_carbonyl distance is 2.814 (2) Å. Molecules are connected into a two-dimensional array via C—H⋯O contacts involving the carbonyl and sulfinyl O atoms.

Related literature

For related literature, see: Zukerman-Schpector, da Silva et al. (2006 ). For structure analysis, see: Cremer & Pople (1975 ); Iulek & Zukerman-Schpector (1997 ). For details of synthesis, see: Bradscher et al. (1954 ); Zukerman-Schpector, Maganhi et al. (2006 ); Drabowicz & Mikolajczyk (1978 ).

Experimental

Crystal data

C₁₃H₁₆O₃S
M_r = 252.33
Monoclinic, P 2₁ /c
a = 11.0510 (4) Å
b = 10.0875 (2) Å
c = 11.3672 (5) Å
β = 93.886 (2)°
V = 1264.27 (8) Å³
Z = 4
Mo Kα radiation
μ = 0.25 mm⁻¹
T = 290 K
0.15 × 0.10 × 0.10 mm

Data collection

Bruker APEXII CCD area-detector diffractometer
Absorption correction: none
8283 measured reflections
2872 independent reflections
2508 reflections with I > 2σ(I)
R_int = 0.024

Refinement

R[F² > 2σ(F²)] = 0.040
wR(F²) = 0.113
S = 1.06
2872 reflections
155 parameters
H-atom parameters constrained
Δρ_max = 0.19 e Å⁻³
Δρ_min = −0.23 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C1—H1⋯O2ⁱ	0.98	2.47	3.257 (2)	137
C3—H3A⋯O2ⁱ	0.97	2.59	3.323 (2)	133
C11—H11⋯O1ⁱⁱ	0.93	2.59	3.500 (2)	167
Symmetry codes: (i) $[x, -y+{\script{1\over 2}}, z+{\script{1\over 2}}]$ ; (ii) $[-x+1, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ .

Data collection: APEX2 (Bruker, 2006 ); cell refinement: SAINT (Bruker, 2006); data reduction: SAINT and SADABS (Bruker, 2006); program(s) used to solve structure: SIR97 (Altomare et al., 1999 ); 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 ), PARST (Nardelli, 1995 ) and MarvinSketch (ChemAxon, 2008 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809013695/tk2419sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536809013695/tk2419Isup2.hkl

checkCIF report

Comment top

The obtained product, which has stereogenic centres at S and C1, was a 3:1 mixture of the [C1(R)S(S)/C1(S)S(R)] and [C1(R)S(R)/C1(S)S(S)] diastereomeric sulfoxides, respectively, as determined from ¹H NMR spectroscopy. From hexane/ethanol fractional crystallization, the pure [C1(R)S(S)/C1(S)S(R)] diastereomer, (I), was obtained. The cyclohexanone ring is in a distorted chair conformation as shown by the ring-puckering parameters (Cremer & Pople, 1975; Iulek & Zukerman-Schpector, 1997) q₂ = 0.143 (2) Å, q₃ = 0.499 (2) Å, Q = 0.519 (2) Å, ϕ₂ = -130.9 (8)°. The methyl moiety is slightly out of the phenyl plane as shown by the C13-O3-C10-C11 torsion angle of 4.9 (2)°. The molecules are linked via intermolecular C—H···O interactions involving the carbonyl- and sulfinyl-oxygen atoms into a 2-D array (Table 1).

Related literature top

For related literature [please be more specific (the second reference is not cited at all in the rest of the CIF)], see: Zukerman-Schpector, Maganhi et al. (2006); Zukerman-Schpector, da Silva et al. (2006). For structure analysis, see: Cremer & Pople (1975); Iulek & Zukerman-Schpector (1997). For details of synthesis, see: Bradscher et al. (1954); Zukerman-Schpector, Maganhi et al. (2006); Drabowicz & Mikolajczyk (1978).

Experimental top

The starting 2-(4-methoxyphenylthio)cyclohexanone was prepared from the reaction of 2-chlorocyclohexanone and 4-methoxythiophenol as previously reported (Bradscher et al. 1954). The sulfoxide 2-[(4-methoxybenzene)sulfinyl]cyclohexanone was prepared by oxidation of 2-(4-methoxyphenylthio)cyclohexanone (Zukerman-Schpector, Maganhi et al. 2006; Drabowicz & Mikolajczyk, 1978). A CH₃OH (10 ml) solution of SeO₂ (1.23 g, 11.08 mmol) and hydrogen peroxide (30% H₂O₂ in aqueous solution; 1.25 ml, 11.08 mmol) was added drop-wise, at 273 K, to a solution of 2-(4-methoxyphenylthio)cyclohexanone (2.62 g, 11.08 mmol) in CH₃OH (5 ml). The reaction mixture was stirred at 273 K for 2 h and then at room temperature for 2 h. After completion of the reaction, a saturated aqueous NaCl solution (30 ml) was added, the aqueous layer was extracted with CH₂Cl₂ (3 x 20 ml) and dried over anhydrous Na₂SO₄. After solvent evaporation under reduced pressure, 1.39 g (5.5 mmol, yield 50%; m.p. 363–365 K) of the crude 2-[(4-methoxybenzene)sulfinyl]cyclohexanone (I) was obtained. Colourless crystals of (I) were obtained by vapour diffusion from n-hexane/acetone at 298 K.

Computing details top

Data collection: APEX2 (Bruker, 2006); cell refinement: SAINT (Bruker, 2006); data reduction: SAINT and SADABS (Bruker, 2006); program(s) used to solve structure: SIR97 (Altomare et al., 1999); 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), PARST (Nardelli, 1995) and MarvinSketch (ChemAxon, 2008).

Figures top

Fig. 1. The molecular structure of (I) showing atom labelling scheme and displacement ellipsoids at the 50% probability level (arbitrary spheres for the H atoms).

2-(4-Methoxyphenylsulfinyl)cyclohexan-1-one top

Crystal data top

C₁₃H₁₆O₃S	F(000) = 536
M_r = 252.33	D_x = 1.326 Mg m⁻³
Monoclinic, P2₁/c	Melting point = 363–364 K
Hall symbol: -P 2ybc	Mo Kα radiation, λ = 0.71073 Å
a = 11.0510 (4) Å	Cell parameters from 5749 reflections
b = 10.0875 (2) Å	θ = 1.0–27.5°
c = 11.3672 (5) Å	µ = 0.25 mm⁻¹
β = 93.886 (2)°	T = 290 K
V = 1264.27 (8) Å³	Irregular, colourless
Z = 4	0.15 × 0.10 × 0.10 mm

Data collection top

Bruker APEXII CCD area-detector diffractometer	2508 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.024
Graphite monochromator	θ_max = 27.5°, θ_min = 2.7°
ϕ and ω scans	h = −10→14
8283 measured reflections	k = −11→13
2872 independent reflections	l = −12→14

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)] = 0.040	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.113	H-atom parameters constrained
S = 1.06	w = 1/[σ²(F_o²) + (0.055P)² + 0.314P] where P = (F_o² + 2F_c²)/3
2872 reflections	(Δ/σ)_max < 0.001
155 parameters	Δρ_max = 0.19 e Å⁻³
0 restraints	Δρ_min = −0.23 e Å⁻³

Crystal data top

C₁₃H₁₆O₃S	V = 1264.27 (8) Å³
M_r = 252.33	Z = 4
Monoclinic, P2₁/c	Mo Kα radiation
a = 11.0510 (4) Å	µ = 0.25 mm⁻¹
b = 10.0875 (2) Å	T = 290 K
c = 11.3672 (5) Å	0.15 × 0.10 × 0.10 mm
β = 93.886 (2)°

Data collection top

Bruker APEXII CCD area-detector diffractometer	2508 reflections with I > 2σ(I)
8283 measured reflections	R_int = 0.024
2872 independent reflections

Refinement top

R[F² > 2σ(F²)] = 0.040	0 restraints
wR(F²) = 0.113	H-atom parameters constrained
S = 1.06	Δρ_max = 0.19 e Å⁻³
2872 reflections	Δρ_min = −0.23 e Å⁻³
155 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
S	0.56721 (4)	0.34807 (4)	0.33452 (3)	0.04990 (15)
O1	0.79251 (14)	0.37910 (14)	0.46227 (15)	0.0817 (4)
O2	0.62133 (13)	0.32131 (15)	0.22034 (11)	0.0697 (4)
O3	0.05306 (12)	0.18455 (16)	0.27603 (13)	0.0739 (4)
C1	0.63097 (13)	0.22233 (13)	0.43728 (12)	0.0417 (3)
H1	0.5837	0.2239	0.5072	0.050*
C2	0.75982 (15)	0.26614 (16)	0.47557 (14)	0.0527 (4)
C3	0.84104 (17)	0.16348 (19)	0.5352 (2)	0.0672 (5)
H3A	0.8218	0.1560	0.6169	0.081*
H3B	0.9245	0.1930	0.5343	0.081*
C4	0.82992 (16)	0.02795 (18)	0.47825 (18)	0.0634 (5)
H4A	0.8630	0.0307	0.4014	0.076*
H4B	0.8762	−0.0360	0.5265	0.076*
C5	0.69875 (16)	−0.01463 (16)	0.46473 (17)	0.0592 (4)
H5A	0.6662	−0.0191	0.5418	0.071*
H5B	0.6933	−0.1024	0.4299	0.071*
C6	0.62411 (16)	0.08211 (15)	0.38717 (15)	0.0546 (4)
H6A	0.5402	0.0532	0.3805	0.066*
H6B	0.6537	0.0823	0.3087	0.066*
C7	0.41425 (14)	0.29147 (14)	0.31844 (12)	0.0458 (3)
C8	0.32744 (16)	0.35031 (15)	0.38466 (14)	0.0536 (4)
H8	0.3502	0.4151	0.4400	0.064*
C9	0.20829 (17)	0.31257 (19)	0.36820 (16)	0.0599 (4)
H9	0.1504	0.3521	0.4124	0.072*
C10	0.17349 (15)	0.21533 (17)	0.28560 (14)	0.0547 (4)
C11	0.25949 (16)	0.15680 (16)	0.21873 (14)	0.0521 (4)
H11	0.2368	0.0918	0.1636	0.063*
C12	0.37932 (15)	0.19623 (15)	0.23499 (13)	0.0490 (3)
H12	0.4371	0.1585	0.1895	0.059*
C13	0.0152 (2)	0.0786 (3)	0.1988 (2)	0.0827 (6)
H13A	0.0360	0.0989	0.1202	0.124*
H13B	−0.0711	0.0674	0.1995	0.124*
H13C	0.0550	−0.0018	0.2249	0.124*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
S	0.0664 (3)	0.0368 (2)	0.0455 (2)	−0.00370 (15)	−0.00423 (17)	0.00762 (14)
O1	0.0843 (9)	0.0525 (7)	0.1038 (11)	−0.0195 (7)	−0.0274 (8)	0.0100 (7)
O2	0.0803 (9)	0.0861 (9)	0.0433 (6)	−0.0128 (7)	0.0071 (6)	0.0172 (6)
O3	0.0567 (7)	0.0870 (10)	0.0771 (9)	0.0022 (7)	−0.0026 (6)	0.0003 (7)
C1	0.0524 (8)	0.0375 (7)	0.0347 (6)	0.0003 (6)	−0.0003 (5)	0.0025 (5)
C2	0.0593 (9)	0.0462 (8)	0.0517 (8)	−0.0041 (7)	−0.0037 (7)	−0.0007 (7)
C3	0.0525 (9)	0.0611 (11)	0.0856 (13)	−0.0019 (8)	−0.0126 (9)	0.0083 (9)
C4	0.0613 (10)	0.0573 (10)	0.0726 (11)	0.0142 (8)	0.0112 (8)	0.0089 (9)
C5	0.0703 (11)	0.0389 (8)	0.0668 (10)	0.0034 (7)	−0.0073 (8)	0.0049 (7)
C6	0.0688 (10)	0.0370 (7)	0.0560 (9)	0.0013 (7)	−0.0107 (7)	0.0000 (7)
C7	0.0617 (9)	0.0356 (7)	0.0389 (7)	0.0043 (6)	−0.0052 (6)	0.0052 (5)
C8	0.0712 (11)	0.0419 (8)	0.0465 (8)	0.0104 (7)	−0.0038 (7)	−0.0032 (6)
C9	0.0674 (10)	0.0588 (10)	0.0535 (9)	0.0166 (8)	0.0038 (8)	−0.0002 (8)
C10	0.0581 (9)	0.0538 (9)	0.0511 (8)	0.0065 (7)	−0.0050 (7)	0.0094 (7)
C11	0.0645 (10)	0.0448 (8)	0.0455 (8)	0.0035 (7)	−0.0073 (7)	−0.0008 (6)
C12	0.0622 (9)	0.0426 (8)	0.0415 (7)	0.0066 (6)	−0.0013 (6)	−0.0006 (6)
C13	0.0746 (13)	0.0998 (17)	0.0715 (13)	−0.0175 (12)	−0.0124 (10)	0.0023 (12)

Geometric parameters (Å, º) top

S—O2	1.4900 (13)	C5—H5A	0.9700
S—C7	1.7819 (16)	C5—H5B	0.9700
S—C1	1.8325 (14)	C6—H6A	0.9700
O1—C2	1.208 (2)	C6—H6B	0.9700
O3—C10	1.364 (2)	C7—C12	1.386 (2)
O3—C13	1.428 (3)	C7—C8	1.392 (2)
C1—C6	1.525 (2)	C8—C9	1.371 (3)
C1—C2	1.526 (2)	C8—H8	0.9300
C1—H1	0.9800	C9—C10	1.394 (2)
C2—C3	1.501 (2)	C9—H9	0.9300
C3—C4	1.514 (3)	C10—C11	1.388 (2)
C3—H3A	0.9700	C11—C12	1.383 (2)
C3—H3B	0.9700	C11—H11	0.9300
C4—C5	1.510 (3)	C12—H12	0.9300
C4—H4A	0.9700	C13—H13A	0.9600
C4—H4B	0.9700	C13—H13B	0.9600
C5—C6	1.520 (2)	C13—H13C	0.9600

O2—S—C7	106.65 (7)	C5—C6—C1	111.56 (13)
O2—S—C1	105.67 (7)	C5—C6—H6A	109.3
C7—S—C1	99.48 (6)	C1—C6—H6A	109.3
C10—O3—C13	117.62 (16)	C5—C6—H6B	109.3
C6—C1—C2	113.39 (13)	C1—C6—H6B	109.3
C6—C1—S	113.37 (10)	H6A—C6—H6B	108.0
C2—C1—S	107.00 (10)	C12—C7—C8	119.70 (15)
C6—C1—H1	107.6	C12—C7—S	120.69 (12)
C2—C1—H1	107.6	C8—C7—S	119.45 (12)
S—C1—H1	107.6	C9—C8—C7	119.90 (15)
O1—C2—C3	122.17 (16)	C9—C8—H8	120.0
O1—C2—C1	121.24 (15)	C7—C8—H8	120.0
C3—C2—C1	116.53 (14)	C8—C9—C10	120.38 (16)
C2—C3—C4	113.65 (16)	C8—C9—H9	119.8
C2—C3—H3A	108.8	C10—C9—H9	119.8
C4—C3—H3A	108.8	O3—C10—C11	124.06 (16)
C2—C3—H3B	108.8	O3—C10—C9	115.92 (16)
C4—C3—H3B	108.8	C11—C10—C9	120.02 (16)
H3A—C3—H3B	107.7	C12—C11—C10	119.29 (15)
C5—C4—C3	110.49 (15)	C12—C11—H11	120.4
C5—C4—H4A	109.6	C10—C11—H11	120.4
C3—C4—H4A	109.6	C11—C12—C7	120.69 (15)
C5—C4—H4B	109.6	C11—C12—H12	119.7
C3—C4—H4B	109.6	C7—C12—H12	119.7
H4A—C4—H4B	108.1	O3—C13—H13A	109.5
C4—C5—C6	110.84 (14)	O3—C13—H13B	109.5
C4—C5—H5A	109.5	H13A—C13—H13B	109.5
C6—C5—H5A	109.5	O3—C13—H13C	109.5
C4—C5—H5B	109.5	H13A—C13—H13C	109.5
C6—C5—H5B	109.5	H13B—C13—H13C	109.5
H5A—C5—H5B	108.1

O2—S—C1—C6	−48.31 (13)	C1—S—C7—C12	−86.59 (13)
C7—S—C1—C6	62.09 (13)	O2—S—C7—C8	−152.43 (12)
O2—S—C1—C2	77.46 (11)	C1—S—C7—C8	97.95 (13)
C7—S—C1—C2	−172.14 (10)	C12—C7—C8—C9	0.9 (2)
C6—C1—C2—O1	143.42 (18)	S—C7—C8—C9	176.38 (12)
S—C1—C2—O1	17.7 (2)	C7—C8—C9—C10	0.1 (2)
C6—C1—C2—C3	−39.3 (2)	C13—O3—C10—C11	4.9 (2)
S—C1—C2—C3	−165.05 (14)	C13—O3—C10—C9	−175.42 (17)
O1—C2—C3—C4	−140.82 (19)	C8—C9—C10—O3	179.84 (15)
C1—C2—C3—C4	41.9 (2)	C8—C9—C10—C11	−0.5 (2)
C2—C3—C4—C5	−51.8 (2)	O3—C10—C11—C12	179.51 (15)
C3—C4—C5—C6	60.5 (2)	C9—C10—C11—C12	−0.1 (2)
C4—C5—C6—C1	−58.4 (2)	C10—C11—C12—C7	1.1 (2)
C2—C1—C6—C5	46.78 (19)	C8—C7—C12—C11	−1.5 (2)
S—C1—C6—C5	169.06 (12)	S—C7—C12—C11	−176.95 (11)
O2—S—C7—C12	23.03 (14)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C1—H1···O2ⁱ	0.98	2.47	3.257 (2)	137
C3—H3A···O2ⁱ	0.97	2.59	3.323 (2)	133
C11—H11···O1ⁱⁱ	0.93	2.59	3.500 (2)	167

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

Experimental details

Crystal data
Chemical formula	C₁₃H₁₆O₃S
M_r	252.33
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	290
a, b, c (Å)	11.0510 (4), 10.0875 (2), 11.3672 (5)
β (°)	93.886 (2)
V (Å³)	1264.27 (8)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.25
Crystal size (mm)	0.15 × 0.10 × 0.10

Data collection
Diffractometer	Bruker APEXII CCD area-detector diffractometer
Absorption correction	–
No. of measured, independent and observed [I > 2σ(I)] reflections	8283, 2872, 2508
R_int	0.024
(sin θ/λ)_max (Å⁻¹)	0.650

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.040, 0.113, 1.06
No. of reflections	2872
No. of parameters	155
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.19, −0.23

Computer programs: APEX2 (Bruker, 2006), SAINT (Bruker, 2006), SAINT and SADABS (Bruker, 2006), SIR97 (Altomare et al., 1999), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 1997), WinGX (Farrugia, 1999), PARST (Nardelli, 1995) and MarvinSketch (ChemAxon, 2008).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C1—H1···O2ⁱ	0.98	2.47	3.257 (2)	137
C3—H3A···O2ⁱ	0.97	2.59	3.323 (2)	133
C11—H11···O1ⁱⁱ	0.93	2.59	3.500 (2)	167

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

Acknowledgements

We thank FAPESP (grant No. 2008/02531-5 to JZ-S), CNPq and CAPES for financial support. Professor R. A. Burrow of the Federal University of Santa Maria is gratefully acknowledged for helping with the collection of intensity data.

References

Altomare, A., Burla, M. C., Camalli, M., Cascarano, G. L., Giacovazzo, C., Guagliardi, A., Moliterni, A. G. G., Polidori, G. & Spagna, R. (1999). J. Appl. Cryst. 32, 115–119. Web of Science CrossRef CAS IUCr Journals Google Scholar
Bradscher, C. K., Brown, F. C. & Grantham, R. J. (1954). J. Am. Chem. Soc. 76, 114–115. Google Scholar
Bruker (2006). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
ChemAxon (2008). MarvinSketch. http://www.chemaxon.com . Google Scholar
Cremer, D. & Pople, J. A. (1975). J. Am. Chem. Soc. 97, 1354–1358. CrossRef CAS Web of Science Google Scholar
Drabowicz, J. & Mikolajczyk, M. (1978). Synthesis, 10, 758–759. CrossRef Web of Science 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
Iulek, J. & Zukerman-Schpector, J. (1997). Quim. Nova, 20, 433–434. CrossRef CAS Web of Science Google Scholar
Nardelli, M. (1995). J. Appl. Cryst. 28, 659. CrossRef IUCr Journals Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Zukerman-Schpector, J., da Silva, R. O., Olivato, P. R., Vinhato, E., Rodrigues, A. & Cerqueira, C. R. Jr (2006). Z. Kristallogr. New Cryst. Struct. 221, 311–312. CAS Google Scholar
Zukerman-Schpector, J., Maganhi, S., Olivato, P. R., Vinhato, E. & Cerqueira, C. R. Jr (2006). Z. Kristallogr. New Cryst. Struct. 221, 165–166. CAS Google Scholar