Dodeca­allyl­hexa­sila­cyclo­hexa­ne

Mizuhata, Y.; Omatsu, Y.; Tokitoh, N.

doi:10.1107/S2414314617008070

organic compounds

IUCrDATA

ISSN: 2414-3146

Volume 2| Part 6| June 2017| x170807

https://doi.org/10.1107/S2414314617008070

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Dodecaallylhexasilacyclohexane

Yoshiyuki Mizuhata,^a Yamato Omatsu ^a and Norihiro Tokitoh ^a ^*

^aInstitute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan
^*Correspondence e-mail: tokitoh@boc.kuicr.kyoto-u.ac.jp

Edited by M. Weil, Vienna University of Technology, Austria (Received 22 May 2017; accepted 31 May 2017; online 2 June 2017)

The molecule of the title compound, C₃₆H₆₀Si₆, exhibits point group symmetry C_i, with the centre of inversion located at the centre of the Si₆ ring. The Si₆ ring has a chair conformation. In the crystal, molecules are linked via C—H⋯π(allyl) interactions.

Keywords: crystal structure; cyclic oligosilane; chair conformation.

CCDC reference: 1553273

Structure description

Hexasilacyclohexane derivatives, i.e. six-membered cyclic oligosilanes, are of interest from the viewpoint of their unique structures and properties. However, it is challenging to prepare such cyclic oligosilanes because of synthetic difficulties, low yields and long purification times. While a number of crystal structures for hexasilacyclohexane derivatives have been reported, those for derivatives with twelve identical carbon subsitituents are limited to dodecamethyl (Carrell & Donohue, 1972 ) and dodecaphenyl (M'hirsi & Brini, 1968 ; Dräger & Walter, 1981 ) as well as to a hexa(1,1-silole) derivative (Yamaguchi et al., 1999 ). Herein, we describe the synthesis and structural characterization of dodecaallylhexasilacyclohexane by utilizing an effective synthesis method, viz. the reaction of [pedeta·SiH₂Cl]₂Si₆Cl₁₄ (pedeta = N,N,N′,N′,N′′-pentaethyldiethylenetriamine; Choi et al., 2001 ) with allylmagnesium bromide.

The crystal structure comprises one molecule of the title compound per unit cell (Fig. 1). The molecule exhibits point group symmetry C_i, with the centre of inversion at the centre of the Si₆ ring. The latter has a chair conformation with typical bond lengths in the range of 2.3500 (6)–2.3598 (5) Å. The average value of the Si—Si bond lengths (2.354 Å) lies between those for the dodecamethyl (2.338 Å) and dodecaphenyl derivatives (2.394 Å). The Si—Si—Si angles are almost the same and range from 110.35 (2)–110.46 (2)°; the average Si—Si—Si angle (110.4°) is smaller than that of Si₆Me₁₂ (111.9°) and of Si₆Ph₁₂ (113.8°). In the crystal structure, molecules are linked by several C—H⋯π(allyl) interactions into a three-dimensional network (Table 1, Fig. 2).

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C2ⁱ—H2ⁱ⋯C11	0.95	2.84	3.622 (3)	140
C7—H7A⋯C8ⁱⁱ	0.99	2.82	3.669 (2)	145
C6—H6A⋯C15ⁱⁱ	0.95	2.88	3.678 (4)	142
C16ⁱⁱⁱ—H16ⁱⁱⁱ⋯C12	0.99	2.75	3.684 (3)	159
Symmetry codes: (i) x-1, y, z; (ii) -x+1, -y+2, -z+1; (iii) -x, -y+1, -z+1.

Figure 1
The molecular structure of the title compound, showing displacement ellipsoids at the 50% probability level. H atoms have been omitted for clarity. Unlabelled atoms are related by labelled atoms by the symmetry code (−x + 1, −y + 1, −z + 1).

Figure 2
Parts of the crystal packing of the title compound, emphasizing intermolecular C—H⋯π(allyl) interactions (light-blue dotted lines). [Symmetry codes: (i) x − 1, y, z; (ii) −x + 1, −y + 2, −z + 1; (iii) −x, −y + 1, −z + 1.]

Synthesis and crystallization

To a THF solution of [pedeta·SiH₂Cl]₂Si₆Cl₁₄ (1.20 g, 0.936 mmol) was slowly added a 1.0 M solution of allylmagnesium bromide in diethyl ether (15 ml, 15 mmol) at 293 K. After stirring for 48 h at 363 K, the mixture was treated with a saturated aqueous NH₄Cl solution and extracted with diethyl ether. The combined organic layer was dried over Na₂SO₄ and concentrated under vacuum. The crude material was then purified by column chromatography on silica gel (eluting with hexane) to give the title compound (275 mg, 0.416 mmol, 44%). Single crystals were obtained by recrystallization from a hexane solution.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2.

Table 2
Experimental details

Crystal data
Chemical formula	C₃₆H₆₀Si₆
M_r	661.38
Crystal system, space group	Triclinic, P $[\overline{1}]$
Temperature (K)	103
a, b, c (Å)	9.6036 (2), 10.8060 (3), 11.4686 (3)
α, β, γ (°)	108.617 (2), 100.558 (2), 109.4774 (12)
V (Å³)	1005.90 (5)
Z	1
Radiation type	Mo Kα
μ (mm⁻¹)	0.23
Crystal size (mm)	0.25 × 0.20 × 0.20

Data collection
Diffractometer	Rigaku Saturn
Absorption correction	Multi-scan (MULABS; Blessing, 1995 )
T_min, T_max	0.902, 0.953
No. of measured, independent and observed [I > 2σ(I)] reflections	13675, 3630, 3398
R_int	0.035
(sin θ/λ)_max (Å⁻¹)	0.600

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.032, 0.089, 1.04
No. of reflections	3630
No. of parameters	190
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.45, −0.18
Computer programs: CrystalClear (Rigaku, 1999 ), HKL-2000 (Otwinowski & Minor, 1997 ), SHELXT (Sheldrick, 2015a ), SHELXL2016 (Sheldrick, 2015b ), Yadokari-XG (Wakita, 2001 ; Kabuto et al., 2009 ), Mercury (Macrae et al., 2008 ), CrystalMaker (Palmer, 2007 ) and publCIF (Westrip, 2010 ).

Structural data

CCDC reference: 1553273

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S2414314617008070/wm4048sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314617008070/wm4048Isup2.hkl

Supporting information file. DOI: https://doi.org/10.1107/S2414314617008070/wm4048Isup3.cdx

Supporting information file. DOI: https://doi.org/10.1107/S2414314617008070/wm4048Isup4.cml

checkCIF report

Computing details top

Data collection: CrystalClear (Rigaku, 1999); cell refinement: HKL-2000 (Otwinowski & Minor, 1997); data reduction: HKL-2000 (Otwinowski & Minor, 1997); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2016 (Sheldrick, 2015b); molecular graphics: Yadokari-XG (Wakita, 2001; Kabuto et al., 2009), Mercury (Macrae et al., 2008) and CrystalMaker (Palmer, 2007); software used to prepare material for publication: Yadokari-XG (Wakita, 2001; Kabuto et al., 2009) and publCIF (Westrip, 2010).

1,1,2,2,3,3,4,4,5,5,6,6-Dodecaallylhexasilinane top

Crystal data top

C₃₆H₆₀Si₆	Z = 1
M_r = 661.38	F(000) = 360
Triclinic, P1	D_x = 1.092 Mg m⁻³
a = 9.6036 (2) Å	Mo Kα radiation, λ = 0.71075 Å
b = 10.8060 (3) Å	Cell parameters from 13675 reflections
c = 11.4686 (3) Å	θ = 2.2–25.3°
α = 108.617 (2)°	µ = 0.23 mm⁻¹
β = 100.558 (2)°	T = 103 K
γ = 109.4774 (12)°	Prism, colorless
V = 1005.90 (5) Å³	0.25 × 0.20 × 0.20 mm

Data collection top

Rigaku Saturn diffractometer	3630 independent reflections
Radiation source: fine-focus sealed tube	3398 reflections with I > 2σ(I)
Detector resolution: 28.5714 pixels mm^-1	R_int = 0.035
ω scans	θ_max = 25.3°, θ_min = 2.2°
Absorption correction: multi-scan (MULABS; Blessing, 1995)	h = −11→11
T_min = 0.902, T_max = 0.953	k = −12→12
13675 measured reflections	l = −13→13

Refinement top

Refinement on F²	0 restraints
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.032	H-atom parameters constrained
wR(F²) = 0.089	w = 1/[σ²(F_o²) + (0.0439P)² + 0.4743P] where P = (F_o² + 2F_c²)/3
S = 1.04	(Δ/σ)_max = 0.001
3630 reflections	Δρ_max = 0.45 e Å⁻³
190 parameters	Δρ_min = −0.18 e Å⁻³

Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Si1	0.62028 (5)	0.70739 (4)	0.68222 (4)	0.02374 (12)
Si2	0.39667 (5)	0.66287 (4)	0.52192 (4)	0.02298 (12)
Si3	0.38195 (5)	0.51111 (4)	0.31623 (4)	0.02389 (12)
C1	0.79247 (18)	0.80929 (17)	0.63994 (16)	0.0298 (3)
H1	0.777913	0.756251	0.547308	0.036*
H1A	0.795241	0.904968	0.651480	0.036*
C2	0.94384 (19)	0.82874 (18)	0.72153 (16)	0.0328 (4)
H2	0.962604	0.744968	0.706635	0.039*
C3	1.0536 (2)	0.9493 (2)	0.81160 (18)	0.0437 (4)
H3	1.040539	1.036134	0.830237	0.052*
H3A	1.146668	0.950252	0.858559	0.052*
C4	0.6406 (2)	0.82817 (18)	0.85323 (15)	0.0340 (4)
H4	0.564939	0.771180	0.884893	0.041*
H4A	0.746680	0.858916	0.911725	0.041*
C5	0.6143 (2)	0.95884 (18)	0.86206 (16)	0.0385 (4)
H5	0.509679	0.948784	0.846449	0.046*
C6	0.7207 (2)	1.0850 (2)	0.88904 (19)	0.0476 (5)
H6	0.827075	1.100392	0.905397	0.057*
H6A	0.692275	1.161954	0.892422	0.057*
C7	0.40334 (19)	0.84318 (16)	0.52689 (16)	0.0321 (4)
H7	0.405292	0.901263	0.614148	0.038*
H7A	0.501467	0.895855	0.514069	0.038*
C8	0.2692 (2)	0.82944 (17)	0.42707 (17)	0.0369 (4)
H8	0.272856	0.804777	0.340775	0.044*
C9	0.1460 (2)	0.8484 (2)	0.4476 (2)	0.0471 (5)
H9	0.137296	0.873155	0.532377	0.057*
H9A	0.065728	0.837287	0.377657	0.057*
C10	0.20865 (18)	0.57289 (16)	0.55145 (15)	0.0283 (3)
H10	0.119715	0.562799	0.484119	0.034*
H10A	0.194912	0.475100	0.542961	0.034*
C11	0.20665 (19)	0.65531 (18)	0.68227 (17)	0.0346 (4)
H11	0.220179	0.751764	0.702115	0.041*
C12	0.1882 (2)	0.6082 (2)	0.77254 (18)	0.0476 (5)
H12	0.174187	0.512519	0.757449	0.057*
H12A	0.188669	0.669719	0.853299	0.057*
C13	0.55616 (19)	0.59051 (17)	0.26470 (16)	0.0321 (4)
H13	0.648570	0.589225	0.318371	0.039*
H13A	0.535167	0.527929	0.173060	0.039*
C14	0.5950 (2)	0.7412 (2)	0.2765 (2)	0.0416 (4)
H14	0.638415	0.815402	0.361902	0.050*
C15	0.5749 (3)	0.7797 (2)	0.1812 (2)	0.0544 (5)
H15	0.531764	0.709246	0.093991	0.065*
H15A	0.603140	0.878307	0.198303	0.065*
C16	0.2031 (2)	0.48798 (18)	0.19265 (16)	0.0345 (4)
H16	0.114083	0.466976	0.226362	0.041*
H16A	0.223758	0.579997	0.183665	0.041*
C17	0.1580 (2)	0.37190 (19)	0.06203 (17)	0.0397 (4)
H17	0.105052	0.275635	0.051906	0.048*
C18	0.1842 (3)	0.3903 (3)	−0.0389 (2)	0.0637 (6)
H18	0.236804	0.484745	−0.033199	0.076*
H18A	0.151028	0.309423	−0.118898	0.076*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Si1	0.0259 (2)	0.0202 (2)	0.0237 (2)	0.00853 (16)	0.00824 (16)	0.00849 (16)
Si2	0.0256 (2)	0.0194 (2)	0.0252 (2)	0.00936 (16)	0.00987 (17)	0.00997 (16)
Si3	0.0279 (2)	0.0223 (2)	0.0239 (2)	0.01044 (17)	0.01077 (17)	0.01121 (17)
C1	0.0302 (8)	0.0251 (8)	0.0317 (8)	0.0087 (6)	0.0105 (7)	0.0117 (6)
C2	0.0299 (8)	0.0325 (8)	0.0394 (9)	0.0129 (7)	0.0151 (7)	0.0169 (7)
C3	0.0344 (9)	0.0455 (11)	0.0412 (10)	0.0133 (8)	0.0100 (8)	0.0104 (8)
C4	0.0406 (9)	0.0321 (8)	0.0265 (8)	0.0171 (7)	0.0090 (7)	0.0078 (7)
C5	0.0460 (10)	0.0358 (9)	0.0295 (9)	0.0205 (8)	0.0081 (7)	0.0070 (7)
C6	0.0543 (12)	0.0375 (10)	0.0427 (11)	0.0194 (9)	0.0101 (9)	0.0093 (8)
C7	0.0360 (9)	0.0238 (8)	0.0388 (9)	0.0134 (7)	0.0128 (7)	0.0144 (7)
C8	0.0546 (11)	0.0264 (8)	0.0330 (9)	0.0196 (8)	0.0113 (8)	0.0150 (7)
C9	0.0438 (10)	0.0429 (10)	0.0576 (12)	0.0192 (9)	0.0082 (9)	0.0278 (9)
C10	0.0264 (8)	0.0276 (8)	0.0319 (8)	0.0105 (6)	0.0108 (6)	0.0135 (7)
C11	0.0293 (8)	0.0324 (9)	0.0398 (9)	0.0129 (7)	0.0155 (7)	0.0097 (7)
C12	0.0481 (11)	0.0658 (13)	0.0377 (10)	0.0340 (10)	0.0197 (9)	0.0182 (9)
C13	0.0365 (9)	0.0326 (8)	0.0359 (9)	0.0161 (7)	0.0196 (7)	0.0186 (7)
C14	0.0468 (10)	0.0387 (10)	0.0523 (11)	0.0202 (8)	0.0303 (9)	0.0242 (9)
C15	0.0679 (14)	0.0512 (12)	0.0698 (14)	0.0315 (11)	0.0393 (12)	0.0396 (11)
C16	0.0388 (9)	0.0373 (9)	0.0311 (9)	0.0195 (8)	0.0104 (7)	0.0156 (7)
C17	0.0420 (10)	0.0356 (9)	0.0348 (9)	0.0158 (8)	0.0038 (8)	0.0117 (8)
C18	0.0889 (18)	0.0539 (13)	0.0342 (11)	0.0196 (12)	0.0166 (11)	0.0138 (10)

Geometric parameters (Å, º) top

Si1—C1	1.8980 (16)	C8—C9	1.315 (3)
Si1—C4	1.9089 (16)	C8—H8	0.9500
Si1—Si2	2.3500 (6)	C9—H9	0.9500
Si1—Si3ⁱ	2.3598 (6)	C9—H9A	0.9500
Si2—C10	1.8931 (15)	C10—C11	1.488 (2)
Si2—C7	1.9100 (16)	C10—H10	0.9900
Si2—Si3	2.3511 (6)	C10—H10A	0.9900
Si3—C13	1.9009 (16)	C11—C12	1.306 (3)
Si3—C16	1.9015 (17)	C11—H11	0.9500
C1—C2	1.485 (2)	C12—H12	0.9500
C1—H1	0.9900	C12—H12A	0.9500
C1—H1A	0.9900	C13—C14	1.499 (2)
C2—C3	1.304 (2)	C13—H13	0.9900
C2—H2	0.9500	C13—H13A	0.9900
C3—H3	0.9500	C14—C15	1.292 (3)
C3—H3A	0.9500	C14—H14	0.9500
C4—C5	1.491 (2)	C15—H15	0.9500
C4—H4	0.9900	C15—H15A	0.9500
C4—H4A	0.9900	C16—C17	1.485 (2)
C5—C6	1.298 (3)	C16—H16	0.9900
C5—H5	0.9500	C16—H16A	0.9900
C6—H6	0.9500	C17—C18	1.290 (3)
C6—H6A	0.9500	C17—H17	0.9500
C7—C8	1.489 (2)	C18—H18	0.9500
C7—H7	0.9900	C18—H18A	0.9500
C7—H7A	0.9900

C1—Si1—C4	106.79 (8)	C8—C7—H7A	108.8
C1—Si1—Si2	105.58 (5)	Si2—C7—H7A	108.8
C4—Si1—Si2	113.40 (6)	H7—C7—H7A	107.7
C1—Si1—Si3ⁱ	112.49 (5)	C9—C8—C7	125.87 (17)
C4—Si1—Si3ⁱ	108.24 (5)	C9—C8—H8	117.1
Si2—Si1—Si3ⁱ	110.35 (2)	C7—C8—H8	117.1
C10—Si2—C7	105.65 (7)	C8—C9—H9	120.0
C10—Si2—Si1	113.07 (5)	C8—C9—H9A	120.0
C7—Si2—Si1	108.47 (5)	H9—C9—H9A	120.0
C10—Si2—Si3	107.10 (5)	C11—C10—Si2	112.41 (11)
C7—Si2—Si3	112.04 (5)	C11—C10—H10	109.1
Si1—Si2—Si3	110.46 (2)	Si2—C10—H10	109.1
C13—Si3—C16	106.55 (8)	C11—C10—H10A	109.1
C13—Si3—Si2	113.06 (5)	Si2—C10—H10A	109.1
C16—Si3—Si2	107.39 (5)	H10—C10—H10A	107.9
C13—Si3—Si1ⁱ	105.61 (5)	C12—C11—C10	126.47 (17)
C16—Si3—Si1ⁱ	113.91 (6)	C12—C11—H11	116.8
Si2—Si3—Si1ⁱ	110.38 (2)	C10—C11—H11	116.8
C2—C1—Si1	112.56 (11)	C11—C12—H12	120.0
C2—C1—H1	109.1	C11—C12—H12A	120.0
Si1—C1—H1	109.1	H12—C12—H12A	120.0
C2—C1—H1A	109.1	C14—C13—Si3	114.81 (11)
Si1—C1—H1A	109.1	C14—C13—H13	108.6
H1—C1—H1A	107.8	Si3—C13—H13	108.6
C3—C2—C1	126.54 (16)	C14—C13—H13A	108.6
C3—C2—H2	116.7	Si3—C13—H13A	108.6
C1—C2—H2	116.7	H13—C13—H13A	107.5
C2—C3—H3	120.0	C15—C14—C13	126.06 (19)
C2—C3—H3A	120.0	C15—C14—H14	117.0
H3—C3—H3A	120.0	C13—C14—H14	117.0
C5—C4—Si1	114.30 (12)	C14—C15—H15	120.0
C5—C4—H4	108.7	C14—C15—H15A	120.0
Si1—C4—H4	108.7	H15—C15—H15A	120.0
C5—C4—H4A	108.7	C17—C16—Si3	114.17 (12)
Si1—C4—H4A	108.7	C17—C16—H16	108.7
H4—C4—H4A	107.6	Si3—C16—H16	108.7
C6—C5—C4	126.23 (18)	C17—C16—H16A	108.7
C6—C5—H5	116.9	Si3—C16—H16A	108.7
C4—C5—H5	116.9	H16—C16—H16A	107.6
C5—C6—H6	120.0	C18—C17—C16	125.72 (19)
C5—C6—H6A	120.0	C18—C17—H17	117.1
H6—C6—H6A	120.0	C16—C17—H17	117.1
C8—C7—Si2	113.75 (11)	C17—C18—H18	120.0
C8—C7—H7	108.8	C17—C18—H18A	120.0
Si2—C7—H7	108.8	H18—C18—H18A	120.0

C4—Si1—C1—C2	66.90 (13)	C7—Si2—C10—C11	−63.26 (13)
Si2—Si1—C1—C2	−172.12 (10)	Si1—Si2—C10—C11	55.23 (12)
Si3ⁱ—Si1—C1—C2	−51.71 (12)	Si3—Si2—C10—C11	177.14 (10)
Si1—C1—C2—C3	−109.91 (18)	Si2—C10—C11—C12	−121.92 (18)
Si1—C4—C5—C6	−92.8 (2)	Si3—C13—C14—C15	−109.0 (2)
Si2—C7—C8—C9	101.37 (18)	Si3—C16—C17—C18	−102.9 (2)

Symmetry code: (i) −x+1, −y+1, −z+1.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C2ⁱⁱ—H2ⁱⁱ···C11	0.95	2.84	3.622 (3)	140
C7—H7A···C8ⁱⁱⁱ	0.99	2.82	3.669 (2)	145
C6—H6A···C15ⁱⁱⁱ	0.95	2.88	3.678 (4)	142
C16^iv—H16^iv···C12	0.99	2.75	3.684 (3)	159

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

Acknowledgements

This work was supported by Integrated Research Consortium on Chemical Science (IRCCS) and Kyoto University Research Coordination Alliance (KURCA). This study was also supported by the Joint Usage/Research Center (JURC, Institute for Chemical Research (ICR), Kyoto University) by providing access to JEOL JNM-ECA600 and Bruker Avance III 600US Plus NMR spectrometers. We are grateful for computation time, which was provided by the Super Computer System (ICR, Kyoto University). Elemental analyses were carried out at the Microanalytical Laboratory of the Institute for Chemical Research (Kyoto University).

Funding information

Funding for this research was provided by: JSPS KAKENHI (award Nos. 16H04110, 26410044, 24109013).

References

Blessing, R. H. (1995). Acta Cryst. A51, 33–38. CrossRef CAS Web of Science IUCr Journals Google Scholar
Carrell, H. L. & Donohue, J. (1972). Acta Cryst. B28, 1566–1571. CSD CrossRef IUCr Journals Web of Science Google Scholar
Choi, S.-B., Kim, B.-K., Boudjouk, P. & Grier, D. G. (2001). J. Am. Chem. Soc. 123, 8117–8118. Web of Science CSD CrossRef PubMed CAS Google Scholar
Dräger, M. & Walter, K. G. (1981). Z. Anorg. Allg. Chem. 479, 65–74. Google Scholar
Kabuto, C., Akine, S., Nemoto, T. & Kwon, E. (2009). J. Crystallogr. Soc. Japan, 51, 218–224. CrossRef Google Scholar
Macrae, C. F., Bruno, I. J., Chisholm, J. A., Edgington, P. R., McCabe, P., Pidcock, E., Rodriguez-Monge, L., Taylor, R., van de Streek, J. & Wood, P. A. (2008). J. Appl. Cryst. 41, 466–470. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
M'hirsi, M. & Brini, M. (1968). Bull. Soc. Chim. Fr. p. 1509. Google Scholar
Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M. Sweet, pp. 307–326. New York: Academic Press. Google Scholar
Palmer, D. (2007). CrystalMaker. CrystalMaker, Bicester, England. Google Scholar
Rigaku (1999). CrystalClear. Rigaku Corporation, Tokyo, Japan. Google Scholar
Sheldrick, G. M. (2015a). Acta Cryst. A71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Sheldrick, G. M. (2015b). Acta Cryst. C71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Wakita, K. (2001). Yadokari-XG. Software for Crystal Structure Analyses. Google Scholar
Westrip, S. P. (2010). J. Appl. Cryst. 43, 920–925. Web of Science CrossRef CAS IUCr Journals Google Scholar
Yamaguchi, S., Jin, R. & Tamao, K. (1999). J. Am. Chem. Soc. 121, 2937–2938. Web of Science CSD CrossRef CAS Google Scholar