Acta Crystallographica Section E: Crystallographic Communications

Acta Crystallogr E Crystallogr Commun. 76(Pt 2): 261-263

A new pseudopolymorph of perchlorinated neopentasilane: the benzene monosolvate Si(SiCl₃)₄·C₆H₆

Jan Tillmanna, Hans-Wolfram Lernera, https://orcid.org/0000-0001-5296-6251Michael Boltea*

a. Institut für Anorganische und Analytische Chemie, Goethe-Universität Frankfurt, Max-von-Laue-Strasse 7, 60438 Frankfurt am Main, Germany

Correspondence e-mail: bolte@chemie.uni-frankfurt.de

© Tillmann et al. 2020

DOI: 10.1107/S2056989020000900

Published online: 31 January 2020

Abstract

A new pseudopolymorph of dodecachloropentasilane, namely a benzene monosolvate, Si₅Cl₁₂ .C₆H₆, is described. There are two half molecules of each kind in the asymmetric unit. Both Si₅Cl₁₂ molecules are completed by crystallographic twofold symmetry. One of the benzene molecules is located on a twofold rotation axis with two C—H groups located on this rotation axis. The second benzene molecule has all atoms on a general position: it is disordered over two equally occupied orientations. No directions interactions beyond normal van der Waals’ contacts occur in the crystal.

Abstract

A new pseudopolymorph of dodecachloropentasilane, namely a benzene monosolvate, Si₅Cl₁₂·C₆H₆, is described. There are two half molecules of each kind in the asymmetric unit. Both Si₅Cl₁₂ molecules are completed by crystallographic twofold symmetry. One of the benzene molecules is located on a twofold rotation axis with two C—H groups located on this rotation axis. The second benzene molecule has all atoms on a general position: it is disordered over two equally occupied orientations. No directional interactions beyond normal van der Waals contacts occur in the crystal.

Chemical context  

Since the 1980s, silicon hydrides, such as Si(SiH₃)₄, have attracted considerable attention as precursors for the liquid phase deposition (LPD) of silicon thin films (Nishimura et al., 1985 ▸). In this context it should be noted that the perchlorinated neopentasilane Si(SiCl₃)₄ (Si₅Cl₁₂) is easily accessible in large amounts by the amine-induced disproportionation (Meyer-Wegner et al., 2011 ▸; Tillmann et al., 2012 ▸) of perchloropolysilanes, e.g. Si₂Cl₆ or Si₃Cl₈ (Meyer-Wegner et al., 2011 ▸; Urry, 1970 ▸). Subsequent hydrogenation of Si(SiCl₃)₄ (I) then yields the neopentasilane Si(SiH₃)₄, which can be used as an LPD agent (Cannady & Zhou, 2008 ▸) (see Fig. 1 ▸).

In this paper we describe the structure of a new pseudo-polymorph of perchlorinated neopentasilane (I), namely the benzene monosolvate Si(SiCl₃)₄·C₆H₆, and make a comparison of its structure with those of Si(SiCl₃)₄ (Meyer-Wegner et al., 2011 ▸) and Si(SiCl₃)₄·SiCl₄ (Fleming, 1972 ▸).

Structural commentary  

There are two half molecules of each kind in the asymmetric unit of (I). Both Si₅Cl₁₂ molecules are completed by crystallographic twofold symmetry, with the rotation axes orientated in the [110] and [10] directions and the central Si atom located on the axis (Fig. 2 ▸). One of the benzene molecules is located on a twofold rotation axis propagating along the a or b axes with two C—H groups located on this rotation axis. The second benzene molecule has all atoms on general positions: it is disordered over two equally occupied orientations about a twofold rotation axis running in the [100] and [010] directions.

Supramolecular features  

A view of the molecular packing of (I) (Fig. 3 ▸) reveals that the benzene molecules fill the voids between the dodecachloropentasilane molecules. There are no identified directional intermolecular interactions.

Database survey  

There are two already known structures of dodecachloropentasilane: first, there is pure Si₅Cl₁₂ (Meyer-Wegner et al., 2011 ▸; CCDC deposition number 793308) and second, a co-crystal with silicon tetrachloride (Fleming, 1972 ▸; CCDC deposition number 1592571). In each of these structures, the Si₅Cl₁₂ molecule is located on a special position. As noted above, in (I), both molecules in the asymmetric unit are found on a twofold rotation axis. Compound (II) also crystallizes with two molecules in the asymmetric unit. One of them is located on a threefold rotation axis and the other is disordered about a special position of site symmetry . In the second molecule, it is noteworthy that only the Si atoms carrying the Cl atoms are disordered: the central Si atom and the Cl atoms themselves are not disordered. In (III), the Si₅Cl₁₂ molecule is located on a special position of site symmetry 23. The central Si atom is located at the intersection of the twofold and the threefold rotation axes (the twofold rotation axis coincides with a axis). The Si—Si and Si—Cl bond lengths in all three structures agree well (Table 1 ▸).

Synthesis and crystallization  

The perchlorinated neopentasilane (I) was synthesized according to a literature procedure (Kaczmarczyk & Urry, 1960 ▸). Single crystals of Si(SiCl₃)₄·C₆H₆ were grown from a solution of Si(SiCl₃)₄ in benzene after one week at room temperature.

Si(SiCl₃)₄ (I). ²⁹Si{¹H}NMR (C₆D₆, external TMS): δ = −80.9 [Si(SiCl₃)₄], δ = 3.5 [Si(SiCl₃)₄].

Refinement  

Crystal data, data collection and structure refinement details are summarized in Table 2 ▸. The H atoms were refined using a riding model with C—H = 0.95 Å and with U iso(H) = 1.2U eq(C). One of the benzene molecules is disordered over two equally occupied orientations: its carbon atoms were isotropically refined. The C—C distances in the non-disordered benzene molecule were restrained to 1.390 (2) Å. The crystal chosen for data collection was found to crystallize as a racemic twin.

Figure 1View larger versionFigure 1. Amine-induced disproportionation of Si₂Cl₆ and Si₃Cl₈: (i) + NMe₃, or NMe₂Et, or NEt₃ in benzene at room temperature; (ii) + LiAlH₄ in diethyl ether at room temperature

Figure 2View larger versionFigure 2. A perspective view of the title compound. Displacement ellipsoids are drawn at the 50% probability level. Symmetry codes: (i) −y, −x, −z + ; (ii) 1 − y, 1 − x, −z + ; (iii) −x, y, −z; (iv) 1 − x, y, −z.

Figure 3View larger versionFigure 3. Packing diagram of the title compound viewed down [010].

See full tableTable 1. Bond lengths (Å) in the different structures containing Si₅Cl₁₂ moleculesFor (I), mean values of the two molecules are given. For (II), mean values of the non-disordered molecule are given. Because of the high symmetry of (III), there is only one value for each bond length.

See full table Table 2. Experimental details

Supplementary Material

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supplementary crystallographic information

Crystal data

See full table

Data collection

See full table

Refinement

See full table

Special details

See full table

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

See full table

Atomic displacement parameters (Å²)

See full table

Geometric parameters (Å, º)

See full table

Symmetry codes: (i) −y+1, −x+1, −z+1/4; (ii) −y, −x, −z+1/4; (iii) −x, y, −z; (iv) −x+1, y, −z.

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References

Cannady, J. P. & Zhou, X. (2008). WO2008051328.

Fleming, D. K. (1972). Acta Cryst. B28, 1233–1236.

Kaczmarczyk, A. & Urry, G. (1960). J. Am. Chem. Soc. 82, 751–752.

Meyer-Wegner, F., Nadj, A., Bolte, M., Auner, N., Wagner, M., Holthausen, M. C. & Lerner, H.-W. (2011). Chem. Eur. J. 17, 4715–4719.

Nishimura, Y., Eguchi, T., Matsuda, H., Haruta, M., Hirai, Y. & Nakagiri, T. (1985). JP, 60219733 A 19851102.

Parsons, S., Flack, H. D. & Wagner, T. (2013). Acta Cryst. B69, 249–259.

Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122.

Sheldrick, G. M. (2015). Acta Cryst. C71, 3–8.

Stoe & Cie (2001). X-AREA. Stoe & Cie, Darmstadt, Germany.

Tillmann, J., Meyer-Wegner, F., Nadj, A., Becker-Baldus, J., Sinke, T., Bolte, M., Holthausen, M. C., Wagner, M. & Lerner, H.-W. (2012). Inorg. Chem. 51, 8599–8606.

Urry, G. (1970). Acc. Chem. Res. 3, 306–312.

Westrip, S. P. (2010). J. Appl. Cryst. 43, 920–925.

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Cl₁₂Si₅·C₆H₆ | Dx = 1.769 Mg m⁻³
Mr = 643.96 | Mo Kα radiation, λ = 0.71073 Å
Tetragonal, P4₁22 | Cell parameters from 62511 reflections
a = 11.9633 (4) Å | θ = 1.9–27.6°
c = 33.7848 (16) Å | µ = 1.62 mm⁻¹
V = 4835.3 (4) Å³ | T = 173 K
Z = 8 | Block, colourless
F(000) = 2528 | 0.28 × 0.18 × 0.16 mm

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Stoe IPDS II two-circle diffractometer | 4790 reflections with I > 2σ(I)
ω scans | Rint = 0.047
Absorption correction: multi-scan (X-AREA; Stoe & Cie, 2001) | θmax = 27.1°, θmin = 1.8°
Tmin = 0.803, Tmax = 1.0 | h = −14→15
39180 measured reflections | k = −15→15
5189 independent reflections | l = −43→43

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Refinement on F² | Hydrogen site location: mixed
Least-squares matrix: full | H-atom parameters constrained
R[F² > 2σ(F²)] = 0.027 | w = 1/[σ²(Fo²) + (0.0375P)² + 2.8317P] where P = (Fo² + 2Fc²)/3
wR(F²) = 0.075 | (Δ/σ)max = 0.001
S = 1.08 | Δρmax = 0.39 e Å⁻³
5189 reflections | Δρmin = −0.42 e Å⁻³
207 parameters | Absolute structure: Flack x determined using 1905 quotients [(I⁺)-(I⁻)]/[(I⁺)+(I⁻)] (Parsons et al., 2013)
5 restraints | Absolute structure parameter: 0.48 (5)
Primary atom site location: structure-invariant direct methods |

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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.

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| x | y | z | Uiso*/Ueq | Occ. (<1)
Si1 | 0.54973 (7) | 0.45027 (7) | 0.125000 | 0.0222 (3) |
Si2 | 0.38834 (7) | 0.45056 (7) | 0.08678 (2) | 0.02447 (19) |
Si3 | 0.54972 (8) | 0.29277 (8) | 0.16530 (3) | 0.0264 (2) |
Cl21 | 0.40377 (8) | 0.34525 (8) | 0.04060 (2) | 0.0400 (2) |
Cl22 | 0.25695 (7) | 0.39988 (8) | 0.11990 (3) | 0.0387 (2) |
Cl23 | 0.35776 (8) | 0.60671 (7) | 0.06658 (3) | 0.0384 (2) |
Cl31 | 0.49743 (8) | 0.15929 (7) | 0.13366 (3) | 0.0408 (2) |
Cl32 | 0.70602 (8) | 0.26452 (9) | 0.18579 (3) | 0.0453 (2) |
Cl33 | 0.44514 (8) | 0.31660 (9) | 0.21128 (3) | 0.0412 (2) |
Si4 | 0.04988 (7) | −0.04988 (7) | 0.125000 | 0.0225 (3) |
Si5 | 0.05165 (7) | 0.11311 (7) | 0.16232 (2) | 0.02420 (19) |
Si6 | 0.20502 (8) | −0.05209 (8) | 0.08356 (3) | 0.0263 (2) |
Cl51 | −0.05058 (7) | 0.09833 (8) | 0.20938 (2) | 0.0382 (2) |
Cl52 | −0.00287 (8) | 0.24225 (7) | 0.12875 (3) | 0.0367 (2) |
Cl53 | 0.20867 (7) | 0.14553 (8) | 0.18124 (3) | 0.0379 (2) |
Cl61 | 0.23134 (9) | 0.10282 (8) | 0.06166 (3) | 0.0449 (2) |
Cl62 | 0.17856 (9) | −0.15973 (8) | 0.03862 (2) | 0.0414 (2) |
Cl63 | 0.34091 (8) | −0.10198 (9) | 0.11430 (3) | 0.0424 (2) |
C1 | 0.000000 | 0.3434 (6) | 0.000000 | 0.100 (4) |
H1 | 0.000000 | 0.263981 | 0.000000 | 0.120* |
C2 | 0.0511 (5) | 0.4024 (4) | 0.03030 (13) | 0.094 (2) |
H2 | 0.087169 | 0.363505 | 0.051231 | 0.113* |
C3 | 0.0495 (5) | 0.5176 (4) | 0.03001 (14) | 0.090 (2) |
H3 | 0.083717 | 0.556596 | 0.051284 | 0.107* |
C4 | 0.000000 | 0.5786 (7) | 0.000000 | 0.087 (3) |
H4 | 0.000000 | 0.657984 | 0.000000 | 0.104* |
C5 | 0.5409 (8) | 0.8628 (10) | 0.0236 (3) | 0.051 (2)* | 0.5
H5 | 0.570943 | 0.806236 | 0.040196 | 0.062* | 0.5
C6 | 0.5561 (8) | 0.9738 (11) | 0.0335 (3) | 0.050 (2)* | 0.5
H6 | 0.594385 | 0.992910 | 0.057205 | 0.059* | 0.5
C7 | 0.5158 (9) | 1.0566 (8) | 0.0092 (3) | 0.054 (3)* | 0.5
H7 | 0.527035 | 1.132987 | 0.015732 | 0.065* | 0.5
C5' | 0.5145 (10) | 0.8339 (8) | 0.0086 (3) | 0.057 (3)* | 0.5
H5' | 0.526088 | 0.757264 | 0.014687 | 0.068* | 0.5
C6' | 0.5559 (9) | 0.9177 (12) | 0.0335 (3) | 0.058 (2)* | 0.5
H6' | 0.594991 | 0.897299 | 0.056942 | 0.069* | 0.5
C7' | 0.5410 (10) | 1.0290 (11) | 0.0247 (4) | 0.062 (3)* | 0.5
H7' | 0.569534 | 1.085379 | 0.041783 | 0.074* | 0.5

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| U ¹¹ | U ²² | U ³³ | U ¹² | U ¹³ | U ²³
Si1 | 0.0213 (4) | 0.0213 (4) | 0.0241 (6) | 0.0004 (5) | 0.0008 (3) | 0.0008 (3)
Si2 | 0.0245 (4) | 0.0238 (4) | 0.0251 (4) | 0.0000 (3) | −0.0010 (3) | 0.0009 (3)
Si3 | 0.0252 (4) | 0.0247 (4) | 0.0294 (4) | 0.0001 (4) | −0.0007 (3) | 0.0046 (3)
Cl21 | 0.0521 (5) | 0.0364 (5) | 0.0316 (4) | −0.0014 (4) | 0.0003 (4) | −0.0084 (3)
Cl22 | 0.0269 (4) | 0.0476 (5) | 0.0418 (4) | −0.0054 (4) | 0.0051 (3) | 0.0042 (4)
Cl23 | 0.0464 (5) | 0.0278 (4) | 0.0411 (4) | 0.0058 (4) | −0.0079 (4) | 0.0060 (3)
Cl31 | 0.0452 (5) | 0.0268 (4) | 0.0503 (5) | −0.0048 (4) | −0.0003 (4) | −0.0032 (4)
Cl32 | 0.0317 (4) | 0.0461 (5) | 0.0579 (5) | 0.0068 (4) | −0.0113 (4) | 0.0116 (4)
Cl33 | 0.0406 (5) | 0.0529 (6) | 0.0302 (4) | −0.0059 (4) | 0.0065 (4) | 0.0031 (4)
Si4 | 0.0214 (4) | 0.0214 (4) | 0.0245 (6) | 0.0000 (5) | 0.0006 (3) | 0.0006 (3)
Si5 | 0.0236 (4) | 0.0242 (4) | 0.0248 (4) | −0.0008 (3) | −0.0010 (3) | −0.0011 (3)
Si6 | 0.0248 (4) | 0.0259 (4) | 0.0282 (4) | 0.0001 (4) | 0.0038 (3) | 0.0010 (3)
Cl51 | 0.0366 (5) | 0.0486 (5) | 0.0295 (4) | 0.0010 (4) | 0.0072 (3) | −0.0013 (4)
Cl52 | 0.0436 (5) | 0.0268 (4) | 0.0398 (4) | 0.0039 (4) | −0.0050 (4) | 0.0042 (3)
Cl53 | 0.0282 (4) | 0.0428 (5) | 0.0429 (4) | −0.0063 (4) | −0.0069 (3) | −0.0033 (4)
Cl61 | 0.0489 (5) | 0.0325 (4) | 0.0533 (5) | −0.0063 (4) | 0.0126 (4) | 0.0108 (4)
Cl62 | 0.0520 (5) | 0.0404 (5) | 0.0317 (4) | 0.0053 (4) | 0.0022 (4) | −0.0084 (4)
Cl63 | 0.0274 (4) | 0.0505 (5) | 0.0494 (5) | 0.0067 (4) | −0.0039 (4) | 0.0003 (4)
C1 | 0.074 (6) | 0.043 (4) | 0.184 (11) | 0.000 | 0.056 (7) | 0.000
C2 | 0.068 (4) | 0.147 (7) | 0.067 (4) | 0.011 (4) | 0.001 (3) | 0.055 (4)
C3 | 0.070 (4) | 0.138 (6) | 0.060 (3) | −0.026 (4) | 0.006 (3) | −0.037 (4)
C4 | 0.067 (5) | 0.068 (5) | 0.125 (8) | 0.000 | 0.040 (5) | 0.000

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Si1—Si2 | 2.3227 (11) | Si6—Cl61 | 2.0202 (13)
Si1—Si2i | 2.3228 (11) | C1—C2 | 1.3855 (18)
Si1—Si3i | 2.3246 (11) | C1—C2iii | 1.3855 (18)
Si1—Si3 | 2.3247 (11) | C1—H1 | 0.9500
Si2—Cl21 | 2.0138 (12) | C2—C3 | 1.378 (3)
Si2—Cl23 | 2.0221 (12) | C2—H2 | 0.9500
Si2—Cl22 | 2.0225 (12) | C3—C4 | 1.3824 (18)
Si3—Cl33 | 2.0150 (13) | C3—H3 | 0.9500
Si3—Cl31 | 2.0209 (13) | C4—H4 | 0.9500
Si3—Cl32 | 2.0223 (13) | C5—C6 | 1.382 (15)
Si4—Si5 | 2.3221 (11) | C5—H5 | 0.9500
Si4—Si5ii | 2.3222 (11) | C6—C7 | 1.375 (14)
Si4—Si6 | 2.3250 (11) | C6—H6 | 0.9500
Si4—Si6ii | 2.3251 (11) | C7—H7 | 0.9500
Si5—Cl51 | 2.0138 (12) | C5'—C6' | 1.399 (15)
Si5—Cl53 | 2.0218 (12) | C5'—H5' | 0.9501
Si5—Cl52 | 2.0243 (12) | C6'—C7' | 1.376 (15)
Si6—Cl62 | 2.0158 (13) | C6'—H6' | 0.9500
Si6—Cl63 | 2.0194 (13) | C7'—H7' | 0.9500
Si2—Si1—Si2i | 107.85 (6) | C2—C1—C2iii | 118.8 (7)
Si2—Si1—Si3i | 110.38 (3) | C2—C1—H1 | 120.6
Si2i—Si1—Si3i | 109.07 (3) | C2iii—C1—H1 | 120.6
Si2—Si1—Si3 | 109.07 (3) | C3—C2—C1 | 119.9 (6)
Si2i—Si1—Si3 | 110.37 (3) | C3—C2—H2 | 120.1
Si3i—Si1—Si3 | 110.06 (7) | C1—C2—H2 | 120.1
Cl21—Si2—Cl23 | 109.46 (5) | C2—C3—C4 | 122.6 (6)
Cl21—Si2—Cl22 | 108.20 (6) | C2—C3—H3 | 118.7
Cl23—Si2—Cl22 | 108.85 (6) | C4—C3—H3 | 118.7
Cl21—Si2—Si1 | 110.71 (5) | C3iii—C4—C3 | 116.3 (7)
Cl23—Si2—Si1 | 109.84 (5) | C3iii—C4—H4 | 121.9
Cl22—Si2—Si1 | 109.75 (4) | C3—C4—H4 | 121.9
Cl33—Si3—Cl31 | 109.11 (6) | C6—C5—C5iv | 106.0 (6)
Cl33—Si3—Cl32 | 109.50 (6) | C6—C5—H5 | 119.4
Cl31—Si3—Cl32 | 109.58 (6) | C5iv—C5—H5 | 134.6
Cl33—Si3—Si1 | 109.69 (5) | C5—C6—C7 | 120.0 (9)
Cl31—Si3—Si1 | 109.31 (5) | C5—C6—C7iv | 104.5 (8)
Cl32—Si3—Si1 | 109.63 (5) | C5—C6—H6 | 120.0
Si5—Si4—Si5ii | 108.07 (6) | C7—C6—H6 | 120.0
Si5—Si4—Si6 | 109.22 (3) | C7iv—C6—H6 | 135.5
Si5ii—Si4—Si6 | 110.07 (3) | C7iv—C7—C6 | 133.9 (6)
Si5—Si4—Si6ii | 110.08 (3) | C6—C7—C6iv | 103.4 (9)
Si5ii—Si4—Si6ii | 109.22 (3) | C7iv—C7—H7 | 105.9
Si6—Si4—Si6ii | 110.15 (7) | C6—C7—H7 | 120.2
Cl51—Si5—Cl53 | 109.35 (5) | C6iv—C7—H7 | 136.4
Cl51—Si5—Cl52 | 108.28 (6) | C5'iv—C5'—C6' | 134.3 (6)
Cl53—Si5—Cl52 | 109.28 (6) | C5'iv—C5'—H5' | 105.1
Cl51—Si5—Si4 | 110.45 (5) | C6'—C5'—H5' | 120.6
Cl53—Si5—Si4 | 109.95 (5) | C6'iv—C5'—H5' | 136.3
Cl52—Si5—Si4 | 109.50 (5) | C7'—C6'—C5' | 121.1 (10)
Cl62—Si6—Cl63 | 108.97 (6) | C7'—C6'—H6' | 119.4
Cl62—Si6—Cl61 | 109.56 (6) | C5'—C6'—H6' | 119.4
Cl63—Si6—Cl61 | 109.51 (6) | C5'iv—C6'—H6' | 134.0
Cl62—Si6—Si4 | 109.60 (5) | C6'—C7'—C7'iv | 104.6 (7)
Cl63—Si6—Si4 | 109.65 (5) | C6'—C7'—H7' | 120.6
Cl61—Si6—Si4 | 109.54 (5) | C7'iv—C7'—H7' | 134.8
C2iii—C1—C2—C3 | 0.6 (4) | C7iv—C6—C7—C6iv | −1 (2)
C1—C2—C3—C4 | −1.2 (9) | C5'iv—C5'—C6'—C7' | 0 (4)
C2—C3—C4—C3iii | 0.6 (4) | C6'iv—C5'—C6'—C7' | 0.0 (10)
C5iv—C5—C6—C7 | −1.7 (13) | C6'iv—C5'—C6'—C5'iv | 0 (3)
C5iv—C5—C6—C7iv | −1.2 (10) | C5'—C6'—C7'—C7'iv | −0.1 (14)
C5—C6—C7—C7iv | 2 (3) | C5'iv—C6'—C7'—C7'iv | −0.2 (11)
C5—C6—C7—C6iv | 1.0 (9) |  |

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Figure 1.

Amine-induced disproportionation of Si₂Cl₆ and Si₃Cl₈: (i) + NMe₃, or NMe₂Et, or NEt₃ in benzene at room temperature; (ii) + LiAlH₄ in diethyl ether at room temperature

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Figure 2.

A perspective view of the title compound. Displacement ellipsoids are drawn at the 50% probability level. Symmetry codes: (i) −y, −x, −z + ; (ii) 1 − y, 1 − x, −z + ; (iii) −x, y, −z; (iv) 1 − x, y, −z.

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Figure 3.

Packing diagram of the title compound viewed down [010].

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Table 1. Bond lengths (Å) in the different structures containing Si₅Cl₁₂ molecules

For (I), mean values of the two molecules are given. For (II), mean values of the non-disordered molecule are given. Because of the high symmetry of (III), there is only one value for each bond length.

| Si—Si | Si—Cl
(I) | 2.324 | 2.019
(II) | 2.340 | 2.026
(III) | 2.332 (9) | 1.994 (7)

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Table 2. Experimental details

Crystal data
Chemical formula | Cl₁₂Si₅·C₆H₆
M r | 643.96
Crystal system, space group | Tetragonal, P4₁22
Temperature (K) | 173
a, c (Å) | 11.9633 (4), 33.7848 (16)
V (Å³) | 4835.3 (4)
Z | 8
Radiation type | Mo Kα
μ (mm⁻¹) | 1.62
Crystal size (mm) | 0.28 × 0.18 × 0.16
Data collection
Diffractometer | Stoe IPDS II two-circle
Absorption correction | Multi-scan (X-AREA; Stoe & Cie, 2001 ▸)
T min, T max | 0.803, 1.0
No. of measured, independent and observed [I > 2σ(I)] reflections | 39180, 5189, 4790
R int | 0.047
(sin θ/λ)max (Å⁻¹) | 0.642
Refinement
R[F ² > 2σ(F ²)], wR(F ²), S | 0.027, 0.075, 1.08
No. of reflections | 5189
No. of parameters | 207
No. of restraints | 5
H-atom treatment | H-atom parameters constrained
Δρmax, Δρmin (e Å⁻³) | 0.39, −0.42
Absolute structure | Flack x determined using 1905 quotients [(I ⁺)−(I ⁻)]/[(I ⁺)+(I ⁻)] (Parsons et al., 2013 ▸)
Absolute structure parameter | 0.48 (5)

Computer programs: X-AREA (Stoe & Cie, 2001 ▸), SHELXS97 (Sheldrick, 2008 ▸), XP in SHELXTL-Plus (Sheldrick, 2008 ▸), SHELXL2018 (Sheldrick, 2015 ▸) and publCIF (Westrip, 2010 ▸).

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