Amine-promoted disproportionation and redistribution of trichlorosilane: formation of tetradecachlorocyclohexasilane dianion

Challenges in the Synthesis and Processing of Hydrosilanes as Precursors for Silicon Deposition

Hydrosilanes are highly attractive compounds, which can be processed as liquids with printing technology to amorphous silicon films on nearly any solid substrate. The silicon layers can be processed for electronic devices like transistors or thin-film solar cells. The endothermic character of hydrosilanes with their positive enthalpies of formation results in favorable properties for processing. The larger the molecules, the lower their decomposition temperature and the higher their photoactivity. Cyclic hydrosilanes such as cyclopentasilane and cyclohexasilane can be easily deposited. The branched neopentasilane is more difficult to deposit but yields better-quality films after processing. The key challenge is the complex synthesis of the precursors and the hydrosilanes. The available preparative methods are presented in this review and their advantages and disadvantages are evaluated. The following synthesis methods are presented and discussed in this article: Wurtz coupling and other reductive coupling processes, dehydrogenative coupling of silanes, plasma synthesis of chlorinated polysilanes, amine- or chloride-induced disproportionations, and transformation of monosilane to higher silanes. Plasma synthesis is already carried out today as a continuous industrial process. The most effective synthesis methods in the laboratory are currently amine- and chloride-induced disproportionations. There is a great need to further optimize the syntheses of hydrosilanes and to develop new simple synthesis variants.

Confined Lewis Pairs: Investigation of the X- →Si20 Interaction in Halogen-Encapsulating Silafulleranes

A joint theoretical and experimental study on 32 endohedral silafullerane derivatives [X@Si20 Y20 ]- (X=F-I; Y=F-I, H, Me, Et) andT h ${T_h }$ -[Cl@Si20 H12 Y8 ]- (Y=F-I) is presented. First, we evaluated the structure-determining template effect of Cl- in a systematic series of concave silapolyquinane model systems. Second, we investigated the X- →Si20 interaction energy (E int ${E_{{\rm{int}}} }$ ) as a function of X- and Y and found the largestE int ${E_{{\rm{int}}} }$ values for electron-withdrawing exohedral substituents Y. Given that X- ions can be considered as Lewis bases and empty Si20 Y20 clusters as Lewis acids, we classify our inseparable host-guest complexes [X@Si20 Y20 ]- as "confined Lewis pairs". Third, 35 Cl NMR spectroscopy proved to be highly diagnostic for an experimental assessment of the Cl- →Si20 interaction as the paramagnetic shielding and, in turn, δ ${\delta }$ (35 Cl) of the endohedral Cl- ion correlate inversely withE int ${E_{{\rm{int}}} }$ . Finally, we disclose the synthesis of [PPN][Cl@Si20 Y20 ] (Y=Me, Et, Br) and provide a thorough characterization of these new silafulleranes.

Dope it with germanium: selective access to functionalized Si5Ge heterocycles

The Cl^- diadduct [nBu₄N]₂[A·2Cl] of the mixed cyclohexatetrelane (SiCl₂)₅(GeMe₂), A, is accessible from Me₂GeCl₂, 6 eq. Si₂Cl₆, and 2 eq. [nBu₄N]Cl in one step (96%). Free, tenfold functionalized A can be released from the primary product by decomplexation with AlCl₃ (78%). Insight into the assembly mechanism of [nBu₄N]₂[A·2Cl] and the reactivity of A is provided.

Selective One-Pot Syntheses of Mixed Silicon-Germanium Heteroadamantane Clusters

Si x Ge y alloys are emerging materials for modern semiconductor technology. Well-defined model systems of the bulk structures aid in understanding their intrinsic characteristics. Three such model clusters have now been realized in the form of the Si x Ge y heteroadamantanes [0] , [1] , and [2] via selective one-pot syntheses starting from Me 2 GeCl 2 , Si 2 Cl 6 , and [nBu 4 N]Cl. Compound [0] contains 6 GeMe 2 and 4 SiSiCl 3 vertices, while one and two of the GeMe 2 groups are replaced by SiCl 2 moieties in compounds [1] and [2] , respectively. Chloride ion-mediated rearrangement quantitatively converts [2] into [1] at room temperature and finally into [0] at 60 °C, which is not only remarkable in view of the rigidity of these cage structures but also sheds light on the assembly mechanism.

Molecular Silicon Clusters

The continuously decreasing size of device features in microelectronics draws growing attention to the structuring of silicon at the molecular level with powerful tools provided by synthetic chemistry. Silicon clusters are of particular importance in this regard not only as potential precursors for silicon deposition but also as well-defined model systems for bulk and surfaces of silicon at the nanoscale as well as possible starting points for future construction of molecularly precise device structures. This review aims to give a comprehensive overview about the state of the art in the synthesis of molecular silicon clusters, which are grouped into (1) electron-precise saturated clusters, (2) soluble polyhedral Zintl anions, and (3) unsaturated silicon clusters, the so-called siliconoids. Particular attention is paid to functionalization as it is generally considered a necessary prerequisite for the design and construction of more extended systems. The interrelations between the three different classes of molecular silicon clusters, e.g., arising from the introduction of negatively charged functional groups, are highlighted on grounds of NMR properties and computed electronic structures.

Solvent-Induced Growth of Free-Standing 2D Si Nanosheets

2D Si nanomaterials draw great interest owing to their fascinating properties and potential applications in electronic devices, catalysts, and energy storage and conversion devices. However, high-quality and large-scale synthesis of Si nanosheets remains a big challenge, despite the limited reports on their preparations via chemical exfoliation of layered Zintl silicide, magnesiothermic reduction of layered silicon oxide, and chemical vapor deposition. In this work, a facile, solution method to produce free-standing Si nanosheets in high yields and low cost, based on the reaction of commercial magnesium powder with trichlorosilane and tripropylamine in dichloromethane under mild conditions, is reported. The prepared Si nanosheets have an average thickness of ≈2 nm and show photoluminescence. Experiments demonstrate that the key to the formation of Si nanosheets is the use of dichloromethane as a solvent. This method can be used to prepare Si nanosheets in large scale for various potential applications and possibly Si crystals with specific crystal morphology.

Syntheses and Molecular Structures of Liquid Pyrophoric Hydridosilanes

Trisilane, isotetrasilane, neopentasilane, and cyclohexasilane have been prepared in gram scale. In-situ cryo crystallization of these pyrophoric liquids in sealed capillaries on the diffractometer allows access to the single crystal structures of these compounds. Structural parameters are discussed and compared to gas-phase electron diffraction structures from literature and with the results from quantum chemical calculations. Significantly higher packing indices are found for the silanes compared to the corresponding alkanes. Radiation with ultraviolet light (365 nm) and parallel ESR (EPR) measurement shows that cyclohexasilane is easily split into radicals, which subsequently leads to the formation of branched and chain-like oligomers. The other compounds form no radicals under these conditions. NMR spectra of all four compounds have been recorded.

One-pot solution synthesis of carbon-coated silicon nanoparticles as an anode material for lithium-ion batteries

Carbon-coated silicon nanoparticles were synthesized via a one-pot solution method, delivering excellent performance in lithium ion batteries.

Why Do Five Ga+ Cations Form a Ligand-Stabilized [Ga5 ]5+ Pentagon and How Does a 5:1 Salt Pack in the Solid State?

The reaction of the Ga⁺ source [Ga(PhF)₂ ]⁺ [Al(OR^F )₄ ]^- with the neutral σ-donor ligand dmap (4-Me₂ N-C₆ H₄ N) produces the unexpectedly large and fivefold positively charged cluster cation salt [Ga₅ (dmap)₁₀ ]⁵⁺ ([Al(OR^F )₄ ]^- )₅ . It includes a regular and planar Ga₅ pentagon with strong metal-metal bonding. Additionally, the compound represents the first salt in which an ionic 1:5 packing is realized. We discuss the nature of this structure which results from the conversion of the non-bonding 4s² lone-pair orbitals into fully Ga-Ga-bonding orbitals and the solid-state arrangement of the ions constituting the lattice as an almost orthohexagonal AX₅ lattice, possibly the aristotype of any 5:1 salt.

New insights into the heat of adsorption of water, acetonitrile, and n-hexane in porous carbon with oxygen functional groups

Isosteric heat of adsorption is exquisitely sensitive to structural changes in carbon surfaces based on the energetic behavior of the interactions between adsorbates and carbon materials. We discuss the relationships between porous structures, oxygen functional groups, and heat of adsorption based on the behavior of the heat of adsorption of polar and non-polar fluids on porous carbon materials with oxygen functional groups. The porosity and functional groups of porous carbon materials were estimated from N₂ adsorption isotherms at 77 K and temperature-programmed desorption. High-resolution adsorption isotherms of water, acetonitrile (polar fluid), and n-hexane (non-polar fluid) were measured on porous carbon materials with different pore size distributions and amounts of oxygen functional groups at various temperatures. The heats of adsorption were determined by applying the Clausius-Clapeyron equation to the adsorption isotherms. The heat of adsorption curves directly reflect the effects of interactions of fluid-oxygen functional groups, fluid-basal planes of pore walls, and fluid-fluid interfaces. In particular, the heat of adsorption curve of water is very sensitive to surface oxygen functional groups. This finding indicates the possibility of estimating the relative amounts of oxygen functional groups on porous carbon materials based on the amounts of water adsorbed at specific relative pressures.

Systematic study of the substitution effect on the tetrel bond between 1,4-diazabicyclo[2.2.2]octane and TH3X

A tetrel bond was characterized in the complexes of 1,4-diazabicyclo[2.2.2]octane (DABCO) with TH3X (T = C, Si, Ge; X= -Me, -H, -OH, -NH2, -F, -Cl, -Br, -I, -CN, -NO2). DABCO engages in a weak tetrel bond with CH3X but a stronger one with SiH3X and GeH3X. SiH3X is favorable to bind with DABCO relative to GeH3X, inconsistent with the magnitude of the σ-hole on the tetrel atom. The methyl group in the tetrel donor weakens the tetrel bond but an enhancing effect is found for the other substituents, particularly -NO2. The substitution effect is also related to the nature of the tetrel atom. The halogen substitution from F to I has a weakening effect in the CH3X complex but an enhancing effect in the SiH3X complex and a negligible effect in the GeH3X complex. The above abnormal results found in these complexes can be partly attributed to the charge transfer from the lone pair on the nitrogen atom of DABCO into the anti-bonding orbital σ*(T-X) of TH3X. The stability of both SiH3X and GeH3X complexes is primarily controlled by electrostatic interactions and polarization.

Orthophosphate and Sulfate Utilization for C-E (E = P, S) Bond Formation via Trichlorosilyl Phosphide and Sulfide Anions

Reduction of phosphoric acid (H₃PO₄) or tetra- n-butylammonium bisulfate ([TBA][HSO₄]) with trichlorosilane leads to the formation of the bis(trichlorosilyl)phosphide ([P(SiCl₃)₂]^-, 1) and trichlorosilylsulfide ([Cl₃SiS]^-, 2) anions, respectively. Balanced equations for the formation of the TBA salts of anions 1 and 2 were formulated based on the identification of hexachlorodisiloxane and hydrogen gas as byproducts arising from these reductive processes: i) [H₂PO₄]^- + 10HSiCl₃ → 1 + 4O(SiCl₃)₂ + 6H₂ for P and ii) [HSO₄]^- + 9HSiCl₃ → 2 + 4O(SiCl₃)₂ + 5H₂ for S. Hydrogen gas was identified by its subsequent use to hydrogenate an alkene ((-)-terpinen-4-ol) using Crabtree's catalyst ([(COD)Ir(py)(PCy₃)][PF₆], COD = 1,5-cyclooctadiene, py = pyridine, Cy = cyclohexyl). Phosphide 1 was generated in situ by the reaction of phosphoric acid and trichlorosilane and used to convert an alkyl chloride (1-chlorooctane) to the corresponding primary phosphine, which was isolated in 41% yield. Anion 1 was also prepared from [TBA][H₂PO₄] and isolated in 62% yield on a gram scale. Treatment of [TBA]1 with an excess of benzyl chloride leads to the formation of tetrabenzylphosphonium chloride, which was isolated in 61% yield. Sulfide 2 was used as a thionation reagent, converting benzophenone to thiobenzophenone in 62% yield. It also converted benzyl bromide to benzyl mercaptan in 55% yield. The TBA salt of trimetaphosphate ([TBA]₃[P₃O₉]·2H₂O), also a precursor to anion 1, was found to react with either trichlorosilane or silicon(IV) chloride to provide bis(trimetaphosphate)silicate, [TBA]₂[Si(P₃O₉)₂], characterized by NMR spectroscopy, X-ray crystallography, and elemental analysis. Trichlorosilane reduction of [TBA]₂[Si(P₃O₉)₂] also provided anion 1. The electronic structures of 1 and 2 were investigated using a suite of theoretical methods; the computational studies suggest that the trichlorosilyl ligand is a good π-acceptor and forms σ-bonds with a high degree of s character.

Facile Solution Synthesis of Red Phosphorus Nanoparticles for Lithium Ion Battery Anodes

Red phosphorus (RP) has attracted extensive attention as an anodic material for lithium-ion batteries (LIBs) due to its high theoretical specific capacity of 2596 mA h g- 1 and earth abundance. However, the facile and large-scale preparation of the red phosphorus nanomaterials via a solution synthesis remains a challenge. Herein, we develop a simple and facile solution method to prepare red phosphorus nanoparticles (RP NPs). PCl3 readily reacts with HSiCl3 in the presence of amines at room temperature to produce amorphous RP NPs with sizes about 100-200 nm in high yields. When used as an anode for rechargeable lithium ion battery, the RP NP electrode exhibits good electrochemical performance with a reversible capacity of 1380 mA h g- 1 after 100 cycles at a current density of 100 mA g- 1, and Coulombic efficiencies reaching almost 100% for each cycle. The study shows that this solution synthesis is a facile and convenient approach for large-scale production of RP NP materials for use in high-performance Li-ion batteries.

Breaking Carbon-Chlorine Bonds with the Unconventional Lewis Acid Dodecachlorocyclohexasilane

c-Si₆Cl₁₂ functions as a Lewis acid strong enough to abstract chloride ions from 2 mol of triphenylchloromethane to form the salt [Tr⁺]₂[Si₆Cl₁₄^2-]. This is the first example of a Lewis acid "hole" breaking a carbon-halogen bond.

Tetrel Bonding Interactions in Perchlorinated Cyclopenta- and Cyclohexatetrelanes: A Combined DFT and CSD Study

In this manuscript, we combined DFT calculations (PBE0-D3/def2-TZVP level of theory) and a Cambridge Structural Database (CSD) survey to evaluate the ability of perchlorinated cyclopenta- and cyclohexatetrelanes in establishing tetrel bonding interactions. For this purpose, we used Tr₅Cl₁₀ and Tr₆Cl₁₂ (Tr = Si and Ge) and HCN, HF, OH⁻ and Cl⁻ as electron donor entities. Furthermore, we performed an Atoms in Molecules (AIM) analysis to further describe and characterize the interactions studied herein. A survey of crystal structures in the CSD reveals that close contacts between Si and lone-pair-possessing atoms are quite common and oriented along the extension of the covalent bond formed by the silicon with the halogen atom.

Mechanism of Charged, Neutral, Mono-, and Polyatomic Donor Ligand Coordination to Perchlorinated Cyclohexasilane (Si6Cl12)

We report the detailed computational study of several perchlorinated cyclohexasilane (Si₆Cl₁₂)-based inverse sandwich compounds. It was found that regardless of the donor ligand size and charge, for example, Cl^- and CN^- anions or neutral HCN and NCPh nitriles, their coordination to the puckered Si₆Cl₁₂ ring results in its flattening. The NBO and CDA studies of the complexes showed that coordination occurs due to hybridization of low-lying antibonding σ*(Si-Cl) and σ*(Si-Si) unoccupied molecular orbitals (UMOs) of Si₆Cl₁₂ and occupied molecular orbitals (OMOs) of donor molecules (predominantly lone-pair-related), resulting in donor-to-ring charge transfer accompanied by complex stabilization and ring flattening. It is known that the Si₆ ring distortion results from vibronic coupling of OMO and UMO pairs (pseudo-Jahn-Teller effect, PJT). Consequently, the Si₆ ring flattening most probably occurs due to suppression of the PJT effect in all of the studied compounds. In this paper, the stabilization energy E(2) associated with donor-acceptor charge transfer (delocalization) was estimated using NBO analysis for [Si₆Cl₁₂·2Cl]^2-, [Si₆Cl₁₂·2(NC)]^2-, Si₆Cl₁₂·2(NCH), and Si₆Cl₁₂·2(NCPh). It was found that the polarizability of the donor might significantly affect the stabilization energy value (Cl^- > CN^- > HCN). For the neutral complexes, the E(2) value is correlated with the charge on the nitrogen atoms. All of these factors, that is, specific donor E(2) value, charge transfer, complex MO energy diagrams, and so on, should be taken into account when choosing the ligands suitable for forming Si-based 1D compounds and other nanoscale materials.

Silicon chemistry in zero to three dimensions: from dichlorosilylene to silafullerane

As one of the simplest examples of functionalized Si(ii) species, the SiCl₂/[SiCl₃]⁻ system is not only fundamentally interesting, but also an important starting point for the assembly of oligosilane chains, rings, and clusters.

The Weakly Coordinating Tris(trichlorosilyl)silyl Anion

Closely following the procedure for the preparation of the base-stabilized dichlorosilylene complex NHC^Dipp ⋅SiCl₂ reported by Roesky, Stalke, and co-workers (Angew. Chem. Int. Ed. 2009, 48, 5683-5686), a few crystals of the salt [NHC^Dipp -H⋅⋅⋅Cl⋅⋅⋅H-NHC^Dipp ]Si(SiCl₃ )₃ were isolated, aside from the reported byproduct [NHC^Dipp -H⁺ ⋅⋅⋅Cl^- ], and characterized by X-ray crystallography (NHC^Dipp =N,N-di(2,6-diisopropylphenyl)imidazo-2-ylidene). They contain the weakly coordinating anion Si(SiCl₃ )₃^- , which was also obtained in high yields upon deprotonation of the conjugate Brønsted acid HSi(SiCl₃ )₃ with NHC^Dipp or PMP (PMP=1,2,2,6,6-pentamethylpiperidine). The acidity of HSi(SiCl₃ )₃ was estimated by DFT calculations to be substantially higher than those of other H-silanes. Further DFT studies on the electronic structure of Si(SiCl₃ )₃^- , including the electrostatic potential and the electron localizability, confirmed its low basicity and nucleophilicity compared with other silyl anions.

Room-Temperature Solution Synthesis of Mesoporous Silicon for Lithium Ion Battery Anodes

As an important optoelectronic and energy-storage material, porous silicon (PSi) has attracted great interest in various fields. The preparation of PSi, however, usually suffers from low yields and/or complicated syntheses. Herein, we report a facile solution method to prepare PSi with controllable high specific surface area. Commercial Zintl compound Mg₂Si readily reacts with HSiCl₃ in the presence of amines at room temperature to produce amorphous PSi in high yields, where in situ formed salt byproducts serve as templates to generate uniform mesopores of ca. 3.8 nm in diameter. After crystallization treatment at 700 °C in flow Ar gas for 40 min, the obtained crystalline PSi coated with carbon layers shows excellent electrochemical performance when served as lithium ion battery anodes. The reversible specific capacity is about 2250 mA h g^-1 at 0.1 A g^-1 and the capacity retention is maintained at 90% after cycling at high current density of 2 A g^-1 for 320 times. This simple, facile preparation method is very promising and paves the way for massive production of porous Si as high-performance anodes in Li-ion battery industry or for other applications, such as drug delivery systems and catalysis.

A Computational Scheme To Evaluate Hamaker Constants of Molecules with Practical Size and Anisotropy

We propose a computational scheme to evaluate Hamaker constants, A, of molecules with practical sizes and anisotropies. Upon the increasing feasibility of diffusion Monte Carlo (DMC) methods to evaluate binding curves for such molecules to extract the constants, we discussed how to treat the averaging over anisotropy and how to correct the bias due to the nonadditivity. We have developed a computational procedure for dealing with the anisotropy and reducing statistical errors and biases in DMC evaluations, based on possible validations on predicted A. We applied the scheme to cyclohexasilane molecule, Si₆H₁₂, used in "printed electronics" fabrications, getting A ≈ 105 ± 2 zJ, being in plausible range supported even by other possible extrapolations. The scheme provided here would open a way to use handy ab initio evaluations to predict wettabilities as in the form of materials informatics over broader molecules.

Branched Hydrosilane Oligomers as Ideal Precursors for Liquid-Based Silicon-Film Deposition

Herein a convenient synthetic method to obtain 2,2,3,3-tetrasilyltetrasilane 3 and 2,2,3,3,4,4-hexasilylpentasilane 4 on a multigram scale is presented. Proton-coupled ²⁹ Si NMR spectroscopy and single-crystal X-ray crystallography enabled unequivocal structural assignment. Owing to their unique properties, which are reflected in their nonpyrophoric character on contact with air and their enhanced light absorption above 250 nm, 3 and 4 are valuable precursors for liquid-phase deposition (LPD) and the processing of thin silicon films. Amorphous silicon (a-Si:H) films of excellent quality were deposited starting from 3 and characterized by conductivity measurements, ellipsometry, optical microscopy, and Raman spectroscopy.

Dodecaallylhexasilacyclohexane

The molecule of the title compound, C36H60Si6, exhibits point group symmetryCi, with the centre of inversion located at the centre of the Si6ring. The Si6ring has a chair conformation. In the crystal, molecules are linkedviaC—H...π(allyl) interactions.

Toward the Mechanism of Perchlorinated Cyclopentasilane (Si5Cl10) Ring Flattening in the [Si5Cl10·2Cl]2- Dianion

We report the detailed computational study of flattening of the puckered Si₅ ring by suppression of the pseudo-Jahn-Teller (PJT) effect through coordination of two Cl^- anions to the molecule forming an inverse sandwich dianion [Si₅Cl₁₀·2Cl]^2- complex. The PJT effect that causes nonplanarity of the Si₅Cl₁₀ structure (C_s) results from vibronic coupling of pairs of occupied molecular orbitals (OMOs) and unoccupied molecular orbitals (UMOs). It was shown that filling the intervenient molecular orbitals of puckered Si₅Cl₁₀ with valent electron pairs of Cl^- donors suppresses the PJT effect, with the Si₅ ring becoming planar (D_5h) upon complex formation. In this paper, the stabilization energy E(2) associated with donor-acceptor charge transfer (delocalization) was estimated using NBO analysis for all studied inverse sandwich compounds [Si₅Cl₁₀·2X]^2- (where X = F, Cl, Br). It was found that the polarizability of the donor ion might significantly affect the stabilization energy value and should be taken into account when choosing the ligands suitable for forming Si-based one-dimensional compounds and other nanoscale materials.

Comparison of tetrel bonds and halogen bonds in complexes of DMSO with ZF3X (Z = C and Si; X = halogen)

A theoretical study of the complexes formed by dimethylsulfoxide (DMSO) with ZF₃X (Z = C and Si; X = halogen) has been performed at the MP2/aug-cc-pVTZ level.

Comparison of hydrogen, halogen, and tetrel bonds in the complexes of HArF with YH3X (X = halogen, Y = C and Si)

Ab initio calculations were performed in order to find equilibrium structures with tetrel, hydrogen or halogen bonds on the potential energy surfaces of the complexes formed between HArF and YH3X (X = halogen, Y = C and Si).

Group 14 inorganic hydrocarbon analogues

This Review article deals with the synthesis and properties of inorganic hydrocarbon analogues: binary chemical species that contain heavier Group 14 elements (Si, Ge, Sn or Pb) and hydrogen as components. Rapid advances in our general knowledge of these species have enabled the development of industrially relevant processes such as the hydrosilylation of unsaturated substrates and the chemical vapor deposition of semi-conducting films.

Lewis acidity of Si6Cl12 and its role as convenient SiCl2 source

The free cyclohexasilane Si6Cl12 (1) was obtained in 66% yield from the corresponding Cl(-) diadduct [nBu4N]2[1·2Cl] and AlCl3 in C6H6. The substituted cyclohexasilane 1,1-(Cl3Si)2Si6Cl10 (2), however, cannot be liberated from [nBu4N]2[2·2Cl] under comparable reaction conditions. Instead, a mixture of several products was obtained, from which the oligosilane Si19Cl36 (3) crystallized in low yields. X-ray crystallography revealed 3 to consist of two Si5 rings, bridged by one silicon atom. Compound 1 possesses Lewis acidic sites above and below the ring centroid. Competition experiments reveal that their corresponding acid strengths are comparable to that of BCl3. The reaction of 1 with 6 equiv of 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (Idipp) leads to a complete breakdown of the cyclic scaffold and furnishes the dichlorosilylene adduct Idipp-SiCl2.

A structural study of Si6-ring-containing [Si6Cl14](2-) chlorosilicates

The crystal structures of four substituted-ammonium dichloride dodecachlorohexasilanes are presented. Each is crystallized with a different cation and one of the structures contains a benzene solvent molecule: bis(tetraethylammonium) dichloride dodecachlorohexasilane, 2C8H20N(+)·2Cl(-)·Cl12Si6, (I), tetrabutylammonium tributylmethylammonium dichloride dodecachlorohexasilane, C16H36N(+)·C13H30N(+)·2Cl(-)·Cl12Si6, (II), bis(tetrabutylammonium) dichloride dodecachlorohexasilane benzene disolvate, 2C16H36N(+)·2Cl(-)·Cl12Si6·2C6H6, (III), and bis(benzyltriphenylphosphonium) dichloride dodecachlorohexasilane, 2C25H22P(+)·2Cl(-)·Cl12Si6, (IV). In all four structures, the dodecachlorohexasilane ring is located on a crystallographic centre of inversion. The geometry of the dichloride dodecachlorohexasilanes in the different structures is almost the same, irrespective of the cocrystallized cation and solvent. However, the crystal structure of the parent dodecachlorohexasilane molecule shows that this molecule adopts a chair conformation. In (IV), the P atom and the benzyl group of the cation are disordered over two sites, with a site-occupation factor of 0.560 (5) for the major-occupied site.