Reactivities of tetrahalosilanes and silane with sulphur trioxide

Reactions of tetrahalosilanes [SiX₄ (X= F, Cl or Br)] and silane (SiH₄) with sulphur trioxide (SO₃) have been studied under different experimental conditions. Each of the silanes behaves differently in accordance with the bond energy of the Si—X bond. While SiF₄ remains unreactive even at 600°C, SiCl₄ reacts with SO₃ at 500°C giving rise to hexachlorodisiloxane [(SiCl₃)₂O] as the major product. In contrast SiBr₄ and SiH₄ react with SO₃ at room temperature and below room temperature, respectively, yielding silica as one of the products of reaction. In all cases the SO₃ is reduced to sulphur dioxide.     

Die Bildungsenthalpien einiger Siliciumtetrahalogenid—Pyridin-Addukte

The enthalpies of formation of the addition compounds F₄Si(py)₂, Cl₄Si(py)₂, Br₄Si(py)₂ and I₄Si(py)₄ have been measured calorimetrically by two different ways (see table 1). It was not possible to confirm enthalpy data published in^{7, 8}. The sequence SiF₄4～SiBr₄>SiI₄(?) is proposed for the acceptor power of the silicon tetrahalides towards pyridine.     

Beiträge zur Chemie der Halogensilan-Addukte. XVII. Darstellung,Kristall- und Molekülstruktur von (2, 2′ -Bipyridin)- trichloro (trichlorosiloxy)- silicium,Cl3SiOSiCl3. bipy

Contributions to the Chemistry of Halosilane Adducts. XVII. Preparation, Crystal and Molecular Structure of (2, 2′ -Bipyridine) - trichloro - (trichlorosiloxy) -silicon, Cl₃SiOSiCl₃. bipy 1 is obtained by the reaction of Cl₃SiOSiCl₃ and bipy. It crystallizes orthorhombic in the space group Pca2₁ (Z = 4). 1 contains a tetracoordinated and a hexacoordinated Si atom. The plain defined by coordinated bipy also contains the SiOSi group. The SiOSi bonding angle (152.8°) is larger than that of Cl₃SiOSiCl₃ (146°). The SiCl bonds are about 8% longer than the tetrahedral SiCl bonds. The two SiO bond lengths are different (1.684; 1.554 Å). The SiN distances (average 1.967 Å) as well as the other bond distances correspond to values found for related compounds. Configuration, SiOSi bond angle and other structural features are due to steric requirements. 1 represents the structure of least steric hindrance. The same structure is found in solution (¹H-NMR). The results confirm that sterically more demanding ligands preferentially occupy the positions vertical to the plain of bipy (phen) in octahedral bip(phen) complexes of Si, hereby minimizing steric repulsions among each other(trans positions) and by CH groups of bipy(phen) exerted on ligands in he plain of bipy(phen).     

Bildung siliciumorganischer Verbindungen. LXII. Teilbromierte Carbosilane

Formation of Organosilicon Compounds. LXII. Partial Brominated Carbosilanes The photobromination of 1 leads to compound 2 as well as to C-chlorinated derivatives if the time of reaction is prolonged. Compound 2 is also formed from (Br₂Si–CH₂)₃; Gl. (1) see ?Inhaltsübersicht”?. In a corresponding reaction (Cl₃Si–CH₂)₂SiCl₂ gives successively Cl₃Si–CHBr–SiCl₂–CH₂–SiCl₃, Cl₃Si–CBr₂–SiCl₂–CH₂–SiCl₃ and Cl₃Si–CCl₂–SiCl₂–CH₂–SiCl₃. (Cl₃Si)₂CBr₂ is accessible through the photobromination of (Cl₃Si)₂CH₂. The reactivity of the CBr₂-group is quite obvious in the reaction of Cl₂Si–CBr₂–SiCl₂–CH₂–SiCl₃ with LiAlH₄ yielding (H₃Si–CH₂)₂SiCl₂ as well as in the reaction of compound 2 with CH₃MgCl yielding [(CH₃)₂Si–CH₂]₃. By treatment of the SiH groups with bromine the preparation of compounds with the general formulas CH₃SiH_nBr_3?n; (H_3?nSiBr_n)₂CH₂; (H_3?nSiBr_n? CH₂)₂SiH_2?nBr_n; (H_2?nBr_nSi? CH₂)₃ and (H_3?nSiBr_n)₂CCl₂ is possible. Analysis of the nmr spectra shows that 1,3-Dibromo-1,3,5-trisilacyclohexane is formed to 67% in the trans and to 33% in the cis configuration; 1,3,5-Tribromo-1,3,5-trisilacyclohexane is formed to 80–90% in teh cis-trans configuration. The results of ¹H and ²⁹Si NMR investigations are reported.     

The stable silylene Si[(NCH2Bu)2C6H4-1,2]: Reactions with Group 14 element halides

Reaction of the thermally stable silylene Si[(NCH₂Bu^t)₂C₆H₄-1,2] (1) [abbrev. as Si(NN)] with SiX₄ (X = Cl or Br) afforded the disilanes (NN)SiX(SiX₃) and [(NN)SiX]₂ (X = Br only), the trisilane (NN)SiX-[(SiX₃)Si(NN)] and the monosilane (NN)SiX₂ (X = Br only), whereas treatment of 1 with MCl₄ (M = Ge or Sn) yielded (NN)SiCl₂ and MCl₂. [(NN)SiBr]₂ and (NN)SiBr₂ were also obtained by reaction of 1 with Br₂. Reaction of 1 with PhSiCl₃ yielded the disilane (NN)SiCl(SiCl₂Ph) and trisilane [(NN)SiCl]₂SiClPh, whereas the disilane (NN)SiCl(SiCl₂Me) was obtained with MeSiCl₃. The trisilane (NN)SiCl-[(SiCl₃)Si(NN)] was thermally labile and converted to [(NN)SiCl]₂SiCl₂.     

Beiträge zur Chemie der Halogensilan-Addukte. VIII. Darstellung und Eigenschaften der kationischen Bis-2,2′-Bipyridin-Silicium-Komplexe, [SiCl2b[py2]2+ und [SiF2bipy2]2+

Contributions to the Chemistry of Halogenosilane Adducts. VIII. Preparation and Properties of the Cationic Bis-2,2′-Bipyridinesilicon Complexes, [SiCl₂bipy₂]²⁺ and [SiF₂bipy₂]²⁺ The reactions of SiCl₂bipy₂ (green isomer) and SiF₂bipy₂ with chlorine yield the new ionic complexes of Si, [SiX₂bipy₂]Cl₂ (X = Cl, F). Bromine and iodine react similarly. With these reagents, however, formation of insoluble polyhalides of the complex cations inevitably occurs rendering further investigations difficult. The compounds contain the cis-octahedral cation [SiX₂bipy₂]²⁺. They are soluble in methanol and water and are unusually stable in these solvents. [SiCl₂bipy₂]Cl₂ starts to react observably with methanol (substitution of SiCl) only after weeks. Thus reactions may be performed in this solvent. It follows from the investigation that the green isomer of SiCl₂bipy₂ is a cis-octahedral molecular complex of silicon. Two other green isomers of SiCl₂bipy₂ are shown to exist. The reactions of chlorine with these isomers yield products different from the cis-octahedral complex reported above. Ion-exchange and metathetical reactions of [SiCl₂bipy₂]Cl₂ yield the new compounds [SiCl₂bipy₂]X₂ (X = Br^?, J^?, NO₃^?, ClO₄^?, [Cr(NH₃)₂(NCS)₄]^?, PtCl₆^2?/2). All compounds contain the [SiCl₂bipy₂]²⁺-cation which is investigated in detail (¹H-, ²⁹Si-NMR, IR, UV, ESCA, conductivity, molecular weight). The use of AgF for the synthesis of ionic SiF-complexes (X = F) gives rise to more complicated reactions.     

Beiträge zur chemie der halogensilan-addukte XV. 2,2′-bipyridin- und 1,10-phenanthrolin-komplexe von halogendisilanen und Si3Cl8

A series of mono-bipy and -phen complexes (bipy = bipyridine, phen = phenanthroline) of the perhalodisilanes, Si₂F₆, Si₂Cl₆ and Si₂Br₆, mixed methylhalodisilanes (Si₂Me_nX_6?n, X = Cl, I; n = 2,3) and Si₃Cl₈ · bipy have been prepared by reaction of the components, and have been characterized. $\text{1}\text{1}$ complexes are obtained exclusively.The structures of all complexes involve coordination of the base to the more acidic silicon and perpendicular alignment of the SiSi axis on the plane of the ligand. This may be rationalised in terms of steric requirements of the different groups, the more demanding groups occupying the sterically more favorable positions vertical to the plane of the ligand. For Si₃Cl₈ · bipy, spectroscopic and chemical evidence suggests bipy-coordination to the center silicon. PMR investigations of the dissociation equilibria of the complexes in solution led to determination of the heats of formation of four of the complexes and to a qualitative estimation of the relative acceptor strengths of several disilanes. Contrary to expectation, silyl groups increase the acceptor strength of silicon considerably and in the order SiMe₃ < SiMe₂Cl < SiMeCl₂ < SiCl₃. The effect of a SiMe₃, substituent group may be compared to that of Cl. Methylchlorosilyl groups may exceed the effect of Cl as indicated by the increase in acceptor strength in the sequence (R =) Me < Ci < SiMe₂Cl < SiMeCl₂ for the acceptor RSiCl₂Me. Si₃Cl₈ is the strongest acceptor in the series. Assuming the structural suggestion for Si₃Cl₈ · bipy (center coordination) to be correct an increase in acceptor strength is indicated in the sequence SiCl₃(Si₂Cl₅) < SiCl₂(SiCl₃)₂ (Si = coordinating center). This may be interpreted mainly in terms of charge accepting capacity of the polarisable silyl groups. Another interesting sequence of acceptor strengths measured in this work is 1,1,2-Si₂Me₃F₃, 1,2-Si₂Me₂F₄ < Si₂Me₃Cl₃ < 1,2-Si₂Me₂Cl₄, showing fluorodisilanes to be weaker acceptors than chlorodisilanes. This result is compared to the heats of formation of SiX₄ · 2py complexes.     

Reactions of Silicon Tetrabromide and -iodide with Potassium Amide in liquid ammonia

SiBr₄ in absolute ether reacts with KNH₂ in liquid ammonia at ?60°C to give K₂Si₃(NH)₇ and K₂Si₂(NH)₅; attempts to prepare K₄Si(NH)₄ by using excess KNH₂ were without success. The reaction of SiI₄ in absolute ether with KNH₂ in liquid ammonia is incomplete at ?60°C even after 48 hours, about 80% SiI₄ remains unreacted. This reaction when carried out at room temperature gave K₂Si(NH)₃. All the three imidosilicates are amorphous and decompose in presence of traces of moisture to give corresponding oxosilicates.     

Alternativ-Liganden. XXII. Rhodium(I)-Komplexe mit Donor/Akzeptor-Liganden des Typs Me2PCH2CH2SiXnMe3−(X = F,Cl, OMe)

Alternative Ligands. XXII. Rhodium(I) complexes with Donor/Acceptor Ligands of the Typs Me₂PCH₂CH₂SiX_nMe_3?n(X = F, Cl, OMe) Donor/acceptor ligand of the type Me₂PCH₂SiX_nMe_3?n react with [Rh(CO)₂Cl]₂ ( 1 ) to give the mononuclear complexes RhCl(CO)(PMe₂CH₂CH₂SiX_nMe_3?n)₂ ( 2-6 , Table 1) with planar geometry of the donor atoms, one exception being Me₂PCH₂CH₂CH₂SiCl₃, yielding the crystalline Rh^III-complex RhCl₂(CO)(PMe₂CH₂CH₂SiCl₂)(PMe₂CH₂CH₂SiCl₃) ( 7 ) by oxidative addition of one of the SiCl bonds to the Rh¹ precursor. Structures with Rh → Si interaction between the basic central atoms and the acceptor group SiX_nMe_3?n could be detected in the isolated products neither spectroscopically nor by X-ray diffraction of the two representatives RhCl(CO)(PMe₂CH₂CH₂SiF₃)₂ ( 2 ) and RhCl(CO)[PMe₂CH₂CH₂siF₃]₂ ( 2 ) and RhCl(CO) [PMe₂CH₂CH₂Si(OMe₃]₂ ( 6 ). The presence of such acid/base adducts in the reaction mixture is indicated for the more acidic acceptor groups SiX_nMe_3?n byv_co values near 1990cm^?1, (see Table 3). The complex RhCl(CO)PMe₃)(PMe₂CH₂CH₂SiF₃ ( 8 ) is obtained by the reaction of RhCl(CO)(PMe₃)₂ ( 9 ) with Me₂PCH₂SiF₃ and has been identified spectroscopically in a mixture with 2 and 9 .     

Bildung siliciumorganischer Verbindungen. 70 [1]. Reaktionen Si-fluorierter 1,3,5-Trisilapentane mit CH3MgCl und LiCH3

Formation of Organosilicon Compounds. 70. Reactions of Si-fluorinated 1,3,5-Trisilapentanes with CH₃MgCl and LiCH₃ F₃Si? CCl₂? SiF₂? CH₂? SiF₃ 3 reacts with meMgCl. (me = Ch₃ starting with a Si-methylation and not with a C-metallation as in the corresponding Si- and C-chlorinated compounds, e. g. (Cl₃Si? CCl₂)₂SiCl₂ [2]. A CCl-hydrogenation is observed too, which in the case of F₃Si? CCl₂? SiF₂? CHCl? SiF₃ 4 gives meS₃Si? CCl₂? Sime₂? CH₂? Sime₃. (F₃Si? CCl₂)_{2 5} reacts with meMgCl to form preferentially 1,2-Disilapropanes by cleaving a Si? Cbond. The isolation of F₃Si? CCl₂H and meF₂Si? CCl₂? SiF₂me allows to locate the bond where 5 is cleaved at the beginning of the reaction. With meLi 5 reacts to form mainly me₃Si? C?C? Sime₃, showing that in the reaction of meLi, being a stronger reagent than meMgCl, and 5 a C-metallation occurs, following the same mechanism as in the reaction with (Cl₃Si? CCl₂)₂)SiCl₂ [2]. The reaction conditions for the synthesis of Si-fluroinated and C-chlorinated 1,3,5-Trisilapentanes in a 0.1 mol scale are reported. N.m.r. data of all investigated compounds are tabulated.     

Salze von Halogennophosphorsäuren. VII Darstellung und Eigenschaften von Siliciumdichlorphosphaten

Salts of Halogenophosphoric Acids. VII. Preparation and Properties of Silicon Dichlorophosphates By reaction of SiCl₄ or SiHCl₃ with dichlorophosphoric acid the compounds H[Si(PO₂Cl₂)₅] · C₂H₅OC₂H₅, H[Si(PO₂Cl₂)₅] or Si(PO₂Cl₂)₄ have been prepared, the composition of which depends on the solvents used. Some properties of these compounds are described and possible Constitutions are discussed.     

Ionische Strukturen von 4- bzw. 5fach koordiniertem Silicium Neue ionische Festkörperstrukturen von 4- bzw. 5fach koordiniertem Silicium: [Me3Si(NMI)]+Cl−, [Me2HSi(NMI)2]+Cl−, [Me2Si(NMI)3]2+ 2 Cl−· NMI

Ionic Structures of 4- and 5-coordinated Silicon. Novel Ionic Crystal Structures of 4- and 5-coordinated Silicon: [Me₃Si(NMI)]⁺ Cl^?, [Me₂HSi(NMI)₂]⁺ Cl^?, [Me₂Si(NMI)₃]²⁺ 2 Cl^?. NMI Me₃SiCl forms with N-Methylimidazole (NMI) a crystalline 1:1-compound which is stable at room temperature. The X-ray single crystal investigation proves the ionic structure [Me₃Si(NMI)]⁺Cl^? 1 which is the result of the cleavage of the Si? Cl bond and the addition of an NMI-ring. The reaction of Me₂HSiCl with NMI (in the molar ratio of 1:2), under cleavage of the Si? Cl bond and co-ordination of two NMI rings, yields the compound [Me₂HSi(NMI)₂]⁺Cl^? 2 . The analogous reaction of Me₂SiCl₂ with NMI (molar ratio 2:1) leads to a compound which consists of Me₂SiCl₂ and NMI in the molar ratio of 1:2. During the sublimation single crystals of the compound [Me₂Si(NMI)₃]²⁺ 2 Cl^?. NMI 3 are formed.     

Austauschreaktionen an komplexgebundenen liganden von elementen der IV. Hauptgruppe : III. Darstellung von halogen-, pseudohalogen- und hydridokomplexen des typs π-C5H5Fe(CO)2SiX3

The complexes CpFe(CO)₂SiBr₃, CpFe(CO)₂SiI₃, CpFe(CO)₂SiBr₂(OMe), and CpFe(CO)₂SiI(NH-cyclo-C₆H₁₁)₂ are prepared by the reaction of CpFe(CO)₂SiR₃ (R = OMe, NH-cyclo-C₆H₁₁) with HBr, HI and CH₃I. Treating CpFe(CO)₂SiCl₃ with a large excess of NaN₃, KOCN or KSCN yields the first tri-pseudohalogensilyl—transition-metal-complexes. The compounds are characterized by IR and mass spectra. A new method of preparation of the already known complex CpFe(CO)₂SiH₃ is described starting from CpFe(CO)₂SiCl₃ and LiAlH₄.     

1,3,2-Diazasiloles derived from 1,2-bis(trimethylsilylimino)acenaphthene

The reduction of 1,2-bis(trimethylsilylimino)acenaphthene (tms-BIAN, 1) with metallic lithium in toluene affords the dilithium salt (tms-BIAN)Li_2· 1,3,2-Diazasiloles (tms-BIAN)SiCl₂ (2) and (tms-BIAN)SiMe₂ (3) were prepared by the reactions of (tms-BIAN)Li₂ with SiCl₄ and Me₂SiCl₂, respectively. The reaction of (tms-BIAN)Li₂ with an excess of Me₂SiCl₂ produces (Cldms-BIAN)SiMe₂ (4), where Cldms-BIAN is 1,2-bis(chlorodimethylsilylimino)-acenaphthene. The compound (tms-BIAN)(SiCl₃)₂ (5) containing two different silyl substituents (Me₃Si and Cl₃Si) at each nitrogen atom was synthesized by the reaction of compound 1 with Cl₃SiSiCl₃. The elimination of SiCl₄ from compound 5 is accompanied by cyclization to give derivative 2. Compounds 2-5 were characterized by ¹H, ¹³C, and ²⁹Si NMR spectroscopy. The crystal structures of 2-5 were established by X-ray diffraction.     

cis‐Bis(2,2′‐bipyridyl‐N,N′)dichlorosilicon diiodide

The crystal and molecular structure of the title compound, C₂₀H₁₆Cl₂N₄Si²⁺·2I^?, has been determined at 173 K. To our knowledge, this is the first crystal structure of a silicon tetrahalide complex with a bidentate base as a ligand. The two chloro ligands are cis relative to each other. The Si—N bonds trans to a chloro ligand are longer than the Si—N bonds trans to an Si—N bond. This feature is observed for the majority of M(bipy)₂Cl₂ (M = metal and bipy = 2,2′‐bipyridyl) complexes, but it does not hold for all structures retrieved from the Cambridge Structural Database. The two pyridyl rings of each bipyridyl unit are nearly coplanar, whereas the bipyridyl units are almost perpendicular to each other. The two I^? ions are more than 5 Å from the silicon centre. As a result, the compound can definitely be described as ionic. The crystal packing is stabilized by short C—H?I contacts.     

Synthese der Silatetraphospholane (tBuP)4SiMe2, (tBuP)4SiCl2 und (tBuP)4Si(Cl)SiCl3 Molekül- und Kristallstruktur von (tBuP)4SiCl2

Synthesis of the Silatetraphospholanes (tBuP)₄SiMe₂, (tBuP)₄SiCl₂, and (tBuP)₄Si(Cl)SiCl₃ Molecular and Crystal Structure of (tBuP)₄SiCl₂ The reaction of the diphosphide K₂[(tBuP)₄] 7 with the halogenosilanes Me₂SiCl₂, SiCl₄ or Si₂Cl₆ in a molar ratio of 1:1 leads via a [4 + 1]-cyclocondensation reaction to the silatetraphospholanes (tBuP)₄SiMe₂ 1,1-dimethyl-1-sila-2,3,4,5-tetra-t-butyl-2,3,4,5-tetraphospholane, 1 , (tBuP)₄SiCl₂, 1,1-dichloro-1-sila-2,3,4,5-tetra-t-butyl-2,3,4,5-tetraphospholane, 2 , and (tBuP)₄Si(Cl)SiCl₃, 1-chloro-1-trichlorsilyl-1-sila-2,3,4,5-tetra-t-butyl-2,3,4,5-tetraphospholane, 3 , respectively, with the 5-membered P₄Si ring system. The reaction leading to 1 is accompanied with the formation of the by-product Me₂(Cl)-Si–(tBuP)₄–Si(Cl)Me₂ 1a (5:1), which has a chain structure. On warming to 100°C 1a decomposes to 1 and Me₂SiCl₂. The compounds 2 and 3 do not react further with an excess of 7 due to strong steric shielding of the ring Si atoms by the t-butyl groups. 1, 2 and 3 could be obtained in a pure form and characterized NMR spectroscopically; 2 was also characterized by a single crystal structure analysis. 1a was identified by NMR spectroscopy only.     

Infrared Laser Photochemistry of Trichlorosilane

IR multiphoton dissociation of trichlorosilane molecules in scavenger gas (O₂, CO₂, OCS, halomethanes, BCl₃, TiCl₄, etc.) media was studied. Stable, volatile dissociation products were determined. It was shown that the product formation mechanism depends on the partial pressure of SiHCl₃. At a high pressure (400–800 Pa) of SiHCl₃, its photolysis in a mixture with fluorine-, chlorine-, or bromine-containing scavengers led to the formation of products of the SiF_{4 – n} Cl _n and SiBr_{4 – n} Cl _n type, where n = 1–4. An SiHCl₃ conversion into SiCl₄ higher than 70% could be achieved. The formation mechanism was proposed for the photolysis products. At a low SiHCl₃ pressure (<70 Pa), the formation of a stable volatile product was observed only in a mixture with BCl₃, which resulted from the reaction of insertion of SiCl₂ in the B–Cl bond.     

Bildung siliciumorganischer Verbindungen. 110. Reaktionen von (Cl3Si)2CCl2, seiner Si-methylierten Derivate,von (Cl3Si)2CHCl, (Cl3Si)2C(Cl)Me und Me2CCl2 mit Silicium (Cu-Kat.)

Formation of Organosilicon Compounds. 110. Reactions of (Cl₃Si)₂CCl₂ and its Si-methylated Derivatives as well as of (Cl₃Si)₂CHCl, (Cl₃Si)₂C(Cl)Me and Me₂CCl₂ with Silicon (Cu cat.) The reactions of (Cl₃Si)₂CCl₂ 1 , its Si-methylated derivatives (Me₃Si)₂CCl₂ 8 , Me₃Si? CCl₂? SiMe₂Cl 9 , (ClMe₂Si)₂CCl₂ 10 , Me₃Si? CCl₂? SiMeCl₂ 11 , Cl₂MeSi? CCl₂? SiCl₃ 12 as well as of (Cl₃Si)₂CHCl 38 , (Cl₃Si)₂CClMe 39 and of Me₂CCl₂ with Si (Cu cat.) in a fluid bed reactor ( 38 and 39 also in a stirred solid bedreactor) arc presented. While (Cl₃Si)₂CCl₂ 1 yields C(SiCl₃)₄ 2 the 1,1,3,3-tetrachloro-2,2,4,4-tetrakis(trichlorsilyl)-1,3-disilacyclobutane Si₆C₂Cl₁₆ 3 and the related C-spiro linked disilacyclobutanes Si₈C₃Cl₂₀ 4 , Si₁₀C₄Cl₂₄ 5 , Si₁₂C₅Cl₂₈ 6 , Si₁₄C₆Cl₃₂ 7 this type of compounds is not obtained starting from the Si-methylated derivatives 8, 9, 10, 11 They Produce a number of variously Si-chlorinated and -methylated tetrasila- and trisilamethanes. However, Cl₂MeSi? CCl₂? SiCl₃ 12 forms besides of Si-chlorinated trisilamethanes also the disilacyclobutanes Si₆C₂Cl₁₅Me 34 and cis- and trans Si₆C₂Cl₁₄Me₂ 35 as well as the spiro-linked disilacyclobutanes Si₈C₃Cl₁₉Me 36 , Si₈C₃Cl₁₈Me₂ 37 . (Cl₃Si)₂CHCl 38 mainly yields HC(SiCl₃)₃ 31 and also the disilacyclobutanes cis- and trans-(Cl₃Si)HC(SiCl₂)₂CH(SiCl₃) 41 and (Cl₃Si)₂C(SiCl₂)₂CH(SiCl₃) 45 the 1,3,5-trisilacyclohexane [Cl₃Si(H)C? SiCl₂]₃ 44 as well as [(Cl₃Si)₂CH]₂SiCl₂, and (Cl₃Si)₂CClMe 39 mainly yields (Cl₃Si)₂C?CH₂and (Cl₃Si)₂besides of HC(SiCl₃)₃, MeC(SiCl₃)₃and (Cl₃Si)₃C? SiCl₂Me.,. Me₂CCl₂ 59 mainly yields Me(Cl)C?CH₂, Me₂CHCl and HCl₂Si? CMe₂? SiCl₃, besides of Me₂C(SiCl₃)₂ and Me₂C(SiCl₂H)₂ Compound 3 crystallizes triclinically in the space group P1 (Nr. 2) mit a = 900,3, b = 914,0, c = 855,3 pm, α = 116,45°, β = 101,44°, γ = 95,86° and one molecule per unit cell. Compound 4 crystallizes monoclinically in thc space group C2/c (no. 15) with a = 3158.3,b = I 103.7, c = 2037.4 pm, β = 1 16.62° and 8 molecules pcr unit cell. The disilacyclobutane ring of compound 3 is plane, showing a mean distance of d (Si-C) =19 1.8 pm and the usual deformations of endocyclic angles: α_Si = 94,2°> 85,8° = α_C.The spiro-linked disilacyclobutane rings of compound 4 are slightly folded by a mean angle of (19.0°). Their mean distances were found to be d (Si? C) = 190.4 pm relating to the central carbon atom and 192.0 pm to the outer ones, respectively. The deformations of endocyclic angles: α_Si = 93,9°> 84,4° = α_C are comparable to those of compound 3.     

Umsetzung von gemischten Siliciumhalogeniden und von Halogendisilanen mit Pyridin und 1,10-Phenanthrolin

Zusammenfassung Die Reaktion gemischter Siliciumhalogenide mit Pyridin (=py) oder 1,10-Phenanthrolin (=phen) führte zu den Additionsverbindungen SiClBr₃(py)₂, SiClBr₃(phen), SiCl₃Br(py)₂, SiCl₃Br(phen), SiCl₂J₂(py)₄, SiCl₂J₂(phen), SiCl₃J(py)₃ und SiCl₃J(phen). Eine Dismutation der gemischten Siliciumhalogenide wurde dabei nicht beobachtet. Ihre Darstellung erfolgte durch Umsetzung von ClSi(Net ₂)₃, Cl₂Si(Net ₂)₂ und Cl₃Si(Net ₂) (et=C₂H₅) mit HBr oder HJ. Si₂Cl₆ reagierte mit 3py zu SiCl₄(py)₂ und 1/n [SiCl₂(py)] _n , Si₂Br₆ analog zu SiBr₄(py)₂ und 1/n [SiBr₂(py)] _n , Si₃Cl₈ mit 4py zu SiCl₄(py)₂ und 2/n [SiCl₂(py)] _n .

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The reactions of mixed silicon halogenides with pyridine (=py), or 1.10-phenanthroline (=phen) resulted in the addition compounds SiClBr₃(py)₂, SiClBr₃(phen), SiCl₃Br(py)₂, SiCl₃Br(phen), SiCl₂I₂(py)₄, SiCl₂I₂(phen), SiCl₃I(py)₃ and SiCl₃I(phen). Dismutation of the mixed silicon halogenides in these reactions was not observed. Their preparation was achieved by cleaving of Si–N-bonds in ClSi(Net ₂)₃, Cl₂Si(Net ₂)₂ and Cl₃Si(Net ₂) (et=C₂H₅) with HBr or HI. Si₂Cl₆ reacted with 3py forming SiCl₄(py)₂ and 1/n [SiCl₂(py)] _n . The analogous reaction of Si₂Br₆ resulted in SiBr₄(py)₂ and 1/n [SiBr₂(py)] _n . Si₃Cl₈ and 4py formed SiCl₄(py)₂ and 2/n [SiCl₂(py)] _n .

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Mit 1 Abbildung

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66. Mitt.:U. Wannagat, K. Hensen, P. Petesch undF. Vielberg, Mh. Chem.98, 1415 (1967).

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Zugleich 7. Mitt. über Verbindungen von Nichtmetallhalogeniden mit Pyridin und seinen Homologen; 6. Mitt.:U. Wannagat, K. Hensen undP. Petesch, Mh. Chem.98, 1423 (1967).

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Mit Auszügen aus den DissertationenF. Vielberg, Techn. Hochsch. Aachen 1956, undK. Hensen, T. H. Aachen 1962.     

A Disilene Base Adduct with a Dative Si–Si Single Bond

An experimental and theoretical study of the base‐stabilized disilene 1 is reported, which forms at low temperatures in the disproportionation reaction of Si₂Cl₆ or neo‐Si₅Cl₁₂ with equimolar amounts of NMe₂Et. Single‐crystal X‐ray diffraction and quantum‐chemical bonding analysis disclose an unprecedented structure in silicon chemistry featuring a dative Si→Si single bond between two silylene moieties, Me₂EtN→SiCl₂→Si(SiCl₃)₂. The central ambiphilic SiCl₂ group is linked by dative bonds to the amine donor and the bis(trichlorosilyl)silylene acceptor, which leads to push–pull stabilization. Based on experimental and theoretical examinations a formation mechanism is presented that involves an autocatalytic reaction of the intermediately formed anion Si(SiCl₃)₃^? with neo‐Si₅Cl₁₂ to yield 1 .