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.     

Bildung siliciumorganischer Verbindungen. 73. Reaktionen C-chlorierter 1,3-Disilapropane mit CH3MgCl

Formation of Organosilicon Compounds. 73. Reactions of C-chlorinated 1,3-Disilapropanes with CH₃MgCl (Cl₃Si)₂CCl₂ reacts with an excess of meMgCl (me = CH₃) in Et₂O (diethylether) forming (me₃Si)₂₂C?CH₂ mainly besides Si-methylated 1,3-disilapropanes with CmeCl, CHCl, CH₂ groups [6]. For investigating the mechanism of formation of the methylidengroup reactions were carried out with differently Si-methylated and Si-chlorinated 2-methyl-1-2-chloro-1,3-disilapropanes and 2,2-dichloro-1,3-disilapropanes. Whereas (me₃Si)₂CmeCl reacts neither with meMgCl nor with Lime. it forms (me₃Si)₂C?CH₂ and (me₃Si)₂CmeH with Li or Mg resp. The reaction starts with the metallation to (me₃Si)₂CmeLi and (me₃Si)₂Cme(MgCl) resp., followed by elimination of LiH and HMgCl resp. with formation of (me₃Si)₂C?CH₂. LiH and HMgCl resp. reduces (me₃Si)₂CmeCl to (me₃Si)₂CmeH. This mechanism is supported by the reactions of (me₃Si)₂CCl(CD₃). The Si-chlorination increases the reactivity of the CmeCl group and the created C?CH₂ group favours Si-methylation. The CCl₂ group is more reactive than the CmeCl group; (me₃Si)₂CCl₂ already forms the methyliden group with meMgCl in Et₂O via the not isolated intermediate (me₃Si)₂CCl(MgCl). which prefers the methylation to (me₃Si)₂Cme(MgCl). The n.m.r. data of the investigated compounds are given.     

Bildung siliciumorganischer Verbindungen. LI. Reaktionen verschieden chlorierter 1,3,5-Trisila-cyclohexane mit CHMgCl und ihre 29SiNMR-Spektren

Formation of Organosilicon Compounds. LI. Reactions of Various Chlorinated 1.3.5-Trisilacyclohexanes with CH₃MgCl and their ²⁹SiNMR Spectra The reaction of (a) with meMgCl starts with the formation of a Grignard compound of (a) and forms (c) via (b). The reaction sequence will be described. The ring contraction of the six-membered ringsystem is also observed with compound (d) leading to (e), whereas (f) reacts to (g), the ringsystem being maintained. No ring-contraction is observed when investigating the reactions of the derivatives containing Si? H- and C? Cl-groups. Compound (i) gives rise to (j), (k) to (l) whereas cleavage occurs with (m) and (n) does not react under the conditions applied. According to the PMR and ²⁹SiNMR spectra, the polarity of the Si? Cl-bond decreases in the compounds containing Si? Cl and CCl-groups by increasing the number of CCl₂ groups. In the compounds containing Si? H and C? Cl-groups the polarity of the Si? H-bond increases with the degree of chlorination at the C-atom. By that, the different chemical behaviour can be understood. The preparations of the starting compounds are described.     

Bildung siliciumorganischer Verbindungen. 109. Reaktionen vollhydrierter Carbosilane mit Lithiumalkylen

Formation of Organosilicon Compounds. 109. Reactions of Perhydrogenated Carbosilanes with Alkyl-Lithium Compounds Si-hydrogenated linear carbosilanes react with MeLi or nBuLi to give the Si-alkylated derivatives. In contrast to the Si-methylated derivatives of (H₃Si? CH₂)₂SiH₂ 1 and (H₃Si)₂CH₂ 2 and to (Me₂Si? CH₂)₃ no lithiation of CH₂ groups is observed. Such, 1 with nBuLi yields nBuH₂Si? CH₂? SiH₂? CH₂? SiH₃ 5 and (nBuH₂Si? CH₂)₂SiH₂ 6 . 2 reacts with nBuLi to give nBuH₂Si? CH₂SiH₃ 7 and (nBuH₂Si)₂CH₂ 8 besides of 1, 5 und 6 . The latter results from a cleavage of a Si? C bond in 2 Producing nBuSiH₃ and LiCH₂? SiH₃ which combines with 2 to 1 . Subsequently 1 forms 5 and 6 . No higher alkylated derivatives of 1 or 2 could be detected.     

Bildung siliciumorganischer Verbindungen. 86. Si-phenylierte und butylierte 1,3,5-Trisilacyclohexane

Formation of Organosilicon Compounds. 86. Si-phenyl and Si-butyl Substituted 1,3,5-Trisilacyclohexanes By treating (BrHSi? CH₂)₃ with phMgBr or t-buLi, resp., and subsequent separation of the isomers, the pure cis-cis substituted 1,3,5-trisilacyclohexanes I are accessible which yield II (Formula see Inhaltsübersicht) by reaction with Br₂. (F₂Si? CH₂)₃ 8 can be transferred into (ph₂Si? CH₂)₃ 7 with phLi. With HCl/AlCl₃ 7 forms (Cl₂Si? CH₂)₃, whereas even with an excess of Br₂ it only yields (phBrSi? CH₂)₃. Cleavage of 7 with one equivalent of Br₂ yields (H₂C? Si)₃ph₅Br 14, which with LiAlH₄ forms (H₂C? Si)₃ph₅H 10. 10 is not so easy to obtain via (H₂C? Si)₃ph₅F 9 from the reaction of 8 with 5 equivalents of phLi. All of the SiH and SiBr groups in I and II, resp., occupy axial positions as well as the Br atom in 14 the H atom at Si in 10 and the F atom in 9.     

Bildung siliciumorganischer Verbindungen. XXXXI. Synthese und Reaktionen des 1,1,3,3,5,5-Hexamethyl-1,3,5-trisila-6-methylen-cyclohexan und des 1,1,3,3,5,5-Hexamethyl-1,3,5-trisila-cyclohepten-6

The compounds (a) and (b) have been synthesized, and their reactions with Br₂, HBr, HSiCl₃ and HSime₂Br (me = CH₃) are described. The synthesis of (a) and (b) can be achieved by cycloaddition of Hme2Si? CH₂? Sime₂? CH₂? Sime₂? C?CH (c). (a) is also formed by cyclisation of (d) and (e) with Li. (d) and (e) can be prepared by ?SiH addition to HC?C? Si? compounds (cat. H₂PtCl₆ · 6 H₂O). With Br₂ (a) yields (f). whereas (b) yields the trans compound (g). The subsequent reactions of (f) and (g) with Br₂ and their decomposition via β-elimination to (i) (j) are reported. Both (a) and (b) react with HBr to (h), changing the size of the ring in the case of (b). (h) decomposes via β-elimination. HSiCl₃ and HSime₂Br addition to (a) yields 1,1,2-trisila-ethane derivates. All intermediate compounds of these syntheses and their NMR data are given.     

Bildung siliciumorganischer Verbindungen. 83. Bildung,Reaktionen und Struktur von Yliden aus perchlorierten Carbosilanen

Formation of Organosilicon Compounds. 83. Formation, Reactions, and Structure of Ylides Generated from Perchlorinated Carbosilanes The CCl-moiety in perchlorinated carbosilanes as (Cl₃Si)₂ a, Cl₃Si? CH₂? SiCl₂? CCl₂? SiCl₃ b, (Cl₃Si? CCl₂)₂SiCl₂ c or (Cl₂Si? CCl₂)₃ d, e.g., cleaves the Si? P bond of me₃Si? Pme₂ e (me = CH₃); and by subsequent rearrangement ylides are formed. Such, treating e with a yields (Cl₃Si)₂CPme₂Cl 1, which also results from the reaction of me₂P? Pme₂ with a. The ylides also can be obtained by means of treating the carbosilanes a, b, c or d with LiPme₂. Thus, c with one mole of LiPme₂ yields Cl₃Si? CCl₂? SiCl₂? C(Pme₂Cl)? SiCl₃ or Cl₃Si? C(Pme₂Cl)? SiCl₂? C(Pme₂Cl)? SiCl₃, resp., with two moles of LiPme₂. The corresponding Si-methylated derivates do not form ylides; (me₃Si)₂CCl₂, e.g., with e in benzene yields me₃Si? CH(Pme₂)? Sime₃. One mole of Lime methylates 1 to yield (Cl₃Si)₂CPme₃ 11. With either LiPme₂, me₃Si? Pme₂ or Me₂P? Pme₂ 1 forms (Cl₃Si)₂CPme₂-Pme₂. Reacting 1 with CH₃OH/(C₂H₅)₂NH, (Cl₃Si)[SiCl₂(OCH₃)]CPme₂(OCH₃) is formed. Ylides also result from the reactions of partially C-chlorinated 1,1,3,3,5,5-hexachloro-1,3,5-trisilacyclohexanes with me₃Si? Pme₂, (Cl₂Si? CCl₂)₃ with three moles of me₃Si? Pme₂ or LiPme₂, resp., yields (Cl₂Si? CPme₂Cl)₃ 16, the 1,1,3,3,5,5-Hexachlor-2,4,6-tris(chlordimethylphosphoranyliden)-1,3,5-trisilacyclohexan, which crystallizes with one mole of monoglyme. X-ray structure determinations revealed that 1, 11 and 16 are planar. As well the (P? C) as the (Si? C) bond lengths are remarkably shortened; in 1 (P? C) to 173.3 pm, (Si? C) to 173.3 pm, (Si? C) to 179.5 pm, in 16 (P? C) to 168.7 pm, (Si? C) to 180 pm. The (Si? C) and (P? C) bond orders amount to about 1.33, and are relatively equally distributed. Therefore, the charge of the formal carbanion is equally distributed, which shall be expressed by means of the following kind of writing for 1 and 16 see “Inhaltsübersicht”.     

Bildung siliciumorganischer Verbindungen. 108. Thermisch induzierte Reaktionen aminosubstituierter Disilane

Formation of Organosilicon Compounds. 108 [1]. Thermally Induced Reactions of Amino-Substituted Disilanes Thermally induced reactions of amino-substituted disilanes yield Si rich silanes. At 300°C, Me₃Si? SiMe₂? NMeH 1 yields Me₃Si? NMeH 2 and Me₃Si? (SiMe₂)₂-NMeH 3 in a ratio 1 : 2 : 3 = 1,6 : 1 : 1, whereas Me₃Si? SiMe₂? N(iPr)H 4 at 350°C yields Me₃Si? N(iPr)H 5 , Me₃Si? (SiMe₂)₂-N(iPr)H 6 and Me₃Si? (SiMe₂)₃? N(iPr)H 7 in a ratio of 4 : 6 : 7 = 0.8 : 1.0 : 0.6. Me₃Si? SiMe₂? NMe₂ 8 at 300°C (72 h) yields Me₃Si? NMe₂ 9 and Me₃Si-(SiMe₂)₂-NMe₂ 10 in a ratio of 9 : 8 : 10 = 1 : 0.22 : 0.44 The thermal stability of these disilanes is determined by the sterical requirements of the amino substituents NMeH < NMe₂ < N(iPr)H. The introduction of a second NMe₂ group decreases the stability and favours the formation of Si rich silanes. Such, Me₂N? (SiMe₂)₂? NMe₂ 11 already at 250°C (2 h) yields Me₂N? SiMe₂? NMe₂ 12 , Me₂N? (SiMe₂)₂? NMe₂ 13 and Me₂N? (SiMe₂)₄? NMe₂ 14 in a ratio of 11 : 13 : 14 = 0.3 : 0.9 : 1.0. The reactions can be understood as insertions of thermally produced dimethylsilylene into the Si? N bond of the disilanes. This process is strongly favoured as compared to the trapping reactions with Ph? C?C? Ph or Et₃SiH. The mentioned reactions correspond closely to those of the methoxy-disilanes[2]. However (MeN? SiMe₂? SiMe₂)₂ 15 , obtained from HMeN? (SiMe₂)₂? NMeH by condensation [3], at 400°C suffers a ring contraction to octymethyl-1,3-diaza-2,4,5-trisilacyclopentane (69 weight %), and yields also some solid residue, the composition of which corresponds to Si₃C₇NH₂₁.     

Bildung siliciumorganischer Verbindungen. 80. Die Si-Metallierung von 1,3,5-Trisilacyclohexanen mit Übergangsmetallkomplexen

Formation of Organosilicon Compounds. 80. Si-Metalation of 1,3,5-Trisilacyclohexanes by Means of Trisition Metal Complexes Several Si-transition metal-substituted 1,3,5-trisilacyclohexanes are reported. l-Bromo-1,3,5-trisilacyclohexane reacts with the metal carbonyl anions W(CO)₅cp^?, Mo(CO)₃cp-, Cr(CO)₃cp^?, Mn(CO)₃^?, Fe(CO)₂cp^?, or Co(CO)_4minus;, resp., yielding monosubstituted derivatives as 6, e. g.(cp = π-cyclopentadienyl). 1,3-Dibromo-1,3,5-trisilacyclohexane forms disubstituted compounds aa 7, e. g., with 2 moles of the metal carbonyl anions Fe(CO)₂cp^?, Mn(CO)₅^? or Co(CO)₄^?. Starting from (H₂c? SiHBr)₃ compound 13 is accessible by reaction with KCo(CO)₄. In the soluted compounds the metal carbonyl groups occupy the equatorial positions in the chair form of the six membered ring. The reaction of 13 with Co₂(CO)₈ yields 17 , whereas 6 preferrably forms 18 . Starting from (H₂C? SiH₂)3 the reaction with Co₂(CO)₂ preferrably yields 19. The reported compounds are crystalline, air – and moisture – sensitive. The reported formulae are assured by analysis, IR, and NMR investigations.     

Bildung siliciumorganischer Verbindungen. 67. Untersuchungen zur metallorganischen Synthese Si-methylierter und C-chlorierter Carbosilane über Chlorcarbenoide

Formation of Organosilicon Compounds. 67. Studies of Metallorganic Synthesis of Si-methylated and C-chlorinated Carbosilanes Using Chlorocarbenoids Synthesis and reactions of C₆H₅me₂Si? CCl₂H (A), (H₅C₆me₂Si)₂CCl₂ (B), and me₂Si(CCl₂H)₂ (C) were investigated in order to find conditions for the synthesis of C-functional carbosilanes via chlorocarbenoids. (A) and (B) react with n-butyl-Li(buLi) (?100°C/THF/ether/pentane) yielding H₅C₆me₂Si? CCl₂Li and (H₅C₆me₂Si)CClLi, respectively. These lithium reagents form (B) and(H₅C₆me₂Si)₃CCl with H₅C₆me₂SiCl. In the reaction of (H₅C₆me₂Si)₃CCl with lithium (H₅C₆me₂Si)₃CLi (D) is obtained. (D) forms with H₂O/HCl the compound (H₅C₆me₂Si)₃CH which is cleaved by HBr yielding (Brme₂Si)₃CH. (C) gives LiCCl₂? Sime₂(CCl₂H) with buLi (molar ratio 1:1) in a low temperature reaction. Clme₂Si? CCl₂? Sime₂(CCl₂H) is formed in the reaction of LiCCl₂? Sime₂? CCl₂H with Sime₂CCl₂ (yield >90%). Reacting (C) and buLi (1:3) and treating this solution with Sime₂CI₂ gives (ClSime₂)₂C?CH Sime₂Cl (>85%) via a monosilacyclopropane intermediate. In the inverse reaction, if (C) is added to buLi, (HCCl₂)me₂SiC?Sime₂(CCl₂H) is one of the isolated reaction products. If buLi is added to (C) (2:l) and this solution is treated with Sime₃Cl, compounds me₃Si? CCL₂? Sime₂? CCL₂H, me₃Si? CClH? Sime₂(CCl₂H), (me₃Si? CC1₂)₂Sime₂, me₃Si? CHCI? Sime₂? CC1₂? Sime₃ are isolated. The same products were obtained in the reaction of me₃Si? CCl₂? Sime₂? CCl₂H with buLi and me₃SiCl.     

Bildung siliciumorganischer Verbindungen. 98. Umsetzung silylierter Phosphorylide mit PCl3

Formation of Organosilicon Compounds. 98. Reaction of Silylated Phosphorus Ylides with PCl₃ The reaction of Si-substituted phosphorus ylides as Me₂Si(CH₂? SiMe₂)₂C?PMe₃Br 1 , Cl₂Si(CH₂? SiCl₂)₂C?PMe₂Cl 2 , and (Cl₃Si)₂C?PMe₂Cl 3 with PCl₃ yields (Cl₂P)₂C?PMe₂Cl 5 by chlorinating cleavage of the Si-ylid-C bond. Besides 5 also (ClMe₂SiCH₂)₂SiMe₂, (Cl₃SiCH₂)₂SiCl₂, resp. SiCl₄ result from the reaction of 1, 2 and 3 with PCl₃. (Cl₂P)₂C?PMe₂Cl forms colourless crystals, mp. 84°C.     

Bildung siliciumorganischer Verbindungen, 79. NMR-spektroskopische Untersuchung der 1,3,5-Trisilacyclohexane und 1,3,5,7-Tetrasilaadamantane

Formation of Organosilicon Compounds. 79. NMR-Spectroscopical Investigation of 1,3,5-Trisilacyclohexanes and 1,3,5,7-Tetrasilaadamantanes For several groups of isomeric 1,3,5-trisilacyclohexanes and 1,3,5,7-tetrasilaadamantanes, structure assignment and conformation analysis of given by elucidation of their ¹H-NMR spectra.     

Bildung siliciumorganischer Verbindungen. XXXXIV. Synthese und Reaktionen Si-funktioneller 1, 3, 5, 7-Tetrasila-cyclo-octane

The synthesis of the HSi?resp. BrSi? containing 1,3,5,7-tetrasila-cyclooctanes (a) and (b) is described. (a) can be prepared from meH₂Si? CH₂? Sime₂? CH₂? SiHme? CH₂? Sime₂? CH₂Br resp. from meBrHSi? CH₂? Sime₂? CH₂? SiHme? CH₂? Sime₂? CH₂Br with Li and converted to (b) with Br₂. The siloxane (c) (m.p. 37–39°C) is formed by hydrolysis of (b) and also during the reaction of (b) with CH₂Br₂ and Li in (C₂H₅)₂O because of a cleavage of the ether.     

Bildung siliciumorganischer Verbindungen. 96. Bildung und Struktur von P-Yliden des 1,3,5-Trisilacyclohexans (Einfluß der Substituenten)

Formation of Organosilicon Compounds. 96. Preparation and Structure of P-Ylides of the 1,3,5-Trisilahexanes (Influence of the Substituents) The influence of the substituents at the silicon atoms on formation and structure of ylides of 1,3,5-trisilacyclohexanesis investigated. The reactions of 1 , 2 , 3 with Me₃Si? PMe₂ lead via cleavage of the Si? P bond and subsequent rearrangement to the ylides 4 , 5 and 6 . The x-ray structure determination reveals, that the atoms of the ylid part of 4 are in a plane with the shortened bond distances d(C? P) = 168.6 pm and d(Si? C) = 180.1 pm, whereas the other endocyclic Si? C distances remain nearly unaffected by the ylid formation. Only the endocyclic bond angles C? Si? C of the Si atoms of the ylid are enlarged (116°). In the molecule 6 d(C? P) = 164.6 pm is much shorter, but d(P? Br) = 236.6 pm is enlarged. This enlargement is coupled with a deviation of 17 pm for the ylidic C atom from the ylid plane. Distances and angles are normal in the methylated trisilnhexane. The ring in 6 has boat conformation, in 4 a flat chair conformation.     

Bildung siliciumorganischer Verbindungen. 92 [1]. Bildung und Struktur des Oktamethyl-hexasila-hexascaphans

Formation of Organosilicon Compounds. 92. Formation and Structure of Octamethylhexasila-hexascaphane By rearrangement and abstraction of CH₄ at the presence of AlBr₃ 2 forms 3 , and 6 forms 7 , which is also obtained reacting 8 and 9 under the same condition. Lithination of 1, 1, 3, 5, 5, 7, 7, 9, 9-Nonamethyl-1, 3, 5, 7, 9-pentasiladecaline yields 12 , which is trapped with me₃SiCl to form 6 . Convertation of 13 to 14 leads to 8 by reaction with ClSi(CH₂—Sime₃)₃. Compound 7 is characterized by NMR and mass spectroscopy as well as X-ray structural analysis. 1, 3, 5, 7, 9, 9, 11, 11-Octamethyl-1, 3, 5, 7, 9, 11-hexasila-hexascaphane 7 crystallizes in the monoclinic space group P2₁/n (No. 14) with a = 3296.7 pm, b = 1536.2 pm, c = 891.9 pm, β 91.71° and Z = 8 formular units. Both crystallographic independent molecules have approximately the symmetry C₂. The differences of corresponding bond lengths, bond angles and torsion angles are unimportant. But there is a distinct dependence of the Si? C bond length relative to the function of the bond in the molecule (Averages: Si? C) (endo) = 188.4 pm, Si? C (exo) = 187.6 (pm).     

Bildung siliciumorganischer Verbindungen. LVIII. Die Synthese eines Carbosilans mit Propellan-Struktur

Formation of Organosilicon Compounds. LVIII. Synthesis of a Carbosilane with Propellane Structure 1 (· ? C resp. CH₂; x ? Si(CH₃)₂ resp. Si) is formed by a coupling reaction of BrSi(CH₂? Sime₂? CH₂? Sime₂Br)₃ 2 with CCl₄ and Li. The reaction of C₆H₅me₂Si? CH₂Li with Clme₂Si? CH₂Br leads to C₆H₅me₂Si? CH₂? Sime₂? CH₂Br. Metallation with lithium and succeeding reaction with Cl₃SiC₆H₅ produces compound C₆H₅Si(CH₂? Sime₂? CH₂? Sime₂C₆H₅)₃, which than forms 2 by cleavage with bromine.     

Bildung siliciumorganischer Verbindungen. XXXVII1,3,5,7-Tetrasila-adamantane aus der Pyrolyse des (CH3)3SiCl und Auftrennung des Pyrolysegemisches

Further separation of the pyrolysis products of (CH₃)₃SiCl can be achieved by reaction with LiAlH₄/LiH (transfer of SiCl to SiH groups). By means of adsorptions chromatography a separation is obtained into 4 groups of components. By application of gel chromatography (sephadex LH 20) separation is improved, thus fractions of carbosilanes are found with average molecular weights between 5000 and 200. A given mixture of the compounds [5], [9], [10] has been separated by means of gel chromatography so that pure compounds were obtained. The mixture of the 1,3,5,7-Tetrasila-adamantanes, which are formed in the pyrolysis of (CH₃)₃SiCl, is separated by gel chromatography (efficiency control of separation is performed by NMR and mass spectrography of the different fractions), a concentration of some compounds is obtained, some of them are isolated purely by further operations. The ratio of the compounds [1], [2], [3], [4], found in the pyrolysis products, is 170:26:3:1. Derivatives are formed with SiH, SiCl, and SiCH₃ groups by complete or respectively partial hydrogenation. Comparing the values of the chemical shift of the CH₃-protones [measured in τ) a linear decrease is found in the compounds [9], [4], [3], [2].     

Bildung siliciumorganischer Verbindungen. XXXVIII. Umsetzung perchlorierter Carbosilane mit LiAlH4

By LiAlH₄ (Cl₃Si)₂CH₂, (Cl₂Si? CH₂)₂SiCl₂ are reduced to (H₃Si)₂CH₂ (a), (H₃Si? CH₂)₂SiH₂ (b) and (H₂Si? CH₂)₃(c). However with the compounds (Cl₃Si)₂CCl₂, (Cl₃Si? CCl₂0₂SiCl₂ and (Cl₂Si? CCl₂)₃ cleavages of the Si? C-bond and reduction of the CCl-groups occur apart from the normal reduction of the Si-Cl-groups to (H₃Si)₂CCl₂ (d), (H₃SiCCl₂)₂SiH₂ (e) and (H₂Si? CCl₂)₃. Excess LiAlH₄ favours this cleavage, the exact amount of a quarter of a mole LiAlH₄ per SiCl-group allows the formation of (d), (e), (f). The cleavage of (e) is in accordance with: (1), (2),(3). Therefore SiH₃₄ and (H₃Si)₂CCl₂ are the main-reaction-products and CH₃SiH₃ is formed acc. to equ. (3). Because of the cleavage of (H₂Si? CCl₂)₃ with LiAlH₄ H₃Si? CCl₂? SiH₂? CH₃and H₃Si? CH₂? SiH₂? CH₂? SiH₂? CH₃ are preferentially formed after the hydrolysis. The CH₂-containing compounds (a), (b), (c) cannot be cleaved in an analogous reaction.     

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.