Bildung siliciumorganischer Verbindungen. 89. Selektive Photobromierung von Si-methylierten Carbosilanen

Formation of Organosilicon Compounds. 89. Selective Photobromination of Si-methylated Carbosilanes A selective photobromination of the C atoms in the skeleton of Si-methylated carbosilanes is reported. (me₃Si? CH₂)₂Sime₂ reacts to me₃Si? CBr₂? Sime₂? CH₂? Sime₃ in good yields (me = CH₃); the second CH₂ group is considerably slower brominated. Photobromination of (me₂Si? CH₂)₃ consecutively yields a and b . Also from (me₂Si? CH₂)₄ the derivative with one CBr₂ group is accessible. Bromination of tertiary CH groups is highly preferred; this is shown by the selective formation of c . The C-bromination of SiBr-substituted carbosilanes is significantly more difficult; nevertheless (Brme₂Si)₂CH₂ selectively forms (Brme₂Si)₂CBr₂. Brme₂Si? CH₂? Sime₂? CH₂? Sime₃ forms Brme₂Si? CH₂? Sime₂? CBr₂? Sime₃, i. e., only the CH₂ group non-adjacent to SiBr is attacked. The formation of CHBr groups could not be detected. Higher temperatures and longer reaction times increase the formation of polymers.     

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. 84 [1]. Synthese und thermische Umlagerung von verschieden substituierten linearen und cyclischen Silanen

Formation of organosilicon compounds. 84. Synthesis and thermal rearrangement of some substituted linear and cyclic silanes In part IR we report on the synthesis of substituted silanes, and in part II on their thermal rearrangement. I: me₃i--Sime₃(me = CH₃) is formed by dropwise addition of THF to a suspension of Li powder in me₃SiCl; yield ～ 80%. The mixture me₃Si--Sime₂Cl, me₃SiCl, Li powder and THF reacts analogously to form me₂Si(Sime₃)₂; yield 80%. By the same type of reaction the following compounds are obtained: compound 1 from Brme₂Si? CH₂? Sime₂Br, 1 from Brme₂Si? CH₂? Sime₂Br, 2 from Brme₂Si? Sime₂? CH₂? Sime₂Br 16 and 3 from Bret₂Si? CH₂? CH₂? Siet₂Br (et = C₂H₅). 2 decomposes during its isolation from THF. 16 is formed from phme₂Si? Sime₂? CH₂? Sime₂ph 17 (ph = C₆H₅) by reaction with HBr, 17 either from phme₂SiLi and Clme₂SiCH₂Cl or from phme₂Si? Sime₂Br and LiCH₂? Sime₂ph. II: me₂Si(Sime₃)₂ rearranges at 440 °C (56 h) with insertion of the CH₂ group (Si? H formation) into the Si? Si bond and the formation of me₃Si? Sime₂? CH₂? Sime₂H, me₂HSi? CH₂? Sime₂? CH₂? SiHme₂, and me₃Si? CH₂? Sime? CH₂? Sime₂H. 1 reacts analogously. Methylated halogenated disilanes like Brme₂Si? Sime₂Br react with separation of: Sime₂ and its insertion into the Si-halogen bond to form trisilanes. Different from both are the phenylated derivatives, though phme₂Si? Sime₂ph still forms phme₂Si? Sime₂? Sime₂ph. 3 reacts with separation of C₂H₄, formation of the Si? H group and insertion of C₂H₄ into the Si? Si bond.     

Bildung siliciumorganischer Verbindungen. XXXIX. Teilchlorierte Carbosilane

1. Photochlorination in CCl₄ of the Si-chlorinated carbosilanes (Cl₃Si? CH₂)₂SiCl₂ and (Cl₂Si? CH₂)₃ leads to totally chlorinated compounds, e. g. (Cl₃Si? CCl₂)₂SiCl₂. After chlorination has started at one CH₂ group, formation of a CCl₂ group is preferred before another CH₂ group is involved into the reaction. Thus preparation of compounds a, b, c is possible. Cl₃Si? CCl₂? SiCl₂? CH₂? SiCl₃ (a) for (b) and (c) (see “Inhaltsübersicht”). SO₂Cl₂ (benzoyl peroxide) as chlorinating agent reacts more slowly, and opens an access to carbosilanes containing CHCl groups such as (d), Cl₃Si-CHCl? SiCl₂? CH₂? SiCl₃ (e). Reactions of compounds (a) to (d) with LiAlH₄ yields carbosilanes with SiH groups, and partially chlorinated C atoms. 2. By the high reactivity of Si? CCl₂? Si groups an exchange of Cl atoms of CCl groups in perchlorinated carbosilanes is possible for H atoms of Si? H groups in perhydrogenated carbosilanes, thus allowing the preparation of compounds containing CHCl and SiHCl groups, e. g. according to Gl.(1) (Inhaltsübersicht). Further reactions, formulated as the last equations in Inhaltsübersicht, are reported as well as the rearrangement of H₃Si? CHCl? SiH₃.     

Bildung siliciumorganischer Verbindungen. 93 [1]. Untersuchungen zum Bildungsmechanismus cyclischer Carbosilane durch Einwirkung von AlBr3

Formation of Organosilicon Compounds. 93. Investigations of the Mechanism of the AlBr₃ Initiated Formation of Cyclic Carbosilanes. The mechanism of the formation of ringsystems in carbosilanes with AlBr₃ is investigated using the deuterium compounds 1a and 3a . The number of deuterium atoms in the methyl groups of the reaction products shows at which points of the molecules the regrouping occurs under formation of the ringsystem. In the first initially the reaction of 1a yields D₃C? Si(CH₃)₃ and 2a under separation of a CD₃ group. The rearrangement forming 2a occurs at the marked Si? C-bonds (formula 1a ). No Al-organic intermediate compound is observed under cleavage of Si? C bond. Therefore the formation of ring-systems is based on the polarisation by the Lewis-acid AlBr₃. Compound 3a reacts in an analogous way, what is shown by the isolation of Sime₄ and 4a . The cleavage of the bonds is marked in formula 3a . The reaction of 8 forming 9 and (Sime₃)₂CH₂ follows the same mechanism; it is investigated by ¹H and ²⁷Al-NMR spectroscopy.     

Zur Bildung von Disilylphosphino-Element-Verbindungen des C,Si, P

The Formation of Disilylphosphino-Element Compounds of C, Si, P The reactions of (me₃Si)₂PLi · OR₂ a (OR₂ = 1 monoglyme or 2 THF; me = CH₃) with CH₃Cl, CH₂Cl₂, ClCH₂CH₂Cl and ClCH₂? C₆H₅ give the compounds (me₃Si)₂Pme, (me₃Si)₂P? CH₂? P(Sime₃)₂, (me₃Si)₂P? CH₂CH₂Cl, (me₃Si)₂P? CH₂CH₂? P(Sime₃)₂ and (me₃Si)₂P? CH₂C₆H₅ respectively. In the same manner a reacts with me₂SiCl₂ in a molar ratio 1:1 to (me₃Si)₂P? Sime₂Cl and in a molar ratio 2:1 to (me₃Si)₂P? Sime₂? P(Sime₃)₂ b . The compound b decomposes to [me₃SiP? Sime₂]₂ and (me₃Si)₃P at 220°C. In the reactions of a with ClP(C₆H₅)₂ and ClPme₂ the compounds (me₃Si)₂P? P(C₆H₅)₂ and (me₃Si)₂P? Pme₂, respectively, are obtained. a reacts with HgCl₂ to (me₃Si)₂P? P(Sime₃)₂. (me₃Si)₃P can be cleaved with ClP(C₆H₅)₂ and ClPme₂ yielding (me₃Si)₂P? P(C₆H₅)₂ and (me₃Si)₂P? Pme₂, respectively. The ¹H- and ³¹P-n.m.r. and mass spectroscopic data are reported.     

Bildung siliciumorganischer Verbindungen. 102. Zur Umsetzung von Chlormethanen mit elementarem Silicium (Bildung und Aufklärung linearer Carbosilane)

Formation of Organosilicon Compounds. 102. Reaction of Chlormethanes with Elemental Silicon. (Formation and Investigation of Linear Carbosilanes) Reactions of CH₂Cl₂, HCCl₃ and CCl₄ with silicon (Cu catalyst) in a fluid bed at about 320°C were carried out to investigate especially the Si-rich compounds. In the reactions of CH₂Cl₂ and CHCl₃, but not of CCl₄, in addition to already published compounds Si-rich viscous products are formed. The SiCl-containing mixtures were reacted with LiAlH₄, and the SiH-containing derivatives were separated by means of HPLC. CH₂Cl₂/Si forms unbranched chains of carbosilanes as Si_nC_n–1H_4n (n = 4—12,2 terminal SiH₃ groups) and Si_nC_nH_4n+2 (n = 4—9, 1 terminal SiH₃ and 1 CH₃ group) as well as 1,3,5-trisilacyclohexanes with carbosilane chains of various length attached either to a Si atom or to a C atom. CHCl₃/Si yields in addition to unbranched chains with terminal silyl group chains with one or two C-branches and 1,3,5-trisilacyclohexanes with 1, 2, or 3 silyl substituents attached to C atoms. The structure of the isolated compounds was investigated by nmr and mass spectrometry.     

Bildung siliciumorganischer Verbindungen. 85 [1]. Bildung,Reaktionen und Struktur des 1,1,3,3-Tetramethyl-2,4-bis(trimethylsilyl)-1,3-disilabicyclo[1, 1, 0]butans

me₃Si? CCl₂?Sime₂Cl (me ? CH₃) läßt sich mit n-buLi (bu ? C₄H₉) bei–100°C (Lösungsmittel THF/Äther) in me₃Si? CCl(Li)? Sime₂Cl a überführen. das mit meJ me₃Si? CClme? Sime₂Cl bildet. Wird a in Abwesenheit eines Abfangreagenzes langsam erwärmt, so bildet sich unter Abspaltung von LiCl (Cl aus der SiCl-Gruppe) über eine reaktive Zwischenstufe des Bicyclobutans b . Die Struktur von b ist durch NMR-Untersuchung, Röntgenstrukturanalyse und Abbaureaktionen gesichert. Mit HBr bzw. CH₃OH werden die Si? C-Bindungen der Dreiringe in b gespalten, so daß sich me₃Si? CH₂? C(Sime₂X)₂Sime₃ (X ? Br, OCH₃) bildet. Formation of Organosilicon Compounds. 85. Formation, Reactions, and Structure of 1,1,3,3-Tetramethyl-2,4-bis(trimethylsilyl)-1,3-disilabicyclo[1, 1, 0]butane me₃Si? CCl₂? Sime₂Cl (me ? CH₃) with n-buLi (bu ? C₄H₉) at –100°C (solvent: THF/ether) yields me₃Si? CCl(Li)? Sime₂Cl a , which forms me₃Si? CClme? Sime₂Cl with meI. By warming a slowly in absence of any trapping reagent the bicyclobutane b is obtained via a reactive intermediate under elimination of LiCl (Cl from the SiCl group). The structure of b is established by nmr investigations, X-ray structure determination and chemical derivatisation.     

Bildung siliciumorganischer Verbindungen. 100. Über die Isolierung höherer Carbosilane aus der Pyrolyse des Tetramethylsilans

Formation of Organosilicon Compounds. 100. Isolation of Higher Molecular Carbosilanes from the Pyrolysis Products of Tetramethylsilane A systematic investigation of the carbosilanes containing 6 to 9 Si atoms per molecule formed by pyrolysis of SiMe₄ was achieved by means of column chromatographic separations combined with HPLC. 11 pure compounds and mixtures of the isomers of 7a and 7b as well as of 11 and 15 were isolated. The predominant structure is that of the carborundanes using only Me and H as Si substituents. Only in compounds 8 and 13 some of the Si? C sixmembered rings are in the chair form. In compounds 17 and 18 another possibility of connecting 1,3,5,7-tetrasilaadamantane frameworks to higher molecular carbosilanes is realized.     

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. XXXXVI. Si-fluorierte Carbosilane

Formation of organosilicon compounds. XXXXVI. Si-fluorinated carbosilanes Compounds (1)–(7) (see “Inhaltsübersicht”) are obtained by reaction of carbosilanes containing Si? Cl groups with ZnF₂. The linear compounds (8) and (9) are prepared from ZnF₂ and (Cl₃Si)₂CCl₂, and (Cl₃Si? CCl₂)SiCl₂, respectively, whereas the cyclic compounds are formed by photochemical chlorination. Photochemical chlorination of (3) goes via compounds (13) and (14) (isolation is possible); both of them can be prepared too by reaction of Si? Cl derivatives with ZnF₂. Compounds (16) and (17) are obtained from the corresponding Si? Cl derivatives.     

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 und Reaktionen P-funktioneller Phosphane

Formation and Reaction of P-functional Phosphanes The reaction of (me₃Si)₂PLi · 2 THF a (me = CH₃) with PCl₃ b at ?78°C via the intermediate (me₃Si)₂P? PCl₂ 1 yields [(me₃Si)₂P]₂PCl 2 and [(me₃Si)₂P]₂P? P(Sime₃)₂ 3 . By addition of me₃CLi c to the reaction mixture of a and b (molar ratio a:b:c (molar ratio a:b:c = 1:1:1) at ?60°C, 2 is formed as a main product, which reacts on to yield [(me₃Si)₂P]₂PH 4 (white crystals, mp = 73°C). By reactions of a:b:c in a molar ratio of 1:1:2 the cyclotetraphosphane (me₃C)₃ (me₃Si)P₄ 7 is accessible, and the additional formation of (me₃Si)₂PLi · 2 THF, (me₃Si)₃P and Li₃P₇ · 3 THF 13 was detected. Warming (me₃Si)₂P? PCl(Cme₃) 5 to 20°C produces cis- and trans-cyclotetraphosphanes (me₃Si)₂(me₃C)₂P₄. By running the reaction of a and b at ?78°C and adding me₃CLi only after 24 h, additionally to (me₃Si)₂P? PH Cme₃) and (me₃Si)₃P also (me₃Si)₂P? P(Cme₃)? P(Cme₃)? P (Sime₃)₂ is obtained, which is formed by metallation of (me₃Si)₂P? PCl(Cme₃) with me₃CLi and by further reaction of the intermediate (me₃Si)₂P? PLi(Cme₃) with (me₃Si)₂P? PCl(Cme₃). The reaction of (me₃Si₃)P with PCl₃ at ?78°C only yields (me₃Si)₂P? PCl₂ 1 and me₃SiCl. On addition of me₃CLi (?78°C, molar ratio = 1:1:1) preferrably 2 and (me₃Si)₂P? PCl(Cme₃) are formed, whereas after warming the mixture to 20°C, 4 and (me₃Si)₂P? PH(Cme₃) are found to be the main products. These reactions are induced by the cleavage of 1 by means of me₃CLi, and by the formation of (me₃Si)₂PLi and me₃C? PCl₂.     

Bildung siliciumorganischer Verbindungen. LVI. Reaktionen Si- und C-chlorierter 1,3,5-Trisilapentane mit CH3MgCl

Formation of Organosilicon Compounds. LVI. Reactions of Si- and C-Chlorinated 1,3,5-Trisilapentanes with CH₃MgCl (Cl₃Si? CCl₂)₂SiCl₂ (1) reacts with an excess of meMgCl (me = CH₃) forming me₃Si? C?C? Sime₃ (2), Sime₄, H₂C?C(Sime₃)[CH(Sime₃)₂] (3) as main products and (me₃Si)₂C? CH(Sime₃) and as by-products. The cleavage reaction of (1) to (2) and (3) does not occur when the meMgCl-concentration is lowered. The reaction is started by the formation of a GRIGNARD reagent at a CCl-group in compound (1). Cl₃Si? CCl₂? SiCl₂? CH₂? SiCl₃ forms with ; me₃Si? CCl₂? SiCl₂? CHCl? SiCl₃ forms (me₃Si)₂C?CH(Sime₃). A reaction sequence is given.     

Bildung siliciumorganischer Verbindungen. 74. Synthese und NMR-Spektren von Si-methylierten und -chlorierten 2,2-Dichloro-1,3-disilapropanen und 2-Methyl-2-chloro-1,3-disilapropanen

Formation of Organosilicon Compounds. 74. Synthesis and NMR-Spectra of Si-methylated and -chlorinated 2,2-Dichloro-1,3-disilapropanes and 2-Methyl-2-chloro-1,3-disilapropanes The compounds me₃Si? CCl₂? Sime_nCl_3?n (n = 1–3; me = CH₃) are synthesized by reaction of me₃Si? CCl₂Li (formed from me₃Si? CCl₂H with n-buLi, bu = butyl) with the appropriate methylchlorosilanes. The compounds Clme₂Si? CCl₂? Sime_nCl_3?n are obtained by analogous reactions of (C₆H₅)me₂Si? CCl₂Li, cleavage of the Si-phenyl group with bromine and conversion of the Si? Br to the Si? Cl group with HCl in PCl₃. The 2-methyl-2-chloro-1,3-disilapropanes are synthesized by lithination of the CCl₂ group of 2,2-dichloro-1,3-disilapropanes, followed by reaction with meI. (Clme₂Si)₂CmeCl is obtained from (C₆H₅me₂Si)₂CCl₂ by reaction with n-buLi to (C₆H₅me₂Si)₂ CClLi, which forms (C₆H₅me₂Si)CClme with meI. Cleavage with bromine to (Brme₂Si)₂CClme and reaction with HCl/PCl₃ leads to the expected compound. The influence of the substitution on the ¹H, ¹³C and ²⁹Si NMR spectra is investigated.     

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. 88. Zur SiH-Addition von 1,3,5-Trisilacyclohexanen an silylierte Alkine

Formation of Organosilicon Compounds. 88. SiH-Addition of 1,3,5-Trisilacyclohexanes to Silylalkynes Catalyzed by means of H₂PtCl₆ the SiH addition of 1,1,3,3,5-pentamethyl-1,3,5-trisilacyclohexane to HC?C? Sime₂CH₂Cl, and of 1,1,3,3,5-pentaphenyl-1,3,5-trisilacyclohexane to HC?C? Sime₂CH₂Br yields a and b , or c and d , resp. (Formulae see Inhaltsübersicht), whereas 1,3,5-trisilacyclohexanes with more SiH groups preferrably yield polymers. The c/d ratio is strongly governed by the solvent: 38% c in n-hexane, 72% c in CCl₄/cyclohexane. Treatment of c and d with HCl/AlCl₃ under cleavage of all of the phenyl groups, addition of HCl to the vinyl group and subsequent β-elimination leads to (Cl₂Si? CH₂)₃ ClSime₂? CH₂Br and compound e , whereas HBr at ?78°C only cleaves one phenyl group per Si atom.     

Untersuchungen zur Reaktionsfähigkeit der höheren Silylphosphane (me3Si)4P2, [(me3Si)2P]2PH, [(me3Si)2P]2P–Sime3 und (me3Si)3P7

Investigations Concerning the Reactivity of the Higher Silylphosphanes (me₃Si)₄P₂, [(me₃Si)₂P]₂PH, [(me₃Si)₂P]₂P—Sime₃, and (me₃Si)₃P₇ The reaction of (me₃Si)₂P? P(Sime₃)₂ 1 in ether solutions (THF, monoglyme) with t-buLi (me ? CH₃; t-bu ? (CH₃)₃C) yields (me₃Si)₃P, (me₃Si)₂PLi and Li₃P₇ via (me₃Si)₂P? P(Li) (Sime₃) 4 . Already at ?40° (me₃Si)₃P₂Li 4 decomposes yielding (me₃Si)₂PLi, Li₃P₇ and (me₃Si)₃P. The metallation of (me₃Si)₃P₂H with t-buLi leads to the same results. t-buLi with [(me₃Si)₂P]₂PH 2 in pentane forms [(me₃Si)₂P]₂PLi, which reacts on with meCl or me₃SiCl to [(me₃Si)₂P]₂Pme or [(me₃Si)₂P]₂PSime₃, resp. On addition of monoglyme to a suspension of [(me₃Si)₂P]₂PLi in pentane, or by treating [(me₃Si)₂P]₂PH in ethers with t-buLi (me₃Si)₂PLi, Li₃P₇, (me₃Si)₃P, are formed. The same compounds are generated by reacting [(me₃Si)₂P]₂P—Sime₃ in ethers with t-buLi. The metallation of (me₃Si)₃P₇ in ethers with t-buLi yields (me₃Si)₂PLi, (me₃Si)₃P, (t-bu)₃P₄?(Sime₃), Li₃P₇ and a red solid. The formation of (me₃Si)₂P₇Li is the first step of this reaction.     

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. 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.