Bildung siliciumorganischer Verbindungen. LIV. Die Kristall- und Molekülstruktur des Tetramethyl-octasila-dodecascaphans Si8C17H36

Formation of Organosilicon Compounds. LIV. Crystal and Molecular Structure of Tetramethyl-octasila-dodecascaphan 3,7,11,15-Tetramethyl-1,3,5,7,9,11,13,15-octasila-dodecascaphan crystallizes in the cubic space group F4 3c–T with a = 17.074(10) Å. In the unit cell there are four molecules of each of the two chiral forms which are arranged in the way of the NaCl-structure. The molecules have the symmetry 23-T with torsion angles of 19° in the twelve six-membered rings with skew-boat conformation. In the polycyclic skeleton the bond length Si? C are nearly the same (1.885(2) Å, 1.893(5) Å and 1.888(6) Å), whereas the bond length Si? CH₃ is slightly shorter (1.874(8) Å). The shortest distances between H-atoms are 2.59 and 2.68 Å (intramolecular) and 2.72 and 2.73 Å (intermolecular) respectively. The thermal motions of all atoms can be reduced to a rigid-body motion. Diffuse scattering (dependent on temperature) is observed and discussed.     

Bildung siliciumorganischer Verbindungen. XXXII. Das Carbosilan Si7C16H36

Si₇C₁₆H₃₆ (1) can be separated from the pyrolysis products of Si(CH₃)₄ by columnchromatography. Its structure is shown to consist of two 1,3,5,7-tetrasilaadamantane skeletons which are connected through the C-atoms 2 and 4 and the Si-atom 3, by analysis of the 100 and 220 MHz PMR spectra in connection with double resonance. Except for the framework bonds carbon atoms are saturated by hydrogen, silicon atoms by CH₃ groups. (1) is a very stable compound (m.p. 225°C without decomposition).     

Bildung siliciumorganischer Verbindungen. 95. Die Kristallstruktur eines Hexadecamethyl-octasila-dispiro-[5.1.5.1]-tetradecans,Si8C22H65

Formation of Organosilicon Compounds. 95. Crystal Structure of a Hexadecamethyloctasila-dispiro [5.1.5.1]tetradecane, Si₈C₂₂H₅₆ 1,1,3,3,5,5,7,7,9,9,11,11,13,13,14,14-Hexadecamethyl-1,3,5,7,9,11,13,14-octasila-dispiro[5.1.5.1]tetradecane crystallizes monoclinically in the space group P2₁/n (No. 14) with a = 1352.4 pm, b = 1215.5 pm, c = 1001.2 pm, β = 92.11° and Z = 2 molecules per unit cell. The dispiro system is formed by a central disilacyclobutane and two C-spiro connected trisilacyclohexane rings. The symmetry of the molecule is 2/m, with flattened six membered rings in chair conformation. The Si? C bonds are enlarged (192 pm) at the strained spiro region whereas the Si? C bonds are distinctly shortened (186 pm) at the opposite Si atoms in the six membered rings.     

Bildung siliciumorganischer Verbindungen. LXI. Die Kristall- und MolekülStruktur des 1,1,3,3,5,5,7,7-Octamethyl-1,3,5,7-tetrasila-cyclooctans Si4C12H32

Formation of Organosilicon Compounds. LXI. Crystal and Molecular Structure of 1.1.3.3.5.5.7.7-Octamethyl-1.3.5.7-tetrasila-cyclooctane Si₄C₁₂H₃₂ Octamethyl-tetrasila-cyclooctan Si₄C₁₂H₃₂ crystallizes in the monoclinic space group C2 with a = 17.807, b = 6.121, c = 10.856 Å, β = 126.09° und 2 molecules in the unit cell. The molecule has a C₂-conformation which deviates slightly from C_2v symmetry. The mean Si? C bond length is 1.879 ± 0.011 Å. The mean Si? CH₂ bond length is greater than the Si? CH₃ bond length (1.897(15) Å and 1.861(10) Å respectively).     

Bildung siliciumorganischer Verbindungen. LIX. Die Kristall- und MolekülStruktur des Dodecamethyl-heptasila-[4,4,4]-propellans Si7C19H48

Formation of Organosilicon Compounds. LIX. Crystal and Molecular Structure of Dodecamethyl-heptasila-[4,4,4]-propellan Si₇C₁₉H₄₈ 1,1,3,3,7,7,9,9,11,11,13,13-Dodecamethyl-1,3,5,7,9,11,13-heptasila-[4,4,4]-propellan Si₇C₁₉H₄₈ crystallizes in the monoclinic space group P2₁/c with a = 11.499, b = 11.411, c = 22.171 Å, β = 96.95° and Z = 4 formula units. The three independent six-membered rings of the molecule have the same skew-boat-conformation. Along the central Si? C? bond the mean value of the torsion angle within the six-membered rings is 19°. The mean value for the bond length is Si-C = 1.893 Å, but the bond length diminishes within the polycyclic system from the axial C-atom to the outer members of the rings (1.916; 1.880; 1.864 Å). The interatomic distances between CH₃- groups and from CH₃- groups to CH₂- groups shows the twisted conformation to be a result of the contacts between these groups.     

Bildung siliciumorganischer Verbindungen. LX. Die Kristall- und MolekülStruktur des Heptamethyl-tetrasila-[2,2,2]-barrelans Si4C11H28

Formation of Organosilicon Compounds. LX. Crystal and Molecular Structure of Heptamethyl-tetrasila-[2,2,2]-barrelan Si₄C₁₁H₂₈ 1,1,3,5,5,7,7-Heptamethyl-1,3,5,7-tetrasila-[2,2,2]-barrelan Si₄C₁₁H₂₈ crystallizes in the orthorhombic space group Pn2₁a with a = 12.293, b = 9.903, c = 14.018 Å and Z = 4 formula units. The six-membered rings have the skew-boat conformation with a torsion angle of 23.5° with respect to the molecular axis. The skew-boat conformation results from the interaction of CH₃- and CH₂- groups. The mean value for the bond length is Si? C = 1.881 Å. The distances Si? CH₂ = 1.873 Å are somewhat smaller than the others (1.887 Å).     

Bildung siliciumorganischer Verbindungen. L. Untersuchungen zur Hydrierung,Methylierung und Spaltung des Octachloro-hexasila-asterans Si6Cl8C6H8

Formation of Organosilicon Compounds. L. Investigations on Hydrogenation, Methylation, and Decomposition of Octachlorohexasila-asteran Si₆Cl₈C₆H₈ Compound (a) reacts with LiAlH₄ (1:2) to form (b), respectively (c) (ratio 1:5). (b), (c) and the intermediates containing Si? H-groups can be rechlorinated to (a) by means of Cl₂. With a excess of LiAlH₄ (1:10) (a) is cleaved to compound (d) under hydrogenation. (a) is methylated to (e) resp. (f) by CH₃MgCl. (a) doesn't react with Cl₂ and Br₂; (f) is cleaved by HBr to yield (g). The different sterical conditions of the secondary and teriary Si---Cl-groups allow preparation of the partially chlorinated compounds (b) and (e).     

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. 101. Darstellung,Struktur und Eigenschaften eines Octamethyl-octasila-heptacyclooctadecans Si8C18H40

Formation of Organosilicon Compounds. 101. Preparation, Structure, and Properties of an Octamethyl-octasilaheptacyclooctadecane, Si₈C₁₈H₄₀ The title compound Si₈C₁₈H₄₀ 1 (systematic name: 1,3,5,7,9,11,11,15-Octamethyl-1,3,5,7,9,11,13,15-octasila-heptacyclo[7,7,1,1^3,15, 0^2,7, 0^4,13, 0^5,10, 0^13,17]octadecane) can be derived from a polycyclic frame of condensed trisilacyclohexane rings presenting the chair-as well as the boat-conformation. This frame is a part of the very frequent 4H-III modification of silicon carbide and represents the smallest molecular unit, which shows all the essential details of this structure namely the adamantane-frame and the wurtzitane-frame. The mean Si? C bond distance is 188.6 pm. Particularly the six-membered rings form nearly ideal conformations.     

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.     

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. 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. 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. 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. XXX. Metallorganische Synthese cyclischer Carbosilane

This paper contains:

• 1 The synthesis of the 1.3-disilacyclopentenes (a)(b)⁽²⁾ and of the 1.3-disilacyclo-butane (c); formulas see above.
• 2 The synthesis of the 1.3-disilacyclopentane skeleton (d) and of the SiCl-functional derivatives (e) (f ) (g) (h) (i) as well as of SiH-containing derivatives, e.g. (j).
• 3 The chlorination of (i) with SO₂,Cl₂, yielding (k) and (l), and the formation of (m) from (k) with K-methypyrrolidine.
• 4 The synthesis of the spirane (n).
• 5 The synthesis of the ten-membered ring(o) and of the unsaturated derivatives (p)and (q). Besides the synthetic routes, spectroscopic data (ir, pmr, and mass spectra) of the cyclic compounds as well as of the intermediate products are given.

     

Bildung siliciumorganischer Verbindungen. 77. Zur Bildung von Carbosilanen aus Methylsilanen

Formation of Organosilicon Compounds. 77. Formation of Carbosilanes from Methylsilanes The products formed by pyrolysis of me₃SiH, me₂SiH₂, and meSiH₃ are reported. Sime₄ and the mentioned methylsilanes were reacted in a plasma, and the products are compared to those of the pyrolysis. The pyrolysis of me₃SiH and me₂SiH₂ essentially yields the same groups of carbosilanes which are accessible by thermal decomposition of Sime₄, if the range is restricted to compounds with 4 Si atoms at most. Cylic carbosilanes are the main products of the pyrolysis of me₃SiH, and amoung these, 1,3,5-trisilacyclohexanes and 1,3,5,7-tetrasilaadamantanes are preferrently formed. From me₂SiH₂ above all linear compounds as 1,3-disilapropanes are obtained. This is attributed to the chosen experimental procedure in which they not subject to further reaction. In the pyrolysis of meSiH₃ a yellow solid is formed besides little amounts of meH₂Si? SiH₂me. Compared to the compounds formed by pyrolysis of Sime₄, the carbosilasen obtained from me₃SiH and me₂SiH₂ possess more SiH substituents. Also the decomposition of Sime₄ in a plasma preferrently yields carbosilanes, mainly linear compounds with 2 or 3 Si atoms.     

Bildung siliciumorganischer Verbindungen. 111. Die Hydrierung Si-chlorierter,C-spiroverbrückter 2,4-Disilacyclobutane mit LiAlH4 und iBu2AlH. Der Zugang zum Si8C3H20

Formation of Organosilicon Compounds. 111. The Hydrogenation of Si-chlorinated, C-spiro-linked 2,4-Disilacyclobutanes with LiAlH₄ or iBu₂AlH. The Access to Si₈C₃H₂₀ The hydrogenation of Si-chlorinated, C-spiro-linked 2,4-disilacyclobutanes containing C(SiCl₃)₂ terminal groups with LiAlH₄ in Et₂O proceeds under complete cleavage of the fourmembered rings and under elimination of one SiH₃ group. Such, Si₈C₃Cl₂₀ 4 forms (H₃Si)₂CH? SiH₂? CH(SiH₃)? SiH₂? CH(SiH₃)₂ 4 α, and even Si₈C₃H₂₀ 4a with LiAlH₄ forms 4 α. The hydrogenation of related compounds containing however CH(SiCl₃) terminal groups similarly proceeds under ring cleavage but no SiH₃ groups are eliminated. Such, (Cl₃Si)CH(SiCl₂)₂CH(SiCl₃) 41 forms (H₃Si)₂CH? SiH₂? CH₂(SiH₃) 41 α. However, in reactions with iBu₂AlH in pentane neither the disilacyclobutane rings are cleaved nor are SiH₃ groups eliminated. Only by this method Si₈C₃H₂₀ is accessible from 4 , Si₆C₂H₁₆ 3a from Si₆C₂Cl₁₆ 3 and Si₄C₂H₁₂ 41a from 41 . C(SiCl₃)₄ cleanly produces C(SiH₃)₄. Based on the knowledge about the different properties of LiAlH₄ and iBu₂AlH in hydrogenation reactions of disilacyclo-butanes it was possible to elucidate the composition and the structures of the hydrogenated derivatives of the product mixture from the reaction of MeCl₂Si? CCl₂? SiCl₃ with Si(Cu) [1] and to trace them back to the initially formed Si chlorinated disilacyclobutanes Si₆C₂Cl₁₅Me 34 , Si₆C₂Cl₁₄Me₂ 35 , Si₈C₃Cl₁₉Me 36 and Si₈C₃Cl₁₈Me₂ 37 . Compound 4a forms colourless crystals of space group P1 with a = 799.7(6), b = 1263.6(12), c = 1758.7(14) pm, α = 103.33(7)°, β = 95.28(6)°, γ = 105.57(7)° and Z = 4.     

Bildung siliciumorganischer Verbindungen. 105. Reaktionen des (Cl3Si)2CPMe2Cl mit Silylphosphanen

Formation of Organosilicon Compounds. 105. Reactions of (Cl₃Si)₂C?PMe₂Cl with Silylphosphanes The reaction of (Cl₃Si)₂C?PMe₂Cl 1 with MeP(SiMe₃)₂ proceeds at 130°C (15 hrs.), by cleavage of all Si? P bonds to compounds 2, 3, 4, 5 . The course of this reaction incorporates a number of stages of which the compounds (Cl₃Si)₂C? PMe₂? P(Me)SiMe₃, (Cl₃Si)₂C?PMe₂? PMe? P(Me)SiMe₃ and ClP(Me)SiMe₃ are important and are yet to be isolated. The reaction of (Cl₃Si)₂C?PMe₂Cl with LiP(SiMe₂)₂ produces compound 2 as well as p₂(SiMe₃)₄ and P(SiMe₃)₃. The formation of 2 can be explained by the initial formation of the intermediate (Cl₃Si)₂C?PMe₂? P(SiMe₂)₂ with reacts with 1 to produce 2 and (ClP(SiMe)₃)₂. The formation of P₂(SiMe₃)₄ is also explained by the reaction of ClP(SiMe₃)₂ with LiP(SiMe₃)₄. The reaction of (Cl₃Si)₂C?PMe₂C(H)PMe₂ at 130°C/15–20 hrs. is related to the formation of (Me₃Si)₂C(H)Pme₂ from corresponding Si-methylated phosphorylides with the exception that, at 0°C, this reaction goes to completion within a few minutes.     

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. 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.