Reactions of dodecamethylcyclohexasilane and polydimethylsilane with metal chlorides

The reactions of dodecamethylcyclohexasilane and high-molecular-weight polydimethylsilane with chlorides of I, II, IV-VI and VIII Group metals at high temperature in the absence of a solvent were studied. The interaction of (Me₂Si)₆ with metal chlorides proceeds with the cleavage of SiSi and SiC bonds with the formation of chloro derivatives of linear and cyclic permethyloligosilanes. The reactions of polydimethylsilane with metal chlorides afford mixtures of α,ω-dichlorooligosilanes, Cl(Me₂Si)_nCl (n=2-9). The influence of the reaction conditions (temperature, reaction time and the reagent ratio) on the composition and yields of the reaction products was examined.     

29Si and 13C NMR spectra of permethylpolysilanes

²⁹Si, ¹³C and ¹H NMR spectra are reported for the series of linear permethylpolysilanes Me(SiMe₂)_nMe where n = 1 to 6, for the cyclic permethylpolysilanes (Me₂Si)_n where n = 5 to 8, and for a few related compounds. For linear polysilanes the ²⁹Si and ¹³C chemical shifts can be accurately calculated from simple additivity relationships based on the number of silicon atoms in α, β, γ and δ positions. Adjacent (α) silicon atoms lead to upfield shifts in the ²⁹Si and ¹³C resonances, whereas more remote silicon atoms lead to downfield shifts. The ²⁹Si chemical shifts of the polysilane chains are linearly related to the ¹³C shifts of the carbon atoms attached to the silicon. The ²⁹Si and ¹³C resonances of the cyclic silanes deviate from this relationship. Ring current effects arising from σ delocalization are suggested as an explanation for the deviations. Proton-coupled ²⁹Si NMR spectra are reported for Me₃SiSiMe₃ and for (Me₂Si)_n, n = 5 to 7.     

Synthesis and desilylation of some bis(trimethylsilyl)alkenes and polymers bearing bis(silyl)alkenyl groups

The synthesis of various vinylbis(silanes) from some aryl and heteroaryl aldehydes and (Me₃Si)₃CLi in Et₂O is described. Friedel-Crafts reaction of 1,1-bis(trimethylsilyl)-2-(2-naphthyl)ethene with various acyl chlorides (RCOCl, R = Me, Et, i-Pr, i-Bu, n-pent) gave the corresponding α-silyl-α,β-unsaturated enones with high E steroselectivity. Moreover, poly(styrene)-co-[2,2-bis(trimethylsilyl)ethenyl(styrene)] obtained via the reaction of polymers bearing pendant enone functions and (Me₃Si)₃CLi, reacts with the same acyl chlorides in the presence of catalytic amount of AlCl₃ to give the new macromolecules bearing α-silyl-α,β-unsaturated enones and α,β-unsaturated enones.     

Cyclic polysilanes : XIX. A temperature study of redistribution equilibria between permethylcyclopolysilanes

Equilibria among the cyclic compounds (Me₂Si)_n where n = 5, 6 and 7 have been studied between 30–58°C. Thermodynamic values for the redistribution reactions between pairs of compounds are, for n = 5 → 6, ΔH = ?18 kcal/mole, ΔS = ?20 cal/deg. mole; for n = 7 → 6, ΔH ?3, ΔS +33; for n = 7 → 5, ΔH +18, ΔS + 51. The enthalpies indicate that the stabilities of the rings increase in the order (Me₂Si)₅ < (Me₂Si)₇ < (Me₂Si)₆. The differences are smaller than corresponding differences among the cycloalkanes, probably because the silicon compounds are less affected by steric repulsions and angle strain.     

Synthesis of Functional Monosilanes by Disilane Cleavage with Phosphonium Chlorides

The Müller–Rochow direct process (DP) for the large-scale production of methylchlorosilanes Me_nSiCl_4−n (n=1–3) generates a disilane residue (Me_nSi₂Cl_6−n, n=1–6, DPR) in thousands of tons annually. This report is on methylchlorodisilane cleavage reactions with use of phosphonium chlorides as the cleavage catalysts and reaction partners to preferably obtain bifunctional monosilanes Me_xSiH_yCl_z (x=2, y=z=1; x,y=1, z=2; x=z=1, y=2). Product formation is controlled by the reaction temperature, the amount of phosphonium chloride employed, the choice of substituents at the phosphorus atom, and optionally by the presence of hydrogen chloride, dissolved in ethers, in the reaction mixture. Replacement of chloro by hydrido substituents at the disilane backbone strongly increases the overall efficiency of disilane cleavage, which allows nearly quantitative silane monomer formation under comparably moderate conditions. This efficient workup of the DPR thus not only increases the economic value of the DP, but also minimizes environmental pollution.     

AlCl3-Catalyzed transformations of organo(trichloromethyl) silanes

Reactions of organo(trichloromcthyl)silanes RMc₂SiCCl₃ (R = Me, Ph, Mc₃Si) with aluminum chloride have been studied. The interaction of trimetltyl(tricltlorometltyl)silane with AlCl₃ carried out in cyclohexane or in benzene leads to Me₃SiCHCI₂ (in 75 % yield) or ClMe₂SiCPh₂Me (in 70 % yield), respectively; whereas no conversions are observed inn-hexane and methylene chloride. Treatment of dimetltyl(phenyl)(ricltloromethyl)silane with aluminum chloride in a_n-C₅H₁₂/CH₂CI₂ mixture gives an aromatic cross-linked insoluble polymer. The reaction of pentamethyl(trichloromcthyl)disilane (R = Mc₃Si) with AICl₃ in pentane affords the rearrangement product, Me₃SiCCl₂SiMc₂Cl, in 65 % yield. In methylene chloride the further cleavage of the disilane occurs to yield Me₂SiCl₂ and CH₂=CHMe₂SiCl.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1511-1515, June, 1996.     

Generation and capture of alkylchlorosilanones

Alkyltrichlorosilanes react with DMSO (molar ratio 1 : 1 0 °C) to give cyclic oligoalkylchlorosiloxanes of the general formula [R(Cl)SiO] _n (where R=Me or Et;n=3–6). With an excess of alkyltrichlorosilane (2: 1), linear oligoalkylchlorosiloxanes Cl[R(Cl)SiO] _m SiCl₂R (where R=Me or Et;m=1–5) are also formed. In the presence of hexamethyldisiloxane (molar ratio Cl₃SiR : DMSO: (Me₃Si)₂O=1:1:2, 20 °C), the reaction products are both cyclic and linear oligoalkyl(trimethylsilyloxy)siloxanes [R(Me₃SiO)SiO] _n (n=3–5) and Me₃Si[OSi(OSiMe₃)R] _m OSiMe₃ (m=1–3), respectively. The reaction of DMSO with trichloro(vinyl)silane and hexamethyldisiloxane occurs in a similar manner. A plausible scheme of formation of the final products via intermediate alkylchlorosilanones RClSi=O and alkyl(trimethylsilyloxy)silanones is discussed. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 361–364, February, 2000.     

Me3SiSiMe2(OnBu): a disilane reagent for the synthesis of diverse silacycles via Brook- and retro-Brook-type rearrangement

Herein, a readily available disilane Me₃SiSiMe₂(OⁿBu) has been developed for the synthesis of diverse silacycles via Brook- and retro-Brook-type rearrangement. This protocol enables the incorporation of a silylene into different starting materials, including acrylamides, alkene-tethered 2-(2-iodophenyl)-1H-indoles, and 2-iodobiaryls, via the cleavage of Si–Si, Si–C, and Si–O bonds, leading to the formation of spirobenzosiloles, fused benzosiloles, and π-conjugated dibenzosiloles in moderate to good yields. Preliminary mechanistic studies indicate that this transformation is realized by successive palladium-catalyzed bis-silylation and Brook- and retro-Brook-type rearrangement of silane-tethered silanols.

A readily available disilane Me₃SiSiMe₂(OⁿBu) as a silylene source has been developed for the synthesis of diverse silacycles via Brook- and retro-Brook-type rearrangement.     

Synthese neuer Aminofluorsilane,sowie Alkoxylierung von Bis (trimethylsilyl)-amino-fluorsilanen

The reaction of aminofluorsilanes of the type (R=H,F) (Me ₃Si)₂N?SiF₂R with two moles of ammonia, or of a mono- or dialkylamine, yields the corresponding amino-compounds, e.g. (Me ₃Si)₂N?Si(F)R?NH₂, (Me ₃Si)₂N?Si(F)R?NHR′ and (Me ₃Si)₂N?Si(F)R?NR₂′ (R′=Me, Et). Analogous products are obtained by reaction of the aminofluorosilanes with lithium salts of amines with bulky organic substituents in a 1 : 1 molar ratio. Alkoxy- and aryloxyaminofluorosilanes are prepared by the reaction of sodium alcoholates and sodium phenolate with (Me ₃Si)₂N?Si(F₂)R (R=H, C₂H₃, C₂H₅, C₆H₅). The i.r.-, mass-,¹H- and¹⁹F-NMR spectra of the above compounds are reported.     

Metallorganische diazoalkane : XVI. Synthese von silyldiazoalkanen Me3Si(LnM)CN2

Silyldiazoalkanes Me₃Si(L_nM)CN₂ (L_nM = Me₃Si, Me₃Ge, Me₃Sn, Me₃Pb; Me₃As, Me₃Sb, Me₃Bi) have been synthesized by three different routes: (a) reactions of the Me₃SiCHN₂ with metal amides L_nMNR¹R² of Group IVB and VB elements, using Me₃SnCl as catalyst; (b) reactions of the in situ prepared organolithium compound Me₃SiC(Li)N₂ with organometallic chlorides Me₃MCl (M = Si, Ge); (c) tincarbon bond cleavage reaction of (Me₃Sn)₂CN₂ with Me₃SiN₃, affording Me₃SnN₃, traces of bis(trimethylsilyl)diazomethane (Me₃Si)CN₂, trimethylsilyl(trimethylstannyl)diazomethane Me₃Si(Me₃Sn)CN₂ and bis(trimethylsilyl)aminoisocyanide (Me₃Si)₂NNC as the major reaction products. IR and NMR data (¹H, ¹³C, ²⁹Si, ¹¹⁹Sn, ²⁰⁷Pb) of the new heterometal-diazoalkanes are reported and discussed in comparison to relevant compounds of the organometallic diazoalkane series.     

Synthesis and characterization of poly(butadiene-b-sulphone) by block-copolycondensation—I. Synthesis from α,ω-dichlorocarbonyl oligobutadienes and α,ω-diphenol oligoarylethersulphones

Synthesis of poly(butadiene-b-sulphone) has been carried out by two methods. Reaction of α,ω-di(sodium phenolate) oligosulphone with α,ω-di(chlorocarbonyl)oligobutadiene or reaction of α,ω-diphenol oligosulphone with α,ω-di(chlorocarbonyl)oligobutadiene in the presence of magnesium. For both methods, the reaction was carried out between two models (bisphenol A and adipoyl chloride) or between a model and an oligomer or between two oligomers. For the first reaction a two-step process, involving the separation and the purification of the phenolate, is described: it is more efficient than the classical one-step process, where acid chloride is added in an alkaline solution of phenol. The second method, which seems never to have been used in polymer synthesis, gives better results than the first, with higher $\text{DP}{}_{\mathrm{n}}$ and less interference from side-reactions.     

SYNTHESIS AND PROPERTIES OF COPOLYMERS FROM 1-[3,5-BIS(TRIMETHYLSILYL)PHENYL]-2-PHENYLACETYLENE

Copolymerization of 1-[3,5-bis(trimethylsilyl)phenyl]-2-phenylacetylene (m,m-(Me₃Si)₂DPA) with other diphenylacetylene derivatives and their copolymer properties were investigated. Homopolymerization of m,m-(Me₃Si)₂DPA by TaCl₅─n-Bu₄Sn (1:2) did not give the polymer due to steric hindrance. However, m,m-(Me₃Si)2DPA copolymerized with diphenylacetylene (DPA), 1-phenyl-2-[p-(trimethylsilyl)phenyl]acetylene (p-Me₃Si DPA), and 1-phenyl-2-[m-(trimethylsilyl)phenyl]acety-lene (m-Me₃SiDPA) in the presence of TaCl₅─n-Bu₄Sn at various feed ratios to give copolymers in moderate yields. The formed copolymers were yellow to orange solids, which were soluble in common organic solvents such as toluene and CHCl₃. The highest weight-average molecular weights (M_w) of these copolymers reached ca. 6 × 105 and tough films could be obtained by solution casting. Their onset temperatures of weight loss in air were observed around 400°C, indicating high thermal stability. The oxygen permeability coefficients at 25°C of copoly(m,m-(Me₃Si)₂ DPA/DPA) (feed ratio 1:1) and copoly(m,m-(Me₃Si)₂DPA/p-Me₃SiDPA) (feed ratio 1:2) were 21 and 100 barrers, respectively, medium in magnitude among polymers from substituted acetylenes.     

Group VIII metal phosphine complexes-catalyzed addition of disilanes to allenic compounds: Formation of new organosilicon compounds containing both vinylsilane and allylsilane units

Addition of chloromethyl- and methoxymethyldisilanes, X₃-_mMe_mSiSiMe_n-X₃-_n (X - Cl and OMe;m, n - 0-2), as well as hexamethyldisilane, to allene and 1, 2-butadiene in the presence of Pd(PPh₃)₄ catalyst gave regioselectively new functionalized organosilicon compounds, 2, 3-bis(organosilyl)prop-1-enes and 2, 3-bis(organosilyl)but-1-enes, respectively. Other group VIII metal-phospine complexes also affected the reaction, but results were found to be less satisfactory. Also, the reaction of any unsymmetrical disilane with an allenic compound gave only a single product; e.g., the addition of chloropentamethyldisilane to 1, 2-butadiene in the presence of Pd(PPh₃)₄ gave CH₂-C(SiMe₃)CH(SiMe₂Cl)Me in 93% yield.     

Effect of catalyst structure on the reaction of α-methylstyrene with 1,1,3,3-tetramethyldisiloxane

Reaction of α-methylstyrene with 1,1,3,3-tetramethyldisiloxane in the presence of the complexes of platinum(II), palladium(II) and rhodium(I) is explored. It is established that in the presence of platinum catalyst predominantly occurs hydrosilylation of α-methylstyrene leading to formation of β-adduct, on palladium catalysts proceeds reduction of α-methylstyrene, on rhodium catalysts both the processes take place. In the reaction mixture proceeds disproportion and dehydrocondensation of 1,1,3,3-tetramethyldisiloxane that leads to formation of long chain linear and cyclic siloxanes of general formula HMe₂Si(OSiMe₂) _n H and (-OSiMe₂-)m (n = 2–6, m = 3–7), respectively. Platinum catalysts promotes formation of linear siloxanes, while both rhodium and palladium catalysts afford linear and cyclic siloxanes as well. Structure of intermediate metallocomplexes is studied.     

The [Cp(CO)2Fe] (Fp) group as a donor in donor/acceptor substituted disilanes: synthesis,structure and electronic properties of FpSi2Me4C6H4CHC(CN)2

UV–vis absorption spectroscopy and cyclic voltammetry are used to study electronic interactions in the donor/acceptor substituted disilane FpSi₂Me₄C₆H₄CHC(CN)₂ (Fp=η⁵-C₅H₅Fe(CO)₂) (1). The synthesis of 1 was achieved by a conventional chemical route, the model substances FpSiMe₃ (2), FpSi₂Me₅ (3) and FpSi₂Me₄C₆H₅ (4) were obtained by the electrolysis of Fp₂ in the presence of the appropriate chlorosilane. The structure of 1, determined by X-ray diffraction, exhibits an all-trans-array of the FeSiSiC_aryl fragment, a basic requirement for optimal through-bond interaction. UV–vis and CV data indicate strong intramolecular donor/acceptor interaction in 1.     

Synthesis and reactivity of ω-haloalkyltin compounds

ω-Haloalkyltin trihalides, X(CH₂)_nSnX₃ (n ≧ 3; X = halogen) can readily be prepared in high yields by the direct reaction of stannous halides with α,ω-dihaloalkanes, catalysed by trialkylantimony compounds. The compounds are versatile starting materials for the synthesis of a variety of ω-functionallysubstituted organotin compounds R_3-mX_mSn(CH₂)_n Y (R = alkyl, phenyl; m = 0-3; X = Cl, Br, O; Y = Br, NMe₂, NEt₂, COOH, CHOHR, R₃Sn). ¹H-NMR spectral data for a series of such compounds are presented. The trends observed in the chemical shifts and the ¹¹⁹Sn—methyl proton coupling constants of Me_3-m Br_mSn(CH₂)_nBr (m = 0-3; n = 3-5) are discussed in terms of inductive effects. Intramolecular coordination between the ω-bromine atom and tin could not be demonstrated.     

Use of Neodymium Diiodide in the Synthesis of Organosilicon, ‐Germanium and ‐Tin Compounds

The reactivity of neodymium diiodide, NdI₂ ( 1 ), towards organosilicon, ‐germanium and ‐tin halides has been investigated. Compound 1 readily reacts with Me₃SiCl in DME to give trimethylsilane (6 %), hexamethyldisilane (4 %) and (Me₃Si)₂O (19 %). The reaction with Et₃SiBr in THF results in formation of Et₃SiSiEt₃ (17 %) and Et₃SiOBuⁿ (34 %). Alkylation of Me₃SiCl with PrⁿCl in the presence of 1 in THF affords Me₃SiPrⁿ (10 %), Me₃SiOBuⁿ (52 %) and Me₃SiSiMe₃ (1 %). The main product identified in the reaction mixture formed upon interaction of 1 with dichlorodimethylsilane Me₂SiCl₂ in THF is di‐n‐butoxydimethylsilane Me₂Si(OBuⁿ)₂ (54 %) together with minor amounts of Me₂Si(OBuⁿ)Cl. The reaction of 1 with Me₃GeBr under the same conditions produces Me₃GeGeMe₃ (44 %), Me₃GeH (3 %), and Me₃GeI (7 %). An analogous set of products was obtained in the reaction with Et₃GeBr. Treatment of trimethyltin chloride with 1 causes reduction of the former to tin metal (74 %). Me₃SnH (7 %) and hexamethyldistannane (11 %) were identified in the volatile products. The reaction of 1 with Me₃SiI provides straightforward access to hepta‐coordinated NdI₃(THF)₄ ( 2 ), the structure of which was determined by X‐ray diffraction.     

Monocyclische organotri- und -tetrastibane: synthese von [(Me3Si)2CHSb]n (n = 3, 4)

Reduction of (Me₃Si)₂CHSbCl₂ with Mg in tetrahydrofuran yields [(Me₃Si)₂CHSb]_n (n = 3, 4).     

含硅铁键环状化合物[Me2Si-η5-C5H4Fe(CO)(PPh3)][Me2Si-η5-C5H4Fe- (CO)2－n(PPh3)n] (n＝0或1)的合成与结构

鉴于含硅-过渡金属键化合物作为催化剂具有重要的应用价值, 在我们最近发现的化合物(η⁵,η⁵-C₅H₄Me₂SiSi-Me₂C₅H₄)Fe₂(CO)₄ (1)的硅硅键和铁铁键复分解重排反应可以有效地合成含有两个硅铁键的环状化合物[Me₂Si-η⁵-C₅H₄- Fe(CO)₂]₂ (2)的基础上, 对该硅铁键环状化合物的三苯基膦取代衍生物[Me₂Si-η⁵-C₅H₄-Fe(CO)(PPh₃)][Me₂Si-η⁵-C₅H₄Fe(CO)_2－n(PPh₃)_n] (3: n＝0, 5: n＝1)的合成方法进行了研究. 发现化合物1在三苯基膦存在下的复分解重排反应是合成单三苯基膦取代产物3的最好方法; 而双三苯基膦取代化合物5则可通过光照条件下2与三苯基膦发生羰基取代反应而得到, 产物中含有的顺反异构体可利用制备薄层色谱法分离. 利用X射线衍射法测定了化合物3的分子结构, 考察了三苯基膦配体的存在对分子结构的影响以及三苯基膦与铁形成的配位键的稳定性.     

Synthesis and characterization of binuclear Zn(II)–cyclen complexes bridged by α,ω-bis(4-methylphenoxy) alkanes

A series of novel α,ω-bis(4-methylphenoxy) alkane functionalized cyclen ligands were synthesized by the nucleophilic substitution reaction of 1,4,7-tris(tert-butyloxycarbonyl)-1,4,7,10-tetraazacyclododecane and α,ω-bis(4-bromomethylphenoxy) alkanes. The corresponding dimeric Zn(II)–cyclen complexes were obtained by reaction of these ligands with Zn(ClO₄)₂·6H₂O. Ligands and complexes were characterized by FT-IR, ¹H NMR, and elemental analysis.