1,3-Migration of a phenyl group in the conversion of (Me3Si)2(PhMe2Si)CSiMePhX into (Me3Si)2(Ph2MeSi)CSiMe2Y species

The finding that compounds of the type (Me₃Si)₂(PhMe₂Si)CSiMePhX react with electrophiles to give very predominantly rearranged products (Me₃Si)₂(Ph₂MeSi)CSiMe₂Y, which would be expected to be thermodynamically disfavoured, can be rationalized in terms of a mechanism in which the anchimerically-assisted departure of X⁻ gives the Ph-bridged cation [(Me₃Si)₂

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MePh]⁺ which is attacked by the nucleophile at the less hindered centre bearing two Me groups rather than that bearing one Me and one Ph group, with the outcome determined by kinetic rather than thermodynamic factors. Both (Me₃Si)₂(Ph₂MeSi)CSiMe₂Br and its isomer (Me₃Si)₂(PhMe₂Si)CSiMePhBr react with AgBF₄ in CH₂Cl₂ or Et₂O to give >95% of the fluoride (Me₃Si)₂(Ph₂MeSi)CSiMe₂F. Reaction of the bromide (Me₃Si)₂(PhMe₂Si)CSiMePhBr with AgO₂CCF₃ in Et₂O, and that of the hydride (Me₃Si)₂(PhMe₂Si)CSiMePhH with ICl in CCl₄, likewise give >95% of the rearranged (Me₃Si)₂(Ph₂MeSi)CSiMe₂O₂CCF₃ and (Me₃Si)₂(Ph₂MeSi)CSiMe₂Cl, respectively.     

Bimolecular displacements of iodine in reactions of dimethyl[tris(trimethylsilyl)methyl]silyl iodide with salts

Direct nucleophilic displacement of iodine to give (Me₃Si)₃ CSiMe₂ Y, where Y = F, NCO, NCS, CN or N₃, takes place when (Me₃Si)₃ CSiMe₂I is treated with solutions of CsF, KOCN, KSCN, KCN, or NaN₃ in MeOH or CH₃ CN. The order of effectiveness of the nucleophiles appears to be N₃ > F > CN > NCS > NCO in MeOH and NCS > NCO > CN, F in CH₃ CN.     

Monomeres Trilithium-tris[tert-butyldimethylsilylamido]phenylsilan,PhSi[NLi(THF)SiMe2CMe3]3 -- Darstellung und Kristallstruktur

Monomeric Trilithium-tris[tert-butyldimethylsilylamido]phenylsilane, PhSi[NLi(thf)SiMe₂CMe₃]₃ – Synthesis and Crystal Structure Lithiated tert-butyldimethylsilylamine reacts with trifluorophenylsilane in a molar ratio 2:1 or 3:1 to give the bis- and tris(silylamino)silanes 1 [(Me₃CSiMe₂NH)₂SiFPh] and 2 [(Me₃CSiMe₂NH)₃SiPh]. The trilithium derivative 3 [Me₃CSiMe₂NLi(thf)]₃SiPh is obtained in the reaction of 2 with n-BuLi in hexane/thf. 3 crystallizes as a monomer forming three planar four-membered (LiNSiN)-rings. The results of the crystal structure of 3 are discussed.     

Organometallic Reactions and Syntheses : Volume 6, E. I. Becker and M. Tsutsui,ed., Plenum Publishing Corporation., New York/ London, 1977, xii + 314 pages $47.40

The (Me₃Si)₃C group causes very large steric hindrance to nucleophilic displacement at a silicon atom to which it is attached, and (Me₃Si)₃CSiMe₂Cl is even less reactive than t-Bu₃SiCl towards base. The compounds (Me₃Si)₃CSiMe₂X (X = Cl, Br, or I) are cleaved by MeOH/MeONa to give (Me₃Si)₂CHSiMe₂OMe, possibly via the silaolefin (Me₃Si)₂ CSiMe₂, and the correspondLug (Me₃Si)₃ CSiPh₂X compounds undergo the analogous reaction even more readily. The halides (Me₃Si)₃CSiR₂X (X = Cl or Br) and (Me₃Si)₃CSiCl₃ do not react with boiling alcoholic silver nitrate, but the iodides (Me₃Si)₃CSiR₂I are rapidly attacked.     

Sur la réaction de reformatsky : I. Préparation et réactivité des organozinciques issus de divers crotonates d''alcoyles

Lithiation of (Me₃Si)₃CH by methyllithium (ether-THF) yields (Me₃Si)₃CLi and by t-butyllithium (C₅H₁₂-TMEDA) yields (Me₃Si)₂CHSiMe₂CH₂Li. Only starting material is recovered when (Me₃Si)₃CH is allowed to react with n-butyl- lithium (ether-THF and C₅H₁₂-TMEDA) and t-butyllithium (C₅H₁₂ and C₅H₁₂- THF). (Me₃Si)₄C is lithiated by t-butyllithium (C₅H₁₂-TMEDA) to give (Me₃Si)₃- CSiMe₂CH₂Li, but not by methyllithium (ether-THF and ether-THF-TMEDA). The structures of the lithiated compounds are based on the carbonation products. The above results are explained in terms of carbanion stability and steric effects. Spectral data are reported on the α-silylacetic acids.     

Reaktionen von Lithiumhydridosilylamiden RR′(H)Si–N(Li)R″ mit Chlortrimethylsilan in Tetrahydrofuran und unpolaren Lösungsmitteln: N‐Silylierung und/oder Cyclodisilazanbildung

Reactions of Lithium Hydridosilylamides RR′(H)Si–N(Li)R″ with Chlorotrimethylsilane in Tetrahydrofuran and Nonpolar Solvents: N‐Silylation and/or Formation of Cyclodisilazanes The lithiumhydridosilylamides RR′(H)Si–N(Li)R″ ( 2 a : R = R′ = CHMe₂, R″ = SiMe₃; 2 b : R = R′ = Ph, R″ = SiMe₃; 2 c : R = R′ = CMe₃, R″ = SiMe₃; 2 d : R = R′ = R″ = CMe₃; 2 e : R = Me, R′ = Si(SiMe₃)₃, R″ = CMe₃; 2 f – 2 h : R = R′ = Me, f : R″ = 2,4,6‐Me₃C₆H₂, g : R″ = SiH(CHMe₂)₂, h : R″ = SiH(CMe₃)₂; 2 i : R = R′ = CMe₃, R″ = SiH(CMe₃)₂) were prepared by reaction of the corresponding hydridosilylamines RR′(H)Si–NHR″ 2 a – 2 i with n‐butyllithium in equimolar ratio in n‐hexane. The unknown amines 1 e – 1 i and amides 2 f – 2 i have been characterized spectroscopically. The wave numbers of the Si–H stretching vibrations and ²⁹Si–¹H coupling constants of the amides are less than of the analogous amines. This indicates a higher hydride character for the hydrogen atom of the Si–H group in the amide in comparison to the amines. The ²⁹Si‐NMR chemical shifts lie in the amides at higher field than in the amines. The amides 2 a – 2 c and 2 e – 2 g react with chlorotrimethylsilane in THF to give the corresponding N‐silylation products RR′(H)Si–N(SiMe₃)R″ ( 3 a – 3 c , 3 e – 3 g ) in good yields. In the reaction of 2 i with chlorotrimethylsilane in molar ratio 1 : 2,33 in THF hydrogen‐chlorine exchange takes place and after hydrolytic work up of the reaction mixture [(Me₃C)₂(Cl)Si]₂NH ( 5 a ) is obtained. The reaction of the amides 2 a – 2 c , 2 f and 2 g with chlorotrimethylsilane in m(p)‐xylene and/or n‐hexane affords mixtures of N‐substitution products RR′(H)Si–N(SiMe₃)R″ ( 3 a – 3 c , 3 f , 3 g ) and cyclodisilazanes [RR′Si–NR″]₂ ( 6 a – 6 c , 6 f , 6 g ) as the main products. In case of the reaction of 2 h the cyclodisilazane 6 h was obtained only. 2 c – 2 e show a very low reactivity toward chlorotrimetyhlsilane in m‐xylene and toluene resp.. In contrast to Me₃SiCl the reactivity of 2 d toward Me₃SiOSO₂CF₃ and Me₂(H)SiCl is significant higher. 2 d react with Me₃SiOSO₂CF₃ and Me₂(H)SiCl in n‐hexane under N‐silylation to give RR′(H)Si–N(SiMe₃)R″ ( 3 d ) and RR′(H)Si–N(SiHMe₂)R″ ( 3 d ′) resp. The crystal structures of [Me₂Si–NSiMe₃]₂ ( I ) ( 6 f , 6 g and 6 h ) have been determined.     

The Diels—Alder reaction in organometallic chemistry VI. Diels—Alder reactions of α-pyrone with group IV element-substituted acetylenes

The Diels—Alder reactions of α-pyrone with Me₃SiCCSiMe₃, Me₃SiCCSiMe₂H, Me₂HSiCCSiMe₂H, Me₃GeCCGeMe₃, Me₃SiCCGeMe₃, Me₃SiCCSnMe₃ and EtCCEt were examined. All except the first two acetylenes gave the expected 1,2-disubstituted benzene product, in line with results obtained previously with Me₃SnCCSnMe₃. The first two acetylenes, Me₃SiCCSiMe₃ and Me₃SiCCSiMe₂H, also yielded benzene products containing substantial amounts of the 1,3-disubstituted benzenes, as well as minor amounts of the 1,4-isomers. This formation of unexpected isomers during these reactions was shown to result from acid-catalyzed rearrangement of the initially formed 1,2-disubstituted products, 1,2-(Me₃Si)₂C₆H₄ and 1-Me₃Si-2-Me₂HSiC₆H₄. The acidic impurities arose from pyrolysis of the bromobenzene solvent used or were introduced as contaminants of the α-pyrone. Such isomerizations were inhibited by addition of small amounts of triethylamine. The fact that no rearrangement took place with the other acetylenes is due to the scavenging of acidic impurities which might cause isomerization by the starting acetylene and the benzene product via metal—carbon bond cleavage processes.     

Alternativ-Liganden. XXI. Neue Donor/Akzeptor-Liganden Me2PCH2CH2SiFnMe3-n,Me2PCH2CH2SiR(C6H4F)2 und (2-Me2PC6H4)SiXMe2

Alternative Ligands. XXI. Novel Donor/Acceptor Ligands Me₂PCH₂CH₂SiF_nMe_3-n, Me₂PCH₂CH₂SiR(C₆H₄F)₂, and (2-Me₂PC₆H₄)SiXMe₂ Donor/acceptor ligands of the type Me₂PCH₂CH₂SiX₃ [X = Cl ( 1 ), F ( 2 ), Me ( 3 ), OMe ( 4 )], (Me₂PCH₂CH₂)₂SiX₂ [X = Cl ( 6 ), F ( 7 )], Me₂PCH₂CH₂SiX(C₆H₄F)₂ [X = F ( 5 ), Me ( 8 )], and Me₂PCH₂CH₂SiX_nMe_3-n[n = 1; X = Cl ( 10 ), F ( 11 ); n = 2; X = F ( 9 )] are prepared in yields between 42 and 95% by photochemical addition of Me₂PH to the corresponding vinylsilane precursors. In case of the halogen containing representatives formation of solid polyadducts, due to Lewis acid/base interaction between P-donor and Si-acceptor function, reduces the yields. Ligands of the type (2-Me₂PC₆H₄)SiXMe₂ [X = NMe₂ ( 12 ), Cl ( 13 ), F ( 14 )] are obtained by two different routes (Abb. 3), using 2-chlorobromobenzene as the starting material. New compounds have been characterized by analytical (C, H) and spectroscopic (NMR, MS) investigations. In order to elucidate the associative properties compounds 2 and 9 were used for the following experiments:

• – Study of the influence of dissolution on the proton and fluorine resonances of 2 and 9 ,
• – investigation of the adduct equilibrium (–H₂CF₃Si←PMe₂CH₂–)n + nBF₃ → n[F₃B←PMe₂CH₂CH₂SiF₃],
• – cleavage of the polyadduct of 2 using [NH₄]F and [Me₄N]F, respectively, for the formation of hexacoordinate complex anions [Me₂PCH₂CH₂SiF₅]^2?.

The results obtained confirm the assumption that oligo- and polymerisation are due to P→Si interaction.     

Zum Reaktionsverhalten lithiierter Aminosilane RR′ Si(H)N(Li)SiMe3

The Reaction Behaviour of Lithiated Aminosilanes RR′Si(H)N(Li)SiMe₃ The bis(trimethylsilyl)aminosubstituted silances RR′Si(H)N(SiMe₃)₂ 11 – 16 (R,R′ = Me, Me₃SiNH, (Me₃Si)₂N) are obtained by the reaction of the lithium silylamides RR′Si(H)N(Li)SiMe₃ 1 – 10 (R,R′ = Me₃SiNLi, Me, Me₃SiNH, (M₃Si)₂N) with chlorotrimethylsilane in the polar solvent tetrahydrofurane (THF). In the reaction of the lithium silylamides [(Me₃Si)₂N]₂(Me₃SiNLi)SiH 10 with chlorotrimethylsilane in THF the rearranged product 1,1,3-tris[bis(trimethylsilyl)amino]-3-methyl-1,3-disila-butane [(Me₃Si)₂N]₂Si(H)CH₂SiMe₂N(SiMe₃)₂ 17 is formed. The reaction of the lithium silyamides RR′ Si(H)N(Li)SiMe₃ 1 – 3 (1: R = R′ = Me; 2: R = Me, R′ = Me₃SiNH; 3: R = Me, R′ = Me₃SiNLi) with chlorotrimethylsilane in the nonpolar solvent n-hexane gives the cyclodisilazanes [RR′ Si? NSiMe₃]₂ 18 – 22 (R = Me, Me₃SiNH, (Me₃Si)₂N; R′ = Me, Me₃SiNH, (Me₃Si)₂N, N(SiMe₃)Si · Me(NHSiMe₃)₂) and trimethylsilane. The lithium silylamides 4 , 5 , 6 , 9 , 10 (4: R = R′ = Me₃SiNH; 5: R = Me₃SiNH, R′ = Me₃SiNLi; 6: R = R′ = Me₃SiNLi; 9: R = (Me₃Si)₂N, R ′ = Me₃SiNLi; 10: R = R′ = (Me₃Si)₂N) shows with chlorotrimethylsilane in n-hexane no reaction. The crystal structure of 17 and 21 are reported.     

Synthesis and reactions of p-vinylbenzyltris(trimethylsilyl)methane

Benzyl chloride was treated with (Me₃Si)₃CLi to give (Me₃Si)₃CCH₂Ph (1). A new styrene derivative, (Me₃Si)₃CCH₂C₆H₄(CHCH₂-p) (2), was synthesized by reaction of p-vinylbenzyl chloride with (Me₃Si)₃CLi in the presence of CuCl. Addition and oxidation reactions on 2 gave a series of new compounds (Me₃Si)₃CCH₂C₆H₄X-p (X = CH₂CH₃, CHBrCH₂Br, CHClCH₂I, CHBrCH₂I, cyclo-C₃H₃Cl₂, CHOHCH₂OH, COOH, CH₂OH).     

Immobilization, Characterization, and Preliminary Reactivity Studies of Halfsandwich Ruthenium Complexes on Silica

Summary. The complexes [RuCp(CH₃CN)₂(Ph₂PCH₂CH₂Si(OMe)₃)]PF₆ and [RuCp(CH₃CN) (Ph₂PCH₂CH₂Si(OMe)₃)₂]PF₆ were obtained in good yields by treatment of [RuCp(CH₃CN)₃]PF₆ with 1 and 2 equivs of Ph ₂PCH₂CH₂Si(OMe)₃. Both free Ph ₂PCH₂CH₂Si(OMe)₃ and the two complexes were grafted onto the surface of powdered silica. The surface coverage was determined independently by ³¹P solid state NMR and IR spectroscopy. IR data revealed that for Ph ₂PCH₂CH₂Si(OMe)₃ and the complexes 52, 52, and 18 molecules, respectively, were immobilized per 100nm² of SiO₂ surface. Similar values were obtained from ³¹P MAS NMR measurements. With the immobilized first complex the catalytic redox isomerization of allyl alcohol to propanal has been studied by means of IR spectroscopy and ¹H NMR spectroscopy showing the quantitative formation of aldehyde. While in the first cycle satisfactory turnover numbers were achieved, the subsequent cycles showed only low conversions to aldehyde presumably due to decomposition of the complex. The immobilized second complex was catalytically inactive.Received February 25, 2003; accepted March 24, 2003 Published online August 18, 2003     

[Li(12-Krone-4){(Me3Si)2N}2TiCH2SiMe2NSiMe3] – ein Ionenpaar mit gestreckter Li–C–Ti-Achse

[Li(12-Crown-4){(Me₃Si)₂N}₂TiCH₂SiMe₂NSiMe₃] – an Ion-Pair with a Linear Li–C–Ti-Axis The title compound ( 1 ) has been prepared from Ti[N(SiMe₃)₂]₃ and n-butyllithium in OEt₂/n-hexane in the presence of 12-crown-4. Smaragd-green single crystals of 1 · C₇H₈ which were suitable for X-ray crystallography were formed from toluene solutions at –18 °C. According to the crystal structure determination 1 forms ion pairs between the lithium atom and the CH₂-carbon atom which is member of a planar Ti–C–Si–N heterocycle. The coordination geometry of the Li–C–Ti axis is linear (bond angle 172.8° in average of the two symmetry independent species) with coordination number five at the CH₂-carbon atom.     

Siliconcarbon multiple-bonded (pπpπ)intermediates : II. Chemical reactivity and selectivity of thermally generated 1,1-dimethyl-1-silaethene (Me2SiCH2)

The order of reactivity and the selectivity of 1,1-dimethyl-1-silaethene (Me₂SiCH₂), generated from 1,1-dimethylsilacyclobutane at 611°, toward a variety of substrates was determined using standard competition experiments. The observed reactivity order was Ph₂CO>ROH, ArOH ? m-ClPhNH₂ CH₃CN, which indicates that with these substrates and under the reaction conditions used, Me₂SiCH₂ is behaving like an electrophilic species. Within a given class of substrates, polar effects were found to be generally unimportant, while increased steric effects caused a decrease in rate (up to 50%).     

A new class of silicon-phosphorus heterocycles: 4-silaphosphorinanes

Radical reactions of Me₃SiPH₂ with Me₂Si(CHCH₂)₂ or Si(CHCH₂)₄ yield the 4-silaphosphorinanes Me₂Si(CH₂CH₂)₂PSiMe₃, (CH₂CH)₂Si(CH₂CH₂)₂PSiMe₃, or [Me₃SiP(CH₂CH₂)₂]₂Si; methanolysis of these produces quantitatively the secondary phosphorinanes Me₂Si(CH₂CH₂)₂PH, (CH₂CH)₂Si(CH₂CH₂)₂PH, or [HP(CH₂CH₂)₂]₂Si. Me₂Si(CH₂CH₂)₂PSiMe₃ with O₂/H₂O yields the phosphinic acid Me₂Si(CH₂CH₂)₂P(O)OH. All compounds are characterized by spectral data; an X-ray crystal analysis confirms the structure of Me₂Si(CH₂CH₂)₂P(O)OH.     

Synthesis and properties of polycarbosilanes with the meta-linkage bending unit by hydrosilylation polymerization

The polycarbosilanes (PCS) with meta-linkage bending unit ((SINGLE BOND)Me₂Si(SINGLE BOND)m(SINGLE BOND)C₆H₄(SINGLE BOND)Me₂Si(SINGLE BOND)CH₂CH₂(SINGLE BOND)) were successfully synthesized in mild conditions by hydrosilylation in the presence of [Pt{(CH₂(DOUBLE BOND)CHSiMe₂)₂O}₂]. The PCS obtained were soluble in various solvents owing to the lowering of the crystallinity. These properties are well compared with those of the PCS [(SINGLE BOND)Me₂Si(SINGLE BOND)p(SINGLE BOND)C₆H₄(SINGLE BOND)Me₂Si(SINGLE BOND)CH₂CH₂(SINGLE BOND)]_n. © 1996 John Wiley & Sons, Inc.     

Über Bildung und Reaktionen der CH2Li‐Derivate von tBu2P–P=P(CH3)tBu2 und (Me3Si)tBuP–P=P(CH3)tBu2

Formation and Reactions of the CH₂Li‐Derivatives of ^tBu₂P–P=P(CH₃)^tBu₂ and (Me₃Si)^tBuP–P=P(CH₃)^tBu₂ With ⁿBuLi, (Me₃Si)^tBuP–P=P(CH₃)^tBu₂ ( 1 ) and ^tBu₂P–P=P(CH₃)^tBu₂ ( 2 ) yield (Me₃Si)^tBuP–P=P(CH₂Li)^tBu₂ ( 3 ) and ^tBu₂P–P=P(CH₂Li)^tBu₂ ( 4 ), wich react with Me₃SiCl to give (Me₃Si)^tBuP–P=P(CH₂–SiMe₃)^tBu₂ ( 5 ) and ^tBu₂P–P=P(CH₂–SiMe₃)^tBu₂ ( 6 ), respectively. With ^tBu₂P–P(SiMe₃)–P^tBuCl ( 7 ), compound 3 forms 5 as well as the cyclic products [H₂C–P(^tBu)₂=P–P(^tBu)–P^tBu] ( 8 ) and [H₂C–P(^tBu)₂=P–P(P^tBu₂)–P(^tBu)] ( 9 ). Also 3 forms 8 with ^tBuPCl₂. The cleavage of the Me₃Si–P‐bond in 1 by means of C₂Cl₆ or N‐bromo‐succinimide yields (Cl)^tBuP–P=P(CH₃)^tBu₂ ( 10 ) or (Br)^tBuP–P=P(CH₃)^tBu₂ ( 11 ), resp. With LiP(SiMe₃)₂, 10 forms (Me₃Si)₂P–P(^tBu)–P=P(CH₃)^tBu₂ ( 12 ), and Et₂P–P(^tBu)–P=P(CH₃)^tBu₂ ( 13 ) with LiPEt₂. All compounds are characterized by ³¹P NMR Data and mass spectra; the ylide 5 and the THF adduct of 4 additionally by X‐ray structure analyses.     

Lithiumhydridosilylamide R2(H)SiN(Li)R′ – Darstellung,Eigenschaften und Kristallstrukturen

Lithium Hydridosilylamides R₂(H)SiN(Li)R′ – Preparation, Properties, and Crystal Structures The hydridosilylamines R₂(H)SiNHR′ ( 1 a : R = CHMe₂, R′ = SiMe₃; 1 b : R = Ph, R′ = SiMe₃; 1 c : R = CMe₃, R′ = SiMe₃; 1 d : R = R′ = CMe₃) were prepared by coammonolysis of chlorosilanes R₂(H)SiCl with Me₃SiCl ( 1 a , 1 b ) as well as by reaction of (Me₃C)₂(H)SiNHLi with Me₃SiCl ( 1 c ) and Me₃CNHLi with (Me₃C)₂(H)SiCl ( 1 d ). Treatment of 1 a–1 d with n-butyllithium in equimolar ratio in n-hexane resulted in the corresponding lithiumhydridosilylamides R₂(H)SiN(Li)R′ 2 a–2 d , stable in boiling m-xylene. The amines and amides were characterized spectroscopically, and the crystal structures of 2 b–2 d were determined. The comparison of the Si–H stretching vibrations and ²⁹Si–¹H coupling constants indicates that the hydrogen atom of the Si–H group in the amides has a high hydride character. The amides are dimeric in the solid state, forming a planar four-membered Li₂N₂ ring. Strong (Si)H … Li interactions exist in 2 c and 2 d , may be considered as quasi tricyclic dimers. The ‘‘NSiHLi rings”︁”︁ are located on the same side of the central Li₂N₂ ring. In 2 b significant interactions occurs between one lithium atom and the phenyl substituents. Furthermore all three amides show CH₃ … Li contacts.     

Nonhydrolytic synthesis and structural study of methoxyl-terminated polysiloxane D/Q resins

Low-viscosity, methoxylated polysiloxane resins incorporating Me₂SiO_2/2 (D) and SiO_4/2 (Q) units were prepared using nonhydrolytic condensation between Si—Cl and Si—OMe groups with the formation of MeCl, catalyzed by a Lewis acid. With the commonly used catalysts, condensation between two Si—OMe groups, with formation of Me₂O, also took place to a large extent, hindering the control of the degree of condensation of the resins. Several catalysts were tested by monitoring the formation of MeCl and Me₂O using sealed NMR tubes and ¹H-NMR spectroscopy. The best compromise between reactivity and selectivity was obtained with ZrCl₄. Resins with various compositions were prepared in the absence of solvent by condensation between Me₂SiCl₂ and Si(OMe)₄ at 130°C, catalyzed by 1 mol % ZrCl₄. They were characterized using viscosimetry, gas chromatography coupled with mass-spectrometry (GC-MS), and quantitative ²⁹Si-NMR spectroscopy. The resins consisted of a complicated mixture of oligomers, linear or branched (n > 1) and cyclic (n > 3), with a high degree of D/Q bonding. The distribution of Si—OMe and Si—OSi bonds and the bonding between D and Q units were found to be nearly random. This was ascribed to the occurrence of Si—OSi/Si—OMe and Si—OSi/Si—OSi redistribution reactions that reached equilibrium during the synthesis. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2415–2425, 1998     

Pentamethyldisilylmethyl and related complexes of iron involving skeletal rearrangements,FeCSiSi → FeSiCSi

For the new complex Me₃ SiMe₂ SiCH₂ Fe(CO)₂Cp the metalcarbon bond undergoes normal insertion reactions;however, under certain conditions the SiSiCFe framework rearranges to the siliconiron bonded system SiC SiFe.     

The reaction of π-cyclopentadienyldicarbonylcobalt with silyl-substituted acetylenes

The reaction of (π-C₅H₅)Co(CO)₂ with PhCCSiMe₂R (R = Me, SiMe₃) gave two isomeric cyclobutadiene complexes, cis- and trans-(π-C₅H₅)Co[Ph₂C₄(SiMe₂R)₂], in almost quantitative yields. However, the reaction with RMe₂SiCCSiMe₂R (R = Me, Ph) led to the formation of new dinuclear cobalt complexes. For example, with bis(trimethylsilyl)acetylene, (π-C₅H₅)₂Co(CO)[(Me₃Si)₂C₂] was obtained quantitatively. The latter was further converted to (π-C₅H₅)Co(Ph₄C₄) and (πC₅H₅)Co[cis-Ph₂C₄(Me₃Si)₂] by treatment with PhCCPh. The physical properties and spectroscopic characteristics of these new compounds are described.