Some highly sterically hindered organo-silanols and -siloxanes

Reaction of the iodides TsiSiMe₂I and TsiSiPh₂I, (Tsi  (Me₃Si)₃C) with AgClO₄ in t-BuOH provides a route to the silanols TsiSiMe₂OH and (Me₃Si)₂-C(SiPh₂Me)(SiMe₂OH), respectively. TsiSiMe₂OH gives the disiloxane TsiSiMe₂OSiMe₃ when treated with either (a) Me₃SiOClO₃ (prepared in situ from AgClO₄ and Me₃SiCl) in benzene, (b) Me₃SiI (in the presence of a little (Me₃Si)₂-NH), (c) O,N-bis(trimethylsilyl)acetamide, or (d) MeLi followed by Me₃SiCl. It does not react with Me₃SiCl, but with Me₂SiCl₂ gives TsiSiMe₂OSiMe₂Cl, and with CH₃COCl gives TsiSiMe₂OCOCH₃. The disiloxane is stable to methanolic acid or base, but reacts with KOH in H₂O/Me₂SO and with CF₃COOH to give TsiSiMe₂OH. The disiloxane (Me₃Si)₂C(SiPh₂Me)(SiMe₂OSiMe₃) is formed by treatment of (Me₃Si)₂C(SiPh₂Me)(SiMe₂OH) with Me₃SiI/(Me₃Si)₂NH. Treatment of TsiSiPhMeI with AgClO₄ in t-BuOH gives the silanols TsiSiPhMeOH and (Me₃Si)₂C(SiPhMe₂)(SiMe₂OH) (which with Me₃SiI/(Me₃Si)₂NH give the corresponding disiloxanes) along with some of the t-butoxide (Me₃Si)₂C(SiPhMe₂)(SiMe₂OBu^t).     

Reaction of tris(trimethylsilyl)methylsilicon halides with methanolic sodium methoxide. Probability of sila-olefin intermediates

The compounds TsiSiR₂X [Tsi = Me₃Si)₃C; R = Me, X = Cl, Br, I, or R = Ph, X = F, Cl, Br, I)] react with boiling 2 M MeONa-MeOH to give products of the type (Me₃Si)₂CHSiR₂OMe. It is suggested that the reaction proceeds through an elimination, analogous to E2 eliminations of alkyl halides, involving synchronous attack of MeO^? at an Me₃Si group, liberation of X^?, and formation of (Me₃Si)₂CSiR₂. The compounds TsiSiPhMeF TsiSiPhCl₂ react analogously to give (Me₃Si)₂CHSiPhMe(OMe) and (Me₃Si)₂CHSiPh(OMe)₂ [tha latter presumably by solvolysis of the initially-formed (Me₃Si)₂CHSiPhCl(OMe)]. The compounds TsiSiMe₂OMe and TsiSiMe₃ do not react, while TsiSiMe₂H gives TsiH. The compound TsiSiCl₃ reacts with 0.1 M MeONa-MeOH to give the substitution and elmination products TsiSiCl₂(OMe) and (Me₃Si)₂CHSi(OMe)₃ in ca. $\text{1}\text{2}$ ratio.     

Preparation of tris(trimethylsilyl)methyl (“trisyl”) derivatives of silicon

Treatment of (Me₃Si)₃CLi (“trisyl”lithium, TsiLi) with appropriate silicon halides has given a range of compounds of the type (Me₃Si)₃CSiRR′X; e.g., TsiSiCl₃, TsiSiMeCl₂, TsiSiMe₂X (X = Cl, OMe), TsiSiPh₂X (X = F, Cl, OMe), and TsiSiPhMeH. The trisyl group causes very large steric hindrance to nucleophilic displacements at the silicon to which it is attached, so that (unless one or more hydride ligands are present) most of the common displacements at silicon do not occur. However, halides can be reduced to hydrides by LiAlH₄, and the hydrides can be converted into halides in electrophilic displacements by hallogens. The presence of even one hydride ligand markedly reduces the hindrance, so that, for example, TsiSiPhHI reacts with refluxing methanol to give TsiSiPhH(OMe).     

Synthesis and reactions of [tris(trimethylsilyl)methyl]ethyl dichlorosilane

The crowded dichlorosilane TsiSiEtCl₂, (1), (Tsi = (Me₃Si)₃C) was prepared from the reaction between EtSiCl₃ and TsiLi, then it was reduced with LiAlH₄ to give TsiSiEtH₂, (2). The hydride (2) was then treated with two equivalents of ICl/CCl₄ or Br₂/CCl₄ to produce TsiSiEtI₂, (3), and TsiSiEtBr₂, (4), respectively. The reaction of compound (2) with one equivalent of ICl/CCl₄ gives TsiSiEtHI, (5). This product reacted with H₂O/dioxane in the presence of AgClO₄ or with dry MeOH to produce TsiSiEtHOH, (6), and TsiSiEtHOMe, (7), respectively. The compound (3) reacted with H₂O in DMSO/CH₃CN to give TsiSiEt(OH)₂, (8), and the compound TsiSiEtIOMe, (9), was prepared from the reaction of the compound (7) with ICl/CCl₄. When the dichloride (1) was treated with NaOMe/MeOH it gave (Me₃Si)₂CHSiEt(OMe)₂. It is suggested that the reaction proceeds through an elimination-addition mechanism. The dichloride (1) was also treated with KSCN, NaN₃ or NaOCN in CH₃CN to give S_N2 substitution products. All the new products were characterized by FTIR, ¹H NMR, and ¹³C NMR spectroscopy, mass spectrometry and elemental analysis.     

Bulky Phenyl Modifications of the Silanide Ligand Si(SiMe3)3 – Synthesis and Reactivity

The synthesis and structural characterization of bulkier variations of the very common organometallic compound MSi(SiMe₃)₃, namely MSi(SiMe₃)(SiPh₃)₂ 3 and MSi(SiPh₃)₃ [M = Li ( 1 ), K ( 5 )] are presented, which can be synthesized via a step by step exchange of SiMe₃ groups by bulkier SiPh₃ groups. This synthetic route is high selective and is performed in good yields via the silanes Si(SiMe₃)₂(SiPh₃)₂ ( 2 ) and Si(SiMe₃)(SiPh₃)₃ ( 4 ). Additionally, the corresponding silanes HSi(SiMe₃)(SiPh₃)₂ ( 6_H ) and HSi(SiPh₃)₃ ( 7_H ) are obtained via the reaction of 3 and 5 with aqueous HCl, respectively. Oxidation of 6_H with CCl₄ gives the chlorsilane Cl‐Si(SiMe₃)(SiPh₃)₂ ( 6_Cl ). The bulkiest chlorsilane Cl–Si(SiPh₃)₃ ( 7 ) is obtained by the reaction of 5 with ECl₂ (E = Sn, Pb).     

1,3-Migration of chloride and azide substituents within organosilicon cations,and anchimeric assistance by the azido group

Migration of the Cl substituent takes place when (Me₃Si)₂C(SiMe₂Cl)(SiEt₂I) or (Me₃Si)₂C(SiEt₂Cl)(SiMe₂I) reacts with AgBF₄, the product in each being a mixture of (Me₃Si)₂C(SiEt₂Cl)(SiMe₂F) and (Me₃Si)₂C(SiEt₂F)(SiMe₂Cl), and analogous migration of N₃ occurs in the corresponding reaction of (Me₃Si)₂C-(SiEt₂N₃)(SiMe₂Br). Anchimeric assistance by the N₃ group facilitates the solvolysis of (Me₃Si)₂C(SiMe₂N₃)(SiMe₂Br).     

Über die Si---N-bindung : XLIV. Die umsetzung von benzophenon mit bis- und tris(trimethylsilyl)amin

The thermal LiHal elimination of

- and

functional compounds provides a simple synthetic route to four-membered SiC and SiN rings. In attempts to inhibit dimerisation sterically, bulky silylmethyl and silylamino substituents were introduced (I–III). (Me₃Si)₃CSiF₂R reacts with LiNHR′, 1,3- migration of a silyl group from carbon to the nitrogen (I, R′= 2,4,6-Me₃C₆H₂) taking place. Substitution occurs for R′ = SiMe₂CMe₂, (II, III) only.Dichloro-bis(trimethylsilyl)methane reacts with halogenosilanes and lithium in THF to give bis(trimethylsilyl)-halogenosilaethanes (Me₃Si)₂CHSi(Hal)RR′; R= Me, R′ = N(SiMe₃)₂, IV, Hal = F; V, Hal = Cl. However a reductive THF cleavage accompanied by a silyl group migration to the oxygen occurs and 1-halogenosilyl-1- trimethylsilyl-5-trimethylsiloxi-pent-1-ene,(Me₃Si)(RR′SiHal)CCH(CH₂)₃OSiMe₃, Are The main products (VII–X) of these reactions. Disubstitution occurs with F₃Si-i-Pr (VI). (Me₃Si)₃CSiFNHSiMe₂CMe₃ (II) reacts with C₄H₉Li in a molar ratio $\text{1}\text{2}$ to give an 1-aza-2,3-disilacyclobutane (XI), involving substitution, LiF elimination, and nucleophilic migration of a methanide ion of the unsaturated precusor.(Me₃Si)₂CHSiFMeN (2,4,6-Me₃C₆H₂)SiMe₃ cyclizes under comparable conditions in the reaction with MeLi via a methylene group of the mesityl group (XII).     

Über Fluoride des zweiwertigen Eisens: Cs7Fe4F15

Concerning the Cleavage of Si? C Bonds in Si-methylated Carbosilanes The chances for the cleavage of Si? Me bonds (Me ? CH₃) and Si? C? Si bonds in their molecular skeletons using ICl or ICl/AlBr₃ are examined in 13 carbosilanes; i. e. (Me₂Si? CH₂)₃ 1 , 1,3,5,7-tetramethyl-1,3,5,7-tetrasilaadamantane 2 , (Me₃Si? CH₂)₂SiMe₂ 3 , HC(SiMe₃)₃ 4 , the 1,3,5,7-tetrasilaadamantane. carrying bhe ? CH₂? SiMe, group at one Si atom 5 , the 1,3,5-trisilacyclohexane, carrying the ? CH₂? SiNe₃ group 6 , three derivatives of the 1,3,5-trisilacyclohexane, carrying SiMe₃ groups at skeletal C atoms 7 , 8 , 9 , three derivatives of the 1,3,5-trisilacyclohexane, carrying CH₃, groups at skeletal C atoms 10 10, 11 , 12 and 13 , derived from (Me₂Si? CH₂)₃ having one ?CBr₂ group. Using ICl one Me group at each Si atom in 1 can be split off successively, finally yielding (ClMeSi? CH₂)₃. 2 is transformed to the Si-chlorinated 1,3,5,7-tetrasilaadamantane. 3 , treated with ICl yields (ClMeSi? CH₂)₂SiMeCl, as 4 forms HC(SiMe₂Cl)₃. Higher chlorinated compounds can be obtained by using ICl and AlBr₃ in catalytic amounts. Thus 1 leads to (Cl₂Si? CH₂)₃, no ring-opening is observed. However, in the reaction of 1 with HBr/AlBr₃ bromination at the Si atoms and ring-opening (ratio 1:1) proceed coincidently. The reaction of either 3 or (ClMe₂Si? CH₂)₂SiMeCl with ICl/AlBr₃ leads to (Cl₂MeSi? CH₂)₂SiCl₂, and (Me₃Si)₂CH₃ forms (Cl₂MeSi? )₂CH₂ similarly. The ? CH₂? SiMe₃ group in 5 and 6 is not cleaved off by ICl; the introduction of a Cl group at each Si atom is observed instead. Furthermore, 6 undergoes cleavage (≈8%) of the Si? C ring adjacent to the chain-substituted Si atom [formation of ClMe₂Si? (CH₂? SiMeCl)₂CH₂? SiMe₂? CH₂Cl]. 7 , 8 , 9 (having the ? SiMe₃ group at the C atoms) react with ICl by splitting off one Si? Me group from each Si atom. In 7 we also observe the ring-opening to an amount of ≈25% [formation of (ClMe₂Si)CH₂? SiMeCl? CH₂? SiMe₂? CH₂Cl]. In ₈ (having two CH(SiMe₃) groups the ring-opening reaction is reduced to about 5% [formation of ClMe₂? CH(SiMe₂Cl)? SiMeCl? CH(SiMe₂Cl)? SiMe₂? CH₂Cl], while in 9 (having three CH(SiMe₃) groups) it is not found at all. In 10 , 11 , 12 (having the CH₃ group at the C atoms) ICl substitutes one Me group (formation of SiCl) at each Si atom (no ring-opening). The CBr₂ group reduces the reactivity of 13 towards ICl. Only the split-off of one Me group at the Si atom in para-position to the CBr₂ group is observed. Using ICl/AlBr₃ higher chlorinated derivatives are obtained (no ring-opening). Most of the mentioned compounds were identified via their Si? H-containing derivatives, thus facilitating the chromatographic separation as well as the ¹H-NMR-spectroscopic investigations.     

Thermolysis of [tris(trimethylsilyl)methyl](diphenyl)fluorosilane. Isomerization of a sila-olefin intermediate

The compound (Me₃Si)₃CSiPh₂F loses Me₃SiF under reflux or on passage through a tube at 450°C to give three products, A, B, and C, in approximately 20/20/60 ratio. Products A and B, which are solids, were shown by X-ray crystallographic analysis to be the diastereoisomeric forms of 1-dimethylsila-2-trimethylsilyl-3-[(methyl)(phenyl)sila]indane. From its mass and ¹H NMR spectra, C (a liquid) was tentatively identified as 1,3-bis(dimethylsila)-2-[(dimethyl)(phenyl)silyl]indane. All three products are isomers of the sila-olefin (Me₃Si)₂CSiPh₂, and it is suggested that the latter is first formed by loss of Me₃SiF from (MeSi)₃CSiPh₂F, and the equilibrium (Me₃Si)₂CSiPh₂ ? (Me₃Si)(Ph₂MeSi)CSiMe₂ ? (Me₃Si)(PhMe₂Si)CSiMePh ? (Me₂PhSi)₂CSiMe₂ is then rapidly established; internal cyclizations involving addition of aryl CH bonds across SiC bonds then occur to give the observed products. Consistent with this is the observation that a mixture of silicon alkoxides, thought to be (Me₃Si)₂CHSiPh₂OMe and its isomers (which would be formed by addition of methanol across the SiC bonds of the four sila-olefins) is produced when methanol is passed through the hot tube with the (Me₃Si)₃CSiPh₂F.Full structural details are given for compounds A and B. Some features of interest are: (a) the conformation of the 5-membered ring is different in the two diastereoisomers; (b) the exocyclic SiCSiMe₃ bond angles, of ca. 120° are unusually large; and (c) there is a little distortion of the fused benzene ring, which is attributed to the effect of silicon substituents on the hybridization of carbon atoms to which they are attached.     

The nature of the anchimeric assistance by the acetoxy group in solvolysis of (Me3Si)2C(SiMe2)OCOMe) (SiMe2Cl)

Solvolysis of (Me₃Si)₂C(SiMe₂OCOMe)(SiMe₂Cl) in 3/2 v/v MeOH/dioxane at 35°C is ca. 11–14 times as fast as that of (Me₃Si)₂C(SiMe₂OMe)(SiMe₂Cl), which suggests that the anchimeric assistance by the acetoxy group is provided through the carbonyl oxygen.     

The reaction of 3,3-dichloroallyltrimethylsilane with n-butyllithium

n-Butyllithium reacts with 3,3-dichloroallyltrimethylsilane to metalate the vinyl proton. Under the reaction conditions the Me₃SiCH₂C(Li)CCl₂ formed undergoes β-elimination of LiCl to give ClCCCH₂SiMe₃ whose subsequent reaction with n-butyllithium produces LiCCCH₂SiMe₃. Addition of trimethylchlorosilane gives Me₃SiCCCH₂SiMe₃. When two molar equivalents of n-butyllithium are used, further metalation of LiCCCH₂SiMe₃ gives LiCCCH(Li)SiMe₃. The action of N-bromosuccinimide on Me₃SiCH₂CHCCl₂ resulted in formation of Me₃SiCHCHCCl₂Br.     

Bildung und Reaktionen silylierter Diphosphane

Preparation and Reactions of Silylated Diphosphanes The preparation of previously not available silylated diphosphanes is reported, i. e. the compounds (Me₃Si)₂P? P(SiMe₃)(CMe₃) 1 , (Me₃Si)₂P? P(CMe₃)₂ 2 and (CMe₃)₂P? P(SiMe₃)(CMe₃) 4 as well as of the respective PH containing derivatives and Li phosphides thereof. The reaction of 1 with MeOH leads to (Me₃Si)₂P? P(CMe₃) H 6 , while 4 generates (Me₃C)₂P? P(CMe₃) H 7 , and finally 3 gives access to (Me₃C)(Me₃Si)P? P(CMe₃) H 8 . LiBu on the other hand forms the Li phosphides Li(Me₃Si)P? P(SiMe₃)(CMe₃) 10 (through 1 ), Li(Me₃Si)P? P(CMe₃)₂ 11 (through 2 ), Li(Me₃C)P? P(SiMe₃)(CMe₃) 12 (through 3 ), and Li(Me₃C)P? P(CMe₃)₂ 13 (through 4 ), the latter being more easily accessible through the reaction of H(Me₃C)P? P(CMe₃)₂ with LiBu. The introduction of one single CMe₃ substituent into 1 is sufficient to obtain the Li phosphide 10 , which is stable in ethers, as opposed to the corresponding Li Phosphide of the persilylated diphosphane.     

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.     

Synthese und Eigenschaften teilsilylierter Tri- und Tetraphosphane. Reaktionen lithiierter Diphosphane mit Chlorphosphanen

Synthesis and Properties of Partially Silylated Tri- and Tetraphosphanes. Reaction of Lithiated Diphosphanes with Chlorophosphanes The reactions of Li(Me₃Si)P? P(SiMe₃)(CMe₃) 1 , Li(Me₃Si)P? P(CMe₃)₂ 2 , and Li(Me₃C)P? P(SiMe₃)(CMe₃) 3 with the chlorophosphanes P(SiMe₃)(CMe₃)Cl, P(CMe₃)₂Cl, or P(CMe₃)Cl₂ generate the triphosphanes [(Me₃C)(Me₃Si)P]₂P(SiMe₃) 4 , (Me₃C)(Me₃Si)P? P(SiMe₃)? P(CMe₃)₂ 6 , [(Me₃C)₂P]₂P(SiMe₃) 7 , and (Me₃C)(Me₃Si)P? P(SiMe₃)? P(CMe₃)Cl 8 . The triphosphane (Me₃C)₂P? P(SiMe₃)? P(SiMe₃)₂ 5 is not obtainable as easily. The access to 5 starts by reacting PCl₃ with P(SiMe₃)(CMe₃)₂, forming (Me₃C)₂ P? PCl₂, which then with LiP(SiMe₃)₂ gives (Me₃C)₂ P? P(Cl)? P(SiMe₃)₂ 11 . Treating 11 with LiCMe₃ generates (Me₃C)₂P? P(H)? P(SiMe₃)₂ 16 , which can be lithiated by LiBu to give (Me₃C)₂P? P(Li)? P(SiMe₃)₂ 13 and after reacting with Me₃SiCl, finally yields 5 . 8 is stable at ?70°C and undergoes cyclization to P₃(SiMe₃)(CMe₃)₂ in the course of warming to ambient temperature, while Me₃SiCl is split off. 7 , reacting with MeOH, forms [(Me₃C)₂P]₂PH. (Me₃C)₂P? P(Li)? P(SiMe₃)₂ 18 , which can be obtained by the reaction of 5 with LiBu, decomposes forming (Me₃C)₂P? P(Li)(SiMe₃), P(SiMe₃)₃, and LiP(SiMe₃)₂, in contrast to either (Me₃C)₂P? P(Li)? P(SiMe₃)(CMe₃) 19 or [(Me₃C)₂P]₂PLi, which are stable in ether solutions. The Li phosphides 1 , 2 , and 3 with BrH₂C? CH₂Br form the n-tetraphosphanes (Me₃C)(Me₃Si)P? [P(SiMe₃)]₂? P(SiMe₃)(CMe₃) 23 , (Me₃C)₂P? [P(SiMe₃)]₂? P(CMe₃)₂ 24 , and (Me₃C)(Me₃Si)P? [P(CMe₃)]₂? P(SiMe₃)(CMe₃) 25 , respectively. Li(Me₃Si)P? P(SiMe₃)₂, likewise, generates (Me₃Si)₂P? [P(SiMe₃)]₂? P(SiMe₃)₂ 26 . Just as the n-triphosphanes 4 , 5 , 6 , and 7 , the n-tetraphosphanes 23 , 24 , and 25 can be isolated as crystalline compounds. 23 , treated with LiBu, does nor form any stable n-tetraphosphides, whereas 24 yields (Me₃C)₂P? P(Li)? P(SiMe₃)? P(CMe₃)₂, that is stable in ethers. With MeOH, 24 , forms crystals of (Me₃C)₂P? P(H)? P(SiMe₃)? P(CMe₃)₂.     

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.     

Lithiierte Siloxy-silylamino-silane – Darstellung und Reaktionen mit Chlordimethylsilan

Lithiated Siloxy-silylamino-silanes — Preparation and Reactions with Chlorodimethylsilane The siloxy-silylamino-silanes (Me₃SiO)Me_3–nSi(NHSiMe₃)_n ( 1 : n = 1, 2 : n = 2, 3 : n = 3) are obtained by coammonolysis of the chlorosiloxysilanes (Me₃SiO)Me_3–nSiCl_n (n = 1–3) with chlorotrimethylsilane. The reaction of 1, 2 , and 3 with n-butyllithium in appropriate molar ratio in n-hexane gives the siloxy-silylamido-silanes (Me₃SiO)Me_3–nSi(NLiSiMe₃)_n ( 4 : n = 1, 5 : n = 2, 6 : n = 3), which were spectroscopically characterized (IR, ¹H-, ⁷Li-, ²⁹Si-NMR) and allowed to react in solution (n-hexane, THF) with Me₂Si(H)Cl. 4 reacts to the N-substitution product (Me₃SiO)Me₂SiN(SiMe₃)SiMe₂H 7, 5 to (Me₃SiO)MeSi[N(SiMe₃)SiMe₂H](NHSiMe₃) 8 , (Me₃SiO)MeSi[N(SiMe₃)SiMe₂H]₂ 9 and to the cyclodisilazane 10. 6 gives in THF the cyclodisilazanes 11 : R = H; 12 : R = HMe₂Si) and ( 13 , in n-hexane only 11 in small amounts. An amide solution of 2 with n-butyllithium in the molar ratio 1:1 in n-hexane leads to 8 (main product), 2 and 10; in THF 10 and 2 are obtained nearly in same amounts and 8 and 9 as byproducts. The amide solutions of 3 with n-butyllithium in the molar ratio 1:1 and 1:2, resp., show nearly the same behaviour in n-hexane and THF. In THF 3, 11 , and 12 and in n-hexane 3, 11, 12 , and (Me₃SiO)Si[N(SiMe₃)SiMe₂H](NHSiMe₃)₂ 14 are formed.     

Reaktionen silylierter Phosphanimine mit Iodmonochlorid und Iodtrichlorid. Die Kristallstrukturen von [Me3SiNPMe3 · ICl], [Ph3PNCl · ICl] und [Me3PN(H)PMe3] [ICl2]2

Reactions of Silylated Phosphorane Imines with Iodine Monochloride and Iodine Trichloride. The Crystal Structures of [Me₃SiNPMe₃ · ICl], [Ph₃PNCl · ICl], and [Me₃PN(H)PMe₃][ICl₂]₂ The donor-acceptor complex [Me₃SiNPMe₃ · ICl] has been prepared from Me₃SiNPMe₃ and ICl in acetonitrile solution forming yellow-orange crystals. [Ph₃PNCl · ICl] can be prepared by the reaction of Me₃SiNPPh₃ with ICl₃ in dichloromethane solution forming pale yellow crystals. [Me₃PN(H)PMe₃][ICl₂]₂ is formed in a small amount by a slow reaction of Me₃SiNPMe₃ with ICl₃ in CCl₄ suspension in the presence of traces of moisture. All samples are characterized by IR spectroscopy and by X-ray structure analyses. [Me₃SiNPMe₃ · ICl] (1) : Space group Iba2, Z = 8, structure solution with 1 727 observed unique reflections, R = 0.051. Lattice dimensions at ?60°C: a = 1 510.7, b = 1 862.8, c = 988.9 pm. 1 has a molecular structure in which the N atom of the phosphorane imine is connected with the iodine atom of the ICl molecule in a linear arrangement N? I? Cl. Bond lengths N? I = 222.7 pm, I? Cl = 265.1 pm. [Ph₃PNCl · ICl] (2) : Space group Pna2₁, Z = 4, structure solution with 1 530 observed unique reflections, R = 0.030. Lattice dimensions at 20°C: a = 1 522.8, b = 1 408.3, c = 865.8 pm. 2 has a molecular structure in which the N atom of the N chlorophosphorane imine is connected with the iodine atom of the ICl molecule in a linear arrangement. Bond lengths N? Cl = 174.4 pm, N? I = 229.5 pm, I? Cl = 251.2 pm. [Me₃PN(H)PMe₃][ICl₂]₂ (3) : Space group P2₁/c, Z = 4, structure solution with 1 989 observed unique reflections, R = 0.029. Lattice dimensions at ?50°C: a = 1 223.1, b = 1 090.2, c = 1 482.8 pm, β = 112.21°. 3 consists of [Me₃PN(H)PMe₃]²⁺ ions and ICl₂^? anions. The PNP bond angle of the dication amounts to 134.4° with PN distances of 165.6 and 166.1 pm, approximately according to double bonds.     

N-Silylierung und Si?O-Bindungsspaltung bei der Reaktion lithiierter Siloxy-silylamino-silane mit Chlortrimethylsilan

N-Silylation and Si? O Bond Splitting at the Reaction of Lithiated Siloxy-silylamino-silanes with Chlorotrimethylsilane Lithiated Siloxy-silylamino-silanes were allowed to react in tetrahydrofurane (THF) and in n-octane (favoured) and n-hexane, resp., with chlorotrimethylsilane. The monoamide (Me₃SiO)Me₂Si(NLiSiMe₃) gives in THF and in n-octane the N-substitution product (Me₃SiO)Me₂Si · [N(SiMe₃)₂] 1 , the diamide (Me₃SiO)MeSi(NLiSiMe₃)₂ only in THF the N-substitution products (Me₃SiO)MeSi[N(SiMe₃)₂]₂ 2 (main product) and (Me₃SiO)MeSi[N(SiMe₃)₂](NHSiMe₃) 3 . In n-octane the diamide reacts mainly under Si? O bond splitting. The cyclodisilazane [(Me₃SiNH)MeSi? NSiMe₃]₂ 6 is obtained as the main product. Byproducts are 2, 3 and the tris(trimethylsilylamino) substituted disilazane (Me₃SiO)(Me₃SiNH)MeSi? N · (SiMe₃)? SiMe(NHSiMe₃)₂ 7 . The triamide (Me₃SiO)Si · (NLiSiMe₃)₃ reacts under Si? O and Si? N bond splitting in n-octane as well as in THF. The cyclodisilazanes [(Me₃SiNH)₂ · Si? NSiMe₃]₂ 10 and ( 11 : R = Me₃SiNH, 12 : R = (Me₃Si)₂N) are formed. in THF furthermore the N-substitution products (Me₃SiO)Si[N(SiMe₃)₂] · (NHSiMe₃)₂ 4 and (Me₃SiO)Si[N(SiMe₃)₂]₂(NHSiMe₃) 5 . The Si? O bond splitting occurs in boiling n-octane also in absence of the chlorotrimethylsilane. An amide solution of (Me₃SiO)MeSi(NHSiMe₃)₂ with n-butyllithium in the molar ratio 1 : 1 leads in n-octane and n-hexane to 6 and 7 , in THF to 3 . The amide solutions of (Me₃SiO)Si · (NHSiMe₃)₃ with n-butyllithium the molar ratio 1 : 1 and 1 : 2 give in THF 4 and 5 , respectively.     

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.     

Diamino-di-tert-butylsilane als Bausteine cyclischer (SiN)2−, (SiNBN)2−, (SiN2Sn)- und spirocyclischer (SiN2)2Si-, (SiN2Sn)2S-Verbindungen

Diamino-di-tert-butylsilanes - Building Blocks for Cyclic (SiN)₂, (SiNBN)₂, (SiN₂Sn), and Spirocyclic (SiN₂)₂Si, (SiN₂Sn)₂S Compounds The aminochlorosilanes (Me₃C)₂SiClNHR ( 1 : R?H, 2 : R?Me) are obtained by the ammonolysis ( 1 ) respectively aminolysis ( 2 ) of di-tert-butyldichlorosilane in the n-hexane. The dilithium derivative of diamino-di-tert-butylsilane reacts with FSiMe₂R′ ( 3 : R′?Me, 4 : R′?F) in a molar ratio 1 : 2 to give the 1,3,5-trisilazanes 3 and 4 , (Me₃C)₂SiNHSiMe₂R′, in a molar ratio 1 : 1 with F₃SiN(SiMe₃)₂ to give the 1,3-diaza-2,4-disilacyclobutane 5 , (Me₃C)₂Si(NH)₂SiFN(SiMe₃)₂, and with F₂BN(SiMe₃)₂ to give the 1,3,5,7-tetraaza-2,6-dibora-4,8-disilacyclooctane 6 , [(Me₃C)₂SiNH-BN(SiMe₃)₂-NH]₂. The dilithium derivative of di-tert-butyl-bis(methylamino)silane reacts with SiF₄ with formation of the 1,3,5-trisilazane 7 , (Me₃C)₂Si(NMeSiF₃)₂, and the spirocycic compound 8 , [(Me₃C)₂Si(NMe)₂]₂Si, with SnCl₂ the cyclosilazane 9 , (Me₃C)₂SiNMe₂ is obtained. The dilithium derivative of 3 reacts with SnCl₂ to give the cyclo-1,3-diaza-2-sila-4-stannylen 10 , (Me₃C)₂Si(NSiMe₃)₂Sn. The oxidation of 10 with elemental sulfur leads to the formation of the spirocyclus 11 , [(Me₃C)₂Si(NSiMe₃)₂SnS]₂.