Darstellung,Eigenschaften und Reaktionsverhalten von 2-(Dimethylaminomethyl)phenyl- und 8-(Dimethylamino)naphthylsubstituierten Lithiumhydridosilylamiden – Bildung von Silaniminen durch Lithiumhydrideliminierung

Preparation, Properties, and Reaction Behaviour of 2-(Dimethylaminomethyl)phenyl- and 8-(Dimethylamino)naphthylsubstituted Lithium Hydridosilylamides – Formation of Silanimines by Elimination of Lithium Hydride The hydridosilylamines Ar(R)Si(H)–NHR′ ( 2 a : Ar = 2-Me₂NCH₂C₆H₄, R = Me, R′ = CMe₃; 2 b : Ar = 2-Me₂NCH₂C₆H₄, R = Ph, R′ = CMe₃; 2 c : Ar = 2-Me₂NCH₂C₆H₄, R = Me, R′ = SiMe₃; 2 d : Ar = 8-Me₂NC₁₀H₆, R = Me, R′ = CMe₃; 2 e : Ar = 8-Me₂NC₁₀H₆, R = Ph, R′ = CMe₃; 2 f : Ar = 8-Me₂NC₁₀H₆, R = Me, R′ = SiMe₃) have been synthesized from the appropriate chlorosilanes Ar(R)SiHCl either by reaction with the stoichiometric amount of Me₃CNHLi ( 2 a , 2 b , 2 d , 2 e ) or by coammonolysis in liquid NH₃ with chlorotrimethylsilane in molar ratio 1 : 3 ( 2 c , 2 f ). Treatment of 2 a–2 f with n-butyllithium in equimolar ratio in n-hexane resulted in the lithiumhydridosilylamides Ar(R)Si(H)–N(Li)R′ 3 a–3 f . The frequencies of the Si–H stretching vibration and ²⁹Si–¹H coupling constants in the amides are smaller than in the analogous amines indicating a higher hydride character for the hydrogen atom of the Si–H group in the amides compared to the amines. Results of NMR spectroscopic studies point to the existence of a (Me₂)N → Si coordination bond in the 8-(dimethylamino)naphthyl-substituted amines and amides. The amides 3 a–3 c are stable under refluxing in m-xylene. At the same conditions 3 d and 3 e eliminate LiH and the silanimines 8-Me₂NC₁₀H₆(R)Si=NCMe₃ ( 4 d : R = Me, 4 e : R = Ph) are formed. The amides 3 a–3 d und 3 f react with chlorotrimethylsilane in THF to give the corresponding N-substitution products Ar(R)Si(H)–N(SiMe₃)R′ 6 a–6 d and 6 f in good yields. 4 d is formed as a byproduct in the reaction of 3 d with chlorotrimethylsilane. In n-hexane and m-xylene these amides are little reactive opposite to chlorotrimethylsilane. 6 a–6 d and 6 f are obtained in very small amounts. In the case of 3 d besides the N-substitution product 6 d the silanimine 4 d is obtained. In contrast to chlorotrimethylsilane the amides 3 a and 3 f react well with chlorodimethylsilane in m-xylene producing 2-Me₂NCH₂C₆H₄(H) SiMe–N(SiHMe₂)CMe₃ ( 7 a ) and 8-Me₂NC₁₀H₆(H)SiMe–N(SiHMe₂)SiMe₃ ( 7 f ).     

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.     

Darstellung,Charakterisierung und Reaktionsverhalten von Natrium‐ und Kaliumhydridosilylamiden R2(H)Si—N(M)R′ (M = Na,K) — Kristallstruktur von [(Me3C)2(H)Si—N(K)SiMe3]2·THF

Preparation, Characterization and Reaction Behaviour of Sodium and Potassium Hydridosilylamides R₂(H)Si—N(M)R′ (M = Na, K) — Crystal Structure of [(Me₃C)₂(H)Si—N(K)SiMe₃]₂ · THF The alkali metal hydridosilylamides R₂(H)Si—N(M)R′ 1a‐Na — 1d—Na and 1a‐K — 1d‐K ( a : R = Me, R′ = CMe₃; b : R = Me, R′ = SiMe₃; c : R = Me, R′ = Si(H)Me₂; d : R = CMe₃, R′= SiMe₃) have been prepared by reaction of the corresponding hydridosilylamines 1a — 1d with alkali metal M (M = Na, K) in presence of styrene or with alkali metal hydrides MH (M = Na, K). With NaNH₂ in toluene Me₂(H)Si—NHCMe₃ ( 1a ) reacted not under metalation but under nucleophilic substitution of the H(Si) atom to give Me₂(NaNH)Si—NHCMe₃ ( 5 ). In the reaction of Me₂(H)Si—NHSiMe₃ ( 1b ) with NaNH₂ intoluene a mixture of Me₂(NaNH)Si—NHSiMe₃ and Me₂(H)Si—N(Na)SiMe₃ ( 1b‐Na ) was obtained. The hydridosilylamides have been characterized spectroscopically. The spectroscopic data of these amides and of the corresponding lithium derivatives are discussed. The ²⁹Si‐NMR‐chemical shifts and the ²⁹Si—¹H coupling constants of homologous alkali metal hydridosilylamides R₂(H)Si—N(M)R′ (M = Li, Na, K) are depending on the alkali metal. With increasing of the ionic character of the M—N bond M = K > Na > Li the ²⁹Si‐NMR‐signals are shifted upfield and the ²⁹Si—¹H coupling constants except for compounds (Me₃C)(H)Si—N(M)SiMe₃ are decreased. The reaction behaviour of the amides 1a‐Na — 1c‐Na and 1a‐K — 1c‐K was investigated toward chlorotrimethylsilane in tetrahydrofuran (THF) and in n‐pentane. In THF the amides produced just like the analogous lithium amides the corresponding N‐silylation products Me₂(H)Si—N(SiMe₃)R′ ( 2a — 2c ) in high yields. The reaction of the sodium amides with chlorotrimethylsilane in nonpolar solvent n‐pentane produced from 1a‐Na the cyclodisilazane [Me₂Si—NCMe₃]₂ ( 8a ), from 1b‐Na and 1‐Na mixtures of cyclodisilazane [Me₂Si—NR′]₂ ( 8b , 8c ) and N‐silylation product 2b , 2c . In contrast to 1b‐Na and 1c‐Na and to the analogous lithium amides the reaction of 1b‐K and 1c‐K with chlorotrimethylsilane afforded the N‐silylation products Me₂(H)Si—N(SiMe₃)R′ ( 2b , 2c ) in high yields. The amide [(Me₃C)₂(H)Si—N(K)SiMe₃]₂·THF ( 9 ) crystallizes in the space group C2/c with Z = 4. The central part of the molecule is a planar four‐membered K₂N₂ ring. One potassium atom is coordinated by two nitrogen atoms and the other one by two nitrogen atoms and one oxygen atom. Furthermore K···H(Si) and K···CH₃ contacts exist in 9 . The K—N distances in the K₂N₂ ring differ marginally.     

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 von Mono- und Bis(silyl)hydroxylaminen

Synthesis of Mono- and Bis(silyl)hydroxylamines Silylamines reacts with hydroxylaminehydrochlorid to give the monosilylhydroxylamines: R₂FSiONH₂ (R = CMe₃ 1 ), R₂R′SiONH₂ (R = CMe₃, R′ = Me 2 ), R₂(NH₂)SiONH₂ (R = CMe₃ 3 ). The reaction of 1 in the present of HCl-acceptors or the reaction of lithiated 1 with Me₃SiCl or F₂Si(CMe₃)₂ leads to the formation of bis(silyl)hydroxylamines, (Me₃C)₂FSiONHSiMe₃ 4 , and (Me₃C)₂FSiONHSiF(CMe₃)₂ 5 . The lithium derivatives of Me₃SiONH₂ and 2 react with fluorosilanes to the bis(silyl)hydroxylamines: Me₃SiONHSiFRR′ (R = R′ = CMe₃, 6 , R = CMe₃, R′ = F 7 , R = R′ = NMeSiMe₃ 8 ), (Me₃C)₂MeSiNHOSiFRR′ (R = CMe₃, R′ = F 9 , R = (Me₃C)₃C₆H₂, R′ = F 10 , R = R′ = CMe₃ 11 , R = R′ = CHMe₂ 12 ). The bis(silyl)hydroxylamines 4 and 6 are structure isomers.     

Zur Bildung der Cyclotetraphosphane cis- und trans-P4(SiMe3)2(CMe3)2 bei der Umsetzung von (Me3C)PCl2 mit LiP(SiMe3)2 · 2 THF

Formation of the Cyclotetraphosphanes cis- und trans-P₄(SiMe₃)₂(CMe₃)₂ in the Reaction of (Me₃C)PCl₂ with LiP(SiMe₃)₂ · 2 THF The mechanism of the reaction of (Me₃C)PCl₂ 1 with LiP(SiMe₃)₂ · 2 THF 2 was investigated. With a mole ration of 1:1 at ?60°C quantitatively (Me₃C)(Cl)P? P(SiMe₃)₂ 3 is formed. This compound eliminates Me₃SiCl on warming to 20°C, yielding Me₃Si? P?P? CMe₃ 4 (can be trapped using 2,3-dimethyl-1,3-butadiene in a 4+2 cycloaddition), which dimerizes to produce the cyclotetraphosphanes cis-P₄(SiMe₃)₂(CMe₃)₂ 5 and trans-P₄(SiMe₃)₂(CMe₃)₂ 6 . Also with a mole ratio of 1:2 initially 3 is formed which remarkably slower reacts on to give [(Me₃Si)₂P]P₂P? CMe₃ 8 . Remaining LiP(SiMe₃)₂ cleaves one Si? P bond of 8 producing (Me₃)₂P? P(CMe₃)? P(SiMe₃)₂Li. Via a condensation to the pentaphosphide 10 and an elimination of LiP(SiMe₃)₂ from this intermediate, eventually trans-P₄(SiMe₃)₂(CMe₃)₂ 6 is obtained as the exclusive cyclotetra-phosphane product.     

O-Halogensilyl-N,N-bis(trimethylsilyl)hydroxylamine – Synthese,Kristallstruktur und Reaktionen

O-Halogenosilyl-N,N-bis(trimethylsilyl)hydroxylamines – Synthesis, Crystal Structure, and Reactions The substitution of halogenosilanes on lithiated N,O-bis(trimethylsilyl)-hydroxylamine in the molar ratio of 1 : 1 occurs on the oxygen atom. The O-halogenosilyl-N,N-bis(trimethylsilyl)hydroxylamines were prepared: RSiF₂ON · (SiMe₃)₂ (R = CMe₃ 1 , CHMe₂ 2 , CH₂C₆H₅ 3 , C₆H₂(CMe₃)₃ 4 ), RR′SiFON(SiMe₃)₂ (R = CMe₃, R′ = C₆H₅ 5 ; R = Me, R′ = C₆H₅ 6 ; R = C₆H₂Me₃, R′ = C₆H₂Me₃ 7 ; R = CH₂C₆H₅, R′ = CH₂C₆H₅ 8 ; R = CHMe₂, R′ = CHMe₂ 9 ; R = CMe₃, R′ = CMe₃ 10 ), RSiCl₂ON(SiMe₃)₂ (R = CMe₃ 11 ; R = Cl 12 ). The reaction of fluorosilanes with lithiated N,O-bis(trimethylsilyl)hydroxylamine in the molar ratio of 1 : 2 leads to the formation of O,O′-fluorosilyl-bis[N,N-bis(trimethylsilyl)hydroxylamines]: RSiF[ON(SiMe₃)₂]₂ (R = CMe₃ 13 ; R = C₆H₅ 14 ). 13 could be prepared in the reaction of 1 with LiON(SiMe₃)₂. Lithiated dimethylketonoxime reacts with 1 to Me₂C=NOSiRF–ON(SiMe₃)₂ [R = CMe₃ ( 15 )]. The first crystal structure of a tris(silyl)hydroxylamine ( 4 ) is shown. The angle at the nitrogen prove a pyramidal geometry.     

Trialkylhydridoalanate RxR′3-xAlH⊖ [R = CMe3; R′ = CH(SiMe3)2]

Trialkylhydridoalanates R_xR′_3?xAlH^? [R = CMe₃; R′ = CH(SiMe₃)₂] The very strong base tert-butyl lithium reacts in the presence of chelating tetramethylethylendiamine with the aluminium organyls Al[CH(SiMe₃)₂]₂CMe₃ 1 and Al[CH(SiMe₃)₂](CMe₃)₂ 2 not under proton abstraction from the C? H acidic elementorganic substituent, but under β-elimination and addition of the thereby formed LiH to the coordinatively unsaturated aluminium atom. Two alanates — [Hal{CH(SiMe₃)₂}₂CMe₃]^? 3 and [HAl{CH(SiMe₃)₂}(CMe₃)₂]^? 4 each with Li(TMEDA)₂^⊕ as counterion — were isolated; they exhibit separate anions and cations in solid state as shown by a crystal structure determination on 3 . In absence of the chelating amine tert-butyl lithium decomposes under the catalytic effect of the aluminium compound to LiH, which does not add to aluminium and precipitates in a reactive form.     

The Reaction of Transient 1,1‐Bis(trimethylsilyl)silenes with Tris(trimethylsilyl)silyllithium – Synthesis and Structure of Sterically Congested 1‐Trimethylsilylalkylpolysilanes

Tris(trimethylsilyl)silyllithium ( 3 ) reacted with aldehydes and ketones (molar ratio 2 : 1) according to a modified Peterson mechanism under formation of transient silenes, which were immediately trapped by excess 3 to give the organolithium derivatives (Me₃Si)₃SiSi(SiMe₃)₂C(Li)R¹R² ( 7 ). Hydrolysis of 7 afforded the alkylpolysilanes (Me₃Si)₃SiSi(SiMe₃)₂CHR¹R² ( 8 ). Depending on the substituents R¹ and R², 7 proved to be rather unstable in THF solution and underwent a rapid rearrangement, involving a 1,3‐Si,C‐trimethylsilyl migration, resulting in the formation of the lithium silanides (Me₃Si)₂Si(Li)Si(SiMe₃)₂C(SiMe₃)R¹R² ( 9 ), which were hydrolized during the aqueous workup to give the H‐silanes (Me₃Si)₂Si(H)Si(SiMe₃)₂C(SiMe₃)R¹R² ( 10 ). Reaction of 9 with chlorotrimethylsilane produced the 1‐trimethylsilylalkylpolysilanes (Me₃Si)₃SiSi(SiMe₃)₂C(SiMe₃)R¹R² ( 11 ). The structures of the products described were elucidated by comprehensive spectral analyses. The results of X‐ray crystal structure analyses, performed for 8 l (R¹ = H, R² = 2,4,6‐(MeO)₃C₆H₂), 10 d (R¹ = H, R² = Mes) and 11 d (R¹ = H, R² = Mes) are discussed and confirm the expected extreme sterical congestion of the molecules.     

Bis- and tris-(trimethylsilyl)methyl derivatives of antimony

Reaction of RMgCl [R = (Me₃Si)₂CH) with SbCl₃ affords RSbCl₂. Also R₂SbCl reacts with RLi to yield R₃Sb, while R′SbCl₂ [R′ = (Me₃Si)₃C] is synthesized from R′Li and SbCl₃. Mass spectra of RSbCl₂ and R′SbCl₂ show that fragmentations proceed with elimination of Me₃SiCl. The chlorides RSbCl₂, R₂SbCl and R′SbCl₂ are thermally very stable.     

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.     

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.     

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).     

Diazaboracyclopropane; synthese und kristallstrukturanalyse

The lithium salt of N,N′-bis(t-butyldimethylsilylhydrazine), CMe₃SiMe₂-NLiNHSiMe₂CMe₃, reacts with aminodifluoroboranes, Me₃SiNRBF₂ (R = CMe₃, SiMe₃) to give the N,N′-bis(silyl)-N-fluoroboryl-hydrazines I (R = CMe₃) and II (R = SiMe₃). The three-membered diazaboracyclopropanes III (R = CMe₃) and IV (R = SiMe₃) are obtained in the reaction of I and II with t-C₄H₉Li. According to crystal structure analysis of IV and NMR measurements, III and IV contain a planar NBN₂ unit with C₂ symmetry. The exocyclic BN bond of IV is 140.6(3) pm, the endocyclic BN bonds 142.6(3) pm and the angle in the BN₂ ring 71.8(1)°.     

Reactions at the B–B Bond of Bis(trisyl)oxadiborirane: Ring Extensions

The B–B bond of bis(trisyl)oxadiborirane OB₂R₂ (R = C(SiMe₃)₃) is opened by amides R′CO(NHR″) to give the dioxaazadiboracyclohexanes [–BR–O–BR–NR″–CHR′–O–] (R′/R″ = H/H, H/Me, H/Et, Me/H: 5 a – d ). The amide MeCO(NHMe) yields 5 e (R′/R″ = Me/Me), when an excess of the amide is applied for 24 h, but yields an isomeric 1 : 1 adduct ( 6 e ), when a stoichiometric amount of the amide is applied for 15 h; upon refluxing this isomer in hexane, it is transformed into 5 e .     

Übergangsmetallphosphidokomplexe. XI. Diphosphenkomplexe des Typs (R3P)2Ni[η2-(PR′)2] und phosphidoverbrückte Nickel(I)-Komplexe des Typs [R3PNiP(SiMe3)2]2 (Ni?Ni)

Transition Metal Phosphido Complexes. XI. Diphosphene Complexes of the Type (R₃P)₂Ni[η²-(PR′)₂] and Phosphido-Bridged Nickel(I) Complexes of the Type [R₃PNiP(SiMe₃)₂]₂(Ni? Ni) From reactions of complexes of the type (R₃P)₂NiCl₂ 1 (R = Me a , Et b , nBu c , iBu d , Ph e , iPr f , Cy g ) with LiP(SiMe₃)₂ in a 1:2 molar ratio the diphosphene complexes (R₃P)₂Ni[η²-(PSiMe₃)₂] 4a–c and the phosphido-bridged nickel(I) complexes [R₃PNiP(SiMe₃)₂]₂ (Ni? Ni) 7a–g are available. Using low temperature n.m.r. measurements the monosubstitution products (R₃P)₂NiClP(SiMe₃)₂ 2a–c and the nickel(0) diphosphane complexes R₃PNi[η¹-P₂(SiMe₃)₄] 6a–g can be detected as intermediates. In reactions in a 1:1 molar ratio the formation of the diphosphorus complexes [(R₃P)₂Ni]₂P₂ 9b, 9c is n.m.r. spectroscopically detectable. 1b reacts with LiP(SiMe₃)CMe₃ to give first the nickel(0) diphosphane complex Et₃PNi[η¹-P(SiMe₃)CMe₃? P(SiMe₃)CMe₃] 10 , which can be isolated at low temperatures, finally yielding (Et₃P)₂Ni[η²-(PCMe₃)₂] 11 and [Et₃PNiP(SiMe₃)CMe₃]₂ (Ni? Ni) 12. 11 as well as (Et₃P)₂Ni[η²-(PPh)₂] 14 can also be obtained reacting 1b with R′P(SiMe₃)₂ (R′ = CMe₃, Ph). The best yields of diphosphene complexes result from [2+1] cyclocondensation reactions of 1a–c with P₂(SiMe₃)₄ to give 4a–c and of 1b with [P(SiMe₃)CMe₃]₂ to give 11 . N.m.r. and mass spectral data are reported.     

Transient Silenes as Versatile Synthons – The Reaction of Dichloromethyl‐tris(trimethylsilyl)silane with Organolithium Reagents

Treatment of dichloromethyl‐tris(trimethylsilyl)silane (Me₃Si)₃Si–CHCl₂ ( 1 ), prepared by the reaction of tris(trimethylsilyl)silane with chloroform in presence of potassium tertbutoxide, with organolithium reagents (molar ratio 1 : 3) affords the bis(trimethylsilyl)methyl‐disilanes Me₃SiSiR₂–CH(SiMe₃)₂ ( 12 a–d ) ( a : R = Me, b : R = n‐Bu, c : R = Ph, d : R = Mes). The formation of 12 a–d is discussed as proceeding through an exceptional series of isomerization and addition reactions involving intermediate silyl substituted carbenoids and transient silenes. The carbenoid (Me₃Si)₂PhSi–C(SiMe₃)LiCl ( 8 c ) is moderately stable at low temperature and was trapped with water to give (Me₃Si)₂PhSi–CH(SiMe₃)Cl ( 9 c ) and with chlorotrimethylsilane affording (Me₃Si)₂PhSi–CCl(SiMe₃)₂ ( 7 c ). For 12 d an X‐ray crystal structure analysis was performed, which characterizes the compound as a highly congested silane with bond parameters significantly deviating from standard values.     

Oxo(trisyl)boran (Me3Si)3C?BO als Zwischenstufe

Oxo(trisyl)borane (Me₃Si)₃C? B?O as an Intermediate The acyclic trisylboranes R? B(OSiMe₃)? Cl ( 4 a ) and R? B(OH)? H ( 5 a ) and the cyclic boranes (? RB? O? CO? CO? O? ) ( 1 a ) and (? RB? O? RB? O? SO₂? O? ) ( 6 a ) [R = (Me₃Si)₃C, “Trisyl”] are thermolyzed in the gasphase to give well-defined products. The tris(trisyl)boroxine (? RB? O? )₃ ( 2 a ) is formed from 4 a and 5 a at 140 and 160°C, respectively, besides Me₃SiCl and H₂, respectively, whereas the six-membered ring [? BMe? CH(SiMe₃)? SiMe₂? O? SiMe₂? CH₂? ] ( 8 ) is the product from 1 a and 6 a at 600 and 700°C, respectively, besides CO/CO₂ and SO₃, respectively. The oxoborane R? B?O is presumably a common intermediate. It is stabilized at the lower temperature by cyclotrimerization to give 2 and at the higher temperature by a sequence of several intramolecular steps: a 1,3-silyl shift along the chain C? B? O, an exchange of Me and Me₃SiO along the chain Si? C? B, and a C? H addition to the B?C double bond; the steps can be rationalized by analogous known reactions. The gas-phase thermolysis at 600°C of the dioxaboracyclohexenes (? BR? O? CR′ = CH? CRR′? O? ) ( 7 b? d ; R = Me, iPr, tBu; R′ = Me) yields the boroxines (RBO)₃ and the enones Me? CO? CH?CHR? Me; the cyclohexene 7 e (R = Me; R′ = CF₃) is not decomposed at 600°C.     

Reaktionen silylierter Cyclotetraphosphane mit Lithiumalkylen

Reactions of Silylated Cyclotetraphosphanes with Lithium Alkyles While the cyclotetraphosphanes P₄(CMe₃)₃SiMe₃ 1 and trans-P₄(CMe₃)₂(SiMe₃)₂ 2 in reaction with LiR (R = Me, n-Bu) in THF yield the cyclic phosphides LiP₄(CMe₃)₃ 3 and trans-LiP₄(CMe₃)₂SiMe₃ 4 , respectively, the compounds P₄(SiMe₃)₄ 5 , P₄(SiMe₃)₃ CMe₃ 6 and cis-P₄(CMe₃)₂(SiMe₃)₂ 7 by cleavage of a P? P bond produce primary n-tetraphosphides, which rearrange (1,3-shift of Li/SiMe₃) in THF even at low temperature to form the corresponding secondary n-tetraphosphides. Warming these solutions to room temperature initiates consecutive reactions including elimination of LiP(SiMe₃)₂, (Me₃Si)₃P, RP(SiMe₃)₂ and producing P-rich compounds. In this way Li₃P₇ is obtained as main-product from compound 5 , and LiP₅(CMe₃)₄, LiP₃(CMe₃)₂, P₄(CMe₃)₄ from compound 7 . However, the reaction of 6 and LiR gives raise only to traces of Li₃P₇ and Li₂P₇CMe₃. The above mentioned primary as well as the secondary n-tetraphosphides generate stable n-tetraphosphane derivatives by reaction with Me₃SiCl, or MeCl, respectively.     

Das 1,2-Bis(trimethylsilyl)3,4-di(tert-butyl)cyclotetraphosphan

1,2-Bis(trimethylsilyl)-3,4-di(tert-butyl) cyclotetraphosphane cis-P₄(SiMe₃)₂(CMe₃)₂ 1 could be prepared by the reaction of (Me₃Si)₂P—P(SiMe₃)—P(SiMe₃)CMe₃ 2 with (Me₃C)PCl₂ 3 The compound 1 forms pale yellow crystals, m. p. 116°C. The ³¹P- and ¹H-NMR data of 1 are given.