Die 2,6-Diisopropyl-phenylgruppe als sperriger Substituent in Bor-Stickstoff-Verbindungen. II [1]

The 2,6-Diisopropyl-phenyl Group as a Bulky Substituent in Boron-Nitrogen Compounds. II Fluoro-bis(amino)boranes R′ (Me₃Si)N–BF–NHR (R = 2,6-)Me₂CH)₂C₆H₃, R′ = Me ( Ia ), CH₂Me ( Ib ), CHMe₂ ( Ic ), CMe ( Id ), SiMe₃ ( Ie ), R ( If ) react with t-butyllithium (molar ratio 1:1) by elimination of HF to give the amino-imino-boranes ( IIa – f ). The thermal stabilities of the latter depend upon the steric requirement of the substituent R′, IIa – c and IIe dimerize to yield the diazaboretidines IIIa – c and IIIe. IId remains unchanged at 200°C and above, and IIf isomerizes forming the B–Me substituted diazasilaboretidine IVf . If a twofold amount of t-butyllithium is employed, B–CMe₃ substituted diazasilaboretidines ( Va – f ) are the main products. All compounds are characterized by elemental (C, H) analyses and their mass- and n.m.r. (¹H, ¹³C, ¹⁵N (in part), ¹⁹F, ²⁹Si) spectra. Characteristic i.r.-bands are reported for the amino-imino-boranes ( II ). An X-ray structure analysis is presented for IVf .     

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.     

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.     

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 ).     

Hydroboration of Alkenes and Alkynes with Aza‐nido‐decaboranes

The 6‐aza‐nido‐decaboranes RNB₉H₁₁ ( 1a—d ; R = H, Ph, 4‐C₆H₄Me, 4‐C₆H₄Cl) act as 1, 2‐hydroboration agents via their 9‐BH vertex, giving products RNB₉H₁₀R′. The boranes 1a, b and 3‐hexyne yield the 9‐(1‐ethyl‐1‐butenyl)‐6‐aza‐nido‐decaboranes 2a, b (R′ = CEt = CHEt). 2, 3‐Dimethyl‐2‐butene is hydroborated by 1a—d under formation of the 9‐(1, 1, 2‐trimethylpropyl)‐6‐aza‐nido‐decaboranes 3a—d (R′ = —CMe₂ —CHMe₂). With the boranes 1a—c and (trimethylsilyl)ethene, a 85:15 mixture of the products (RNB₉H₁₀)CH₂CH₂(SiMe₃)( 4a—c ) and their chiral isomers (RNB₉H₁₀)CH(SiMe₃)CH₃ ( 5a—c ) is obtained. The action of BH₃(SMe₂) on the mixtures 4b/5b or 4c/5c results in a closure of the nido‐NB₉ skeleton of 4b or 4c , respectively, with a closo‐NB₁₁ skeleton of the products RNB₁₁H₁₀R′ ( 6b or 6c;R′ = CH₂CH₂(SiMe₃)); R′ is found in position 7 of 6b, c . All products of the type 2—6 are characterised by NMR.     

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)°.     

Supermesityl-stabilisierte Iminoborane. III

Supermesityl stabilized Iminoboranes. III New Iminoboranes R? B?N? R′ (R = 2,4,6(t-Bu)₃C₆H₂), IIa – IIf , were obtained by base-induced HF-elimination from RBF? NHR′ ( Ia-Ie ) or directly from RBF₂ and lithiated H₂NR′ (for IIf ). Compounds II exhibit a differentiated behaviour upon thermal treatment depending on R′. While IIa (R′ = H) immediately reacts to give the corresponding benzo[1]borolane IIIa , the dimeric diazadiboretidine is formed from IIb (R′ = Me) at 100°C; IIc (R = Et) and IId (R = C₆H₅) deliver the benzo[1]borolanes IIIc and IIId when they are heated to 180°C (in melt). IIe (R = 2,6(i-Pr)C₆H₃) and IIf (R = adamantyl) are stable at 250°C. All compounds were characterized by elemental analyses and spectroscopically (MS, IR, NMR: ¹H, ¹³C, ¹¹B, ¹⁹F and in part ¹⁵N).     

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.     

Homoleptische Amide von Zink,Cadmium und Quecksilber

Homoleptic Amides of Zinc, Cadmium, and Mercury ZnCl₂, CdCl₂ and HgCl₂ react with the lithium salts ( 1 a–5 a ) of the sterically demanding secundary amines HN(SiMe₃)Ph ( 1 ), HN(SiMe₃)C₆H₃Me₂‐2,6 ( 2 ), HN(SiMe₃)C₆H₃ⁱPr₂‐2,6 ( 3 ), HN(SiMe₃)C₆H₃^tBu₂‐2,5 ( 4 ), and HN(SiMe₂NMe₂)C₆H₃ⁱPr₂‐2,6 ( 5 ) yielding the corresponding homoleptic metal amides Zn[N(SiMe₂R′)R]₂ ( 1 b–5 b ), Cd[N(SiMe₂R′)R]₂ ( 1 c , 5 c ), and Hg[N(SiMe₂R′)R]₂ ( 1 d–5 d ), respectively. Except the dimeric {Zn[N(SiMe₃)Ph]₂}₂ ( 1 b ), all complexes are monomeric. The compounds were characterized by elemental analyses, molecular weight determinations, NMR and mass spectra. Furthermore, the zinc amides ( 1 b–5 b ) and the mercury amides 1 d–3 d and 5 d were characterized by single crystal X‐ray structure analysis. Except 1 b and 5 b , they show a linear N–M–N arrangement.     

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.     

1,2‐Diaza‐3‐silacyclopent‐5‐ene – Synthese und Reaktionen

1,2‐Diaza‐3‐silacyclopent‐5‐ene – Synthesis and Reactions The dilithium salt of bis(tert‐butyl‐trimethylsilylmethylen)ketazine ( 1 ) forms an imine‐enamine salt. 1 reacts with halosilanes in a molar ratio of 1:1 to give 1,2‐diaza‐3‐silacyclopent‐5‐enes. Me₃SiCH=CCMe₃ [N(SiR,R′)‐N=C‐C]HSiMe₃ ( 2 ‐ 7 ). ( 2 : R,R′ = Cl; 3 : R = CH₃, R′ = Ph; 4 : R = F, R′ = CMe₃; 5 : R = F, R′ = Ph; 6 : R = F, R′ = N(SiMe₃)₂; 7 : R = F, R′ = N(CMe₃)SiMe₃). In the reaction of 1 with tetrafluorosilane the spirocyclus 8 is isolated. The five‐membered ring compounds 2 ‐ 7 and compound 9 substituted on the silicon‐fluoro‐ and (tert‐butyltrimethylsilyl) are acid at the C(4)‐atom and therefore can be lithiated. Experiments to prepare lithium salts of 4 with MeLi, n‐BuLi and PhLi gave LiF and the substitution‐products 10 ‐ 12 . 9 forms a lithium salt which reacts with ClSiMe₃ to give LiCl and the SiMe₃ ring system ( 13 ) substituted at the C(4)‐atom. The ring compounds 3 ‐ 7 and 10 ‐ 12 form isomers, the formation is discussed. Results of the crystal structure and analyses of 8 , 10 , 12 , and 13 are presented.     

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.     

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 .     

Neutrale Bora-Silatropie an B-Halogen-substituierten Boryl-bis(silyl)hydroxylaminen

Neutral Rearrangement between Boryl and Silyl Groups in B-Halogenosubstituted Boryl-bis(silyl)hydroxylamines Dihalogenboranes, RBX₂, react with lithiated N,O-Bis(trimethylsilyl)hydroxylamine to give B-halogeno-borylhydroxylamines RB(X)ON(SiMe₃)₂: X = F, R = Trip (Trip = 2,4,6-triisopropylphenyl) ( I a ), N(SiMe₃)₂ ( I b ), N(CHMe₂)₂ ( I c ), N(SiMe₃)Dip (Dip = 2,6-diisopropylphenyl) ( I d ) and X = Cl, R = N(SiMe₃)₂ ( I e ). Depending upon the substituents on the boron atom a dyotropic rearrangement can be effected which transforms the compounds I a , I b und I e into the isomeric borylhydroxylamines RB(X)N(SiMe₃)OSiMe₃ II a , II b and II e . The compounds are characterized by their m. s. and n. m. r. (¹H, ¹¹B, ¹³C, ¹⁹F, ²⁹Si) spectra and by elemental analyses.     

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.     

PPh4{MoNCI3[N(SiMe3)2]}, ein Nitrido-Amido-Komplex von MoIybdän(VI)

Inhaltsübersicht. PPh₄{MoNCl₃[N(SiMe₃)₂]} entsteht aus PPh₄[MoNCl₄] und N,N,N′-Tris-(trimethylsilyl)benzamidin in siedendem Dichlormethan in Form bernsteinfarbener Kristalle, die wir IR-spektroskopisch und durch eine röntgenographische Strukturanalyse charakterisiert haben. Raumgruppe P2₁/n, Z = 4, R = 4,3% für 5168 unabhängige beobachtete Reflexe. Die Gitterkonstanten betragen für ?65°C: A = 918,9; b = 2850,5; c = 1353,9 pm; β = 107,51°. Die Verbindung besteht aus PPh₄⁺-Ionen und Anionen [MoNCl₃[N(SiMe₃)₂]}^–, in denen das Molybdänatom verzerrt tetragonal-pyramidal von dem Nitridoliganden in Apical-Position (r MoN = 165 pm), von drei Chloratomen und von dem N-Atom des Bis(trimethylsilyl)amido-Liganden (r MoN = 194 pm) umgeben ist. Das N-Atom des Amido-Liganden besitzt eine planare Umgebung. PPh₄{MoNCl₃[N(SiMe₃)₂]}, a Nitrido Amido Complex of Molybdenum (VI) PPh₄{MoNCl₃[N(SiMe₃)₂}] has been prepared by the reaction of PPh₄[MoNCl₄] with N,N,N′-Tris(trimethylsilyl)benzamidine in boiling dichloromethane, forming amber coloured crystals, which were characterized by their IR spectrum as well as by an X-ray structure determination. Space group P2₁/n, Z = 4, R = 0.043 for 5168 observed independent reflexions. The lattice dimensions are at ?65°C: A = 918.9; b = 2850.5; c = 1353.9 pm; β = 107.51°. The compound consists of PPh₄⁺ ions and anions {MoNCl₃[N(SiMe₃)₂]}^– in which the complex molybdenum anion forms a distorted tetragonal pyramid with the nitrido ligand (r MoN 165 pm) in the apical position and the chlorine atoms along with the nitrogen atom of the amido ligand (r MoN 194 pm) in the basical positions. The N atom of the amido ligand has a planar geometry.     

Monomere Dialkylmetallkomplexe des Typs R2M(NR′)2XR mit M = Al,Ga, In,TI; X = S,C und R,R′ = Alkyl und Silyl

Monomeric Dialkyl Metal Complexes of the R₂M(NR′)₂XR Type with M = Al, Ga, In, Tl; X = S, C and R, R′ = Alkyl and Silyl N,N′-Bis(trimethylsilyl)sulfurdiimide reacts with the trimethyl derivatives of aluminium, gallium, and indium within insertion. Hereby monomeric sulfinic acid imidamidates Me₂M(NSiMe₃)₂SMe (Me = CH₃) are formed. The lithium amidinates Li(NR′)₂CMe (R′ = i-C₃H₇ and SiMe₃) are formed likewise by insertion reactions with LiMe and the corresponding carbodiimides R′N?C?NR′ and were used in reactions with R₂MCl (M = Al to Tl) to synthesize dialkyl metal amidinates R₂M(NR′)₂CMe. The NMR (¹H and ¹³C) and the vibrational spectra (IR and Raman) are discussed and applied to describe the structure of these chelat complexes.     

Über die Umsetzung von Thiazylfluorid mit mehrfunktionellen Stickstoffderivaten

Reaction of Thiazylfluoride with Multifunctional Nitrogen Derivatives From the reaction of NSF 1 with LiN(SiMe₃)R′ (R′ = CMe₃, SiMe₃), linear [e. g. (Me₃C? N?S?N? )₂S ( 11 ), Me₃C? N?S?N? CMe₃ ( 14 ), Me₃Si? N?S?N? SiMe₃ ( 17 ), (Me₃Si)₂N? S? N?S?N? SiMe₃ ( 19 )] and cyclic thiazenes (S₄N₅F ( 22 )) are isolated, (S₃N₄)_n ( 23 ) is obtained in high yield from 1 and 17 (in the ratio 2:1). Possible structures for 23 are discussed; the reaction of 23 with AsF₅ gives S₄N₄ · AsF₅ ( 24 ) in a hitherto unknown modification. Possible reactions of the terminal SN groups are discussed and the structures of 11 and 24 are reported.     

A Heteroleptic (E)-1,2-Diaryl-1,2-disilyldistannene without Donor Stabilization

The reaction of the stannylene R₂Sn : (R = 2-tBu-4,5,6-Me₃C₆H) with R′₂Sn (R′ = Si(SiMe₃)₃) proceeds with substituent exchange to afford the heteroleptic stannylene RR′Sn : which, in the solid state, forms the distannene RR′Sn = SnRR′ ( 7 ). The X-ray structure analysis of 7 reveals a trans-bent arrangement of the substituents with a large fold angle of 44.9° and an Sn–Sn double bond length of 279.14(4) pm.     

Neue Komplexe des Titans mit Bis(trimethylsilyl)amido-Liganden

New Complexes of Titanium with Bis(trimethylsilyl)amido Ligands The reaction of cp′TiCl₃ with LiN(SiMe₃)₂ · Et₂O 1 yield the compounds cp′TiCl₂N(SiMe₃)₂ (cp′ = C₅H₅ 2 , C₅H₄SiMe₃ 3 , C₅H₃(SiMe₃)₂ 4 , C₅Me₅ 5 ) and cp′TiCl[N(SiMe₃)₂]₂ (cp′ = C₅H₅ 6 ). Compound 2 was characterized by an X-ray structural analysis with space group P2₁/n and unit cell dimensions of a = 1 660.9(7), b = 688.6(3), c = 1 739.1(8) pm and β = 117.18(3)°.