From Disilene (SiSi) to Phosphasilene (SiP) and Phosphacumulene (PCN)

The generation of heavier double‐bond systems without by‐ or side‐product formation is of considerable importance for their application in synthesis. Peripheral functional groups in such alkene homologues are promising in this regard owing to their inherent mobility. Depending on the steric demand of the N‐alkyl substituent R, the reaction of disilenide Ar₂Si?Si(Ar)Li (Ar=2,4,6‐iPr₃C₆H₂) with ClP(NR₂)₂ either affords the phosphinodisilene Ar₂Si?Si(Ar)P(NR₂)₂ (for R=iPr) or P‐amino functionalized phosphasilenes Ar₂(R₂N)Si? Si(Ar)?P(NR₂) (for R=Et, Me) by 1,3‐migration of one of the amino groups. In case of R=Me, upon addition of one equivalent of tert‐butylisonitrile a second amino group shift occurs to yield the 1‐aza‐3‐phosphaallene Ar₂(R₂N)Si? Si(NR₂)(Ar)? P?C?NtBu with pronounced ylidic character. All new compounds were fully characterized by multinuclear NMR spectroscopy as well as single‐crystal X‐ray diffraction and DFT calculations in selected cases.     

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.     

Reactivity of titanium imidazolin-2-iminato complexes with 2,6-diisopropylaniline and 2-{(2,6-diisopropylphenyl)-iminomethyl}pyrrole

Abstract

We report the reactions of imidazolin-2-iminato titanium complexes [(Im^RN)Ti(NMe₂)₃] (R = Mes, 2b; R = Dipp, 2c; Mes = mesityl, Dipp = 2,6-diisopropylphenyl) with 2,6-diisopropylaniline in a 1:3 molar ratio to yield the titanium imido complexes of composition [(Im^RNH)Ti = N(^Dipp)(HN^Dipp)₂] (R = Mes, 3b; R = Dipp, 3c) in good yield by the Ti-Niminato bond cleavage at 60 °C. In contrast, the reaction of [(Im^RN)Ti(NMe₂)₃] with 2,6-diisopropylaniline in a 1:1 molar ratio afforded mono-substituted products [(Im^RN)Ti(NMe₂)₂(HN^Dipp)] (R = Mes, 4b; R = Dipp, 4c) in good yield. The reaction of [(Im^RN)Ti(NMe₂)₃] with the iminopyrrole ligand [2-(2,6-iPr₂C₆H₃-N = CH)C₄H₃NH] (N^DippPyH) in a 1:1 ratio afforded mixed ligands, titanium complexes [(Im^RN)Ti(NMe₂)₂(N^Dipp-Py)] (R = tBu, 5a; R = Dipp, 5c) with imidazolin-2-iminato and iminopyrrolide ligands. Molecular structures of 3b, 3c, 4c, 5a, and 5c were determined by single-crystal X-ray analysis. The solid-state structures of 3b and 3c clearly indicate the formation of true Ti = N double bonds, measuring 1.730(2) Å and 1.727(1) Å, respectively. The solid-state structures of 5a and 5c reveal the formation of five-coordinate titanium complexes.     

Präkeramische Polyazane über die Sol‐Gel‐Route im Ammonosystem und aus molekularen Einkomponentenvorläufern — ein Leistungsvergleich

Preceramic Polyazanes via Sol Gel Route in the Ammono System and via Molecular Single Source Precursors — a Comparison of Performance All steps of the sol gel process in the oxo system can be transferred analogously to the ammono system. For this purpose, element alkyl amides of titanium, zirconium, tantalum and boron, have been co‐ammonolised with silicon alkyl amides in aprotic solvents. Pyrolysis of the resulting polyazanes yields multinary nitridic ceramic powders. For the model systems Si(NHMe)₄/Ti(NMe₂)₄, Si(NHMe)₄/Zr(NMe₂)₄, Si(NHMe)₄/Ta(NMe₂)₅, and Si(NHMe)₄/B(NMe₂)₃ the corresponding polymeric polyboro‐, polytitano‐, polyzirkono‐ and polytantalosilazanes were synthesised. Pyrolysis in flowing ammonia at 1000°C results in ternary amorphous silicon nitrides; further heating in nitrogen leads to partly crystalline composites. The process of pyrolysis as well as the morphology and composition of the final pyrolysis products were analysed by means of NMR, MAS‐NMR, FT‐IR, DTA‐TG‐MS, XRD, SEM, EDX, and elemental analyses. In order to verify this new and convenient access to multinary nitride ceramics, single source precursors were synthesised and, via polymer intermediates, processed to ceramic powders. A specially developed reaction sequence is generally applicable to syntheses of single source precursors for various ternary metal silicon nitrides. Dilithiated silazanes of the type Si(NMe₂)₂(NLiR)₂, with R = t‐Butyl, SiMe₃, CH₃, synthesised and structurally characterised for the first time, are good silicon synthones. While forming nitrido bridges, those compounds react with e.g. two‐ or four valent transition metal chlorides, to silicon transition metal adducts. Actually, we have analysed the reaction of Si(NMe₂)₂(NLiR)₂ and TiCl₄, ZrCl₄, TaCl₅, CrCl₃, MnCl₂, and ZnCl₂, respectively. The adducts as formed were crosslinked with ammonia and pyrolysed. In the case of the chlorides of the 4.—6. group metals, amorphous ceramics were obtained. Treatment at higher temperatures results in composites of transition metal nitride and an amorphous matrix. MnSiN₂ and a new hexagonal modification of ZnSiN₂ were obtained in the systems Mn/ Si/ N and Zn/ Si/ N. Surprisingly, during the synthesis of ZnSiN₂, ZnCN₂ was obtained as a side product.     

Synthese und Charakterisierung von [Zn{Si(NMe2)2(NHCMe3)(NCMe3)}‐(μ‐NC5H4)]2, einem molekularen Einkomponentenvorläufer zur Darstellung von ZnSiN2

Synthesis and Characterization of [Zn{Si(NMe₂)₂(NHCMe₃)(NCMe₃)}(μ‐NC₅H₄)]₂, a Molecular Single Source Precursor for ZnSiN₂ For an application as single source precursor for ZnSiN₂ the siladiazazinca cyclo butane [Zn{Si(NMe₂)₂(NHCMe₃)(NCMe₃)}(μ‐NC₅H₄)]₂has been synthesised for the first time from Si(NMe₂)₂(NLi t‐Butyl)₂ and ZnCl₂(NC₅H₅)₂. It has been characterized by single crystal structure analysis (P1, a = 870.5(3) pm, b = 903.8(3) pm, c = 1530.6(4) pm, α = 96.982(5)°, β = 106.501(5)°, γ = 104.729(5)°). The CP‐MAS‐NMR data for the nuclei ¹³C, ¹⁵N and ²⁹Si are reported. ZnSiN₂ was prepared by thermal decomposition of the precursor molecule and characterized by elemental analysis, EDX, IR spectroscopy and thermal analysis. The crystal structure was determined (X‐ray powder diffraction data, profile matching: P6₃mc, a = 315.33(1) pm, c = 508.07(2) pm, R_B = 4.87). The thermal behaviour of the precursor molecule, the preparation of polymers by linking with NH₃ and the decomposition of the polymers in an argon or NH₃ stream were investigated.     

Unerwartete Reduktion von [Cp*TaCl4(PH2R)] (R = But,Cy, Ad,Ph, 2,4,6‐Me3C6H2; Cp* = C5Me5) durch Reaktion mit DBU – Molekülstruktur von [(DBU)H][Cp*TaCl4] (DBU = 1,8‐Diazabicyclo[5.4.0]undec‐7‐en)

Unexpected Reduction of [Cp*TaCl₄(PH₂R)] (R = Bu^t, Cy, Ad, Ph, 2,4,6‐Me₃C₆H₂; Cp* = C₅Me₅) by Reaction with DBU – Molecular Structure of [(DBU)H][Cp*TaCl₄] (DBU = 1,8‐diazabicyclo[5.4.0]undec‐7‐ene) [Cp*TaCl₄(PH₂R)] (R = Bu^t, Cy, Ad, Ph, 2,4,6‐Me₃C₆H₂ (Mes); Cp* = C₅Me₅) react with DBU in an internal redox reaction with formation of [(DBU)H][Cp*TaCl₄] ( 1 ) (DBU = 1,8‐diazabicyclo[5.4.0]undec‐7‐ene) and the corresponding diphosphane (P₂H₂R₂) or decomposition products thereof. 1 was characterised spectroscopically and by crystal structure determination. In the solid state, hydrogen bonding between the (DBU)H cation and one chloro ligand of the anion is observed.     

Übergangsmetall-substituierte Acylphosphane und Phosphaalkene. 17 [1] Synthese und Struktur der μ-Isophosphaalkin-Komplexe [(η5-C5H5)2(CO)2Fe2(μ-CO)(μ-CPC6H2R3-2,4,6)] (R = Me,iPr, tBu)

Transition Metal Substituted Acylphosphanes and Phosphaalkenes. 17. Synthesis and Structure of the μ-Isophosphaalkyne Complexes [(η⁵-C₅H₅)₂(CO)₂Fe₂(μ-CO)(μ-C?PC₆H₂R₃)] (R = Me, iPr, tBu) . Condensation of (η⁵-C₅H₅)₂(CO)₂Fe₂(μ-CO)(μ-CSMe)}⁺SO₃CF₃^? ( 6 ) with 2,4,6-R₃C₆H₂PH(SiMe₃) ( 7 ) ( a : R = Me, b : R = iPr, c : R = tBu) affords the complexes (η⁵-C₅H₅)₂(CO)₂Fe₂(μ-CO)(η-C?PC₆H₂R₃-2,4,6) ( 9 a–c ) with edge-bridging isophosphaalkyne ligands as confirmed by the x-ray structure analysis of 9 a .     

Mobility Studies on Siloxane‐Based Inorganic‐Organic Hybrid Polymers by Dynamic Solid State,Suspended State,and Deuterium NMR Spectroscopy: Supported Organometallic Complexes. XXVI [1]

Organic modified siloxanes of the type RSi(OMe₂)₂(CH₂)₃C₆D₄(CH₂)₃(OMe₂)₂SiR [R = Me ( 4 ), R = OMe ( 5 )] were sol‐gel processed employing solvents of different polarity (MeOH and THF) to yield the corresponding inorganic‐organic hybrid polymers X4a — X5b with different physical properties. These polymers were investigated by multinuclear (²H, ¹³C, and ²⁹Si) solid state and ¹H suspension state NMR spectroscopy, including dynamic NMR techniques, in order to correlate the mobilities of these xerogels with physical properties, especially with the cross‐linkage.     

Theoretical insights into the relative bonding of normal and abnormal N‐heterocyclic carbenes in [PdCl2(NHCR)2] and [PdCl2(NHCR)(aNHCR)] (R = H,Ph, Mes)

Quantum chemical insights into normal Pd‐C2(NHC^R) and abnormal Pd‐C5(aNHC^R) bonding, dominated by dispersion interactions in N‐hetereocyclic carbene complexes [PdCl₂(NHC^R)₂] ( I , R = H; II , R = Ph; III , R = Mes (2,4,6‐trimethyl)phenyl)) and [PdCl₂(NHC^R)(aNHC^R] ( IV , R = H; V , R = Ph; VI , R = Mes) have been investigated at DFT and DFT‐D3(BJ) level of theory with particular emphasis on the effects of the noncovalent interactions on the structures and the nature of Pd‐C2(NHC^R) and Pd‐C5(aNHC^R) bonds. The optimized geometries are good agreement with the experimental values. The Pd‐C bonds are essentially single bond. Hirshfeld charge distributions indicate that the abnormal aNHC^R carbene ligand is relatively better electron donor than the normal NHC^R carbene ligand. The C2 atom has larger %s contribution along Pd‐C2 bond than the C5 atom along Pd‐C5 bond. As a consequence the Pd‐C2(NHC^R) bonds are relative stronger than the Pd‐C5(aNHC^R) bonds. Thus, the results of natural hybrid orbital analysis support the key point of the present study. Calculations predict that for bulky substituent (R = Ph, Mes) at carbene, the Pd‐C2(NHC^R) bond is stronger than Pd‐C5(aNHC^R) bond due to large dispersion energy in [PdCl₂(NHC^R)₂] than in [PdCl₂(NHC^R)(aNHC^R)]. However, in case of non‐bulky substituent with small and almost equal contribution of dispersion energy, the Pd‐C2(NHC^R) bond is relative weaker than Pd‐C5(aNHC^R) bond. The bond dissociation energies are dependent on the R substituent, the DFT functional and the inclusion of dispersion interactions. Major point of this study is that the abnormal aNHCs are not always strongly bonded with metal center than the normal NHCs. Effects of dispersion interaction of substituent at nitrogen atoms of carbene ligand are found to play a crucial role on estimation of relative bonding strengths of the normal and abnormal aNHCs with metal center. © 2016 Wiley Periodicals, Inc.     

1,1‐Ethylboration of alkyn‐1‐yl‐chloro(methyl)silanes: alkenes with chloro(methyl)silyl and diethylboryl groups in cis positions

The 1,1‐ethylboration of alkyn‐1‐yl‐chloro(methyl)silanes, Me₂Si(Cl)? C?C? R ( 1 ) and Me(H)Si(Cl)? C?C? R ( 2 ) [R = Bu ( 2a ), CH₂NMe₂ ( 2b )] requires harsh reaction conditions (up to 20 days in boiling triethylborane), and leads to alkenes in which the boryl and silyl groups occupy cis ((E)‐isomers: 3a , 3b , 5a , 5b ) or trans positions ((Z)‐isomers in smaller quantities: 4b and 6b ). The alkenes are destabilized in the presence of SiH(Cl) and CH₂NMe₂ units ( 5b , 6b ). NMR data indicate hyper‐coordinated silicon by intramolecular N? Si coordination in 3b and 5b , by which, at the same time, weak Si? Cl? B bridges are favoured. Copyright © 2005 John Wiley & Sons, Ltd.     

Preparation of organoalkoxysiloxanes by partial acidolysis of organoalkoxysilanes

Partial polycondensation of RSi(OMe)₃ (R = C₆H₅, CH₃) by the reaction with AcOH in the presence of HCl is studied. Oligoorganomethoxysiloxanes are obtained of the average composition [RSi(OMe)O]₄, [RSi (OMe)_4/6O_7/6]₆, RSi(OMe)_0.5O_1.25]₈, and [RSi(OMe)_0.4O_1.3]₁₀. Using the method of ²⁹Si NMR spectroscopy they were shown to contain three types of structural fragments: RSi(OMe)₂O-, RSiOMe(O-)₂, RSi(O-)₃. Based on the kinetic data, on the composition, properties, and the ²⁹Si NMR spectroscopy data of the products the conclusion is made that the obtained compounds have polycyclic structure with branched fragments. Using the GLC method the reaction was shown to have an induction period, whose duration can be substantially shortened by addition of HCl or methanol.     

An Alternative Mechanistic Paradigm for the β‐Z Hydrosilylation of Terminal Alkynes: The Role of Acetone as a Silane Shuttle

The β‐Z selectivity in the hydrosilylation of terminal alkynes has been hitherto explained by introduction of isomerisation steps in classical mechanisms. DFT calculations and experimental observations on the system [M(I)₂{κ‐C,C,O,O‐(bis‐NHC)}]BF₄ (M=Ir ( 3 a ), Rh ( 3 b ); bis‐NHC=methylenebis(N‐2‐methoxyethyl)imidazole‐2‐ylidene) support a new mechanism, alternative to classical postulations, based on an outer‐sphere model. Heterolytic splitting of the silane molecule by the metal centre and acetone (solvent) affords a metal hydride and the oxocarbenium ion [R₃Si? O(CH₃)₂]⁺, which reacts with the corresponding alkyne in solution to give the silylation product [R₃Si? CH?C? R]⁺. Thus, acetone acts as a silane shuttle by transferring the silyl moiety from the silane to the alkyne. Finally, nucleophilic attack of the hydrido ligand over [R₃Si? CH?C? R]⁺ affords selectively the β‐(Z)‐vinylsilane. The β‐Z selectivity is explained on the grounds of the steric interaction between the silyl moiety and the ligand system resulting from the geometry of the approach that leads to β‐(E)‐vinylsilanes.     

N(B(NMe2)2)(Si(NMe2)3)(Ti(NMe2)3), [N(Si(NMe2)3)(Ti(NMe2)2)]2 und N(SiMe3)(Si(NMe2)3)(Ti(NMe2)3) — Synthese und Charakterisierung neuer molekularer Einkomponentenvorläufer für nitridische und carbonitridische Keramiken

N(B(NMe₂)₂)(Si(NMe₂)₃) (Ti(NMe₂)₃), [N(Si(NMe₂)₃)(Ti(NMe₂)₂)]₂ und N(SiMe₃)(Si(NMe₂)₃)(Ti(NMe₂)₃) — Synthesis and Characterization of New Molecular Single-source Precursors for Nitride and Carbonitride Ceramics Synthesis and spectroscopic data of the title compounds are reported. [N(Si(NMe₂)₃)(Ti(NMe₂)₂)]₂ crystallizes in the space group P1 , a = 8.406(7), b = 10.673(8), c = 10.872(6) Å, α = 68.45(4)°, β = 71.72(4)°, γ = 78.11(7)°, 2 877 diffractometer data (F_o ? 2σF_o), R = 0.051. The compound is characterized by a planar four-membered Ti₂N₂-ring with exocyclic tris(dimethylamino)silyl substituents attached to the nitrogen atoms of the ring.     

Synthese „anorganischer”︁ Tintenfisch-Moleküle. II

Synthesis of “Inorganic” Pode-type Molecules. II The reaction of the amino compounds Me_yB? NMe₂ (B ? As, y ? 2; B ? Si, y ? 3) with 1, n-dioles results in the formation of the compounds HO(CH₂)_nOBMe_y. These compounds can be used as the arms of pode-type molecules Me_xA[? O(CH₂)_nOBMe_y]_z with A ? Si, As. The influence of A, B, n, and z in the rearrangement of these molecules is examined. A second type of pode molecules can be prepared by the reaction of Me₂As? R? OH (R ? CH₂CH₂, CH₂CH₂(OCH₂CH₂)₂) with the amino compounds Me_x(NMe₂)_z (A ? As, Si). These reactions result in the formation of molecules as Me_xA(ORAsMe₂)_z.     

Synthesis and Characterization of Intramolecularly Stabilized Chiral Dimethylindium Alkoxides and their Use as Cross Coupling Reagents

The enantiomerically pure dimeric N, O‐5‐chelates [Me₂In(μ‐OCH₂CH(R)NMe₂)]₂ {R = Me (S) ( 2 ); R = ⁱPr (S) ( 3 ); R = ⁱBu (S) ( 4 ); R = Bz (S) ( 5 )}, and [Me₂In‐{μ‐(1R, 2S)‐OCH(Ph)CH(Me)NMe₂}]₂ ( 6 ), as well as the achiral dimeric N, O‐6‐chelate [Me₂In(μ‐O(CH₂)₃NMe₂)]₂ ( 7 ) have been synthesized from trimethylindium and equimolar amounts of the corresponding enantiomerically pure dimethylamino alcohols or of the achiral dimethylaminopropanol by elimination of methane. Their ¹H NMR, ¹³C NMR, and mass spectra as well as the X‐ray single crystal structure analyses of [Me₂In{μ‐O(CH₂)₂NMe₂}]₂ ( 1 ), 3, 5, 6 and 7 are described and discussed. The coordinative N→In bonds of the five‐coordinate indium complexes show dynamic dissociation/association processes. 1—6 were found to be useful reagents for the partial kinetic resolution of 2‐carbomethoxy‐1, 1′‐binaphthyl triflate.     

Darstellung,Charakterisierung und Struktur funktionalisierter Fluorphosphaalkene des Typs R3E–P=C(F)NEt2 (R/E = Me/Si,Me/Ge,CF3/Ge,Me/Sn)

Preparation, Characterization, and Structure of Functionalized Fluorophosphaalkenes of the Type R₃E–P=C(F)NEt₂ (R/E = Me/Si, Me/Ge, CF₃/Ge, Me/Sn) P‐functionalized 1‐diethylamino‐1‐fluoro‐2‐phosphaalkenes of the type R₃E–P=C(F)NEt₂ [R/E = Me/Si ( 2 ), Me/Ge ( 3 ), CF₃/Ge ( 4 ), Me/Sn ( 5 )] are prepared by reaction of HP=C(F)NEt₂ ( 1 , E/Z = 18/82) with R₃EX (X = I, Cl) in the presence of triethylamine as base, exclusively as Z‐Isomers. 2–5 are thermolabile, so that only the more stable representatives 2 and 4 can be isolated in pure form and fully characterized. 3 and 5 decompose already at temperatures above –10 °C, but are clearly identified by ¹⁹F and ³¹P NMR‐measurements. The Z configuration is established on the basis of typical NMR data, an X‐ray diffraction analysis of 4 and ab initio calculations for E and Z configurations of the model compound Me₃Si–P=C(F)NMe₂. The relatively stable derivative 2 is used as an educt for reactions with pivaloyl‐, adamantoyl‐, and benzoylchloride, respectively, which by cleavage of the Si–P bond yield the push/pull phosphaalkenes RC(O)–P=C(F)NEt₂ [R = tBu ( 6 ), Ad ( 7 ), Ph ( 8 )], in which π‐delocalization with the P=C double bond occurs both with the lone pair on nitrogen and with the carbonyl group.     

Synthesis and Some Reactions of the Metal Phosphorus Double-bonded Complexes C5R5 (CO)2Mo=P(NMe2)2

Abstract

The reaction of the metalhydrides C₅R₅(CO)₃Mo-H (R=H (la), Me (lb) with P(NMe₂)₃ leads to the metal-phosphorus double-bonded species 2a,b via the intermediate formation of C₅(CO)₂ (Me₂N)₃P)Mo-H, which can only be identified spec-troscopically in solution.     

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.     

Solid‐State NMR and DFT Studies on the Formation of Well‐Defined Silica‐Supported Tantallaaziridines: From Synthesis to Catalytic Application

Single‐site, well‐defined, silica‐supported tantallaaziridine intermediates [≡Si‐O‐Ta(η²‐NRCH₂)(NMe₂)₂] [R=Me ( 2 ), Ph ( 3 )] were prepared from silica‐supported tetrakis(dimethylamido)tantalum [≡Si‐O‐Ta(NMe₂)₄] ( 1 ) and fully characterized by FTIR spectroscopy, elemental analysis, and ¹H,¹³C HETCOR and DQ TQ solid‐state (SS) NMR spectroscopy. The formation mechanism, by β‐H abstraction, was investigated by SS NMR spectroscopy and supported by DFT calculations. The C?H activation of the dimethylamide ligand is favored for R=Ph. The results from catalytic testing in the hydroaminoalkylation of alkenes were consistent with the N‐alkyl aryl amine substrates being more efficient than N‐dialkyl amines.