Alternativ-Liganden. XXV. Neue Chelatliganden des Typs Me2ESiMe2(CH2)2E′Me2 (E=P,As; E′=N,P, As)

Alternative Ligands. XXV. New Chelating Ligands of the Type Me₂ESiMe₂(CH₂)₂E′Me₂ (E=P, As; E′=N, P, As) Chelating ligands of the type Me₂EsiMe₂(CH₂)₂E′ Me₂, have been prepared by the following routes: Starting from Me₂Si(Vi)Cl, the compounds with E=N and E′ =N ( 1 ), P ( 2 ), As ( 3 ) are obtained in yields of 65 to 78% by aminolysis to yield Me₂NSiMe₂Vi, followed by the LiE′ Me₂ catalyzed addition of He′Me₂ to the vinyl group. The intermediates ClSiMe₂(CH₂)E′Me₂ [E′=N ( 4 ), P ( 5 ), As ( 6 )] are produced by the reactions of 1 to 3 with PhPCl₂. 5 and 6 can be prepared in a purer form by the photochemical addition of HPMe₂ and HAsMe₂, respectively, to the vinyl group of Me₂Si(Vo)Cl. 4 to 6 react with LiEMe₂, in situ prepared from n-BuLi and HEMe₂, to yield the ligands Me₂ESiMe₂(CH₂)₂E′Me₂ ( 7–12 ) (E=P, As; E′=N, P, As). The new compounds have been characterized by analytical and spectroscopic investigations (NMR, MS).     

Alternativ-Liganden. VIII. Chelatkomplexe des Typs M(CO)4(Me2XGeMe2CH2X′Me2) (M = Cr,Mo, W; X,X′ = N,P, As; Me = CH3)

Chelate Complexes of the Type M(CO)₄(Me₂XGeMe₂CH₂X′Me₂) (M) = Cr, Mo, W; X, X′ = N, P, As; Me = CH₃) The ligands (Me₂)XGeMe₂CH₂X′Me₂ (M) = Cr, Mo, W) react with M(CO)₄norbor (norbor = Norbornadiene) (M = Cr, Mo, W) yielding the chelate complexes M(CO)₄(Me)₂XGeMe₂CH₂X′Me₂). compounds of low thermal stability are formed with the ligands (Me₂NGeMe₂CH₂X′Me₂ because of the weak donor ability of the GeNMe₂ group and with Me₂AsGeMe₂CH₂NMe₂ caused by strong steric ring tension. The new compounds are characterized by analytical and spectroscopic (n.m.r., i.r., m.s.) investigations.     

Alternativ-Liganden. XXVI [1]. M(CO)4L-Komplexe (M  Cr,Mo, W) der Chelatliganden Me2ESiMe2(CH2)2E′Me2 (Me  CH3; E  P,As; E′  N,P, As)

Alternative Ligands. XXVI. M(CO)₄ L-Complexes (M ? Cr, Mo, W) of the Chelating Ligands Me₂ESiMe₂(CH₂)₂E′ Me₂ (Me ? CH₃; E ? P, As; E′ ? N, P, As) The reaction of M(CO)₄NBD (NBD = norbornadiene; M ? Cr, Mo, W) with the ligands Me₂ESiMe₂(CH₂)₂E′ Me₂ yields the chelate complexes (CO)₄M[Me₂ESiMe₂]) for E,E′ ? P, As, but not for E and /or E′ ? N. The NSi group is not suited for coordination because of strong (p-d)π-interaction. In the case of the ligands with E ? P or As and E′ ? N chelate complexes can be detected in the reaction mixture, but isolable products are complexes with two ligands coordinated via the E donor group. The new compounds are characterized by analytical and spectroscopic (IR, NMR, MS) investigations. The spectroscopic data are also used to deduce the coordinating properties of the ligands. X-ray diffraction studies of the molybdenum complexes (CO)₄Mo[Me₂ESiMe₂(CH₂)₂AsMe ₂] (E ? P, As) in accord with the observed coordination effects show only small differences between SiE and CE donor functions. Attempts to use the ligands Me₂ESiMe₂(CH₂)₂AsMe₂ (E ? P, As) for the preparation of Fe(CO)₃L complexes result in the fission of the SiE bonds and the formation of the binuclear systems Fe₂(CO)₆(EMe₂)₂ (E ? P, As) together with the disilane derivative [Me₂Si(CH₂)₂AsMe₂]₂.     

Atran-analoge Verbindungen III. Atran-analoge Verbindungen des Typs Me2DCH2CH2OSi(Me) (OCH2CH2)2D′ Me (I) und Me2DCH2CH2OSi(Me) (OCH2CH2D′Me2)OCH2CH2D″ Me2 (II) (MeCH3; D,D′, D‴N,P, As)

Atrane-analogous Compounds. III. Atrane-analogous Compounds of the Type Me₂DCH₂CH₂OSi(Me)(OCH₂ CH₂)₂ D′Me (I) and Type Me₂DCH₂CH₂OSi(Me) OCH₂CH₂₂D″Me₂ (II) (Me?CH₃; D, D′, D″?N, P, As) Atrane analogous compounds I and II (Abb. 1) have been prepared by condensation reactions of trifunctional silanes RSiX₃ (X?Cl, OEt, NMe₂) with N-methyldiethanolamine, ß-chloroethanol, ß-dimethylaminoethanol, and ß-dimethylarsanoethanol according to eqn. (1) to (3) and reaction schemes of Figs. 2 and 3, respectively. For compounds of type I weak N→Si adduct bonding is indicated for the MeN-donor of the eight-membered ring by significant shifts of the MeNCH₂ and OCH₂ proton n.m.r. signals. For compounds of type II there is no n.m.r. evidence for D→Si interactions. In spite of equal Lewis acidity of the Si atoms differences in adduct formation are observed for cage, ring, and acyclic podand systems, which can be explained mainly by entropy effects connected to the formation of five-membered rings.     

Perfluormthyl-Element-Liganden. XVII. Adduktbildung von MenE(CF3)3−n-Liganden mit BX3-Verbindungen (Me = CH3; E = P,As, Sb; n = 0–3; X = H,CH3, Hal)

Perfluoromethyl-Element-Ligands. XVII. Formation of Adducts of Me_nE(CF₃)_3?n Ligands with BX₃ Compounds (Me = CH₃; E = P, As, Sb; n = 0–3; X = H, CH₃, Hal) The ligands Me_nE(CF₃)_3?n (Me = CH₃; E = P, As, Sb; n = 0–3) have been prepared (partly using new methods) and studied by n.m.r. spectroscopy (¹H, ¹⁹F, ³¹P, ¹³C). In order to deduce their relative donor strength their reactions with the Lewis acids “BH₃”, BMe₃, BMe₃, Me₂BBr, and BX₃ (X = F, Cl, Br) have been studied. Control of adduct formation occurs by n.m.r. spectroscopy (¹H, ¹⁹F). The following series of decreasing basicity or acidity are obtained:      

Alternativ-Liganden. III. Koordinatives verhalten von chelatliganden des typs me2XSi(Me2)CH2XMe2 (X  N und/oder P: Me  CH3)

Co-ordinative Properties of Chelating Ligands of the Type Me₂XSi(Me₂)CH₂XMe₂ (X ? N and/or P; Me ? CH₃) The reactions of the ligands L ? Me₂XSi(Me₂)CH₂XMe₂ (X ? N and/or P; Me ? CH₃) with M(CO)₆ and M(CO)₄norbor (norbor ? norbornadiene) (M ? Cr, Mo), respectively, yield derivatives of the types M(CO)₅L, M(CO)₄L, and M(CO)₄L₂, respectively. M(CO)₅L compounds are formed from the hexacarbonyls with Me₂NSiMe₂CH₂PMe₂, whereas the ligand Me₂NSiMe₂CH₂NMe₂ does not afford analogous derivatives under the same conditions. Even on substitution of the diene-ligand in M(CO)₄norbor by Me₂NSiMe₂CH₂PMe₂ the chelate complexes M(CO)₄NMe₂SiMe₂CH₂PMe₂ are not obtained, but the cis-disubstituted products M(CO)₄[PMe₂CH₂SiMe₂NMe₂]₂ with phosphorus acting as donor atom are produced. The ligands Me₂PSiMe₂CH₂XMe₂(X ? N, P) give the chelate complexes M(CO)₄PMe₂SiMe₂CH₂XMe₂ in high yields. The new compounds were identified by analytical and spectroscopic (PMR, IR, mass spectra) methods.     

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

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

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

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

Gemischtligandkomplexe des Rheniums. V. Die Bildung von Nitrenkomplexen durch Kondensation von Aceton an koordinierten Nitridoliganden. Darstellung und Strukturen von fac-[Re{NC(CH3)2CH2C(O)CH3}X3(Me2PhP)2]-Komplexen (X = Cl,Br)

Mixed-ligand Complexes of Rhenium. V. The Formation of Nitrene Complexes by Condensation of Acetone at Coordinated Nitrido Ligands. Syntheses and Structures of fac-[Re{NC(CH₃)₂CH₂C(O)CH₃}X₃(Me₂PhP)₂] Complexes (X = Cl, Br) The reaction of rhenium(V)-mixed-ligand complexes of the general formula [ReN(Cl)(Me₂PhP)₂(R₂tcb)] (HR₂tcb = N? (N,N-dialkylthiocarbamoyl)benzamidine) with HCl or HBr in acetone initializes a condensation of the solvent and results in nitrene-like compounds as a consequence of a nucleophilic attack of the coordinated nitrido ligand on the condensed acetone. The chelate ligands are removed during this reaction and complexes of the type fac-[Re{NC(CH₃)₂CH₂C(O)CH₃}X₃(Me₂PhP)₂] (X = Cl, Br) are formed. fac-[Re{NC(CH₃)₂CH₂C(O)CH₃}Cl₃(Me₂PhP)₂] crystallizes triclinic in the space group P1, a = 8.575(4); b = 9.088(3); c = 18.389(9) Å; α = 75.67(3)°, β = 85.30(3)°, γ = 70.58(4)°; Z = 2. A final R value of 0.031 was obtained on the basis of 6011 independent reflections with I ≥ 2σ(I). Rhenium is coordinated in a distorted octahedral environment with the three chloro ligands in facial positions. The rhenium-nitrogen bond (1,68(1) Å) is only slightly longer than typical Re? N bonding distances in nitrido complexes. fac-[Re{NC(CH₃)₂CH₂C(O)CH₃}Br₃(Me₂PhP)₂] is isomorphous with the chloro complex. Triclinic cell with a = 8.625(4); b = 9.198(3); c = 18.581(5) Å; α = 75.62(3)°, β = 85.40(3)°, γ = 70.91(3)°; Z = 2. The R value converged at 0.049 on the basis of 3644 independent reflections with I ≥ 2σ(I). fac-[Re{NC(CH₃)₂CH₂C(O)CH₃}Cl₃(Me₂PhP)₂] as well as fac-[Re{NC(CH₃)₂CH₂C(O)CH₃}Br₃(Me₂PhP)₂] crystallizes in the noncentrosymmetric space group P1.     

Neue Synthesen von Me2SbX (X = Cl,I) und Kristallstrukturen von Me2SbI und [(Me3Si)2CH]2SbCl

Novel Syntheses of Me₂SbX (X = Cl, I) and Crystal Structures of Me₂SbI and [(Me₃Si)₂CH]₂SbCl The crystal structures of Me₂SbI (Me = CH₃) and [(Me₃Si)₂CH]₂SbCl have been determined by X‐ray methods. Both molecules are pyramidal. The Me₂SbI molecules are associated to chains through short intermolecular Sb…I distances (366,7(1) pm) with linear I–Sb…I units (171,87(4)°) and bent Sb–I…Sb bridges (116,83(3)°).     

Reaktive E=C(p‐p)π‐Systeme. 54 [1] Reaktionen des Perfluor‐2‐arsapropens,F3CAs=CF2 (1), mit H‐aciden Verbindungen Me2EH (E = N,P, As) und MeE′H (E′ = O,S, Se)

Reactive E=C(p‐p)π‐Systems. 54 [1] Reactions of perfluoro‐2‐arsapropene, F₃CAs=CF₂ (1), with H‐acidic compounds Me₂EH (E = N, P, As) and MeE′H (E′ = O, S, Se) The reactions of the perfluoro‐2‐arsapropene ( 1 ) with H‐acidic compounds Me₂EH (E = N, P, As) and MeE′H (E′ = O, S, Se), respectively, proceed via addition to the As=C double bond yielding either secondary arsanes F₃C(H)AsCF₂X (X = NMe₂, PMe₂, OMe, SMe) or AsX derivatives (X = AsMe₂, SeMe). Me₂‐AsH is obviously a border case nucleophile because, besides the AsX derivative as main product, small amounts of the arsane are formed indicative for the reverse addition pathway. With the strong base Me₂NH, the addition is followed immediately by HF elimination producing the fairly stable arsaalkene F₃CAs=C(F)NMe₂ ( 4 ) which had already been obtained by reaction of HAs(CF₃)₂ with three equivalents of Me₂NH. The novel rather labile compounds were identified by spectroscopic (NMR, GC/MS) investigations. – Quantum chemical DFT calculations [B3LYP/6‐311+G(d,p)] were carried out to determine the relative energy of the isomeric products and the thermodynamics of the addition reactions.     

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.     

Perfluormethyl‐Element‐Liganden. XLIII [1] Neue Synthesewege zu Zweikernkomplexen des Typs MM′(CO)8ER2X (M/M′ = Mn/Mn,Mn/Re,Re/Re; E = P,As; R = CF3, Me; X = Hal)

Perfluoromethyl Element Ligands. XLIII [1] Novel Synthetic Routes to Binuclear Complexes of the Type MM′(CO)₈ER₂X (M/M′ = Mn/Mn, Mn/Re, Re/Re; E = P, As; R = CF₃, Me; X = Hal, ) Mn(CO)₅I reacts with compounds of the type (CF₃)₂EAsMe₂ (E = P, As) as with the symmetric E₂(CF₃)₄ ligands in the first step with cleavage of the E‐As bond to yield the pro ducts (CO)₅MnE(CF₃)₂ and Me₂AsI. Reaction of the mononuclear complexes with excess of Mn(CO)₅I leads in good yields to the known dinuclear compounds (CO)₄Mn[E(CF₃)₂, I]Mn(CO)₄ and CO. Me₂AsI, the second product of the EAs cleavage, attacks the starting compound Mn(CO)₅I giving cis‐Mn(CO)₄I(AsMe₂I) and CO. This result encouraged us to thoroughly investigate the preparation of cis‐M(CO)₄X(EMe₂Y) complexes with most of the possible combinations of M = Mn, Re; E = P, As and X, Y = Cl, Br, I. An alternative route to these compounds was opened by the cleavage of the dinuclear manganese or rhenium halides M₂(CO)₈X₂ with the halophosphanes or ‐arsanes Me₂EY. This route was found to be especially advantageous for the preparation of the rheniumcarbonyl precursors, since milder conditions than for the CO‐substitution in Re(CO)₅X compounds are sufficient for the halogen‐bridged dinuclear complexes. Cis‐M(CO)₄X(EMe₂Y) complexes were used as precursors for the synthesis of novel homo‐ and heterodinuclear complexes of the type (CO)₄M(EMe₂, X)M′(CO)₄ by reacting the EY function with transition metal carbonylates Kat[M′(CO)₅] (Kat = Na, Bu₄N, Ph₄As). Thus the preparation of a wide range of complexes was possible, which before had been successfully prepared by the direct reaction of Mn₂(CO)₁₀ with Me₂EX only in few cases, e. g. with Me₂AsI. Spectroscopic investigations, using the CO valence frequencies and the ¹H‐NMR data of the ligands EMe₂Y or of the Me₂E bridges, were applied to study the influence of the variables M, M′, E, X, Y and Kat on the reactivity of the mononuclear complexes and the bonding situation in both the mono‐ and the dinuclear systems. The new compounds were characterized by spectroscopic (IR, NMR, MS) and analytic methods (C, H).     

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.     

Synthesis and Structural Characterization of Some Novel Trialkylsilyl‐substituted Lithium Benzyl Complexes [Li(tmeda)][CHRSiMe2R′] (R = Ph, 3,5‐Me2C6H3; R′ = Me,tBu, Ph)

The reactions of PhCH₂SiMe₃ ( 1 ), PhCH₂SiMe₂^tBu ( 2 ), PhCH₂SiMe₂Ph ( 3 ), 3,5‐Me₂C₆H₃CH₂SiMe₃ ( 4 ), and 3,5‐Me₂C₆H₃CH₂SiMe₂^tBu ( 5 ) with ⁿBuLi in tetramethylethylenediamine (tmeda) afford the corresponding lithium complexes [Li(tmeda)][CHRSiMe₂R′] (R, R′ = Ph, Me ( 6 ), Ph, ^tBu ( 7 ), Ph, Ph ( 8 ), 3,5‐Me₂C₆H₃, Me ( 9 ), and 3,5‐Me₂C₆H₃, ^tBu ( 10 )), respectively. The new compounds 5 , 7 , 8 , 9 and 10 have been characterized by ¹H and ¹³C NMR spectroscopy, compounds 7 , 8 and 9 also by X‐ray structure analysis.     

Alternativ-Liganden. XXII. Rhodium(I)-Komplexe mit Donor/Akzeptor-Liganden des Typs Me2PCH2CH2SiXnMe3−(X = F,Cl, OMe)

Alternative Ligands. XXII. Rhodium(I) complexes with Donor/Acceptor Ligands of the Typs Me₂PCH₂CH₂SiX_nMe_3?n(X = F, Cl, OMe) Donor/acceptor ligand of the type Me₂PCH₂SiX_nMe_3?n react with [Rh(CO)₂Cl]₂ ( 1 ) to give the mononuclear complexes RhCl(CO)(PMe₂CH₂CH₂SiX_nMe_3?n)₂ ( 2-6 , Table 1) with planar geometry of the donor atoms, one exception being Me₂PCH₂CH₂CH₂SiCl₃, yielding the crystalline Rh^III-complex RhCl₂(CO)(PMe₂CH₂CH₂SiCl₂)(PMe₂CH₂CH₂SiCl₃) ( 7 ) by oxidative addition of one of the SiCl bonds to the Rh¹ precursor. Structures with Rh → Si interaction between the basic central atoms and the acceptor group SiX_nMe_3?n could be detected in the isolated products neither spectroscopically nor by X-ray diffraction of the two representatives RhCl(CO)(PMe₂CH₂CH₂SiF₃)₂ ( 2 ) and RhCl(CO)[PMe₂CH₂CH₂siF₃]₂ ( 2 ) and RhCl(CO) [PMe₂CH₂CH₂Si(OMe₃]₂ ( 6 ). The presence of such acid/base adducts in the reaction mixture is indicated for the more acidic acceptor groups SiX_nMe_3?n byv_co values near 1990cm^?1, (see Table 3). The complex RhCl(CO)PMe₃)(PMe₂CH₂CH₂SiF₃ ( 8 ) is obtained by the reaction of RhCl(CO)(PMe₃)₂ ( 9 ) with Me₂PCH₂SiF₃ and has been identified spectroscopically in a mixture with 2 and 9 .     

N,N,N′,N′-Tetramethylethylendiamin-di(tert-butyl)aluminium-Kationen — Molekülstruktur des [(Me3C)2Al · TMEDA]⊕[(Me3C)2AlBr2]⊖

(N,N,N′,N′ -tetramethylethylendiamine) di(tert-butyl)aluminium Cations — Molecular Structure of [(Me₃C)₂Al(TMEDA)]^⊕[(Me₃C)₂AlBr₂]^? Dimeric di(tert-butyl)aluminium halides (Me₃C)₂AlX (X = Cl, Br) react with N,N,N′,N′ -tetramethylethylendiamine (TMEDA) to give three compounds: the salt-like [(Me₃C)₂Al(TMEDA)]^⊕[(Me₃C)₂AlX₂]^? 1 , characterized by crystal structure determination, and [(Me₃C)₂Al(TMEDA)]^⊕X^? 3 both with chelating amine, and the more covalent, pentane soluble (Me₃C)₂AlX(TMEDA) 2 with TMEDA bound by only one nitrogen atom. The reaction resembles the symmetrical and unsymmetrical cleavage of diborane(6). 3 (X = Cl) is also formed by treatment of 1 with boiling n-hexane in the presence of TMEDA over a period of 24 hours, while for X = Br the more covalent 2 is the main product under similar conditions. In solution 2 decomposes slowly yielding different products in dependency of the solvent: in benzene 3 and in n-pentane 1 are formed.     

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

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