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.     

Comparative Study of Phosphine and N‐Heterocyclic Carbene Stabilized Group 13 Adducts [L(EH3)] and [L2(E2Hn)]

Quantum chemical calculations using density functional theory at the BP86/TZ2P level have been carried out to determine the geometries and stabilities of Group 13 adducts [(PMe₃)(EH₃)] and [(PMe₃)₂(E₂H_n)] (E=B–In; n=4, 2, 0). The optimized geometries exhibit, in most cases, similar features to those of related adducts [(NHC^Me)(EH₃)] and [(NHC^Me)₂(E₂H_n)] with a few exceptions that can be explained by the different donor strengths of the ligands. The calculations show that the carbene ligand L=NHC^Me (:C(NMeCH)₂) is a significantly stronger donor than L=PMe₃. The equilibrium geometries of [L(EH₃)] possess, in all cases, a pyramidal structure, whereas the complexes [L₂(E₂H₄)] always have an antiperiplanar arrangement of the ligands L. The phosphine ligands in [(PMe₃)₂(B₂H₂)], which has C_s symmetry, are in the same plane as the B₂H₂ moiety, whereas the heavier homologues [(PMe₃)₂(E₂H₂)] (E=Al, Ga, In) have C_i symmetry in which the ligands bind side‐on to the E₂H₂ acceptor. This is in contrast to the [(NHC^Me)₂(E₂H₂)] adducts for which the NHC^Me donor always binds in the same plane as E₂H₂ except for the indium complex [(NHC^Me)₂(In₂H₂)], which exhibits side‐on bonding. The boron complexes [L₂(B₂)] (L=PMe₃ and NHC^Me) possess a linear arrangement of the LBBL moiety, which has a B?B triple bond. The heavier homologues [L₂(E₂)] have antiperiplanar arrangements of the LEEL moieties, except for [(PMe₃)₂(In₂)], which has a twisted structure in which the PInInP torsion angle is 123.0°. The structural features of the complexes [L(EH₃)] and [L₂(E₂H_n)] can be explained in terms of donor–acceptor interactions between the donors L and the acceptors EH₃ and E₂H_n, which have been analyzed quantitatively by using the energy decomposition analysis (EDA) method. The calculations predict that the hydrogenation reaction of the dimeric magnesium(I) compound L′MgMgL′ with the complexes [L(EH₃)] is energetically more favorable for L=PMe₃ than for NHC^Me.     

Unusual Structure,Fluxionality, and Reaction Mechanism of Carbonyl Hydrosilylation by Silyl Hydride Complex [(ArN)Mo(H)(SiH2Ph)(PMe3)3]

The reactions of bis(borohydride) complexes [(RN?)Mo(BH₄)₂(PMe₃)₂] ( 4 : R=2,6‐Me₂C₆H₃; 5 : R=2,6‐iPr₂C₆H₃) with hydrosilanes afford new silyl hydride derivatives [(RN?)Mo(H)(SiR′₃)(PMe₃)₃] ( 3 : R=Ar, R′₃=H₂Ph; 8 : R=Ar′, R′₃=H₂Ph; 9 : R=Ar, R′₃=(OEt)₃; 10 : R=Ar, R′₃=HMePh). These compounds can also be conveniently prepared by reacting [(RN?)Mo(H)(Cl)(PMe₃)₃] with one equivalent of LiBH₄ in the presence of a silane. Complex 3 undergoes intramolecular and intermolecular phosphine exchange, as well as exchange between the silyl ligand and the free silane. Kinetic and DFT studies show that the intermolecular phosphine exchange occurs through the predissociation of a PMe₃ group, which, surprisingly, is facilitated by the silane. The intramolecular exchange proceeds through a new non‐Bailar‐twist pathway. The silyl/silane exchange proceeds through an unusual Mo^VI intermediate, [(ArN?)Mo(H)₂(SiH₂Ph)₂(PMe₃)₂] ( 19 ). Complex 3 was found to be the catalyst of a variety of hydrosilylation reactions of carbonyl compounds (aldehydes and ketones) and nitriles, as well as of silane alcoholysis. Stoichiometric mechanistic studies of the hydrosilylation of acetone, supported by DFT calculations, suggest the operation of an unexpected mechanism, in that the silyl ligand of compound 3 plays an unusual role as a spectator ligand. The addition of acetone to compound 3 leads to the formation of [trans‐(ArN)Mo(OiPr)(SiH₂Ph)(PMe₃)₂] ( 18 ). This latter species does not undergo the elimination of a Si? O group (which corresponds to the conventional Ojima′s mechanism of hydrosilylation). Rather, complex 18 undergoes unusual reversible β‐CH activation of the isopropoxy ligand. In the hydrosilylation of benzaldehyde, the reaction proceeds through the formation of a new intermediate bis(benzaldehyde) adduct, [(ArN?)Mo(η²‐PhC(O)H)₂(PMe₃)], which reacts further with hydrosilane through a η¹‐silane complex, as studied by DFT calculations.     

Diimido‐, Imido(oxo)‐, Dioxo‐ und Imido(alkyliden)‐Halbsandwich‐Verbindungen über selektive Hydrolyse und α—H‐Abstraktion an Organylkomplexen des sechswertigen Molybdäns und Wolframs

Diimido, Imido Oxo, Dioxo, and Imido Alkylidene Halfsandwich Compounds via Selective Hydrolysis and α—H Abstraction in Molybdenum(VI) and Tungsten(VI) Organyl Complexes Organometal imides [(η⁵‐C₅R₅)M(NR′)₂Ph] (M = Mo, W, R = H, Me, R′ = Mes, tBu) 4 — 8 can be prepared by reaction of halfsandwich complexes [(η⁵‐C₅R₅)M(NR′)₂Cl] with phenyl lithium in good yields. Starting from phenyl complexes 4 — 8 as well as from previously described methyl compounds [(η⁵‐C₅Me₅)M(NtBu)₂Me] (M = Mo, W), reactions with aqueous HCl lead to imido(oxo) methyl and phenyl complexes [(η⁵‐C₅Me₅)M(NtBu)(O)(R)] M = Mo, R = Me ( 9 ), Ph ( 10 ); M = W, R = Ph ( 11 ) and dioxo complexes [(η⁵‐C₅Me₅)M(O)₂(CH₃)] M = Mo ( 12 ), M = W ( 13 ). Hydrolysis of organometal imides with conservation of M‐C σ and π bonds is in fact an attractive synthetic alternative for the synthesis of organometal oxides with respect to known strategies based on the oxidative decarbonylation of low valent alkyl CO and NO complexes. In a similar manner, protolysis of [(η⁵‐C₅H₅)W(NtBu)₂(CH₃)] and [(η⁵‐C₅Me₅)Mo(NtBu)₂(CH₃)] by HCl gas leads to [(η⁵‐C₅H₅)W(NtBu)Cl₂(CH₃)] 14 und [(η⁵‐C₅Me₅)Mo(NtBu)Cl₂(CH₃)] 15 with conservation of the M‐C bonds. The inert character of the relatively non‐polar M‐C σ bonds with respect to protolysis offers a strategy for the synthesis of methyl chloro complexes not accessible by partial methylation of [(η⁵‐C₅R₅)M(NR′)Cl₃] with MeLi. As pure substances only trimethyl compounds [(η⁵‐C₅R₅)M(NtBu)(CH₃)₃] 16 ‐ 18 , M = Mo, W, R = H, Me, are isolated. Imido(benzylidene) complexes [(η⁵‐C₅Me₅)M(NtBu)(CHPh)(CH₂Ph)] M = Mo ( 19 ), W ( 20 ) are generated by alkylation of [(η⁵‐C₅Me₅)M(NtBu)Cl₃] with PhCH₂MgCl via α‐H abstraction. Based on nmr data a trend of decreasing donor capability of the ligands [NtBu]^2— > [O]^2— > [CHR]^2— ? 2 [CH₃]^— > 2 [Cl]^— emerges.     

Gold(I) and Silver(I) Complexes with Thioether Functionalized Silylamido Ligands

The thioether functionalized aminosilanes Me₂Si(NH‐C₆H₄‐2‐SR)₂ (R = Ph, Me) were lithiated with nBuLi and subsequently reacted with AgCl in the presence of PMe₃ or with [AuCl(PMe₃)]. In the case of Me₂Si(NH‐C₆H₄‐2‐SPh)₂ the dinuclear complexes [M₂{Me₂Si(NC₆H₄‐2‐SPh)₂}(PMe₃)₂] (M = Ag; Au) were isolated. The analogous reactions starting from Me₂Si(NH‐C₆H₄‐SMe)₂ afforded the dinuclear gold complex [Au₂{Me₂Si(NC₆H₄‐2‐SMe)₂}(PMe₃)₂] and the tetranuclear silver complex [Ag₄{Me₂Si(NC₆H₄‐2‐SMe)₂}₂(PMe₃)₂]. In the dinuclear compounds of the type [M₂{Me₂Si(NC₆H₄‐2‐SR)₂}(PMe₃)₂], each of the silylamide N atoms is connected to a M(PMe₃) group to give a nearly linear N–M–P arrangement with Ag–N and Au–N bonds in the range of 212.0(4)–213.3(4) pm and 205.3(3)–208.1(9) pm, respectively. [Ag₄{Me₂Si(NC₆H₄‐2‐SMe)₂}₂(PMe₃)₂] consists of a central Si₂N₄Ag₂ ring with linearly coordinated Ag atoms (Ag‐N: 223.1(4)–222.1(4) pm) and two peripheral Ag(PMe₃) units, which are connected to the amido N atoms in a chelating mode. The relatively short transannular Ag ··· Ag separation (277.6(1) pm) within the Si₂N₄Ag₂ ring hints for argentophilic interactions. The peripheral Ag atoms are three coordinated with Ag–N distances of 233.9(4)–242.8(4) pm.     

Synthesen und Kristallstrukturen von Cu‐ und Ag‐Komplexen mit [Ta6S17]4—‐Ionen als Liganden

Syntheses and Crystal Structures of Cu and Ag Complexes with [Ta₆S₁₇]^4— Ions as Ligands In the presence of phosphines saturated solutions of the thiotantalates (NEt₄)₄[(Ta₆S₁₇)] · 3MeCN react with copper or silver salts to give new heterobimetallic Ta—M—S clusters (M = Ag, Cu). These clusters contain the intact cluster core of the [Ta₆S₁₇]^4— anion. Compounds [Cu(PMe₃)₄]₃[(Ta₆S₁₇)Cu(PMe₃)] · 2MeCN ( 1 ), (NEt₄)[(Ta₆S₁₇)Ag₃(PMe₂ⁱPr)₆] · 5MeCN ( 2 ), [(Ta₆S₁₇)Cu₄ (PMe₂ⁱPr)₈] · MeCN ( 3 ), [(Ta₆S₁₇)Cu₅Cl(PMe₂ⁱPr)₉] · MeCN ( 4 ) and [Ta₂Cu₂S₄Cl₂(PMe₂ⁱPr)₆] · 2MeCN ( 5 ) are presented herein. The structures of these compounds were elucidated by single crystal X‐ray structural analyses.     

Transition‐Metal Complexes [(PMe3)2Cl2M(E)] and [(PMe3)2(CO)2M(E)] with Naked Group 14 Atoms (E=C–Sn) as Ligands; Part 2: Complexation with W(CO)5

Density functional calculations at the BP86/TZ2P level were carried out to understand the ligand properties of the 16‐valence‐electron(VE) Group 14 complexes [(PMe₃)₂Cl₂M(E)] ( 1ME ) and the 18‐VE Group 14 complexes [(PMe₃)₂(CO)₂M(E)] ( 2ME ; M=Fe, Ru, Os; E=C, Si, Ge, Sn) in complexation with W(CO)₅. Calculations were also carried out for the complexes (CO)₅W–EO. The complexes [(PMe₃)₂Cl₂M(E)] and [(PMe₃)₂(CO)₂M(E)] bind strongly to W(CO)₅ yielding the adducts 1ME–W(CO)₅ and 2ME–W(CO)₅ , which have C_2v equilibrium geometries. The bond strengths of the heavier Group 14 ligands 1ME (E=Si–Sn) are uniformly larger, by about 6–7 kcal mol^?1, than those of the respective EO ligand in (CO)₅W‐EO, while the carbon complexes 1MC–W(CO)₅ have comparable bond dissociation energies (BDE) to CO. The heavier 18‐VE ligands 2ME (E=Si–Sn) are about 23–25 kcal mol^?1 more strongly bonded than the associated EO ligand, while the BDE of 2MC is about 17–21 kcal mol^?1 larger than that of CO. Analysis of the bonding with an energy‐decomposition scheme reveals that 1ME is isolobal with EO and that the nature of the bonding in 1ME–W(CO)₅ is very similar to that in (CO)₅W–EO. The ligands 1ME are slightly weaker π acceptors than EO while the π‐acceptor strength of 2ME is even lower.     

Die Reaktion des [(Me3Si)2CH]2Al?CH2?Al [CH(SiMe3)2]2 mit LiCH(PMe2)2; Bildung eines fünfgliedrigen Al2C2P-Heterozyklus

The Reaction of [(Me₃Si)₂CH]₂Al? CH₂? Al [CH(SiMe₃)₂]₂ with LiCH(PMe₂)₂; Formation of a Five-membered Al₂C₂P Heterocycle The recently synthesized methylene bridged dialuminium compound [(Me₃Si)₂CH]₂Al? CH₂? Al [CH(SiMe₃)₂]₂ 3 reacts with one equivalent of LiCH(PMe₂)₂ in the presence of TMEDA to give an adduct with one aluminium atom coordinated by the carbanionic carbon atom and the second one coordinated by one phosphorus atom. A five-membered heterocycle 5 is formed, which was characterized by a crystal structure determination showing a strongly bent ring with the phosphorus atom located above the plane of the four remaining atoms (Al₂C₂). 5 is unstable in ethereal solution decomposing under ether cleavage to the educt 3 and the diphosphinomethane derivative CH₂(PMe₂)₂.     

CH Bond Activation during and after the Reactions of a Metallacyclic Amide with Silanes: Formation of a μ‐Alkylidene Hydride Complex,Its H–D Exchange,and β‐H Abstraction by a Hydride Ligand

Metallacyclic complex [(Me₂N)₃Ta(η²‐CH₂SiMe₂NSiMe₃)] ( 3 ) undergoes C?H activation in its reaction with H₃SiPh to afford a Ta/μ‐alkylidene/hydride complex, [(Me₂N)₂{(Me₃Si)₂N}Ta(μ‐H)₂(μ‐C‐η²‐CHSiMe₂NSiMe₃)Ta(NMe₂)₂] ( 4 ). Deuterium‐labeling studies with [D₃]SiPh show H–D exchange between the Ta?D ?Ta unit and all methyl groups in [(Me₂N)₂{(Me₃Si)₂N}Ta(μ‐D)₂(μ‐C‐η²‐CHSiMe₂NSiMe₃)Ta(NMe₂)₂] ([D₂]‐ 4 ) to give the partially deuterated complex [D_n]‐ 4 . In addition, 4 undergoes β‐H abstraction between a hydride and an NMe₂ ligand and forms a new complex [(Me₂N){(Me₃Si)₂N}Ta(μ‐H)(μ‐N‐η²‐C,N‐CH₂NMe)(μ‐C‐η²‐C,N‐CHSiMe₂NSiMe₃)Ta(NMe₂)₂] ( 5 ) with a cyclometalated, η²‐imine ligand. These results indicate that there are two simultaneous processes in [D_n]‐ 4 : 1) H–D exchange through σ‐bond metathesis, and 2) H?D elimination through β‐H abstraction (to give [D_n]‐ 5 ). Both 4 and 5 have been characterized by single‐crystal X‐ray diffraction studies.     

Imino‐Bridged Bisphosphaalkenes (2,4‐Diphospha‐3‐azapentadienes)

Deprotonation of aminophosphaalkenes (RMe₂Si)₂C?PN(H)(R′) (R=Me, iPr; R′=tBu, 1‐adamantyl (1‐Ada), 2,4,6‐tBu₃C₆H₂ (Mes*)) followed by reactions of the corresponding Li salts Li[(RMe₂Si)₂C?P(M)(R′)] with one equivalent of the corresponding P‐chlorophosphaalkenes (RMe₂Si)₂C?PCl provides bisphosphaalkenes (2,4‐diphospha‐3‐azapentadienes) [(RMe₂Si)₂C?P]₂NR′. The thermally unstable tert‐butyliminobisphosphaalkene [(Me₃Si)₂C?P]₂NtBu ( 4 a ) undergoes isomerisation reactions by Me₃Si‐group migration that lead to mixtures of four‐membered heterocyles, but in the presence of an excess amount of (Me₃Si)₂C?PCl, 4 a furnishes an azatriphosphabicyclohexene C₃(SiMe₃)₅P₃NtBu ( 5 ) that gave red single crystals. Compound 5 contains a diphosphirane ring condensed with an azatriphospholene system that exhibits an endocylic P?C double bond and an exocyclic ylidic P⁽⁺⁾? C^(?)(SiMe₃)₂ unit. Using the bulkier iPrMe₂Si substituents at three‐coordinated carbon leads to slightly enhanced thermal stability of 2,4‐diphospha‐3‐azapentadienes [(iPrMe₂Si)₂C?P]₂NR′ (R′=tBu: 4 b ; R′=1‐Ada: 8 ). According to a low‐temperature crystal‐structure determination, 8 adopts a non‐planar structure with two distinctly differently oriented P?C sites, but ³¹P NMR spectra in solution exhibit singlet signals. ³¹P NMR spectra also reveal that bulky Mes* groups (Mes*=2,4,6‐tBu₃C₆H₂) at the central imino function lead to mixtures of symmetric and unsymmetric rotamers, thus implying hindered rotation around the P? N bonds in persistent compounds [(RMe₂Si)₂C?P]₂NMes* ( 11 a , 11 b ). DFT calculations for the parent molecule [(H₃Si)₂C?P]₂NCH₃ suggest that the non‐planar distortion of compound 8 will have steric grounds.     

Facile Access to Silicon‐Functionalized Bis‐Silylene Titanium(II) Complexes

A series of unprecedented bis‐silylene titanium(II) complexes of the type [(η⁵‐C₅H₅)₂Ti(LSiX)₂] (L=PhC(NtBu)₂; X=Cl, CH_3, H) has been prepared using a phosphane elimination strategy. Treatment of the [(η⁵‐C₅H₅)₂Ti(PMe₃)₂] precursor ( 1 ) with two molar equivalents of the N‐heterocyclic chlorosilylene LSiCl ( 2 ), results in [(η⁵‐C₅H₅)₂Ti(LSiCl)₂] ( 3 ) with concomitant PMe₃ elimination. The presence of a Si? Cl bond in 3 enabled further functionalization at the silicon(II) center. Accordingly, a salt metathesis reaction of 3 with two equivalents of MeLi results in [(η⁵‐C₅H₅)₂Ti(LSiMe)₂] ( 4 ). Similarly, the reaction of 3 with two equivalents of LiBHEt₃ results in [(η⁵‐C₅H₅)₂Ti(LSiH)₂] ( 5 ), which represents the first example of a bis‐(hydridosilylene) metal complex. All complexes were fully characterized and the structures of 3 and 4 elucidated by single‐crystal X‐ray diffraction analysis. DFT calculations of complexes 3 – 5 were also carried out to assess the nature of the titanium–silicon bonds. Two σ and one π‐type molecular orbital, delocalized over the Si‐Ti‐Si framework, are observed.     

Formation of ferraboranes from pentaborane(9) or BH3 · thf and an electron-rich cyclopentadienyl iron phosphine hydride

[(η⁵-C₅R₅)Fe(PMe₃)₂H] (R = H, Me) can be made in good yields in a simple one-pot reaction between FeCl₂, PMe₃, C₅R₅H (R = H, Me) and Na/Hg in thf. Reaction of [(η⁵-C₅H₅)Fe(PMe₃)₂H] with pentaborane(9) gives the known metallaborane [(η⁵-C₅H₅)-nido-2-FeB₅H₁₀] (1) in improved yield as well as the new metallaboranes [(η-C₅H₅)-nido-2-FeB₅H₈{μ-5,6-Fe(η⁵-C₅H₅)(PMe₃)(μ-6,7-H)}] (2), [(η-C₅H₅)(PMe₃)-arachno-2-FeB₃H₈] (3), [(η⁵-C₅H₅)₂-capped-nido-2,3-Fe₂B₄H₈] (4), [(η⁵-C₅H₅)-nido-2-FeB₄H₇(PMe₃)] (5) and [(η⁵-C₅H₅)-nido-2-FeB₅H₈(PMe₃)] (6). Reaction of [(η⁵-C₅Me₅)Fe(PMe₃)₂H] with pentaborane(9) gives predominantly [(η⁵-C₅Me₅)-nido-2-FeB₅H₁₀] (7) and [(η⁵-C₅Me₅)(PMe₃)-arachno-2-FeB₃H₈] (8). Reaction of [(η⁵-C₅H₅)Fe(PMe₃)₂H] with 2 equiv. of BH₃ · thf gives low yields of ferrocene and compound 3. Compound 7 thermally isomerises to the apical isomer [(η⁵-C₅H₅)-nido-2-FeB₅H₁₀] (9) in low yield. Compounds 1 and 7 deprotonate cleanly in the presence of KH at the unique B-H-B bridge to give [(η⁵-C₅H₅)-nido-2-FeB₅H₉⁻][K⁺] (10) and [(η⁵-C₅Me₅)-nido-2-FeB₅H₉⁻][K⁺] (11) respectively, whilst 6 deprotonates more slowly at one of two equivalent B-H-B bridges to give the fluxional anion [(η⁵-C₅H₅)-nido-2-FeB₅H₇(PMe₃)⁻] (12).     

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 .     

Transients from a mixture of [(R(O)Sn)2C(CH3)2]2 and (RCl2Sn)2C(CH3)2 [R = (SiMe3)2CH]: an identification in situ by 1D 119Sn and 2D 1H?119Sn HMQC NMR spectroscopy and electrospray mass spectrometry

The reaction of the 2,2‐bis(organodichlorostannyl)propane [(Me₃Si)₂CH(Cl₂)Sn]₂CMe₂ (A) with the corresponding organotin oxide {[(Me₃Si)₂CH(O)Sn]₂CMe₂}₂ (B) does not provide the corresponding normally expected tetraorganodistannoxane {[(Me₃Si)₂CH(Cl)SnCMe₂Sn(Cl)CH(SiMe₃)₂]O}_n but a complex reaction mixture. One major product, namely the 2,4,6,8‐tetraorgano‐2,6‐dichloro‐1,5,9‐trioxa‐2,4,6,8‐tetrastannabicyclo[3.3.1]nonane derivative [(Me₃Si)₂CHSnCMe₂Sn(Cl)CH(SiMe₃)₂]₂O₃ (C) was identified in situ by 2D ¹H? ¹¹⁹Sn and ¹H? ¹³C heteronuclear multiple quantum coherence and heteronuclear multiple bond correlation NMR spectroscopy as well as electrospray mass spectrometry. Compound C is proposed to be in equilibrium with an ionic species C′, the cation of which has an adamantane‐type structure. Copyright © 2003 John Wiley & Sons, Ltd.     

A Cyclic (Alkyl)(boryl)germylene Derived from a Cyclic (Alkyl)(amino)germylene

A cyclic (alkyl)(amino)germylene undergoes a ring expansion reaction with dibromomesitylborane (MesBBr₂) to afford a six‐membered dibromogermane derivative. In the presence of Lewis bases (PMe₃ or ^MeNHC), reduction of the latter with two equivalents of potassium graphite (KC₈) gives rise to cyclic (alkyl)(boryl)germylene–Lewis base adducts. Upon heating, the germylene—PMe₃ adduct reacts with H₂ to yield a germane, probably via a base‐free germylene featuring a small HOMO–LUMO gap.     

A Copper(I)–Arene Complex With an Unsupported η6 Interaction

Addition of PR₃ (R=Ph or OPh) to [Cu(η²‐Me₆C₆)₂][PF₆] results in the formation of [(η⁶‐Me₆C₆)Cu(PR₃)][PF₆], the first copper–arene complexes to feature an unsupported η⁶ arene interaction. A DFT analysis reveals that the preference for the η⁶ binding mode is enforced by the steric clash between the methyl groups of the arene ligand and the phenyl rings of the phosphine co‐ligand.     

Dimeric Structure of [(η2‐NO3)2(tpy)Bi(μ‐OH)2Bi(tpy)(η2‐NO3)2]

The synthesis and single crystal X‐ray structure determination are reported for the 2,2′ : 6′,2″‐terpyridine (= tpy) adduct of bismuth(III) nitrate. The hydroxide‐bridged dimer [(η²‐NO₃)₂(tpy)Bi(μ‐OH)₂Bi(tpy)(η²‐NO₃)₂] with nine‐coordinate geometry about Bi was the only isolable product from all crystallization attempts in varying ratios of Bi(NO₃) : terpy.; [(η²‐NO₃)₂(tpy)Bi(μ‐OH)₂Bi(tpy) · (η²‐NO₃)₂] is triclinic, P 1, a = 7.941(8), b = 10.732(9), c = 11.235(9) Å; α = 63.05(1), β = 85.01(1), γ = 79.26(1)°, Z = 1, dimer, R = 0.058 for N₀ = 2319.     

Trapping a Silicon(I) Radical with Carbenes: A Cationic cAAC–Silicon(I) Radical and an NHC–Parent‐Silyliumylidene Cation

The trapping of a silicon(I) radical with N‐heterocyclic carbenes is described. The reaction of the cyclic (alkyl)(amino) carbene [cAAC_Me] (cAAC_Me=:C(CMe₂)₂(CH₂)NAr, Ar=2,6‐i Pr₂C₆H₃) with H₂SiI₂ in a 3:1 molar ratio in DME afforded a mixture of the separated ion pair [(cAAC_Me)₂Si:^.]⁺I⁻ ( 1 ), which features a cationic cAAC–silicon(I) radical, and [cAAC_Me−H]⁺I⁻. In addition, the reaction of the NHC–iodosilicon(I) dimer [I_Ar(I)Si:]₂ (I_Ar=:C{N(Ar)CH}₂) with 4 equiv of I_Me (:C{N(Me)CMe}₂), which proceeded through the formation of a silicon(I) radical intermediate, afforded [(I_Me)₂SiH]⁺I⁻ ( 2 ) comprising the first NHC–parent‐silyliumylidene cation. Its further reaction with fluorobenzene afforded the C_Ar−H bond activation product [1‐F‐2‐I_Me‐C₆H₄]⁺I⁻ ( 3 ). The isolation of 2 and 3 confirmed the reaction mechanism for the formation of 1 . Compounds 1 – 3 were analyzed by EPR and NMR spectroscopy, DFT calculations, and X‐ray crystallography.     

[μ‐(Me3SiCH2Sb)5–Sb1,Sb3–{W(CO)5}2] und [{(Me3Si)2CHSb}3Fe(CO)4] – zwei cyclische Komplexe mit Antimon‐Liganden

Syntheses and Crystal Structures of [μ‐(Me₃SiCH₂Sb)₅–Sb¹,Sb³–{W(CO)₅}₂] and [{(Me₃Si)₂CHSb}₃Fe(CO)₄] – Two Cyclic Complexes with Antimony Ligands cyclo‐(Me₃SiCH₂Sb)₅ reacts with [(THF)W(CO)₅] (THF = tetrahydrofuran) to form cyclo‐[μ‐(Me₃SiCH₂Sb)₅–Sb¹,Sb³–{W(CO)₅}₂] ( 1 ). The heterocycle cyclo‐ [{(Me₃Si)₂CHSb}₃Fe(CO)₄] ( 2 ) is formed by an insertion reaction of cyclo‐[(Me₃Si)₂CHSb]₃ and [Fe₂(CO)₉]. The crystal structures of 1 and 2 are reported.     

Komplexchemie P‐reicher Phosphane und Silylphosphane. XXII. Die Bildung von [η2‐{tBu–P=P–SiMe3}Pt(PR3)2]aus (Me3Si)tBuP–P=P(Me)tBu2 und [η2‐{C2H4}Pt(PR3)2]

Coordination Chemistry of P‐rich Phosphanes and Silylphosphanes. XXII. The Formation of [η²‐{^tBu–P=P–SiMe₃}Pt(PR₃)₂] from (Me₃Si)^tBuP–P=P(Me)^tBu₂ and [η²‐{C₂H₄}Pt(PR₃)₂] (Me₃Si)^tBuP–P = P(Me)^tBu₂ reacts with [η²‐{C₂H₄}Pt(PR₃)₂] yielding [η²‐{^tBu–P=P–SiMe₃}Pt(PR₃)₂]. However, there is no indication for an isomer which would be the analogue to the well known [η²‐{^tBu₂P–P}Pt(PPh₃)₂]. The syntheses and NMR data of [η²‐{^tBu–P=P–SiMe₃}Pt(PPh₃)₂] and [η²‐{^tBu–P=P–SiMe₃}Pt(PMe₃)₂] as well as the results of the single crystal structure determination of [η²‐{^tBu–P=P–SiMe₃}Pt(PPh₃)₂] are reported.