Organoborierung von alkinylstannanen : V. Zur reaktion von dialkyldi-1-propinylstannanen mit trialkylboranen

Treatment of R′₂Sn(CCCH₃)₂ (R′ = CH₃, C₂H₅) with BR₃ (R = CH₃, C₂H₅, i-C₃H₇) gives 1-bora-4stannacyclohexadienes and 2,5-bis(dialkylboryl)-1-stannacyclopent-3-enes. The formation of the heterocycles depends in a complex manner upon the ratio of the starting compounds, upon the nature of groups R and R′ and also upon the solvent. The proposed structures are discussed on the basis of ¹H, ¹¹B, ¹³C and ¹¹⁹Sn NMR data.     

Metallorganische verbindungen des 1,2-diethinylbenzols vom typ o-C6H4(CCMR3)2 (M = Si,Ge, Pb)

The preparation of the compounds o-C₆H₄(CCMR₃)₂ (M = Si, Ge, Pb; R = CH₃; M = Pb; R = C₆H₅) is described. Their properties are compared with those of o-C₆H₄(CCSnR₃)₂ (R = CH₃, C₆H₅) and those of their p-isomers. The structures and bonding conditions proposed for these molecules are supported by dipole measurements, mass spectroscopy, IR, Raman, ¹H NMR and ¹³C NMR data.     

A multinuclear NMR spectroscopy study of alkoxysilanes

¹⁷O, ²⁹Si, and ¹³C NMR spectra of more than 100 mono-, di-, tri- and tetra-alkoxysilanes R_4−nSi(OR′)_n; R = C_nH_2n+1, Ph, CH₂Cl, CH₂Br; R′ = C_nH_2n+1, CH₂Ph, CH₂CH₂Cl, CH₂CHCH₂, CH₂CCH, CH₂CF₃. (CH₂)₃Cl, (CH₂)₃CN have been studied.Linear relationships between the chemical shifts of ¹⁷O, ²⁹Si, ¹³C in alkoxysilanes and the inductive and steric constants of substituents R and R′ were observed. Different transmission of electronic effects along the SiO bond in various directions was revealed by means of ¹³C, ²⁹Si, ¹⁷O NMR spectroscopy and correlation analysis. The results are discussed in terms of (pd)_π-bonding between the oxygen and silicon atoms in compounds containing an SiO bond.     

Reaction of [Fe4(μ3-CCH3)(CO)12]− with alkynes: Ethylidyne-alkyne coupling on a tetranuclear iron cluster anion

The [Fe₄(μ₄-η³-C(CH₃)C(R)C(R′)(μ-CO)₂(CO)₉]⁻ cluster anions have been obtained by the reaction of the Fe₄(μ₃-CCH₃)(CO)₁₂⁻ anion with RCCR alkynes in boiling 3-pentanone. In the cases in which R = R′ = C₆H₅ or CH₃, and R = H, R′ = C₆H₅ or t-Bu, only one isomer has been detected. In the case in which R = CH₃, and R′ = C₆H₅, two isomers with the C(CH₃)C(C₆H₅)C(CH₃) and C(CH₃)C(CH₃)C(C₆H₅) fragments have been identified.     

Silicium-stickstoff-fluorverbidungen: V. Darstellung neuer silylaminofluorsilane

Compounds of the composition RR′SiFNR″Si(CH₃)₃ (R = H, F, CH₃, C₂H₅, C₃H₇, C₂H₃, C₆H₅, C(CH₃)₃; R = F, CH₃, C₆H₅; R″ = CH₃, C(CH₃)₃, Si(CH₃)₃) are obtained by the reaction of silicontetrafluoride or organo-substituted silicon-fluorides with the lithium salts of alkylsilylamines in a molar ratio of $\text{1}\text{1}$. The disubstituted compounds RSiF(NR′Si(CH₃)₃)₂ (R = H, F, CH₃, C₂H₃, C₆H₅; R′ = CH₃, C(CH₃)₃) result when the reactants are in a $\text{1}\text{2}$ molar-ratio. Likewise the unsymmetrical siliconfluorsilylamines of the formulae F₂Si(NRSi(CH₃)₃) (NR′Si(CH₃)₃) (R = CH₃, R′ = C(CH₃)₃), as well as the trisubstituted compounds FSi(NCH₃Si(CH₃)₃)₃ and FSi(NCH₃Si(CH₃)₃)₂(N(Si(CH₃)₃)₂) were made. By reacting phenyltrifluorsilane with dialkylamines ($\text{1}\text{2}$) C₆H₅SiF₂NR₂(R = CH₃, C₂H₅) was obtained. The IR-, mass-, ¹H and ¹⁹F NMR spectra of the above-mentioned compounds are reported.     

Darstellung neuer Alkylaminofluorsilane

Preparation of New Alkylaminofluorosilanes Aminofluorosilanes of the composition RSiF₂NR′R″ (R = H, CH₃, C₂H₃, C₆H₅; R′ = Si(CH₃)₃; R″ = C(CH₃)₃; R′ = R″ = i-C₃H₇), as well as C₆H₅SiF₂N[C(CH₃)₂CH₂]₂CH₂ are obtained by the reaction of fluorosilanes with the lithium salts of the corresponding amines in a molar ratio 1:1. The further reaction of these compounds with the lithium salts of alkylamines and anilin leads to the formation of the diaminofluorosilanes RSiFNR′R″NHR? (R? = C(CH₃)₃, i-C₃H₇, C₆H₅). The ¹H, ¹⁹F, ²⁹Si n.m.r. and mass spectra of the above mentioned compounds are reported.     

13C- und 199Sn-NMR untersuchungen an alkinylstannanen

Chemical shifts δ(¹³C), δ(¹¹⁹Sn) and coupling constants J(¹¹⁹Sn¹³C) for alkynylstannanes of the type R_4-nSn(CCR′)_n (n = 1–4) are reported. The values of ¹J(¹¹⁹Sn¹³C) and ²J(¹¹⁹SnC¹³C) depend upon the nature of the substituent R′. ¹J(¹¹⁹Sn¹³C) in Sn(CCCH₃)₄ is 1168 Hz, much larger than a value predicted in the literature of ca. 700 Hz. The comparison of δ(¹¹⁹Sn) for (CH₃)₂Sn(CCR′)₂ and 1,1,4,4-tetramethyl-1-stannacyclohexadi-2,5-ene suggests that the δ(¹¹⁹Sn) of alkynylstannanes are determined only to a small extent by the diamagnetic anisotropic effect of the CC-triple bond.     

Reactions involving alkynes and tungsten-tungsten triple bonds supported by alkoxide ligands

W₂(OR)₆L_n compounds [R = Bu^t n = 0; R = Prⁱ or Np (Np = neopentyl), L = py (py = pyridine) or HNMe₂, n = 2] react with alkynes (R′C-CR′) under mild conditions (hexane solutions, room temperature or below) to yield a variety of products depending upon the nature of the alkoxide, the alkyne and the mole ratio of the reactants. The products include alkylidyne complexes L_n(RO)₃W CR′ (n = 1 or 0) (Schrock et al., Organometallics 1985, 4, 74), alkyne adducts, W₂(OR)₆(py)_n(μ-C₂R′₂), alkylidyne-capped tritungsten complexes, W₃(μ₃-CR′)(OR)₉, and W₂(OR)₆(L)(μ-C₄R′₄) or W₂(OR)₆(μ-C₄R′₄) (μ²-C₂R′₂) compounds. Evidence for equilibria involving alkyne adducts and alkylidyne species is found for certain combinations of R and R′. (1) The alkylidyne complexes (Bu^tO)₃ WCMe and (py)₂(Pr_iO)₃ W CNMe₂ react with CO (1 atm 22°C, in hexane) to yield alkyne adducts W₂(OBu^t)₆(μ-C₂Me₂)(CO) and W₂[(OPrⁱ)₆(CO)₂(η²-C₂(NMe₂)₂], respectively. (2) The alkylidyne complexes [Pr_iO)₂(HNMe₂)(R′C)W(μ-OPr_i)]₂ react with alkynes R′CCR′ (> 2 equiv, hexane, 22°C) to give W₂(OPr_i)₆(μ-C₄R′₄)(η²-C₂R′₂) compound (R′ = Me or Et). (3) The alkyne adducts W₂(ONp)₆(py)_n(μ-C₂R′₂) (R′ = Et or Ph, n = 1; R′ = Me, n = 2) react with W₂(ONp)₆(py)₂ in a 1:2 mole ratio at 22°C in hexane to yield W₃(μ₃-CR′)(ONp)(₉ compounds. In related reactions involving 1,2-bishydrocarbyl-tetraalkoxides, W₂(CH₂R″)₂(OR)₄, and alkynes (R′CCR′) (2 equiv), alkyne adducts of formula W₂(CH₂R″)₂(η²-C₂R′₂)₂(OPrⁱ)₄ and W₂(CH₃)₂(μ-C₂R′₂)(OBu^t)₄(py), alkylidyne-bridged complexes HW₂(μ-CR″)(μ-C₄R′₄)(OPr_i)₄ and products of WW and CC metathesis have been isolated for various combinations of R, R′ and R″.     

Unterschiedliche Cyclisierungsmechanismen von Aminofluorsilanen

Different Mechanisms of the Cyclisation of Aminofluorosilanes The reaction of aminofluorosilanes of the type RR′SiFNHR″ (R = H, F, CH₃, C₂H₃, C₆H₅, C(CH₃)₃; R′ = C(CH₃)₃, NiC₃H₇Si(CH₃)₃, NC(CH₃)₃Si(CH₃)₃, N[Si(CH₃)₃]₂; R″ = iC₃H₇, C(CH₃)₃, C₆H₅) with butyllithium depends on the steric influence of the ligands. With increasing size of the ligands the reaction takes its pathway from the substitution under LiF elimination via dimerisation with additional elimination of butan to the C? H cleavage and cyclisation via a methylen group. A further increase of the size of the substituted groups leads through the intermediate formation of a silicenium-ylid to ring closure reactions. These occure by migration of a methanid ion leading to intermolecular nucleophilic substitution. The isolated acyclic and heterocyclic compounds are described and the mass and ¹H-n.m.r. spectra are reported.     

Composés propargyliques et alléniques du Si,Ge, Sn chiraux possédant en α un carbone asymétrique mise en évidence des diastéréoisomères

The propargylic R¹R²R³MCH(CH₃)CCH and allenic R¹R²R³MCHCCHCH₃ compounds (M = Si, Ge, Sn) with two neighbouring asymmetric centres exist in two diastereotopic erythro and threo forms observable in NMR.     

X-ray analysis of 1,3-dioxa-6-aza-2-silacyclooctane derivatives

X-ray analysis has been conducted on four dioxaazasilacyclooctanes R₂Si(OCH₂CH₂)₂NR′ with R = C₆H₅, R′ = CH₃ (IV); R = C₆H₅, R′ = (CH₃)₃C (V); R = CH₃, R′ = C₆H₅ (VI) and R = R′ = C₆H₅ (VII). The interatomic distances SiN measured for these compounds had the values: 2.68 (IV), 3.16 (V), 3.19 (VI) and 3.08 Å (VII), indicating weak nitrogen—silicon interaction and a virtual lack of coordinate Si ← N bonding. The data of other authors and our own evidence suggest that the Si ← N interaction in these compounds is strongly influenced by the electronic effects of Si- and N-substituents and, in particular, by the steric effects of the latter.     

Preparation de β-cetonitriles via l'acylation du cyanacetate de trimethylsilyle par les anhydrides mixtes.

β-ketonitriles R¹COCH₂CN and R¹COCH(R²)CN are respectively prepared from (CH₃)₃SiOCOCHLiCN or R²CHLiCN by acylation reaction with mixed anhydrides RCOOCO₂Et.     

Radical ions : XXVII. Radical ions of tetrakis(trimethylsilyl)butatriene

One-electron oxidation and one-electron reduction of the electron-rich acetylene derivative, hexakis(trimethylsilyl)-2-butyne [H₃C₃)₃Si]₃CCCC[Si(CH₃)₃]₃, unexpectedly produce the persistent radical cation and radical anion of the hitherto unknown neutral compound, tetrakis(trimethylsilyl)butatriene (R₃Si)₂CCCC(SiR₃)₂. The radical anion can also be generated from the corresponding diacetylene, bis(trimethylsilyl)-1,3-butadiyne R₃SiCCCCSiR₃ and potassium metal, obviously via disproportionation. Photoelectron and electron spin resonance spectroscopic data permit the detection and characterization of the individual species. The stability of both the radical anion and the radical cation of the same molecule can be rationalized by the unique combination of the twofold butatriene π-system with 4 R₃Si substituents, which can act either as electron donors or electron acceptors and thus stabilize the ground state of either the cation or the anion.     

Multinuclear NMR spectra of (CH3)3SnCH2M(CH3)3 (MSn,Ge, Si,C) and some halogenated derivatives

Chemical shift and scalar coupling constant information has been obtained from the ¹H, ¹³C, ²⁹Si and ¹¹⁹Sn NMR spectra of a series of compounds (CH₃)₃SnCH₂M(CH₃)₃, where M = Sn, Ge, Si or C and with one or two CH₃? (Sn) groups replaced by Cl, Br or I. The (CH₃)₃M and (CH₃)₃MCH₂ groups appear to have opposite substituent effects on chemical shifts.     

Trivalent-pentavalente Phosphorverbindungen/Phosphazene. IV. Darstellung und Eigenschaften neuer N-silylierter Diphosphazene

Trivalent-Pentavalent Phosphorus Compounds/Phosphazenes. IV. Preparation and Properties of New N-silylated Diphosphazenes Phosphazeno-phosphanes, R₃P = N? P(OR′) ₂ (R = CH₃, N(CH₃)₂; R′ = CH₂? CF₃) react with trimethylazido silane to give N-silylated diphosphazenes, R₃P = N? P(OR′)₂ = N? Si(CH₃)₃ compounds decompose by atmospherical air to phosphazeno-phosphonamidic acid esters, R₃ P?N? P(O)(O? CH₂? CF₃)(NH₂). Thermolysis of diphosphazene R₃P = N? P(OR′) ₂ = N? Si(CH₃)₃ (R = CH₃, R′ = CH₂? CF₃) produces phosphazenyl-phosphazenes [N?P(N?P(CH₃)₃)OR′] _n. The compounds are characterized by elementary analysis, IR-, ¹H_-, ²⁹Si-, ³¹P-n.m.r., and mass spectroscopy.     

Allylstannation: VII. Preparation of carboxylic acid 1-alkene-4-yl and 1-alkyne-4-yl esters by transalkoxylation of 4-n-dibutylchlorostannoxy-1-alkenes and 4-n-dibutylchlorostannoxy-1-alkynes with acyl chlorides

Carboxylic acid 1-alkene-4-yl and 1-alkyne-4-yl, esters (RCH(CH₂CHCH₂)OCOR′ ad RCH(CH₂CCH)OCOR′, R = R′ or R ≠ R′ = alkyl or alkenyl group) can be readily prepared in high yields by transalkoxylation reactions between 4-n-dibutylchlorostannoxy-1-alkenes or 4-n-dibutylchlorostannoxy-1-alkynes with acyl chlorides. This represents a general route for preparation of esters containing allyl or propargyl groups.     

Synthesis,characterization and antimicrobial activity of triorganotin(IV) derivatives of some bioactive Schiff base ligands

Triorganotin(IV) complexes of the type Me₃Sn[OC(R¹):CH(CH₃)C:NR²OH] and Ph₃Sn[OC(R′):CH(CH₃)C:NR″OH] (R′ = ─CH₃, ─C₆H₅; R″ = ─(CH₂)₂─, ─(CH₂)₃─) have been synthesized by the reactions of trimethyl/phenyltin(IV) chloride with the sodium salt of corresponding Schiff base ligands in unimolar ratio in refluxing tetrahydrofuran. All these compounds have been characterized using elemental analyses and their probable structures have been proposed on the basis of infrared, ¹H NMR, ¹³C NMR, ¹¹⁹Sn NMR and mass spectroscopic studies. In the trimethyltin(IV) derivatives the central tin atom is tetracoordinated, whereas in the analogous triphenyltin(IV)derivatives the central tin atom is pentacoordinated. All these ligands, metal precursors and corresponding triorganotin(IV) complexes have been screened for antimicrobial activities. A comparison of activities of the ligands and their corresponding triorganotin(IV) derivatives has been made. Attempts have also been made to relate the activity to the structure of these compounds.     

ÜBER EINIGE REAKTIONEN DER DIALKYLBENZYLPHOSPHINIMIDE

Abstract

Dialkylbenzylphosphine imides C₆H₅CH₂–PRR′[dbnd]N″ (R, R′ = CH₃, C₂H₅; R″ = H, CH₃, Si(CH₃)₃ react with aliphatic and aromatic aldehydes in benzene solution on heating to 80°C directly and in high yields according to a Horner-Wittig-reaction with formation of an olefine whereas ketones like benzophenone and acetophenone only perform an O/NR″ exchange (R″ = H).

Dialkylbenzylphosphinimide C₆H₅CH₂–PRR′[dbnd]N″ mit R, R′ = CH₃, C₂H₅ und R″ = H, CH₃, Si(CH₃)₃ reagieren mit aliphatischen und aromatischen Aldehyden in benzolischer Lösung beim Erwärmen auf 80°C direkt und mit hohen Ausbeuten im Sinne einer Horner-Wittig-Reaktion unter Olefinbildung, während sich mit Ketonen wie Benzophenon oder Acetophenon nur ein O/NR″-Austausch (R″ = H) vollzieht.     

Convenient synthesis of (triphenyl)germyl and (triphenydstannyl substituted allenes

Allenyl-germanes and -stannanes, Ph₃MC(R)CCR′R″ (M = Ge, Sn) can be obtained, generally in excellent yield, through alkylcopper(I)-induced 1,3-substitution of the propargylic chlorides Ph₃MCCCR′R″Cl. In the tin series, however transmetallation is the main process when MeCu, H₂CCHCu or PhCu are used. The allenyl compounds in which R is (trimethylsilyl)ethynyl or 4,4-dimethyl-1,2-pentadienyl can be obtained by using the organozinc compounds instead of the copper(I) compound and using tetrakis(triphenylphosphine)palladium as catalyst.     

A new pyridine synthesis from conjugated acetylenes and substituted methylamines

Conjugated acetylenes RCCCCR react with substituted methylamines R′CH₂NH₂ at 145–180° to produce corresponding pyridines and/or the corresponding pyridine N-oxides when the reaction is carried out in the presence of air or dimethylsulfoxide. For R = Ph and R′ = cyclo C₆H₁₁, n C₈H₁₇ and PhCH₂, 2,5-diphenylpyridine was also formed, in the last case as the dominant product. For R = PhOCH₂ and R′ = Ph, equivalent amounts of 2-phenyl-3-methyl-6-phenoxymethylpyridine and 2-phenyl-3-phenoxymethyl-6-methylpyridine were formed together with phenol. These results indicate formation of dihydropyridines and their oxidation via radical intermediates.