Synthese neuer Aminofluorsilane,sowie Alkoxylierung von Bis (trimethylsilyl)-amino-fluorsilanen

The reaction of aminofluorsilanes of the type (R=H,F) (Me ₃Si)₂N?SiF₂R with two moles of ammonia, or of a mono- or dialkylamine, yields the corresponding amino-compounds, e.g. (Me ₃Si)₂N?Si(F)R?NH₂, (Me ₃Si)₂N?Si(F)R?NHR′ and (Me ₃Si)₂N?Si(F)R?NR₂′ (R′=Me, Et). Analogous products are obtained by reaction of the aminofluorosilanes with lithium salts of amines with bulky organic substituents in a 1 : 1 molar ratio. Alkoxy- and aryloxyaminofluorosilanes are prepared by the reaction of sodium alcoholates and sodium phenolate with (Me ₃Si)₂N?Si(F₂)R (R=H, C₂H₃, C₂H₅, C₆H₅). The i.r.-, mass-,¹H- and¹⁹F-NMR spectra of the above compounds are reported.     

Synthesis and Diels-Alder Reactivity of 2,3,5,6-Tetramethylidenenorbornane

Pd-catalyzed double carbomethoxylation of the Diels-Alder adduct of cyclo-pentadiene and maleic anhydride yielded the methyl norbornane-2,3-endo-5, 6-exo-tetracarboxylate ( 4 ) which was transformed in three steps into 2,3,5,6-tetramethyl-idenenorbornane ( 1 ). The cycloaddition of tetracyanoethylene (TCNE) to 1 giving the corresponding monoadduct 7 was 364 times faster (toluene, 25°) than the addition of TCNE to 7 yielding the bis-adduct 9 . Similar reactivity trends were observed for the additions of TCNE to the less reactive 2,3,5,6-tetramethylidene-7-oxanorbornane ( 2 ). The following second order rate constants (toluene, 25°) and activation parameters were obtained for: 1 + TCNE → 7 : k₁ = (255 + 5) 10^?4 mol^?1 · s^?1, ΔH≠ = (12.2 ± 0.5) kcal/mol, ΔS≠ = (?24.8 ± 1.6) eu.; 7 + TCNE → 9 , k₂ = (0.7 ± 0.02) 10^?4 mol^?1 · s^?1, ΔH≠ = (14.1 ± 1.0) kcal/mol, ΔS≠ = ( ?30 ± 3.5) eu.; 2 + TCNE → 8 : k₁ = (1.5 ± 0.03) 10^?4 mol^?1 · s^?1, ΔH≠ = (14.8 ± 0.7) kcal/mol, ΔS≠ = (?26.4 ± 2.3) eu.; 8 + TCNE → 10 ; k₂ = (0.004 ± 0.0002) 10^?4 mol^?1 · s^?1, ΔH≠ = (17 ± 1.5) kcal/mol, ΔS≠ = (?30 ± 4) eu. The possible origins of the relatively large rate ratios k₁/k₂ are discussed briefly.     

Organocobalt cluster complexes XXIX. Novel silicon compounds containing the nonacarbonyl tricobaltcarbon substituent

The reaction of bromomethylidynetricobalt nonacarbonyl or, more effectively, of methylidynetricobalt nonacarbonyl with diverse silicon hydrides (R₃SiH, Ph₃SiH, Me₂(EtO)SiH, R_nCl_3-nSiH (n = 02), etc. results in formation of silylmethylidynetricobalt nonacarbonyl complexes. Silicon-functional interconversions such as SiCl → SiOH, SiCl → SiOMe, SiOH → SiF, and SiOH → SiOSiMe₃, have provided still other substituted silylmethylidynetricobalt nonacarbonyl complexes, generally in high yield. The compounds Me(HO)₂SiCCO₃(CO)₉ and (HO)₃SiCCo₃(CO)₉ have been incorporated into methylsilicone polymers by H₂SO₄-induced reactions with cyclo-(Me₂SiO)₃.     

The kinetics and thermochemistry of S2F10 pyrolysis

Data on the kinetics of S₂F₁₀ pyrolysis, which gives SF₄ + SF₆, have been reinterpreted to give a value for the equilibrium constant of S₂F₁₀ ? SF₄ + SF₆. This, together with statistical estimates of the entropy and heat capacity of S₂F₁₀, can be used to give for this reaction values of ΔH = 19.7 ± 1.0 kcal/mole and ΔS = 47.6 ± 2 gibbs/mole. ΔH(S₂F₁₀) = –494 kcal/mole. A compatible mechanism is shown to be S₂F₁₀ ? 2SF₅ (fast); 2SF₅ ? SF₆ + SF₄ (slow) with step 2 rate-determining. The overall, best first order rate constant is proposed as k_meas = 10^{17.42–43.0/θ} sec^?1 = K₁k₂, where θ = 2.303RT in kcal/mole. Independent measurements of δH and S° for the SF₅ radical, permits the evaluation of the equilibrium constant K₁ = 10^{8.92–(27.1 ± 6)/θ} l./mole-sec and yields k₂ = 10^{8.50–15.9/θ} l./mole-sec. The observed homogeneous catalysis by NO and CHCl ? CHCl can be explained in terms of a direct abstraction of F from S₂F₁₀ : C + S₂F₁₀ → CF + S₂F₉, followed by S₂F₉ → SF₅ + SF₄ and SF₅ + CF ? SF₆ + C (C ? NO or C₂H₂Cl₂).     

Gas-phase solvation of Cl− with H2O,CH3OH,C2H5OH,i-C3H7OH,n-C3H7OH,and t-C4H9OH

The gas-phase clustering reactions Cl⁻ (ROH)n−1 + ROH ⇄ Cl⁻ (ROH)_n with n ⩽ 11 for ROH = H₂O, CH₃OH, C₂H₅OH, i-C₃H₇OH, n-C₃H₇OH, and t-C₄H₉OH were measured using a high-pressure mass spectrometer. It seems likely that for CH₃OH and C₂H₅OH, six ligands complete the shell structure and that ligands with n ⩾ 7 belong to the outer shell. The bond energies D(ROH---Cl⁻) increase in the order H₂O < CH₃OH < C₂H₅OH < i-C₃H₇OH < t-C₄H₉OH < n-C₃H₇OH. The observed strong bond of n-C₃H₇OH---Cl⁻ may be due to the fact that both the acidic hydrogen atoms in the −OH and terminal −CH₃ of n-C₃H₇OH interact with Cl⁻ with the most favorable configuration. For Cl⁻ switching reactions, Cl⁻ (H₂O)_n + (ROH)_n ⇄ Cl⁻ (ROH)_n + (H₂O)_n, the ΔG⁰_n values converge to the values of free energies of transfer of Cl⁻ from water to ROH solvent ( = ΔG⁰_n with n → ∞) with n ≈ 7. The observed convergence of ΔG⁰_n is due to compensation of changes in enthalpy and entropy, i.e. both ΔH⁰_n and TΔS⁰_n show increasing divergence from the values of enthalpies and entropies of transfer of Cl⁻ from water to ROH solvent, respectively, with n = 1 → 7. This is due to the stronger interactions of ROH with Cl⁻ than that of H₂O in the inner shell of Cl⁻ (ROH)_n at the expense of the less favorable entropy changes (less freedom of motion for ligands in the inner shell).     

Thermochemistry of the hydrates of k2CoCl4

A study of the dissociation pressure of crystalline K₂CoCl₄·2H₂O. The reactions can be summed up as K₂CoCl₄·nH₂O(c) = K₂CoCl₄·mH₂O(c)+(nm)H₂O (v). Below 50°C, n = 2 and 1, m = 1 and 0, above 50°C, n = 2 and m = 0. Below 50°C, the dihydrate is octahedral, the monohydrate and anhydrous compounds are tetrahedral. ΔH° and ΔS° are respectively 7.0 kcal and 14.2 e.u. for the loss of the first mole of water and 12.7 kcal and 32.0 e.u. for the loss of the last mole of water. Above 50°C, ΔH° and ΔS° are respectively 29.8 kcal and 77.6 e.u. for the loss of both waters. The changes in structure are discussed using the spectral and magnetic properties as indications for structural changes.     

CsCu4S3 und CsCu3S2: Sulfide mit tetraedrisch und linear koordiniertem Kupfer

Thermodynamics of the System Si? Cl? H By static and dynamic methods the equilibria 4SiHCl₃,g = 3SiHCl₄,g + Si,s + 2H₂,g (1) between 800 and 1140 K and SiCl₄,g + H₂,g = SiHCl₃,g + HCl,g (2) between 1170 and 1450 K were investigated. The expression for the temperature dependence of the equilibria were found to be lg Kp [Torr] = (5.688–1520/T) ± 0.32 (1) and lg Kp = (1.38/3250/T) ± 0.16 (2). The values measured for reaction pressures and equilibrium constants lead to the conclusion, that the difference of enthalpies of formation of SiCl₄ and SiHCl₃ found in literature is nessecarily to be corrected by 5–6 kcal/mole. With ΔH(SiCl₄,g) = ?157.1 kcal/mole the equilibrium measurements lead to the enthalpy of formation for SiHCl₃,g of ΔH(SiHCl₃,g) = ?118.2 kcal/mole.     

Darstellung und spektroskopische Eigenschaften von Alkoxyaminosilanen (RO)nMe3–nSiNHC6H4X

Preparation and Spectroscopic Properties of Alkoxyaminosilanes (RO)_nMe_3–nSiNHC₆H₄X By reaction of chlorosilanes with anilines and aminolysis of silylamines 22 new alkoxyaminosilanes of general formula (RO)_nMe_3-nSiNHC₆H₄X, n = 0, 1, 2, 3 have been prepared. Their IR und ¹H-NMR spectra were measured and the influence of variabel polarizability effects of the (RO)_nMe_3-nSi groups on the Hammett's correlations of Δv and δ of the N? H proton were discussed.     

Mechanism of the reaction of N-p-tosylsulphilimine and related compounds with thiophenolate ion

The reaction of alkyl aryl N-p-tosylsulphilimines with thiophenolate ion was found to afford quantitatively the sulphide that arises by an S_N2 like reaction on the carbon atom adjacent to the tri-valent sulphur atom. This reaction was also found to proceed smoothly with such compounds as sulphoxides and sulphones and sulphoxmanes. The kinetic study on the reaction between aryl methyl N-p-tosylsulphilimine with thiophenolate ion in DMF reveals that the reaction is of second order, namely, first order with respect to each thiophenolate ion and the sulphilimine. The enthalpy and entropy of activation for the reaction are ΔH^≠ = ?17· kcal/mol and ΔS^≠ = ?5·7 eu respectively. The effect of substituents in the reaction, p-XC₆H₄⁺(^?SO₂C₆H₄Y-p)CH₃ + p-ZC₆H₄SK is nicely correl with Hammett σ values giving ?_x = + 2·4, ?_y = + 1·2 and ?_z = ?1·8 respectively. Meanwhile, a marked steric retardation by a bulky alkyl group in alkyl phenyl N-p-tosylsulphilimine is observed. Furthermore, from the stereochemical study of the reaction using an optically active sec-octyl phenyl N-p-tosylsulphilimine with thiophenolate ion it is concluded that the reaction proceeds via a typical S_N2 process on α-carbon atom attached to the tri-valent sulphur atom.     

The Decomposition of Aqueous Dithionite and its reactions with polythionates SnO2−6 (n = 3–5) studied by ion-pair chromatography

Aqueous dithionite decomposes at 20°C and pH values not far from 7.0 to give thiosulfate and sulfite from which trithionate may form. Addition of thiosulfate accelerates this reaction only at pH < 6. The pH dependence is explained by formation of HS₂O₃^? ions which are reduced by dithionite to HS^? and SO^2?₃. Sulfide destroys dithionite by nucleophilic cleavage, probably with formation of sulfoxylate and thiosulfite ions. The polythionates S_nO^2?₆ (n = 3–5) are reduced by dithionite at pH = 7.0 and 20°C according to S_nO^2?₆ + S₂O^2?₄ + 2 H₂O→S₂O₃^2? + S_n–3SO₃^2? + 4H¹ + 2SO₃^2? The reaction rate rapidly increases with the number n of sulfur atoms. In secondary reactions sulfite attacks S_nO₆^2? ions with thiosulfate formation.     

Kinetics and mechanism of some fast anation reactions of a series of substituted dien complexes of palladium(II). Temperature and pressure dependencies in weakly acidic aqueous solution1

Anation reactions of the type [Pd(L)(H₂O)]²⁺ + X^? »[Pd(L)X]⁺ + H₂O with L = 1, 4, 7-Et₃dien, 1, 1, 7, 7-Me₄dien and 1, 1, 4, 7, 7-Me₅dien and X^? = Cl^?, Br^?, I^? and N₃? have been studied kinetically as a function of [X?], temperature and pressure (up to 1 kbar). Second-order anation rate constants decrease with an increase in the size of L, and are accompanied by an increase in ΔH≠. For a given L the sequence Cl^? < Br^? < I^? < N₃^? holds, and the values of ΔS≠ and ΔV≠ are consistent with an associative mechanism. The results are discussed with reference to similar anation reactions previously investigated.     

13C NMR spectra of metal σ-cyclopentadienyls

Proton decoupled ¹³C NMR spectra have been measured for the cyclopentadienyl compounds C₅H₅Si(CH₃)_nCl_3?n(n = 1, 2, 3), C₅H₅Ge(CH₃)₃, CH₃C₅H₄Ge(CH₃)₃, C₅H₅Sn(CH₃)₃, σ-C₅H₅Fe(CO)₂-π-C₅H₅ and C₅H₅HgCH₃. A fast metallotropic rearrangement occurring in the compounds causes the spectra to be temperature dependent for the Si, Ge, Sn and Fe derivatives. For the derivatives of silicon or germanium, the olefinic signals are unsymmetrically broadened by the 1,2-shift at lower migration rates. Line widths of the ring carbon signals have been measured to give an estimate for the activation parameters of the rearrangement in C₅H₅Ge(CH₃)₃ (E_a = 10·7 ± 0·9 kcal/mole, ΔG^? = 13·4 ± 0·9 kcal/mole) and C₅H₅Sn(CH₃)₃ (E_a = 6·8 ± 0·7 kcal/mole, ΔG^? = 7·1 ± 0·7 kcal/mole). At room temperature, the spectrum of C₅H₅HgCH₃ displays just one narrow signal responsible for the cyclopentadienyl ligand. The spectrum of CH₃C₅H₄Ge(CH₃)₃ at –30° demonstrates that two isomers containing methyl in the vinylic position are present, the ratio being ca. 2:1. The ¹³C spectra of the vinylic isomers have been analysed in the case of C₅H₅Si(CH₃)_nCl_3?n.     

Fourier transform NMR studies of organometallic compounds. II—synthesis and NMR spectroscopy of propenyl and isopropenyl derivatives of silicon and lead

Isomeric mixtures of compounds Me_nM(CH?CHMe)_4?n (M=Si, Pb; n=0?3) have been prepared and studied, as well as pure Me₃M(CMe?CH₂) and mixtures containing propenyl isopropenyl residues bonded to silicon and lead. ¹H, ¹³C, ²⁹Si and ²⁰⁷Pb NMR data are presented; as previously observed for the corresponding tin compounds, the ²⁹Si and ²⁰⁷Pb shifts for the Me₃MC₃H₅ isomers can be used to calculate the shifts expected for the other isomers; while for lead the agreement is good, calculated and observed values for silicon diverge with decreasing n due, at least in part, to steric factors.     

Complexation of neptunium(V) by salicylate,phthalate and citrate ligands in a pH 7.5 phosphate buffered system

Conditional stability constants, enthalpies and entropies of complexation at pH 7.5 and ionic strength 0.1 have been determined for neptunium(V) complexes of phosphate, salicylate, phthalate and citrate. Phosphate forms a complex with log β = 2.36 ± 0.42 at 25°C, ΔH°_c = ? 69.9 kJ/mole and ΔS°_c = ? 188 J/mole-K. At pH 7.5 salicylate does not form a complex with neptunium(V) due to the low charge density of the NpO₂⁺ ion and incomplete ionization of the salicylate ion. Phthalate forms a complex with log β = 3.43 ± 0.33 at 25°C, ΔH°_c = 33.5 kJ/mole and ΔS°_c = 182 J/mole-K. Citrate forms a complex with log β = 4.84 ± 0.72 at 25°C, ΔH°_c = 14.0 kJ/mole and ΔS°_c = 140 J/mole-K. In all cases, only 1:1 complexes were identified.     

Equilibrium cyclotrimerization of ether oxygen-substituted aliphatic aldehydes

This article describes the equilibrium cyclotrimerization of β-methoxypropionaldehyde (MPA), 4,7-dioxaoctanal (DOA), and n-octanal (OA) initiated by boron trifluoride etherate in toluene at a temperature range of ?10 to 25°C. The enthalpy and entropy changes corresponding to the conversion of 1 mole of the monomers to 1/3 mole of their cyclic trimers in toluene solution, at the initial monomer concentration of 1 mole/liter, were evaluated as follows: ΔH_ss = ?5.9 ± 0.3 kcal/mole and ΔS_ss = ?19.1 ± 1.3 cal/mole deg for the MPA system; ΔH_ss = ?7.4 ± 0.4 kcal/mole and ΔS_ss = ?24.1 ± 1.7 cal/mole deg for the DOA system; ΔH_ss = ?6.1 ± 0.4 kcal/mole and ΔS_ss = ?21.2 ± 1.5 cal/mole deg for the OA system. The comparison of these values with those in their polymerization indicates that the cyclotrimerization of aldehydes is thermodynamically of greater advantage than their polymerization. The effects of long and polar substituents are discussed from the view-point of the intermolecular interactions by the polar groups in monomers and their cyclic trimers.     

Synthesis and structure of chiral-at-metal complexes with the ligand (S)-2-[(Sp)-2-(diphenylphosphino)ferrocenyl]-4-isopropyloxazoline

Half-sandwich complexes of formula [(ηⁿ-ring)MClL]PF₆ [L = (S)-2-[(S_p)-2-(diphenylphosphino)ferrocenyl]-4-isopropyloxazoline; (ηⁿ-ring)M = (η⁵-C₅Me₅)Rh; (η⁵-C₅Me₅)Ir; (η⁶-p-MeC₆H₄iPr)Ru; (η⁶-p-MeC₆H₄iPr)Os] have been prepared and spectroscopically characterised. The molecular structures of the rhodium and iridium compounds have been determined by X-ray crystallography. The related solvate complexes [(η⁵-C₅Me₅)ML(Me₂CO)]²⁺ (M = Rh, Ir) are active catalysts for the Diels-Alder reaction between methacrolein and cyclopentadiene.     

Arene-rhodium(I) complexes with trimethyltetrafluorobenzobarrelene. Crystal structure of [Rh(Me3TFB)(1,4-C6H4Me2)]ClO4

The preparation of arene-rhodium(I) complexes of the general formula Rh(Me₃TFB)PhBPh₃ and [Rh(Me₃TFB)(arene)]ClO₄ (Me₃TFB = trimethyltetrafluorobenzobarrelene; arene = C₆H_6?nMe_n (n = 0, 1, 2, 3, 4 or 6); C₆H_6?nX_n (X = F, n = 2 or 6; X = Cl, n = 1 or 2) are described. For arenes of the type C₆H_6?nX_n the dissociation of the coordinated arene (studied by NMR spectroscopy in deuteroacetone) is complete, but for arenes of the type C₆H_6?nMe_n it decreases with increasing methyl substitution in the arene ligand.The crystal structure of [Rh(Me₃TFB)(1,4-C₆H₄Me₂)]ClO₄ has been determined by X-ray diffraction. The compound crystallizes in the Pbca space group, with lattice periodicities of 17.7393(4), 15.7816(3) and 16.0071(3) Å. δR-analysis, for the 3953 total recorded reflections, support the refinement carried out to a final R-value of 0.062. The bonding of the arene to the rhodium is η⁶, with the ring slightly puckered to give a distorted skew conformation.     

Light‐Induced Rearrangement of Thioether‐Substituted Phosphanide Ligands: Scope and Limitations of a Remarkable Isomerization

Treatment of the thioether‐substituted secondary phosphanes R²PH(C₆H₄‐2‐SR¹) [R²=(Me₃Si)₂CH, R¹=Me ( 1_PH ), iPr ( 2_PH ), Ph ( 3_PH ); R²=tBu, R¹=Me ( 4_PH ); R²=Ph, R¹=Me ( 5_PH )] with nBuLi yields the corresponding lithium phosphanides, which were isolated as their THF ( 1 – 5_Pa ) and tmeda ( 1 – 5_Pb ) adducts. Solid‐state structures were obtained for the adducts [R²P(C₆H₄‐2‐SR¹)]Li(L)_n [R²=(Me₃Si)₂CH, R¹=nPr, (L)_n=tmeda ( 2_Pb ); R²=(Me₃Si)₂CH, R¹=Ph, (L)_n=tmeda ( 3_Pb ); R²=Ph, R¹=Me, (L)_n=(THF)_1.33 ( 5_Pa ); R²=Ph, R¹=Me, (L)_n=([12]crown‐4)₂ ( 5_Pc )]. Treatment of 1_PH with either PhCH₂Na or PhCH₂K yields the heavier alkali metal complexes [{(Me₃Si)₂CH}P(C₆H₄‐2‐SMe)]M(THF)_n [M=Na ( 1_Pd ), K ( 1_Pe )]. With the exception of 2_Pa and 2_Pb , photolysis of these complexes with white light proceeds rapidly to give the thiolate species [R²P(R¹)(C₆H₄‐2‐S)]M(L)_n [M=Li, L=THF ( 1_Sa , 3_Sa – 5_Sa ); M=Li, L=tmeda ( 1_Sb , 3_Sb – 5_Sb ); M=Na, L=THF ( 1_Sd ); M=K, L=THF ( 1_Se )] as the sole products. The compounds 3_Sa and 4_Sa may be desolvated to give the cyclic oligomers [[{(Me₃Si)₂CH}P(Ph)(C₆H₄‐2‐S)]Li]₆ (( 3_S )₆) and [[tBuP(Me)(C₆H₄‐2‐S)]Li]₈ (( 4_S )₈), respectively. A mechanistic study reveals that the phosphanide–thiolate rearrangement proceeds by intramolecular nucleophilic attack of the phosphanide center at the carbon atom of the substituent at sulfur. For 2_Pa / 2_Pb , competing intramolecular β‐deprotonation of the n‐propyl substituent results in the elimination of propene and the formation of the phosphanide–thiolate dianion [{(Me₃Si)₂CH}P(C₆H₄‐2‐S)]^2?.     

Fragmentation of symmetrically substituted methylferrocenes under electron impact

Mass spectra of a series of individual methylferrocenes (Me_nC₅H_5?n)₂Fe (where n = 1–5) are reported. The manner of fragmentation of these compounds is discussed.     

Über Chalkogenolate. 179. Kupfer(I)-thioxanthate und Thioxanthatocuprate(I)

On Chalcogenolates. 179. Copper(I) Thioxanthates and Thioxanthatocuprates(I) Copper(I) thioxanthates Cu[S₂C? SR], where R = C₂H₅, ⁿC₄H₉, and CH₂? C₆H₅, have been prepared by two procedures and studied by means of diverse methods. They are soluble in ethanolic and acetonic solutions containing the corresponding [S₂C? SR]^? ions in excess to yield thioxanthatocuprates(I) [Cu_n(S₂C? SR)_n+1]^?. The compounds [(C₆H₅)₄P][Cu_n(S₂C? SC₂H₅)_n+1] with n = 1, 4, 6 have been isolated. The existence of [(C₆H₅)₄P][Cu₄(S₂C? SC₄H₉)₅] and [(C₆H₅)₄P][Cu₆(S₂C? SCH₂? C₆H₅)₇] has been ascertained.