Kinetic study of an epoxy system badge (n=0)/1, 2 dch modified with an epoxy reactive diluent

The curing reaction of an epoxy system consisting of a diglycidyl ether of bisphenol A (n=0) and 1, 2 diaminecyclohexane (DCH) with an epoxy reactive diluent vinylcyclohexane dioxide was studied by temperature modulated differential scanning calorimetry (TMDSC). The models proposed by Kamal and by Horie et al. were employed in the kinetic study. From these studies reaction orders, rate constants, and activation energies were determined. The technique of TMDSC allows to include in the kinetic study the effect of diffusion by means of the mobility factor, calculated from the curves of the complex heat capacity registered during the curing isothermal experiments. The results were compared to those obtained for the same system employing the reaction rate data. This revised version was published online in July 2006 with corrections to the Cover Date.     

Comparative Study of the Thermal Stability of the Epoxy Systems BADGE n=0/1, 2 DCH and BADGE n=0/1, 2 DCH/CaCO3

The thermal degradation of the epoxy systems diglycidyl ether of bisphenol A (BADGE n=0)/1, 2 diamine cyclohexane (DCH) and diglycidyl ether of bisphenol A (BADGE n=0)/1, 2 diaminecyclohexane (DCH) containing calcium carbonate filler immersed and not immersed in hydrochloric acid have been studied by thermogravimetric analysis in order to compare their decomposition processes and to determine the reaction mechanism of the degradation processes. The value of the activation energies, necessary for this study, were calculated using various integral and differential methods. Analysis of the results suggests that hydrochloric acid does not affect the decomposition of the epoxy network and that the reaction mechanisms produce sigmoidal-type curves for the systems not immersed in HCl and deceleration curves for the same systems immersed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Analysis of curing of diglycidyl ether of bisphenol A (BADGE n = 0) with 2‐adamantylethanamine

The epoxy resin diglycidyl ether of Bisphenol A (BADGE n = 0) has been cured with a new synthesized hardener (2‐adamantylethanamine) and the crosslinking reaction was characterized by DSC. Values of 413.3 J/g and 95°C have been obtained for the enthalpy of the reaction and the glass transition temperature, respectively. The experimental results obey Kamal's model over all conversion range of temperatures (70°C‐100°C). The activation energies of the mechanisms involved in the curing reaction have been determined for both the autocatalytic and the n‐order mechanism, the values being 63.3 and 29.8 kJ/mol, respectively. The value for T_g is 23°C higher than the one for (BADGE n = 0)/amantadine, while the activation energy for the n‐order mechanism is around 13 kJ/mol lower. This is consistent with a higher steric effect of the adamantyl group in the second hardener since it will hinder the opening the oxirane ring by the nitrogen atom of the amino group. As the polymerization reaction progress, this effect will disappear as the distance adamantyl‐oxirane increase when new oxirane groups react with the hydroxyl groups (autocatalyzed reaction). Consequently, by selecting the appropriate cross‐linking agent, it is possible to simultaneously increase T_g while reducing theactivation energy, two effects which may be desirable for some industrial applications of the material.     

Theoretical Investigations on Fluorine-Substituted Ethylene Dications C2HnF4-n 2+(n = 0–4)

The optimized geometries and energies of fluorine-substituted ethylene dications C₂H_nF_4-n ²⁺ (n = 0–4) have been investigated by means of ab initio methods. At the MP3/6-31G**//6-31G* + zero-point energy level of theory, the results predict that C₂F₄²⁺ and C₂HF₃²⁺ are planar, while C₂H₄²⁺, C₂H₃F²⁺ and 1,1—C₂H₂F₂²⁺ prefer a perpendicular geometry. For 1,2—C₂H₂F₂²⁺ an energy difference of only 0.3 kcal/mol is found between the (trans) planar and perpendicular structure. The stabilizations attributed to hyperconjugation, fluorine lone-pair donation, and (C? F) double-bond conjugation are discussed. A comparison is made for the C? C and C? F stretching frequencies determined at 6-31G*//6-31G* between the neutral and dicationic species. The theoretically determined ionization energies for the vertical process N⁺ → N²⁺ at the MP3/6-31G*//3-21G level are compared with experimental Q_min values.     

Substitution Kinetics of [Fe(PDT/PPDT)n(phen)m]2+ (n ≠ m; n,m = 1,2) with 2,2′‐Bipyridine, 1,10‐Phenanthroline,and 2,2′,6,2″‐Terpyridine

The triazines 3‐(2‐pyridyl)‐5,6‐diphenyl‐1,2,4‐triazine (PDT), 3‐(4‐phenyl‐2‐pyridyl)‐5,6‐diphenyl‐1,2,4‐triazine (PPDT), and 1,10‐phenanthroline (phen) were coordinated to the Fe²⁺ ion to form (1) , (2) , , (3) and (4) . The complexes were synthesized and characterized by mass spectroscopy and elemental analysis. The rate of substitution of these complexes by 2,2′‐bipyridine (bpy), 1,10‐phenanthroline (phen), and 2,2′,6,2″‐terpyridine (terpy) was studied in a sodium acetate–acetic acid buffers over the range 3.6–5.6 at 25, 35, and 45°C under pseudo–first‐order conditions. The reactions are first order with respect to the concentration of the complexes. The reaction rates increase with increasing [bpy/phen/terpy] and pH, whereas ionic strength has no influence on the rate of reaction. Plots of k _obs versus [bpy/phen/terpy] and 1/[H⁺] are linear with positive slopes and significant y‐intercepts. This indicates that the reactions proceed by both dissociative as well as associative pathways for which the associative pathway predominates the substitution kinetics. Observed temperature‐depended rate constants at the three temperatures at which substitution reactions were studied together with the protonation constants of the substituting ligands (phen, bpy, terpy) were used to evaluate the specific rate constants (k ₁ and k ₂) and thermodynamic parameters (E_a , ΔH ^#, ΔS ^#, and ΔG ^#). The reactivity order of the four complexes depends on the phenyl groups present on the triazine (PDT/PPDT) molecule. The π‐electrons on phenyl rings stabilizes the charge on the metal center by inductive donation of electrons toward the metal center resulting in a decrease in reactivity of the complex, and the order is 1 < 2 < 3 < 4 . The rate of substitution is also influenced by the basicity of the incoming ligand (bpy/phen/terpy), and it decreased in the order: phen > terpy > bpy. Higher rate constants, low E_a values_, and more negative entropy of activation (−ΔS ^#) values were observed for the associative path, revealing that substitution reactions at the octahedral iron(II) complexes by bpy, phen, and terpy occur predominantly by the associative mechanism. Density functional theory calculations support the interpretations.     

Mass spectrometric investigation of polyfluorinated C60. Evidence for the existence of C60F2n (n = 0–30)

Electron-capture negative ion chemical ionization (EC-NICI) and field desorption (FD) mass spectrometric techniques were utilized to examine polyfluorinated C₆₀. Two different samples from the same preparation, one prior to sublimation and the other sublimed material, were investigated. From the raw non-sublimed product in EC-NCI six series of ions corresponding to different numbers of attached oxygen atoms were obtained, which are represented by the formula [C₆₀F_2nO_m]^?, where n ranged from 0 to 30 and m from 0 to 5. The sublimed material in EC-NICI produced the same six series of ions with up to 48 fluorine atoms attached to C₆₀. The field desorption of the same sample produced similar results, but the signal-to-noise ratios of the spectra were low. Both samples, in the two different techniques examined, yielded C₆₀F₆₀ ions with only an even number of fluorine atoms attached. The present investigation, for the first time, provides direct experimental evidence for the existence of higher fluorinated C₆₀ up to C₆₀F₆₀ and multiple oxides of polyfluoro-C₆₀ with up to five oxygen atoms attached.     

Rate constants and conversion ratios for aqueous‐phase reactions of SO with CnF2n+1C(O)O− (n = 4–7) at 298 K

Kinetic data for aqueous‐phase reactions of sulfate anion radicals (SO) with perfluorocarboxylates (C_nF_2n+1C(O)O^?) are needed to evaluate removal and transformation processes of C_nF_2n+1C(O)O^? species in the environment, but rate constants for the reactions of SO with C_nF_2n+1C(O)O^? (k_n) have been reported only for short‐chain C_nF_2n+1C(O)O^? species (n = 1–3). Since C_nF_2n+1C(O)O^? reacted with SO to form C_mF_2m+1C(O)O^? (m < n), we determined relative rates k_n?1/k_n for the reactions of SO with C_nF_2n+1C(O)O^? (n = 4–7), along with conversion ratios for conversion of C_nF_2n+1C(O)O^? into C_n?1F_2n?1C(O)O^? (α_n) and into C_n?2F_2n?3C(O)O^? (β_n) at 298 K. SO was photolytically generated from S₂O by use of sunlamps (λ ≈ 310 nm). Even if k_n and k_n?1 change with increasing ionic strength, k_n?1/k_n can be determined when k_n?1/k_n and α_n remain almost constant during the reaction. The values of k_n/k₁ for n = 4–7 were nearly equal, and their average was 0.82 ± 0.04 (2σ). Conversion ratios of α_n and β_n were mostly independent of n for n = 4–7, and their averages were 0.77 ± 0.07 (2σ) and 0.13 ± 0.08, respectively. Branching ratios of reactions of a possible intermediate (C_nF_2n+1O^?), reaction of C_nF_2n+1O^? with H₂O, and fission of the C? C bond of C_nF_2n+1O^?, seemed to determine α_n and β_n. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 41: 735–747, 2009     

Curing reaction of unsaturated (epoxy) polyesters based on different aliphatic glycols

The influence of the structure of succinic or glutaric anhydride modified linear unsaturated (epoxy) polyesters on the course of the cure reaction with styrene initiated by benzoyl peroxide (BPO) or the mixture of benzoyl peroxide/tetrahydrophthalic anhydride (BPO/THPA) or benzoyl peroxide/maleic anhydride, as well as viscoelastic properties and thermal behavior of their styrene copolymers have been studied by DSC, DMA, and TGA analyses. Additionally, mechanical properties: flexural properties using three-point bending test and Brinell’s hardness for studied copolymers were evaluated. It was confirmed that the structure of used polyesters had a considerable influence on the course of the cure reaction with styrene, viscoelastic, thermal, and mechanical properties of prepared styrene copolymers. Generally, one or two asymmetrical peaks for the cure reaction of succinic or glutaric anhydride modified linear unsaturated epoxy polyesters with styrene were observed. They were connected with various cure reaction, e.g., copolymerization of carbon–carbon double bonds of polyester with styrene, thermal curing of epoxy groups, polyaddition reaction of epoxy to anhydride groups in dependence of used curing system. In addition, only one asymmetrical, exothermic peak attributed to the copolymerization process of succinic or glutaric anhydride modified linear unsaturated polyesters with styrene was visible. Moreover, the obtained styrene copolymers based on succinic or glutaric anhydride modified linear unsaturated epoxy polyesters were characterized by higher values of E_{20 ^°\textC}^￠ E_{{20\,^{\circ}{\text{C}}}}^{\prime} , T _g, E″, ν _e, E _mod, F _max, hardness, IDT, FDT but lower ε − F _max compared to those values observed for styrene copolymers prepared in the presence of succinic or glutaric anhydride modified linear unsaturated polyesters. This supported to the production of stiffer and more thermally stable polymeric structure of copolymers based on unsaturated epoxy polyesters. Moreover, the copolymers prepared in the use of glutaric anhydride modified linear unsaturated (epoxy) polyesters were described by lower values of E_{20 ^°\textC}^￠ E_{{20\,^{\circ}{\text{C}}}}^{\prime} , T _g, E″, ν _e, E _mod, F _max, hardness, IDT, FDT but higher ε − F _max than those based on succinic anhydride modified linear unsaturated (epoxy) polyesters. The presence of longer aliphatic chain length in polyester’s structure leads to produce more flexible network structure of styrene copolymers based on glutaric anhydride modified linear unsaturated (epoxy) polyesters than those based on succinic anhydride modified linear unsaturated (epoxy) polyesters.     

Syntheses of (C_5H_9C_5H_4)_2LnCl(THF)_n (Ln=Nd, Sm, Er, Yb) and crystal structure of [(C_5H_9C_5H_4)_2-LnCl(THF)_n]_2(Ln=Sm, n=1; Ln=Er, n=0)

Reactions of lanthanoid trichlorides with sodium cyclopentylcyclopentadienyl in THFafford bis(cyclopentylcyclopentadienyl) lanthanoid chloride complexes (C_5H_9C_5H_4)_2LnCl(THF)_n (Ln=Nd, Sm, n=1; Ln= Er, Yb, n= 0). The compound [CP'_2SmCl(THF)]_2 (2) (Cp' =cyclopentylcy-clopentadienyl) crystallizes from mixed solvent of hexane and THF in monoclinic space group P_2_1/cwith a = 11.583 (3), b = 23.019(6), c = 8.227 (2), β= 90.26 (2)°, V= 2194 (1)~3, D_c= 1.59 g/cm~3.μ= 28.6 cm~(-1), F(000) = 1060, Z= 2 (dimers). Its crystal molecule is a dimer with a crystallographicsymmetry center. The central metal atom Sm is coordinated to two Cp' rings, two bridging chlorineatoms and one THF forming a distorted trigonal bipyramid. The crystal of [Cp'_2ErCl]_2 (3) belongs tothe triclinic space group P with a = 11.264 (2), b= 13.296(5), c = 14.296(6), a = 96.99 (3), β=112.47(2), γ= 102.78(2)°, V= 1865(1)~3, D_c= 1.67 g /cm~3, μ= 48.0 cm~(-1), F(000) = 924, Z = 2 (dimers).The molecule is a dimer consisting of two Cp'_2 ErCl species bridged by two Cl atoms. The centralmetal atom Er is coordinated to two Cp' rings and two bridging chlorine atoms forming a pseudo-tetrahedron. All these complexes are soluble in THF, DME, Et_2O, toluene and hexane.     

Trennung und Charakterisierung der metallgemischten Cluster [(Nbn Ta6–n) Cl]2+, n = 0–6

Separation and Characterization of Mixed-Metal Clusters [(Nb_n Ta_6–n)Cl ]²⁺, n = 0–6 By reaction of NbCl₅ with Ta or TaCl₅ with Nb in fused NaCl the mixed-metal compounds [(Nb_nTa_6–n)Cl]²⁺, n = 0–6, are obtained. The anions formed in NaF solution by coordination of F^?? are kinetically stable at lower temperatur (–5°C). They have been separated by repeated ion exchange chromatography on DEAE cellulose to give the mixed-metal clusters, for n = 1 and 5 as pure compounds, for n = 2, 3, 4 as pairs of geometric isomers according to statistical distribution. The clusters are distinguishable by intense charge transfer bands shifting on metal substitution by steps of about 12 nm from 327 (Ta₆) to 396 nm (Nb₆). The IR spectra (80 K) exhibit only in the region of the antisymmetric metal–metal vibration distinct band patterns, which are assigned to the components of the degenerated T_1u vibration of the octahedral homonuclear clusters at 233 (Nb₆) and 209 cm^?1 (Ta₆), due to the lower symmetry D_4h, C_4v, and C_2v of the mixed-metal clusters. Along with the substitution of Nb by Ta the metal-Clⁱ vibrations are systematically shifted to lower frequencies, whereas all deformation modes remain uninfluenced.     

Thermo-oxidative degradation kinetics and mechanism of the system epoxy nanocomposite reinforced with nano-Al2O3

We have synthesized epoxy nanocomposites with various percents of nanoalumina by using ultrasonic dispersion treatment. Scanning calorimetry studies revealed that the composition having 1% nanoalumina results in the highest value of cross-link density as evidenced by the glass transition temperature (T _g). Thermal degradation of the systems consisting of diglycidyl ether bisphenol A (DGEBA)/1,3-Poropane diamine and with 1% and without nanoalumina were studied by thermogravimetry analysis to determine the reaction mechanism in air. The obtained results indicated that a relatively low concentration of nanoalumina led to an impressive improvement of thermal stability of epoxy resin. The Coats?CRedfern, Van Krevelen, Horowitz?CMetzger, and Criado methods were utilized to find the solid state thermal degradation mechanism. Analysis of our experimental results suggests that the reaction mechanism is depending on the applied thermal history. For the nanocomposite, the mechanism was recognized to be one-dimensional diffusion (D₁) reaction at low heating rates and it changes to be a random nucleation process with one nucleus on the individual particle (F₁) at high heating speeds. The results also indicated that the degradation mechanism of organic phase is influenced by the presence of inorganic nanofiller.     

Experimental measurement of the rate of the reaction o(3P) + H2(v = 0) → OH(v = 0) + H at T = 298 K

Measurement of the rate of the reaction is reported. The measurements were made in a flow tube apparatus. The result is based on data for the absolute density of OH(v = 0) obtained from laser-induced fluorescence measurements in the (0–0) band of the OH(A²Σ⁺ → X²II) system. The density of oxygen atoms was varied by changing the flow rate of NO which is consumed in the reaction N + NO → O + N₂. We find that k₁ (298 K) = (5.5 ± 3.0) × 10⁶ cm³/mol sec. This result was obtained with consideration and control of the effect of reaction (2): for which vibrationally excited hydrogen is created by energy transfer in the presence of active nitrogen. It was found that the addition of N₂ or CO₂ effectively suppressed the excitation of H₂(v = 1). Measurements of the density of H₂(v = 1) were made by VUV absorption in the Lyman band system of H₂. All of the reports of low-temperature measurements and some recent theoretical calculations for k₁ are discussed. The present result confirms and extends the growingevidence for significant curvature in the low-temperature end of a modified Arrhenius plot of k₁ (T).     

Dynamics of the formation of excited hydrogen,H(n=2,3,4), during a pulse discharge in methane

The dynamics of the formation and decay of excited hydrogen during a pulse discharge in methane at a pressure of 200 Pa and energy density of 0.05 J/cm³ has been studied. The population of hydrogen in the n=2 state was monitored by the laser absorption method. The time constant of the decay of the excited hydrogen was measured to be 95±15 ns. The concentration of free electrons reached a maximum value of 7×10¹⁴ cm^–3, and the time constant of their recombination was 220±50 ns. The formation of appreciable amounts of atomic hydrogen in the ground state during the discharge, H(n=1)>10¹⁶ cm^–3, was estimated on the basis of a kinetic model.Notation absorption coefficient - wave number, cm^–1 - c velocity of light - e electron charge - m _e mass of electron - A _mn Einstein coefficient - F _mn collisional deexcitation rate constant - S _m ionization rate constant - f ₂₄ oscillator strength - n _e electron concentration - n _H(n=2,3,4) excited-state hydrogen concentration - v _e electron velocity - q _mn excitation cross-section - (q _mnve) excitation rate constants - T _e electron temperature - E (t) electrical field strength - j current density - t _ei ^–1 electron-ion collision frequency - _2,m two-body recombination rate constant - _3,m three-body recombination rate constant     

Kinetics of the gas-phase reaction between iodine and trifluorosilane and the bond dissociation energy D(F3Si?H)

The title reaction has been investigated in the temperature range 667–715K. The only reaction products were trifluorosilyl iodide and hydrogen iodide. The rate law was obeyed over a wide range of iodine and trifluorosilane pressures. This expression is consistent with an iodine atom abstraction mechanism and for the step log k₁(dm³/mol·sec) = (11.54 ± 0.17) ? (130.5 ± 2.2 kJ/mol)/RT In 10 has been deduced. From this the bond dissociation energy D(F₃Si? H) = (419 ± 5) kJ/mol (100.1 kcal/mol) is obtained. The kinetic andthermochemical implications of this value are discussed.     

Kinetics and mechanism of the oxidation ofbis(2,4,6-tripyridyl-1,3,5-triazine)iron(II) bytrans-1,2-diaminocyclohexanetetraacetatomanganate(III) in acetate buffer

The rapid oxidation ofbis(2,4,6-tripyridyl-1,3,5-triazine)-iron(II), [Fe(TPTZ)₂]²⁺, bytrans-1,2-diaminocyclohexanetetraacetatomanganate(III), [Mn^III(Y)]⁻, in acetate buffers was monitored using stopped-flow spectrophotometry. The reaction is first order in the substrate and evidence was obtained for pre-complexation between the oxidant and the substrate. The reaction rate increases as the pH increases. Characterisation of the products using the radiotracers⁵⁴Mn and⁵⁹Fe indicated that [Mn^II(Y)]²⁻ and [Fe(TPTZ)₂]³⁺ are the final products. The reaction obeys the rate law:

The preparation,structure and spectra properties of dual μ3-oxo bridged tetranuclear complexes containing the (CrFe4-nO2]8+ core (n =0, 2, 4)

The preparation and characterization of [Cr_nFe_4-nO₂(O₂CMe)₇(bipy)₂]Cl (1, n=0; 2, n=2; 3, n=4, bipy=2,2'-bipyridine) are described. The three complexes (1, 2 and 3) are obtained by bipyridine-mediated conversion of trinuclear [Cr_nFe_3-nO(O₂CMe)₆(H₂O)₃]⁺(1, n=0; 2, n=1; 3, n=3), and crystallized as three of approximate isomorphs. Crystal 2 is monoclinic with space group C2/c, a=27.454(5)Å, b=11.789(1)Å, c=16.570(3)Å, β=118.78(1)°, V=4700.8ų, z=4, μ(MoK)=11.64cm^?1, F(000)=2056, final R=0.058 and R_w=0.066 for 3479 reflections with I ? 3σ(I). The Fe and Cr atoms in the cation are all +3 oxide state and disordered in the lattice, which is also supported by its Mossbauer studies. The [Cr₂Fe₂O₂]⁸⁺ core can be thought of as being derived from two edge-sharing M₃O units (M=Fe or Cr), and as a butterfly-like structure. The cations' structure of all three crystals are similar to each other and have C₂ symmetry. The species are characterized by IR spectra and magnetic techniques, with particular emphasis on differentiation of coordination bond strengths and electronic environment of metal atoms in these complexes.     

Cycloarsanes (AsCF3)n (n = 4, 5) – Precursors for the Highly Reactive Diarsene F3CAs=AsCF3

Tetrakis(trifluoromethyl) cyclotetraarsane (F₃CAs)₄ ( 2 ) was used to repeat the UV initiated [4+2]‐cycloaddition reaction of the diarsene F₃CAs=AsCF₃ ( 1 ) with cyclohexa‐1,3‐diene (CHD) and to isolate single crystals of the cycloadduct 4 for a X‐ray diffraction analysis. 4 crystallizes in the space group and contains the diarsene group in its E‐configuration. 2 was also applied for [2+2]‐cycloaddition reactions of 1 with tBuC≡P and MeC≡CNⁱPr₂, but in contrast to positive results with (F₃CP)₄ the products were too labile for isolation. However, 2 was successfully used at room temperature as precursor for coordinating 1 as π‐donor ligand to the Pd(PPh₃)₂ complex fragment yielding η²‐bis(trifluoromethyl)diarsene‐bis(triphenylphosphane)‐palladium(0) 5 , which was characterized by X‐ray diffraction of single crystals and by spectroscopic investigations (NMR, IR, MS). Attempts to prove the existence of the diarsene 1 , generated by different methods, by spectroscopic studies very probably failed due to its extreme reactivity, not allowing the necessary concentrations for detection. Quantum chemical calculations of the stability of 1 with respect to dimerization, the stability of the [2+2]‐cycloadduct with 1‐di(isopropyl)aminopropyne and the energy difference between 4 and the 2,3‐dimethyl‐1,3‐butadiene cycloadduct of 1 were performed to understand the considerable differences between 1 and the related diphosphene F₃CP=PCF₃.     

Kinetics of the reaction of OH radicals with acetylene in 25–8000 torr of air at 296 K

Relative rate techniques were used to study the kinetics of the reaction of OH radicals with acetylene at 296 K in 25–8000 Torr of air, N₂/O₂, or O₂ diluent. Results obtained at total pressures of 25–750 Torr were in good agreement with the literature data. At pressures >3000 Torr, our results were substantially (～35%) lower than that reported previously. The kinetic data obtained over the pressure range 25–8000 Torr are well described (within 15%) by the Troe expression using k_o = (2.92 ± 0.55) × 10^?30 cm⁶ molecule^?2 s^?1, k_∞ = (9.69 ± 0.30) × 10^?13 cm³ molecule^?1 s^?1, and F_c = 0.60. At 760 Torr total pressure, this expression gives k = 8.49 × 10^?13 cm molecule^?1 s^?1. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 35: 191–197, 2003     

Crystal Structures and Magnetic Properties of Charge-Transfer Salts: Cobaltocenium Bis(cis 1,2-diphenylethene-1,2-dithiolato)metalates (Metal = Ni,Pd, Pt)

Charge-transfer salts [Co(C₅H₅)₂][M(dpt)₂] (M = Ni and Pt; dpt = cis-1,2-diphenylethene-1,2-dithiolate) were synthesized and crystallographically characterized. [Co(C₅H₅)₂][Ni(dpt)2] crystallizes in the monoclinic space group C2/c with a = 25, 607(3) Å, b = 9.4151(11) Å, c = 14.407(4) Å, β = 101.373(22)°, V = 3405.3(10) Å₃ and Z = 4. [Co(C₅H₅)₂][Pt(dpt)₂] belongs to the triclinic space group $ {\rm P}\bar 1 $ with a = 9.4666(11) Å, b = 13.9869(12) Å, c = 14.2652(9) Å, α = 99.983(6)°, β = 90.034(7)°, γ = 109.751(7)°, V = 1747.2(3) ų and Z = 2. Both structures consist of ··· D⁺A^?D⁺A^?D⁺A^? ··· linear chains with the local C₅ axis of the eclipsed [Co(C₅H₅)₂]⁺ cation parallel to the best MS₄ plane of the [M(dpt)₂]^? anion. Magnetic susceptibility measurements show that χ_M T values of the complexes [Co(C₅H₅)₂][M(dpt)₂] (M = Ni, Pd, and Pt) remain nearly constant in the temperature range 15–300 K, but decrease rapidly with further decreasing of temperature, indicating weak antiferromagnetic interactions at low temperatures.     

Lithium-silylindolide als Precursor für 1,2-, 1,3-Bis(silyl)indole und Bis(indol-1,3-yl)silane

Lithium-silylindolide as Precursor of 1,2-, 1,3-Bis(silyl)indoles and Bis(indole-1,3-yl)silane Lithium-indolide reacts with difluorosilanes (F₂SiR₂: R = CHMe₂ ( 1 ); CMe₃ ( 2 )) in a molar ratio 2 : 1 with formation of bis(indole-1-yl)silanes. The 1-(di-tert-butylfluorosilyl)-3-(fluorodiisopropylsilyl)indole ( 3 ) is obtained in the reaction 1-(di-tert-butylfluorosilyl)-3-lithium-indolide and F₂Si(CHMe₂)₂. In a molar ratio 2 : 1 the bis(1-di-tert-butylfluorosilyl-indole-3-yl)diisopropylsilane 4 is formed. As a byproduct bis(1-di-tert-butylfluorosilyl-indole-3-yl)dimethylmethane ( 5 ) is isolated. A cleavage of THF and the formation of (indole-1-yl)diisopropylvinyloxysilan ( 6 ) occurs in the reaction of 1-diisopropylfluorosilylindole with t-BuLi in THF. 1-(di-tert-butylfluorosilyl)indole reacts with n-BuLi/TMEDA accompanied by an 1,2-anionic silyl group migration to give the 2-(di-tert-butylfluorosilyl)-1-lithiumindolide 7 . Hydrolysis of 7 gives the 2-(di-tert-butylfluorosilyl)indole ( 8 ). In the reaction of 7 with F₂Si(CHMe₂)₂ the 1-(diisopropylfluorosilyl)-2-(di-tert-butylfluorosilyl)indole 9 is obtained. 1-n-Butyl-diisopropylsilylindole ( 10 ) is the product of the reaction of F₂Si(CHMe₂)₂, n-BuLi/TMEDA and indole at –70 °C. Lithium-indolide reacts with 3 to give the 1-(di-tert-butylfluorosilyl)indole-3-yl)(indole-1-yl)-diisopropylsilane ( 11 ), the first example of this class of substances. In the reaction of 1 , F₂SiMe₂, and t-BuLi in THF the 1-(diisopropyl(indole-1-yl)silyl)-3-dimethyl-(3.3-dimethylbutylsilyl)indole 12 is isolated. The crystal structures of 2 , 5 and 9 are discussed.