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1.
The reaction of tributylphosphine with the catalytic system (C 5H 5) 2 TiCl 2–LiC 4H 9 prepared in an atmosphere of H 2 has been investigated in toluene solution. By using the ESR technique, a hydride complex Cp 2Ti(H) (PBu 3) has been detected. The proportionality between the rate of cyclohexene hydrogenation and the complex concentration has been established. The kinetics of cyclohexene hydrogenation has been investigated and a reaction mechanism is proposed.
Cp2TiCl2–LiC4H9 (Cp–C5H5), H2, Cp2Ti(H) (PBu3). Ti (III). . 相似文献
2.
Experimental results obtained when studying the kinetics of ethylene polymerization in toluene, as well as data on fractionating polyethylene, are analysed and compared with the results of theoretical consideration of molecular weight distribution on the basis of the proposed kinetic scheme.The constants of the reactions of propagation, initiation, transfer and termination of polymer chains are evaluated and compared with literature data. 相似文献
4.
LnCl 3 (Ln=Nd, Gd) reacts with C 5H 9C 5H 4Na (or K 2C 8H 8) in THF (C 5H 9C 5H 4 = cyclopentylcyclopentadienyl) in the ratio of 1 : to give (C 5H 9C 5H 4)LnCl 2(THF) n (orC 8H 8)LnCl 2(THF) n], which further reacts with K 2C 8H 8 (or C 5H 9C 5H 4Na) in THF to form the litle complexes. If Ln=Nd the complex (C 8H 8)Nd(C 5H 9C 5H 4)(THF) 2 (a) was obtained: when Ln=Gd the 1 : 1 complex [(C 8H 8)Gd(C %H 9)(THF)][(C 8H 8)Gd(C 5H 9H 4)(THF) 2] (b) was obtained in crystalline form. The crystal structure analysis shows that in (C8H8)Ln(C5H9C5H4)(THF)2 (Ln=Nd or Gd), the Cyclopentylcyclopentadieny (η5), cyclooctatetraenyl (η8) and two oxygen atoms from THF are coordinated to Nd3+ (or Gd3+) with coordination number 10. The centroid of the cyclopentadienyl ring (Cp′) in C5H9C5H4 group, cyclooctatetraenyl centroid (COTL) and two oxygens (THF) form a twisted tetrahedron around Nd3+ (or Gd3+). In (C8H8)Gd(C5H9C5H4)(THF), the cyclopentyl-cyclopentadienyl (η5), cyclooctatetraenyl (η8) and one oxygen atom are coordinated to Gd3+ with the coordination number of 9 and Cp′, COT and oxygen atom form a triangular plane around Gd3+, which is almost in the plane (dev. -0.0144 Å). 相似文献
5.
The reaction pathway between the components of the catalytic system Cp 2TiCl 2-LiAlH 4-unsaturated hydrocarbon, depends considerably on the nature of the reaction medium. In dienes which are able to form stable η 3-allyltitanocene derivatives, these represents the main reaction product; they are catalytically active in the double bond shifts. In dienes not forming stable η 3-allyltitanocene derivatives and in α-olefins, the catalytically-active η 1-alkenyl- and alkyl-titanocenes are transiently formed, deactivating rapidly to give the [(C 5H 5)(C 5H 4)TiHAlR 2] 2 complexes and minor amounts of η 3-allyltitanocene derivatives in a side reaction involving intermolecular hydrogen transfer. In all α-olefinic hydrocarbons, the formation of alkyl-, η 1-alkenyl- or η 3-allyl-titanocene derivatives is preceded by the hydroalumination reaction, yielding Cp 2TiCl 2AlR 2 complexes. In internal olefins the hydroalumination reaction does not occur and the alkyltitanocenes which are formed catalyze the transformation of (Cp 2TiCl) 2 into μ-(η 5 : η 5-fulvalene)-di-μ-chlorobis(η 5-cyclopentadienyltitanium), thus inducing the self-deactivation of the system. 相似文献
6.
The catalytic system (C 5H 5) 2TiEtCl-AlEtCl 2 in benzene and heptane was investigated. Only two species are formed at an equimolar ratio Al: Ti, viz. active (C 5H 5) 2TiEtCl.AlEtCl 2 (I) and inactive (C 5H 5) 2TiCl.AlEtCl 2 formed from (I). The rate constant of propagation is kp20° = 6.4 l/mole sec and is independent of the medium. The rate of polymerization decreases with time because of valence reduction. The bimolecular law is obeyed during a run but the apparent termination constant is inversely proportional to the initial catalyst concentration. The kinetic data with different ratios Al:Ti and the dependence of the number of polymer molecules/Ti atom show that AlEtCl 2 is a termination agent and a chain transfer agent. 相似文献
7.
Supported catalysts for ethylene polymerization were prepared by anchoring tetrakis(1-bicycloheptyl) titanium [Ti(C 7H 11) 4] on alumina. The influence of the dehydration temperature of the support and the conditions of catalyst activation on the catalytic properties was studied. At low content of Ti these catalysts were found to be highly active for ethylene polymerization with the formation of superhigh molecular weight polymers.
(1-) [Ti(C7H11)4] . , . , . 相似文献
8.
用同步辐射对(C2H3Cl)2分子团簇进行了光电离研究,发现该团簇内部发生了离子-分子化学反应,生成了十分稳定的反应产物C4H5Cl^+,不再是varderWaals弱键络合物,本文对反主尖机理进行了初步探讨。 相似文献
9.
We report a new synthesis and characterization of Ir(C 2H 4) 2(C 5H 7O 2) [(acetylacetonato)-bis(η 2-ethene)iridium(I)], prepared from (NH 4) 3IrCl 6 · H 2O in a yield of about 45%. The compound has been characterized by X-ray diffraction crystallography, infrared, Raman, and NMR spectroscopies and calculations at the level of density functional theory. Ir(C 2H 4) 2(C 5H 7O 2) is isostructural with Rh(C 2H 4) 2(C 5H 7O 2), but there is a substantial difference in the ethylene binding energies, with Ir-ethylene having a stronger interaction than Rh-ethylene; two ethylenes are bound to Ir with a binding energy of 94 kcal/mol and to Rh with a binding energy of 70 kcal/mol. 相似文献
10.
The complex (di-η 5-C 5H 4CH 2CH 2CH 2C 5H 4)Ti(η 1-C 5H 5) 2 (I) can be obtained unambiguously starting from the corresponding bridged titanocene dichloride. Attempts to synthesize the isomeric compounds (η 5-C 5H 5) 2 Ti(di-η 1-C 5H 4-CH 2CH 2CH 2C 5H 4) (I′) by the action of a convenient bridged dianion on (C 5H 5) 2 TiCl 2 afford several compounds, one of them is the complex I. The possibility of interconversion of these complexes by a fluctional process is discussed. 相似文献
11.
Reaction of photogenerated (η 5?C 5H 5) 2W 2(CO) 4 with acetylene at 25°C yields a complex of the formula (η 5-C 5H 5) 2W 2(CO) 4(C 2H 2). The crystal structure of the complex shows it to have a tetrahedrane-like W 2C 2 core. The C—C bond distance of the C 2H 2 unit is 1.33 Å which is close to that of ethylene, considerably longer than the 1.20 Å for acetylenes. The W—W distance is 2.987 Å which is ~0.25 Å shorter than the W—W distance in (η 5-C 5H 5) 2W 2(CO) 6 but longer than that expected for (η 5-C 5H 5) 2W 2(CO) 4. By analogy to the parent (η 5-C 5H 5) 2M 2(CO) 6 species, the near-UV absorption in (η 5-C 5H 5) 2M 2(CO) 4(C 2H 2) is assigned to a σ b → σ * transition. Owing to the shorter M—M bond in the C 2H 2 adducts, the σ b → σ * absorption is at higher energy than in the (η 5-C 5H 5) 2M 2(CO) 6 complexes. 相似文献
12.
A new chemical oxidant [N(4-C 6H 4Br) 3][B(C 6F 5) 4], was prepared and used to synthesize [Fe(C 5H 5) 2][B(C 6F 5) 4]. The crystal structure of [Fe(C 5H 5) 2][B(C 6F 5) 4] was determined. 相似文献
13.
The ethylene butadiene copolymerization with systems of three components Al[N(CH 3) 2] 3, Al(C 2H 5)Cl 2 and VOCl 3 or VCl 4, is described. In the resulting copolymers, the butadiene units are substantially in trans-1,4 configuration. Although it is possible to obtain copolymers with a wide range of composition, attention was paid to products with a low content of unsaturation (less than 2% mole of butadiene). These copolymers are highly homogeneous. They show high crystallinity of the polyethylene type and they can be crosslinked with conventional sulphur recipes. 相似文献
14.
The complex dicarbonylbis(diphenylethylphosphine)platinum, Pt(CO) 2[P(C 6H 5) 2(C 2H 5)] 2, crystallizes in either of the enantiomorphous space groups P3 121 (No. 152) and P3 221 (No. 154) with cell dimensions a = 10.64(1), c = 22.06(1) Å, U = 2163 Å 3; pc = 1.564 g/cm 3 for Z = 3, pm = 1.55(3) g/cm 3. The intensities of 1177 independent reflections have been determined by counter methods with MoKα monochromatized radiation. The structure has been solved by the heavy atom method. The refinement, carried out by full-matrix least squares down to a final R factor of 0.042, has enabled the absolute configuration of the crystal sample (space group P3 121) to be ascertained. The molecule is roughly tetrahedral, and has the metal atom lying on a two-fold axis of the cell. Bond parameters are: PtC = 1.92(2) Å, PtP = 2.360(4) Å, CPtC = 117(1)° and PPtP = 97.9(2)°. The PtC 2 and PtP 2 moieties make a dihedral angle of 86.0(3)°. The overall C2 symmetry of the molecule is probably only a statistically averaged situation, a disorder in the PtCO interactions being apparent from the orientations of the thermal ellipsoids of the C and O atoms. 相似文献
15.
The rates of the thermal reaction of the nickel(0) complex Ni[P(C 2H 5) 3] 4 with the alkyl halides CH 3Br, CH 3I in toluene have been compared with those of the reactions of the nickel(I) complexes Ni(X)[P(C 2H 5) 3] 3 (X Br,I). The organic products from CH 3X are methane and ethane, and those from C 2H 5I are ethane and ethylene. The reactivity of the nickel(I) complexes is 10–20 times less than that of the nickel(0) complex. The result suggest that the first step of the reaction of nickel(0) with CH 3I is the expected oxidative addition of the halide to the metal substrate. The intermediate thus formed decomposes to produce ethane (and small amounts of methane) without further reaction with the organic halide. This mechanism is supported by deuterium-labeling experiments. 相似文献
16.
Reaction of YbI 2 with two equivalents of cyclopentylindenyl lithium (C 5H 9C 9H 6Li) affords ytterbium(II) substituted indenyl complex (C 5H 9C 9H 6) 2Yb(THF) 2 (1) which shows high activity to ring-opening polymerization (ROP) of lactones. The reaction between YbI 2 and cyclopentylcyclopentadienyl sodium (C 5H 9C 5H 4Na) gives complex [(C 5H 9C 5H 4) 2Yb(THF)] 2O 2 (2) in the presence of a trace amount of O 2, the molecular structure of which comprises two (C 5H 9C 5H 4) 2Yb(THF) bridged by an asymmetric O 2 unit. The O 2 unit and ytterbium atoms define a plane that contains a Ci symmetry center. 相似文献
17.
Ohne Zusammenfassung
(C5H5FeSi1.5)4: A new quadrinuclear Fe-S cluster in a (C5H5FeS)4 matrix 相似文献
18.
The crystal and molecular structure of hexaphenylditin selenide (C 6H 5) 3SnSeSn(G 6H 5) 3 was determined by X-ray diffraction data and was refined to R 0.055. The compound is monoclinic, space group P2 1, with a 9.950(4), b 18.650(7), c 18.066(6) Å, β 106.81(4)°, Z 4. The two molecules in the asymmetric unit differ slightly in their conformations, both having approximate C2 symmetry. Bond lengths and angles are: SnSe 2.526 (2.521(3) ? 2.538(3)) Å; SnC 2.138 (2.107(16)?2.168(19)) Å; SnSeSn 103.4(1)°, 105.2(1)°. There are only slight angular distortions at the SnSeC 3 tetrahedra (SeSnC angles: 104.3(5)?114.8(4)°). The bond data indicate essentially single bonds around the Sn atoms. 相似文献
19.
en Two differnt crystal modifications of hexaphenyldigermanium sulfide (C 6H 5GeSGe(C 6H 5) 3 (I and II were obtained by crystallization from hot benzene/methanol or form ethanol at 20°C. Single crystal X-ray structural analyses for both I (low temperature data at ?130°C) and II (at 20°C) (I, R = 0.046; II, R = 0.048) were performed. I is monoclinic, P2 1/c, with a = 11.020(3), b = 15.473(3), c 18.606(3) »,π = 106.92(2)°, Z = 4; II is orthorhombic, P2 12 12 1, with a = 2.617(2), b = 17.345(3), c = 18.408(3) », Z = 4.The molecules have different conformeric structures with respect to a rotation of the (C 6H 6) 3Ge groups around the Ge bonds with very similar bond lenghts and angles. Bond data for I(II) are: GeS 2.212(1) and 2.261(1) » (2.227(2) and 2.240(2) »); GeC 1.933(4) ? 1.971(4), mean 1.945(5) » (1.931(7)?1.954(7), mean 1.943(4) »); GeSGe 111.2(1)° (110.7(1)°). The Ge bond lenghts are comparable to those in thiogermanates and do not indicate significant π-bond contributions. 相似文献
20.
Heat-capacity measurements have been made in the temperature range 110 to 300 K. In the range 160 to 240 K the chromocene curve shows an anomaly related to an order-disorder phase transition in the solid. On the other hand the dibenzene chromium curve indicates no phase transition and is in accordance with an ordered structure at room temperature. 相似文献
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