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1.
The reaction of tributylphosphine with the catalytic system (C5H5)2 TiCl2–LiC4H9 prepared in an atmosphere of H2 has been investigated in toluene solution. By using the ESR technique, a hydride complex Cp2Ti(H) (PBu3) 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). .
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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   

3.
4.
The reaction pathway between the components of the catalytic system Cp2TiCl2-LiAlH4-unsaturated hydrocarbon, depends considerably on the nature of the reaction medium. In dienes which are able to form stable η3-allyltitanocene derivatives, these represents the main reaction product; they are catalytically active in the double bond shifts. In dienes not forming stable η3-allyltitanocene derivatives and in α-olefins, the catalytically-active η1-alkenyl- and alkyl-titanocenes are transiently formed, deactivating rapidly to give the [(C5H5)(C5H4)TiHAlR2]2 complexes and minor amounts of η3-allyltitanocene derivatives in a side reaction involving intermolecular hydrogen transfer. In all α-olefinic hydrocarbons, the formation of alkyl-, η1-alkenyl- or η3-allyl-titanocene derivatives is preceded by the hydroalumination reaction, yielding Cp2TiCl2AlR2 complexes. In internal olefins the hydroalumination reaction does not occur and the alkyltitanocenes which are formed catalyze the transformation of (Cp2TiCl)2 into μ-(η5 : η5-fulvalene)-di-μ-chlorobis(η5-cyclopentadienyltitanium), thus inducing the self-deactivation of the system.  相似文献   

5.
Supported catalysts for ethylene polymerization were prepared by anchoring tetrakis(1-bicycloheptyl) titanium [Ti(C7H11)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] . , . , .
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6.
We report a new synthesis and characterization of Ir(C2H4)2(C5H7O2) [(acetylacetonato)-bis(η2-ethene)iridium(I)], prepared from (NH4)3IrCl6 · H2O 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(C2H4)2(C5H7O2) is isostructural with Rh(C2H4)2(C5H7O2), 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   

7.
The complex (di-η5-C5H4CH2CH2CH2C5H4)Ti(η1-C5H5)2 (I) can be obtained unambiguously starting from the corresponding bridged titanocene dichloride. Attempts to synthesize the isomeric compounds (η5-C5H5)2 Ti(di-η1-C5H4-CH2CH2CH2C5H4) (I′) by the action of a convenient bridged dianion on (C5H5)2 TiCl2 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   

8.
Reaction of photogenerated (η5?C5H5)2W2(CO)4 with acetylene at 25°C yields a complex of the formula (η5-C5H5)2W2(CO)4(C2H2). The crystal structure of the complex shows it to have a tetrahedrane-like W2C2 core. The C—C bond distance of the C2H2 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 (η5-C5H5)2W2(CO)6 but longer than that expected for (η5-C5H5)2W2(CO)4. By analogy to the parent (η5-C5H5)2M2(CO)6 species, the near-UV absorption in (η5-C5H5)2M2(CO)4(C2H2) is assigned to a σb → σ* transition. Owing to the shorter M—M bond in the C2H2 adducts, the σb → σ* absorption is at higher energy than in the (η5-C5H5)2M2(CO)6 complexes.  相似文献   

9.
The ethylene butadiene copolymerization with systems of three components Al[N(CH3)2]3, Al(C2H5)Cl2 and VOCl3 or VCl4, 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   

10.
A new chemical oxidant [N(4-C6H4Br)3][B(C6F5)4], was prepared and used to synthesize [Fe(C5H5)2][B(C6F5)4]. The crystal structure of [Fe(C5H5)2][B(C6F5)4] was determined.  相似文献   

11.
The complex dicarbonylbis(diphenylethylphosphine)platinum, Pt(CO)2[P(C6H5)2(C2H5)]2, crystallizes in either of the enantiomorphous space groups P3121 (No. 152) and P3221 (No. 154) with cell dimensions a = 10.64(1), c = 22.06(1) Å, U = 2163 Å3; pc = 1.564 g/cm3 for Z = 3, pm = 1.55(3) g/cm3. The intensities of 1177 independent reflections have been determined by counter methods with MoKα 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 P3121) 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: PtC = 1.92(2) Å, PtP = 2.360(4) Å, CPtC = 117(1)° and PPtP = 97.9(2)°. The PtC2 and PtP2 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 PtCO interactions being apparent from the orientations of the thermal ellipsoids of the C and O atoms.  相似文献   

12.
The rates of the thermal reaction of the nickel(0) complex Ni[P(C2H5)3]4 with the alkyl halides CH3Br, CH3I in toluene have been compared with those of the reactions of the nickel(I) complexes Ni(X)[P(C2H5)3]3 (X  Br,I). The organic products from CH3X are methane and ethane, and those from C2H5I 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 CH3I 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   

13.
The crystal and molecular structure of hexaphenylditin selenide (C6H5)3SnSeSn(G6H5)3 was determined by X-ray diffraction data and was refined to R  0.055. The compound is monoclinic, space group P21, 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: SnSe 2.526 (2.521(3) ? 2.538(3)) Å; SnC 2.138 (2.107(16)?2.168(19)) Å; SnSeSn 103.4(1)°, 105.2(1)°. There are only slight angular distortions at the SnSeC3 tetrahedra (SeSnC angles: 104.3(5)?114.8(4)°). The bond data indicate essentially single bonds around the Sn atoms.  相似文献   

14.
Reaction of YbI2 with two equivalents of cyclopentylindenyl lithium (C5H9C9H6Li) affords ytterbium(II) substituted indenyl complex (C5H9C9H6)2Yb(THF)2 (1) which shows high activity to ring-opening polymerization (ROP) of lactones. The reaction between YbI2 and cyclopentylcyclopentadienyl sodium (C5H9C5H4Na) gives complex [(C5H9C5H4)2Yb(THF)]2O2 (2) in the presence of a trace amount of O2, the molecular structure of which comprises two (C5H9C5H4)2Yb(THF) bridged by an asymmetric O2 unit. The O2 unit and ytterbium atoms define a plane that contains a Ci symmetry center.  相似文献   

15.
Ohne Zusammenfassung
(C5H5FeSi1.5)4: A new quadrinuclear Fe-S cluster in a (C5H5FeS)4 matrix
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16.
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   

17.
The Raman and infrared spectra (4000200 cm?1) of (C4H4P)Mn(CO)3 and (C4D4P)Mn(CO)3, and of [C4H2(CH3)2P]Mn(CO)3 and [C4D2(CH3)2P]Mn(CO)3 in the liquid and solid states (10–400 K) have been investigated. A complete vibrational assignment is proposed and valence force fields of the (C5H5) and (C4H4P) cycles are compared. From these results, it is clearly shown that the (C4H4P) rings are more electrophilic and weaker π-electron donors than (C5H5) rings, this is in agreement with their chemical behavior.  相似文献   

18.
en Two differnt crystal modifications of hexaphenyldigermanium sulfide (C6H5GeSGe(C6H5)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, P21/c, with a = 11.020(3), b = 15.473(3), c 18.606(3) »,π = 106.92(2)°, Z = 4; II is orthorhombic, P212121, 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 (C6H6)3Ge groups around the Ge bonds with very similar bond lenghts and angles. Bond data for I(II) are: GeS 2.212(1) and 2.261(1) » (2.227(2) and 2.240(2) »); GeC 1.933(4) ? 1.971(4), mean 1.945(5) » (1.931(7)?1.954(7), mean 1.943(4) »); GeSGe 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   

19.
η5-C5H5(CO)2FeNa reacts with the benzimide chlorides C6H5(Cl)CNR (R  CH(CH3)2, C6H5) in boiling THF to give the η1-iminoacyl complexes η5-C5H5 (CO)2Fe[η1-C(C6H5)NR]. Alternatively, the new Fe complexes [η5-C5H5(CO)FeC(C6H5)N(CH3)C(C6H5)NCH3PF6 (IV) and [η5-C5H5(CO)2FeC(C6H5)N(CH3)C(C6H5)NCH3]PF6 (V) are formed under the same conditions, if R  CH3. Hudrolysis of the CN single bond of the ligand in V, not stabilized by a chelate effects as in IV, results in the formation of [η5-C5H5(CO)2FeC(C6H5)NHCH3]PF6 (VII). Reaction of η5-C5H5(CO)2 with N-benyzylbenzimido chloride yields η5-C5H5(CO)2FeCH2C6H5 as the only isolated product.  相似文献   

20.
The hydrolysis of a complex of diethyl zinc (DEZ) with propylene sulphide (PS) in PS solution has been investigated. Suitable conditions have been found for the quantitative hydrolysis of DEZ with the formation of a catalyst system containing (ZO)n groups and ZnS bonds and effective for initiating the polymerization of PS. This polymerization was investigated and a tentative scheme for polymerization by a coordinate anionic mechanism is suggested. The structure of polypropylene sulphide (PPS) was investigated by high-resolution NMR spectroscopy and X-rays. The Zn(C2H5)2—H2O system prepared in situ is highly selective in the reactions of breaking the α-thioxide ring. Amorphous PS consists entirely of head-to-tail bonded units with equal content of iso- and syndiotactic diads. It was also shown that extremely high values of the molecular mass of PPS, the unusual dependence of [η] on conversion and the instability of polymer solutions are due to the presence of polymer aggregates formed in the polymerization of PS on complex associated active centres with a steric structure. Conditions were found for the stabilization of PS solutions containing zinc and for the purification of the polymer from traces of the catalyst system. It was shown that it is incorrect to use equations available in the literature to calculate Mη for PPS obtained with the DEZ—H2O system from viscometric data without thorough purification of the polymer. Osmometry and light scattering technique were used to estimate true values of the molecular mass of polymer aggregates and of linear PPS.  相似文献   

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