共查询到20条相似文献,搜索用时 15 毫秒
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S. L. Malhotra A. B. Deshpande S. L. Kapur 《Journal of polymer science. Part A, Polymer chemistry》1968,6(1):193-203
The polymerization of styrene with two catalyst systems consisting of Al(C2H5)3 in combination with ZrCl4 or ZrCl3 has been studied. The rate of polymerization with catalyst concentration was first-order with ZrCl4 system and second-order with ZrCl3 system, but at higher catalyst concentrations in both cases, the rate progressively decreases and finally attains a low value. The rate of polymerization is, however, proportional to the square of the monomer concentration in both the cases. The overall energy of activation was 10.9 kcal./mole and 6.45 kcal./mole in these systems. The polymers obtained with ZrCl4 were of lower molecular weights as compared to those obtained with ZrCl3. The polymers in both the cases had amorphous character. 相似文献
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K.-H. Thiele U. Bhme K. Peters E.-M. Peters L. Walz H. G. Von Schnering 《无机化学与普通化学杂志》1993,619(4):771-774
Synthesis and Molecular Structure of [1,3-(Me3Si)2C5H3](Me3SiC5H4)ZrCl2 . The unsymmetrically substituted zirconocene dichloride was prepared by reaction of trimethylsilylcyclopentadienyl lithium and 1,3-bis(trimethylsilyl)cyclopentadienyl lithium with ZrCl4 · 2 THF. The molecular structure was determined (P21/a; a = 1 357.9, b = 1 900.0, c = 1 043.2 pm, β = 105,16°). The Zr? Cl distance are remarkably short. 相似文献
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A. N. Nesmeyanov E. G. Perevalova L. I. Leont'eva E. V. Shumilina 《Russian Chemical Bulletin》1977,26(12):2603-2605
Conclusions The photochemical reactions of (CO)2(PPh3)MnC5H4Fe(CO)2C5H5 and (CO)2(PPh3)MnC5H4COFe(CO)2C5H5 with PPh3 gave the products of replacing the CO on the Fe atom by PPh3: respectively (CO)2(PPh3)MnC5H4Fe (CO)(PPh3)C5H5 and (CO)2(PPh3)MnC5H4COFe(CO)(PPh3)C5H5.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2813–2815, December, 1977. 相似文献
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IntroductionThe accidental discovery of ferrocene, (C,H,)ZFe, has been well recognized as a majorcause of the subsequent explosive growth of organometallic chemistry['--'1. Metallocenes havebecome the most famous organometallic compounds. Recently, a considerable attention hasbeen given to the study of the vibrational spectra of metallocenes and the complexes containingthe M-(f-C,H,) unit. The problems concerning the spectroscopy and the structure of cyclopentadienyl complexes have been dis… 相似文献
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本文用电化学方法和X射线单晶结构分析, 研究了混合簇合物(C5H5FeC5H4C2Ph)Co2(CO)6的结构, 由循环伏安结果, 分别讨论了簇合物中(C5H5FeC5H4和C2O2中心的成键性质, X射线单晶结构分析表明: 晶体属单斜晶系, 空间群为P21, 晶胞参数a=11.845(6), b=8.155(6), c=24.031(6)A, β=90.88°,晶胞中分子数Z=4, 密度Do=1.637g.cm^-^2, 分析了(C5H5FeC5H4C2Ph)Co2(CO)6的结构特点, 并从成键角度讨论了(RC2R^1)Co(CO)6类簇合物的结构随RC2R^1不同而变化的规律。 相似文献
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本文以二茂镍为母体化合物,以氧化铝和氧化硅为担体制备了担载镍催化剂。为了表征其结构特点,对这些催化剂热分解处理前后的样品在日本筑波高能物理研究所(Photon-Factory)的同步辐射加速器BL—10B EXAFS实验站进行了外延x-光精细结构谱测定(透射法)。以单散射球面波理论对实验结果进行了多参数拟合,同时对母体化合物也进行了平行测定和拟合,以验证数据及拟合方法的可靠性。研究结果表明,母体化合物的EXAFS结果与文献XRD相一致;母体化合物与担体表面发生了强烈的化学作用;镍组分在催化剂表面高度分散,氧化铝与Ni(C_5H_5)_2有更强的相互作用形成。Ni[(O)_s]_n(n≈4),近一半的镍原子周围有0.30 nm处的镍原子散射;氧化硅上除Ni[(CO)_s]_n(n≈3)外,在0.30 nm处有配位数为2的非成键Ni原子。 相似文献
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[(C6H5CH2C5H4)2GdCl.THF]2 (1) and (C6H5CH2C5H4)2ErCl.THF (2) were prepared by the reaction of LnCl3 (Ln? Gd, Er) with benzylcyclopentadienyl sodium in THF and characterized by elemental analysis, IR, 1H NMR, 13C NMR, MS and thermal gravimetry. The crystal structures of both compounds were determined. Complex 1 is dimeric and its structure belongs to the monoclinic, P21/c space group with a=1.1432(2), b=1.2978(2), c=1.7604(3) nm, β=108.75(2), V=2.4732(9) nm3, Z=2(four monomers), Dc“1.54 g.cm?3. R=0.0342 and Rw“0.0362. Complex 2 is monomer and its structure belongs to the orthorhombic, P212121 space group with a=0.8645(2), b=1.1394(3), c=2.5289(4) nm, V=2.4919(9) nm3, Z=4, Dc“1.56 g.cm?3. R=0.0514, Rw“0.0529. The determination of the crystal structure shows that in complex 1 the benzyl groups on the cyclopentadienyls coordinated to Gd3+ are located in the opposite direction (139°); in complex 2 the benzyl groups on the cyclopentadienyls coordinated to Er3+ are located in the same direction (6.5°). 相似文献
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《Journal of organometallic chemistry》1986,312(2):241-248
Biferrocenium tetrabromoferrate, [(C5H5)Fe(C5H4)-(C5H4)Fe(C5H5)]FeBr4 (1) obtained as a by-product in the synthesis of biferrocenium trihalide salts, crystallizes in the noncentrosymmetric orthorhombic space group, P212121: (at 296 K) a 7.492(2), b 9.903 (2), c 31.604(9) Å, V 2345(1) Å3, and Z = 4. The cation, similar to other structurally characterized biferrocenium salts, adopts a trans-configuration, but, in contrast, possesses no crystallographically imposed symmetry relating the two ferrocenyl environments. Different average Fe-ring distances at the two environments: Fe(1), 2.02(2) and Fe(2), 2.08(2) Å are typical of iron(II) and iron(III) states, respectively, indicating the presence of trapped oxidation states. Interionic contacts are both shorter and more numerous for the iron(III) ferrocenyl fragment than for the iron(II) fragment. Both ferrocenyl units have non-eclipsed ring configurations, with a staggering angle of 6.5(3)° at Fe(1) and 23.5(3)° at Fe(2). The FeBr4− counterion is tetrahedral and ordered. 相似文献
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Clausen HF Overgaard J Chen YS Iversen BB 《Journal of the American Chemical Society》2008,130(25):7988-7996
The charge density (CD) of coordination polymer Co3(C8H4O4)4(C4H12N)2(C5H11NO)3 (1) has been determined from multipole modeling of structure factors obtained from single-crystal synchrotron X-ray diffraction measurements at 16 K. The crystal structure formally contains a negatively charged framework with cations and neutral molecules in the voids. However, the CD suggests that the framework is close to neutral, and therefore qualitative conclusions based on formal charge counting, e.g., about guest inclusion properties, will be incorrect. There are considerable differences in the charge distributions of the three unique benzenedicarboxylic acid linkers, which are widely used in coordination polymers. This suggests that the electrostatic properties of coordination polymer cavities, and thereby their inclusion properties, are highly tunable. The electron density topology shows that the tetrahedrally coordinated Co atom has an atomic volume which is 15% larger than that of the octahedrally coordinated Co atom. The crystal structure has both ferromagnetic and antiferromagnetic interactions, but no direct metal-metal bonding is evidenced in the CD. The magnetic ordering therefore takes place through superexchange in the oxygen bridges and the aromatic linkers. Bonding analysis of the experimental CD reveals that two oxygen atoms, O(1) and O(11), have significant covalent contributions to the metal-ligand bonding, whereas all other oxygen atoms have closed-shell interactions with the metals. This indicates that these two oxygen atoms are the key mediators of the magnetic ordering. 相似文献
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Bond AD Doyle EL García F Kowenicki RA McPartlin M Riera L Wright DS 《Chemical communications (Cambridge, England)》2003,(24):2990-2991
The in situ reaction of the phosphazane dimer [CIP(mu-N-2-NC5H4)]2 (2) with CuCl in the presence of CsH5N/H2O gives the title complex [(P(mu-N-2-NC5H4))2(mu-O)]2(CuCl x (C5H5N)2)4 (1), containing a tricyclic [(P(mu-N-2-NC5H4))2(mu-O)]2 ligand which is isoelectronic with species of the type [(P(mu-NR))2NR]2. 相似文献