烯基取代环戊二烯基钌配合物的合成及晶体结构

本文通过环戊二烯基钠(茂钠)与溴丙烯反应制得单取代的环戊二烯,茂钠与氯丙烯得到双取代的环戊二烯。利用这两个配体合成了烯基取代的环戊二烯基(双三苯膦)氯化钌(1,2)并对化合物(2)进行了晶体结构分析。     

新型二茂钛氧杂环络合物的合成与结构

有机钛杂环化合物的研究是有机钛化学的重要方面。我们在合成取代环戊二烯基钛络合物的过程中,发现一类新型钛杂环化合物的合成方法:     

茂钛类络合物催化碳酸二甲酯和苯酚酯交换反应合成碳酸二苯酯的研究

首次将二氯二茂钛用于碳酸二甲酯和苯酚酯交换合成碳酸二苯酯的反应, 发现二氯二茂钛对该反应来讲是一种性能优良的催化剂; 和钛酸酯类催化剂相比, 茂钛类催化剂在空气中更稳定, 从而更适合于工业化应用. 同时探讨了不同种类茂钛类化合物的催化性能, 发现位阻效应、环戊二烯环的电子分散效应以及取代基的吸电子效应等, 都会影响中心钛原子的Lewis酸性以及相应的催化活性. 总体来讲, 位阻效应越小、环戊二烯环的电子分散效应越大、与中心钛原子连接的取代基的吸电子能力越强, 越有利于反应的进行.     

甲基环戊二烯基水杨酸钛(Ⅳ)配合物的合成与表征

采用不相法和两相法用二氯二甲茂钛与相应的水杨酸反应合成了6个配合物：二甲基环戊二烯基水杨酸钛（I），二甲基环戊二烯基二水杨酸钛（Ⅱ），二甲基环戊二烯基-5硝基水杨酸钛（Ⅲ），二甲基环戊二烯基二5-硝基水杨酸钛（IV），二甲基环戊二烯基3，5-二硝基水杨酸钛（V），二甲基环戊二烯硫代水杨酸钛（VI），对这些化合物进行了元素分析，测定了熔点，计论了它们的红外光谱和核磁共振谱。     

双环戊二烯基钛衍生物的水相化学及双环戊二烯基二水杨酸钛的晶体结构

（ＫＣｎ）２ＴｉＣｌ２的乙酰丙酮体系在水相中与硫氰酸钾、吡咯烷基二硫代氨基甲酸钠、取代苯甲酸钠等反应，合成得到相应的（单）双环戊二烯基（或甲基环戊二烯基）钛衍生物。双环戊二烯基二水杨酸钛单晶的结构分析表明，水杨酸作为单齿配体通过梭基氧原子与钛键联。     

双环戊二烯基钛衍生物的水相化学及双环戊二烯基二水扬酸钛的晶体结构

（ＲＣｐ）２ＴｉＣｌ２的乙酰丙酮体系在水相中与硫氰酸钾，吡咯烷基二硫代氨基甲酸钠，取代苯甲酸钠等反应，合成得到相应的（单）双环戊二烯基（或甲基环戊二烯基）钛衍生物，双环戊二烯基二水杨酸钛单晶的结构分析表明，水杨酸作为单齿配体通过羧基氧原子与钛键联。     

环状双(环戊二烯基)钛、双(甲基环戊二烯基)钛芳氧基衍生物的合成

在氨基钠存在下,二氯二茂钛或二氯二(甲基环戊二烯基)钛分别与2,2′—二羟基联苯、1,1′—二羟基—2,2′—联萘或间苯二酚等摩尔量反应,得到了四种新的环状有机钛芳氧基衍生物。而间苯二酚与二氯二(甲基环戊二烯基)钛反应,只得到单取代产物。新合成的衍生物都经元素分析、红外、核磁鉴定。     

烯基取代的茂钛族络合物合成及应用于烯烃催化聚合的进展

综述了烯基取代基的茂钛族络合物的合成，取代基上双键的化学反应，以及它们在α－烯烃催化聚合上的最新进展。     

烯基环戊二烯基ⅣB族金属衍生物的合成和1HNMR谱

6,6-二烷基富烯与烯丙基氯化镁发生环外双键的加成反应,形成1,1-二烷基-3-丁烯基环戊二烯基氯化镁,同苯乙炔基钠则和6-位碳上甲基或亚甲基的c:-H反应,环外双键移位得到乙烯基环戊二烯基钠。这些阴离子与ⅣB族金属氯化物反应合成了一系列新的烯基取代环戊二烯基金属衍生物。     

二(甲基环戊二烯基)二氯化钛及某些取代苯氧基衍生物的合成

二(甲基环戊二烯基)二氯化钛[(MeCp)₂TiCl₂](Ⅰ),Wilkinson等人^[1]曾用四氯化钛和甲基环戊二烯基钠反应来制备,产率26％.后来Brantly^[2]用四氯化钛和MeC₅H₄MgCl在乙醚-苯混合溶液中于-70℃反应.以上两种方法不但操作复杂,且条件苛刻,产率低.最近吴绍祖等^[3]用二乙胺作为氯化氢的接受体,四氢呋喃作溶剂,由TiCl₄和甲基环戊二烯直接反应来合成.产率43％.我们采用甲基环戊二烯基锂与TiCl₄反应来合成,产率为63％.     

A chelating beta-diketonate/phenoxide ligand and its coordination behavior toward titanium and scandium

Dibenzoylmethane derivatives with one (L1H2) or both (L2H3, L3H3) benzenes linked at their ortho positions to 4,6-di-tert-butylphenol moieties by two-carbon linkers have been synthesized. The mono-beta-diketone-monophenol ligand L1H2 is metalated by titanium alkoxides to form the homoleptic complex (L1)2Ti and heteroleptic complexes (L1)Ti([OCH2CH2]2NR) (R = H, CH3), and reacts with Cp3Sc to form CpSc(L1). These are the first examples of complexes of a beta-diketonate ligand which is further chelating to a single metal center. Crystallographic analysis of (L1)2Ti indicates that the 10-membered ring allows chelation of the phenoxide with little strain, and both fac and mer geometries are accessible in solution. Protonolysis of the second cyclopentadienyl ring of Cp3Sc appears to take place by an indirect, Cp3Sc-catalyzed pathway.     

The preparation of a substituted titanocene-supported polymer and its application in catalytic reactions

A series of polymer-supported RCpCpTiCl₂ (Cp = η⁵  C₅H₅; RCp=η⁵  RC₅H₄) has been prepared and reduced by i-C₃H₇MgBr in situ, then used as catalysts in hydrogenation of styrene, isomerization of 1,5-cyclooctadiene and 1,5-hexadiene, and reduction of carbonyl compounds. In some cases, the introduction of a polymer ligand on the Cp ring restricts the aggregation of active sites and the formation of the inactive dimer of the titanocene species, and results in an increase of activity. Regeneration of polymer-supported titanocene catalysts was performed and the results are presented and briefly discussed.     

Studies on olefin isomerization catalyzed by transition metals: Part IV. Isomerization of 1,5-cyclooctadiene catalyzed by (R-Cp)2TiCl2/R'MgX systems

The isomerization of 1,5-cyclooctadiene (1,5-COD) to 1,4-COD and 1,3-COD catalyzed by (R-Cp)₂TiCl₂ (Cp = η⁵-C₅H₅)/R'MgX systems was studied. Cp₂TiCl₂/i-C₃H₇MgBr was found to have excellent catalytic activity for the isomerization of 1,5-COD to 1,3-COD at room temperature. The effects of solvent, Ti/Mg ratio, peroxide content in 1,5-COD, substituents on the cyclopentadienyl ligand of (R-Cp)₂TiCl₂, and alkyl groups in the Grignard reagents were examined and a titanium hydride addition-elimination mechanism was proposed.     

Highly efficient redox isomerization of allylic alcohols at ambient temperature catalyzed by novel ruthenium-cyclopentadienyl complexes--new insight into the mechanism

A range of ruthenium cyclopentadienyl (Cp) complexes have been prepared and used for isomerization of allylic alcohols to the corresponding saturated carbonyl compounds. Complexes bearing CO ligands show higher activity than those with PPh3 ligands. The isomerization rate is highly affected by the substituents on the Cp ring. Tetra(phenyl)methyl-substituted catalysts rapidly isomerize allylic alcohols under very mild reaction conditions (ambient temperature) with short reaction times. Substituted allylic alcohols have been isomerized by employing Ru-Cp complexes. A study of the isomerization catalyzed by [Ru(Ph5Cp)(CO)2H] (14) indicates that the isomerization catalyzed by ruthenium hydrides partly follows a different mechanism than that of ruthenium halides activated by KOtBu. Furthermore, the lack of ketone exchange when the isomerization was performed in the presence of an unsaturated ketone (1 equiv), different from that obtained by dehydrogenation of the starting allylic alcohol, supports a mechanism in which the isomerization takes place within the coordination sphere of the ruthenium catalyst.     

Latest News: Reactions of Group 4 Bis(trimethylsilyl)acetylene Metallocene Complexes and Applications of the Obtained Products

Recently published reactions of group 4 metallocene bis(trimethylsilyl)acetylene (btmsa) complexes from the last two years are reviewed. Complexes like Cp’₂Ti(η²-Me₃SiC₂SiMe₃) and Cp₂Zr(py)(η²-Me₃SiC₂SiMe₃) with Cp’ as Cp (cyclopentadienyl) and Cp* (pentamethylcyclopentadienyl) have been considered (py=pyridine). These complexes can liberate a reactive low-valent titanium or zirconium center by dissociation of the ligands and act as ‘‘masked’’ M^II complexes (M=Ti, Zr). They represent excellent sources for the clean generation of the reactive coordinatively and electronically unsaturated complex fragments [Cp’₂M]. This is the reason why they were used for many synthetic and catalytic reactions during the last years. As an update to several review articles on this topic, this contribution provides an update with recent examples of preparative organometallic and organic chemistry of these complexes, acting as reagents for a wide range of coordinating and coupling reactions. In addition, applications and investigations concerning reaction products derived from this chemistry are mentioned, too.     

(Co)polymerization behavior of supported metallocene catalysts. I. Ligand and substituent effect

Ethylene polymerization and its copolymerization with 1‐hexene with a set of supported metallocene catalysts were studied. As a carrier, the complex of magnesium chloride with tetrahydrofuran, which was previously pretreated with a triisobutylaluminium (TIBA), was used. The investigated metallocene compound differs in the metal type (Zr or Ti), the nature of the alkyl substituent in the cyclopentadienyl ring, and the type of ligand (Cp or Ind). The effect of catalyst composition on the anchored metal content, catalyst activity, comonomer reactivity, and polymer properties was investigated. The results obtained with supported catalysts were compared with those obtained with their homogeneous counterparts under the same (co)polymerization conditions. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5562–5570, 2005     

双环戊二烯基二芳氧基钛的酸解反应

本文研究了双环戊二烯基二芳氧基钛于氢卤酸中的酸解反应。证明反应是分步进行的。因反应条件不同可得到二次酸解产物--双环戊二烯基二卤化钛或一次酸解产物--双环戊二烯基芳氧基卤化钛。对影响反应的诸因素进行了讨论。通过上述酸解反应合成了一系列新的双环戊二烯基芳氧基卤化钛,收率较高。由双环戊二烯基芳氧基卤化钛开始,又合成了几个新的Cp₂Ti(OAr)Ar＇及Cp₂Ti(OAr)(OAr＇)类型衍生物。     

Syndiospecific polymerization of styrene with BzCpTiCl3 and methylaluminoxane as cocatalysts

Benzyl cyclopentadienyl titanium trichloride (BzCpTiCl₃) was synthesized from benzyl bromide, cyclopentadienyl lithium, and titanium tetrachloride and used in combination with methylaluminoxane (MAO) for the syndiospecific polymerization of styrene. Kinetic measurements of the polymerization were carried out at different temperatures. The polymerization with BzCpTiCl₃/MAO differs from the polymerization with cyclopentadienyl titanium trichloride in its behavior toward the Al/Ti ratio. In addition, high activities are observed at high Al/Ti ratios. By analyzing the polymerization runs and the physical properties of the polymers with differential scanning calorimetry, ¹³C NMR spectroscopy, wide‐angle X‐ray scattering measurements, and gel permeation chromatography, we found that the phenyl ring coordinates to the titanium atom during polymerization. Other known substitutions of the cyclopentadienyl ring (V. Scholz, Dissertation, University of Hamburg, 1998) in principle influence the polymerization activity. The physical properties of the polymers produced by the catalysts already known are nearly identical. BzCpTiCl₃ is the first catalyst that leads to polystyrene obviously different from the polystyrene produced by other highly active catalysts. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2805–2812, 2001     

Guanidinates as Alternative Ligands for Organometallic Complexes

For decades, ligands such as phosphanes or cyclopentadienyl ring derivatives have dominated Coordination and Organometallic Chemistry. At the same time, alternative compounds have emerged that could compete either for a more practical and accessible synthesis or for greater control of steric and electronic properties. Guanidines, nitrogen-rich compounds, appear as one such potential alternatives as ligands or proligands. In addition to occurring in a plethora of natural compounds, and thus in compounds of pharmacological use, guanidines allow a wide variety of coordination modes to different metal centers along the periodic table, with their monoanionic chelate derivatives being the most common. In this review, we focused on the organometallic chemistry of guanidinato compounds, discussing selected examples of coordination modes, reactivity and uses in catalysis or materials science. We believe that these amazing ligands offer a new promise in Organometallic Chemistry.