Monoand bis(q-cyclopentadieny1)zirconium complexes show interesting stereochemical features with regard to their use in organometallic and organic synthesis as well as in catalysis. An example is described where the zirconocene unit serves to stabilize a planar tetracoordinate carbon center. Next, various building blocks (a metal carbonyl, an organic carbonyl compound, a conjugated diene, plus ...

Ferrocene and Ruthenocene are dicyclopentadienyl complexes, where the metal (Fe and Ru) is sandwiched between two cyclopentadienyl structures. The paper describes a comparative study of the electronic and geometric structural properties of ferrocene and ruthenocene. The various physical properties (stability, geometry, symmetry etc.) of the two are reviewed to elucidate the differences between ...

EEthylene polymerization catalysts became available in an enormous variety. The challenge in this research is to find catalysts that are able to connect ethylene molecules in such a way that not only linear chains are produced but variations like branched materials that possess very interesting mechanical properties like linear low density polyethylene (LLDPE). In this contribution, three diffe...

Non-bridged half-metallocene dimethyl complexes of group 4 metals 2a-4a with an N-4-methoxyphenyl(iminomethyl)pyrrolyl ligand 1a were synthesized and characterized by NMR spectroscopy and X-ray analysis. Upon activation with [Ph3C][B(C6F5)4], these complexes became active catalysts for the polymerization of 1-hexene. A series of hafnium complexes with various N-substituents on the imine group o...

Models for the likely active catalysts in homogeneous Ziegler-Natta systems have been studied using ab initio quantum chemical methods. We investigated the geometries of the isoelectronic model complexes, X2M-R where X = C1 or Cp = (q5-CsHs); where M = Sc and Ti+ (and also Ti); and where R = H, CH3, or SiH3. The general trend is that the M = Sc compounds strongly prefer a planar configuration, ...

The synthesis of a series of C1-symmetric metallocene complexes rac-[1-(5,6-dialkoxy-2-methyl1-η5-indenyl)-2-(9-η5-fluorenyl)ethane]zirconium dichlorides (alkyl: n-butyl, n-hexyl, n-octyl, ndecyl) is described. These complexes are versatile catalysts in the polymerization of propylene after in situ activation with triisobutylaluminum (TIBA) and Ph3C[B(C6F5)4] in toluene and heptane solution. Al...

A commercial SiO2 modified by the addition of a TiO2 layer on its surface and pore walls offers support for metallocene-based ethylene polymerization catalysts with 35% improved catalytic activity. The effect such modification catalyst particle fragmentation during reactions were assessed. This was performed exposing internal cross-section several Ti/SiO2-based metallocene particles, polymerize...