High-resolution electron-energy-loss spectroscopy has been used to study the molecular adsorption of nickelocene, Ni(C5H5)2, on Ag(100). Results indicate that at up to one monolayer coverage, nickelocene adsorbs molecularly with its axis approximately perpendicular to the surface. At very high coverages, the molecular axis is not exclusively oriented along the surface normal. This is possibly d...

The first metalated porphyrazinediols 11 have been prepared from (L)-(+)-dimethyl tartrate via conversion into the corresponding dispoke or 2,3-dimethoxy-2,3-butanediyl protected 2,3-dihydroxymaleonitrile, Linstead macrocyclization, transmetalation, and deprotection. Their stability is very dependent on the nature of the metal ion in the cavity of the porphyrazine. Reaction of these porphyrazin...

The super-Brownian motion X % in a super-Brownian medium % constructed in DF96a] is known to be persistent (no loss of expected mass in the longtime behaviour) in dimensions one ((DF96a]) and three ((DF96b]). Here we ll the gap in showing that persistence holds also in the critical dimension two. The key to this result is that in any dimension (d 3); given the catalyst, the variance of the proc...

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 ...

in this study we have tested the ability of a standard dft computational protocol to reproduce the experimentally obtained stereoselectivity of 26 different c2-symmetric zirconocene catalysts active in propylene polymerization. the catalysts were chosen for their relevance in metallocene catalyzed polymerization of propylene. to this end, primary insertion of both si- and re-propylene enantiofa...

beside ziegler-natta and phillips catalysts the development of methylaluminoxane (mao) as cocatalyst incombination with metallocenes or other transition metal complexes for the polymerization of olefins haswidely increased the possibilities in controlling the polymer composition, polymer structure, tacticity and special properties with high precision. these catalysts allow the synthesis of isot...

bis(2-r-ind)zrcl2 (r: h or phenyl) was supported on different types of silica by in situ impregnation method and used for ethylene polymerization. in this method, the step of catalyst loading on support was eliminated and common alkyl aluminum (triisobutylaluminum, tiba) cocatalyst was used instead of expensive methyl aluminiumoxane (mao) cocatalyst in the polymerization. the effect of surface ...