Penta-carbonyl-2κC-chlorido-1κCl-bis-[1(η)-cyclo-penta-dien-yl][μ(2)-oxido(meth-yl)methyl-ene-1:2κO:C]tungsten(0)zirconium(IV).

The title compound, [ZrW(C(5)H(5))(2)(C(2)H(3)O)Cl(CO)(5)] or [W(CO)(5)C(CH(3))OZr(C(5)H(5))(2)Cl], consists of two metal centres, with a (tungsten penta-carbon-yl)oxymethyl-carbene group coordinating as a monodentate ligand to the chloridozirconocene. The two halves of the mol-ecule are related by a crystallographic mirror plane. Delocalization through the Zr-O-C=W unit is indicated by a short Zr-O distance and a nearly linear Zr-O-C angle.

Ethylene trimerisation and tetramerisation catalysts with polar-substituted diphosphinoamine ligands.

Chromium-based catalyst systems with polar-substituted diphosphinoamine ligands are selective for either trimerisation or tetramerisation of ethylene, depending on the position of the polar groups on the aryl rings.

Highly selective chromium-based ethylene trimerisation catalysts with bulky diphosphinoamine ligands.

In situ prepared chromium catalysts containing bulky diphosphinoamine (PNP) ligands, upon activation with MAO, are extremely efficient catalysts for the trimerisation of ethylene to 1-hexene.

Thione complexes of Rh(I): a first comparison with the bonding and catalytic activity of related carbene and imine compounds.

Heterocyclic mono(thione), trans-bis(thione), cis-bis(thione), trans-(carbene-thione), cis-(carbene-thione), trans-(phosphine-thione) and mono(imine) complexes of rhodium(I) have been prepared and fully characterised. Chloro(eta(4)-1,5-cyclooctadiene)(L)rhodium(I)(1a, L = 1,3-diisopropyl-4,5-dimethyl-2,3-dihydro-1H-imidazol-2-thione; 1b L = 1,3,4,5-tetramethyl-2,3-dihydro-1H-imidazol-2-thione) appear as isomers at room temperature due to slow coordination exchange on the S-donor atom. In the three structures determined, the substituent on the sulfur appears syn to Cl.

Ethylene tetramerization: a new route to produce 1-octene in exceptionally high selectivities.

Linear alpha-olefins, such as 1-hexene and 1-octene, are important comonomers in the production of linear low-density polyethylene (LLDPE). The conventional method of producing 1-hexene and 1-octene is by oligomerization of ethylene, which yields a wide spectrum of linear alpha-olefins (LAOs). While there exists several processes for producing 1-hexene via ethylene trimerization, a similar route for the selective production of 1-octene has so far been elusive.